[MUSIC PLAYING] Stanford University. Picking up from Monday,
OK, so we are now well into our second topic
of the second half, looking at aggression,
competition, cooperation, empathy, all those guys. And we've got the drill down
by now, starting with behavior all the way to the right,
working our way to the left all the way back to evolution,
genetics, blah, blah. Where we left off the
other day was just getting into the first
box worth of what's going on in the brain? What is the neurobiology
of what's occurring seconds before that aggressive act, that
compassionate act, all of that? As we know already, right in
the middle of the limbic system, of course, as we know
already, the amygdala is playing a really
central role, and seeing all the
evidence for it-- lesion studies, stimulation
studies, the bizarre rarer realm of humans who have
had lesions, or stimulation there, accidents, or intentional
psycho surgical interventions, beginning to look at
the amygdala there, and the role that it plays. Now, part of what
becomes relevant there is seeing the
kind of information that the amygdala is getting. And an important
thing to focus on is something that
was mentioned back in the limbic
lecture, the notion we ended with the other
day, the amygdala. OK, so you look at somebody
who has had amygdala damage. And they tend to not be able
to detect fear-evoking faces. They are overly trustful. They are underlie skeptical. They are not taking in
the sort of information we would that leads
us to conclude this is a circumstance
that demands arousal, vigilance, so on. One of the things that was
seen, interesting study that I noted at the
end the other day, was looking at people with
amygdala lesions, Damasio and his group looking at
this, keeping track of where the eyes are looking. When they see another face, they
are not looking with the eyes any or near as much as
everybody else would. They are instead tracking around
all sorts of extraneous parts of the face. Normally, people look
at the eyes a whole lot. And what that winds
up showing is not only is the amygdala playing
a role in deciding this is a fear or
aggression-evoking stimulus, the amygdala is also
on the lookout for it. And what we will see in a little
while is one of the things testosterone does is
make the amygdala better at looking for fear and
anger-evoking faces. So part of what the
amygdala is doing is taking in
sensory information. We touched in the limbic lecture
on one interesting aspect of it. OK, back to that business,
that the limbic strategy of counting the number of
synapses, that strange business about olfaction being
only one synapse away from lots of parts
of the limbic system, including the amygdala
if you were dealing with a [INAUDIBLE],
the olfactory world as being so emotional
for a rodent. For us, we've got something
else interesting happening. And I think I mentioned this. OK, so you've got
the visual system. And what we have
is the usual rule that visual information--
just like auditory, just like tactile--
comes in, and goes by way of a way station along
the way, whose name we won't worry about, and goes
through all these levels of cortical processing,
and [? bio cort ?] people will remember layer one,
doing dots, to lines, to moving lines, all of
that, eventually processing assessment, come up with
an idea that, oh, dear, this is a menacing face. And then let the
amygdala know about this. What was also found
a number of years ago is that there is a shortcut. There is a branch coming off
of this way station called the lateral geniculate. There's a branch coming
off, which then is only one synapse away from the amygdala. What we heard is
that's really useful, in that it can get you
fear-evoking, arousing information that much faster
than going through all this cortical processing. It is a short cut. It is not a one synapse away. But it certainly makes
for fewer synapses. That's a faster
system that we've got in order to
very quickly pick up information that
should be of interest to the amygdala and all
of its fear, anxiety, aggression-type concerns. So that's wonderful. That's terrific
for the amygdala. What I think we
also heard it is it comes with a downside, which is
you send all this information through all these
different steps there because it's doing
all this cortical processing for you. It's figuring out
all the details of the sensory information
you're getting in. This way, it gets to
the amygdala faster. But what gets there
is less accurate. You're more likely
to make a mistake. And that's the whole world of
people reacting really quickly to some peripheral
piece of information, which turns out to be different
than they thought it was. And before they knew
it, they had reacted. This is the cortex sitting
there, still trying to decide, is this a
three-dimensional object or a two-dimensional one? And through this route, you've
already stabbed the individual. This is a very, very clear
trade-off-- faster information, less accurate. And there is, by now,
a lot of evidence to suggest that this
particular pathway is hyper excitable in individuals
with post-traumatic stress disorder, where that
whole world of all sorts of acute sensory stimuli
suddenly fling the person back into where they were when
that happened to them, and without the processing
time to figure out, this isn't exactly the same. In fact, this is a world away
from where that happened. Already, the amygdala
is responding. So these short cuts--
but telling you, one of the things you give
up with the short cuts is the analytical accuracy. OK, so amygdala for that,
amygdala equals fear, equals anxiety,
equals aggression. Isn't that interesting? In a world in which
amygdala is not afraid, there's no aggression,
that whole theme there. The amygdala isn't
always about fear, and aggression, and anxiety. And it's very
informative, the examples where that's not the case. One case, really
interesting syndrome called Williams
syndrome, which we're going to hear a lot about
in the language lecture. Williams syndrome appears to be
a poorly understood imprinted genetic disorder where you
get, among other things, kids who are unbelievably
facile with language and emotional expressivity. This whole world
of Williams kids, it's this fascinating
disorder where you get kids who are basically
borderline retarded in terms of cognitive function. Yet, they have this spectacular
adeptness at language, at reading emotions in other
people, at communicating them. They are famously
affectionate kids amid being very
cognitively impaired. We'll see in the
language lecture, most people think
about Williams syndrome as an interesting example of
the modularity of language control in the cortex. You can have very, very
facile language skills in these individuals who,
nonetheless, are typically in the IQ range of about
70, argument being, we'll see in a couple of weeks,
that there are specialized cortical areas for language. For our purposes,
the interesting thing about Williams kids, and
eventually Williams adults, is they are extremely trustful. They are extremely gregarious. They are incredibly
vulnerable as adults to being taken advantage
of by other people. And what you see with Williams
individuals is you basically cannot evoke amygdala
activation with scary faces. They don't register in
someone with Williams. So there, we see that
this is not universally serving that role. Another example
where there seems to be an exception
until you think about it a little bit, people
with social phobias. What studies have shown
is, show a social phobic any sort of face-- human face--
and their amygdala activates. Oh, that's not telling
us anything informative. It's telling us something
very informative, which is if you have a
severe social phobia, any face is a scary face to you. All faces do that, rather
than only ones communicating certain threatening emotions. Another one that seems
puzzling, but which then makes perfect sense
when you think about it, when you take people with clinical
depression the amygdala doesn't necessarily
activate when you show them a picture
of something frightening. It activates when you show them
a picture of something sad. OK, so now instead of
doing fear and depression, the amygdala does
sadness or something. If you think about
it for a minute, that makes perfect sense. What the amygdala might
very well be doing is responding to whatever it
is that is most ethologically frightening to you-- you as a
species, you as an individual. If you are somebody
who's depressed, the most frightening
thing on Earth is something sad around you, as
more justification for feeling even more depressed, the
amygdala being far more subtle than, oh, here's a scary
predator with a knife coming at me, very much contextual. OK, another thing that the
amygdala is brilliant at, which we will come
back to in more detail, but on a first pass
it is so depressing, is the amygdala is probably
the part of your brain that is best at doing
dichotomizing between us and them-- forming categories
in-group, out-group, and responding to
out-group stimuli. And we will see two things down
the line, probably on Friday. Number one, it is
really, really depressing how readily the
amygdala forms some of these us-them dichotomies,
and the sort of them that it responds to--
really depressing. But also some good
news in there, remarkably subtle social
manipulations that will change the sort
of us-them dichotomies that the amygdala responds to. So stay tuned for that. OK, so shifting
from the amygdala, going to the incredibly
interesting and important frontal cortex. And frontal cortex, obviously,
was doing all sorts of stuff two lectures ago
in the sex lecture, getting you to have
the appropriate context for sexual behavior, getting
to do the harder thing, like leaping over
streams, and head butting with other antlered
beasts if that's part of your mating season. Where the frontal cortex
is particularly involved is this whole world of
regulating appropriate behavior in the context of violence,
aggression, competition, cooperation. Frontal cortex is
incredibly important here. OK, back to the limbic
lecture-- the limbic system is about sub-cortical structures
underneath, things like that. And the cortex is
about the cortex. And we heard in
the limbic lecture, instead what was originally
that heretical view by that neuroanatomist
Nauta saying, actually, the frontal cortex
is part of the limbic system. It should be viewed as such. And over the years since,
it being viewed as, this is the cortical part
of the limbic system. This is the cortical region
that is intensely involved with limbic function,
with emotional function. On an anatomical level,
what we've already seen is just as a first pass, tons
of bidirectional connections, everything in the
limbic system talking to the frontal
cortex, frontal cortex sending projections back
over the limbic system. So anatomically, it's there. So in terms of what it's doing--
the best way to describe what the frontal cortex is
about is when there's a choice between doing something
harder and something easier, and the harder thing is
the better thing to do, it's the thing that makes
you do the harder thing. And we'll see this
plays out in all sorts of domains, the
frontal cortex getting you to do the harder thing. First beginning to see the way
it works in terms of wiring-- OK, here we have
reduced the entire world down to a simplified,
there's two neurons that account for all the easier
things you do in your life. And there's three
neurons that account for all the harder ones. Here, we have some
circumstance where there's a circuit at some
juncture, the easier but less desirable outcome. Behavior is this way,
the harder one that way. And what you see is this has
more inputs then this one. This is obviously some
entire circuit of neurons. And this is highly
simplified, blah, blah. But what we see is the
way it's set up here is that there are more
inputs into this pathway. This is what makes
this neuron easier to activate than this one. There are stronger
inputs into this pathway. This one has only two
axons going to it. This one has three--
yes, simplified. When you look at the wiring
of the frontal cortex, it's sending projections
all over the limbic system, all over motor areas. A characteristic
of the projections is that very rarely are
they very strong projections to any given target area. They're not the sort of
projections where, here's this frontal cortical
neuron that is now dumping all of its axon
terminals into this one neuron down there. It does not exert a
very strong influence over the excitation
of any given neuron. Instead, what it has is a
whole lot of weak but diffuse projections. What is the frontal
cortex doing? It's slowly massaging
the area there. It is giving biasing bits of
de-polarization of excitation. So what we've got here
is-- OK, the numbers are not quite working. But in any case,
what we have here is, here's doing the right
thing that's harder. And it's a lot harder
to get this neuron to do the right
thing that's harder, because there is less of
an input than this pathway. What the frontal
cortex tends to do is have these relatively weak
inputs into all these systems where it makes it a little
bit harder to just fall for this one. It gives more strength
into this pathway. The frontal
projections very rarely are activating on their own. Yes, indeed, we have another
example here of modulating. If and only if this
pathway is already struggling to do
the right thing, the frontal cortex tends
to be able to push it over the top there
to pull it off. Frontal projections as very
diffuse, relatively weak, but biasing towards excitation,
rather than causing it, that tends to be the
thing that it does. What you see in terms of making
sense of frontal function is, as we heard
the other day also, a huge whopping projection
from that nucleus accumbens. You remember ventral
tegmental, nucleus accumbens, this huge dopamine releasing
projection into there. And on a certain level--
you want a totally useless metaphor, but on a certain level
with the dopamine projection is about is-- so here, you've
got the frontal cortex. The frontal cortex,
for a living, makes you do the
harder thing when it's the right thing to do. Dopamine is, in a sense,
the fuel for that activity. Dopamine, the expectation,
the anticipation, the capacity of dopamine to generate
goal-directed behaviors is heavily running
through this pathway. Dopamine is a thing
that's giving, in a sense, the frontal
cortex the energy to just push you over the
edge, and to tell you, yes, go this way instead of
this way, which also intrinsic in this lots and lots of frontal
projections that are inhibitory in that realm. An awful lot of what
frontal cortex is also doing is whispering to
this pathway saying, you really shouldn't do that. You're going to regret it. I know it's tempting right now. Don't do it, don't do it-- this
super ego sort of neuroanatomy there of frontal cortex,
dopamine as very strongly stimulatory in there, the
whole role of dopamine as driving
goal-directed behavior. And that was that critical
business we saw in that study showing you let the monkey
know that it's now entered one of those periods where
if it lever presses, it gets the reward. Oh, I know just how this works--
anticipation, that's great. Up goes dopamine. If you prevent the
dopamine from going up, you don't get the
lever pressing. Dopamine is not just
about anticipation. Dopamine is about driving
the behavior needed to get the reward that
you are anticipating, dopamine as
goal-directed behavior. OK, so what you
begin to see in terms of how this frontal
cortex does this making you do the harder thing,
it's manifest in all sorts of domains. Easiest, most
accessible realm is seeing what it has
to do with cognition, the way in which the
frontal cortex gets you to do the harder thing. What it helps you to do is
organize bits of information in ways that makes it
easier to make sense of. Here is, if you ever find
yourself being borderline demented, and somebody
is giving you a test, this is one of the tests
they're going to give you. So start preparing. This is this
horrifying test called the CVLT-- the California
Verbal Learning Task or some such thing like that. But here's what they do. Some neuropsychologist
sits you down. And says, oh, I'm just
going to tell you something, a list of things here. See if you can remember. Today I went to the market. And I bought one tomato, one
hammer, one box of cereal, one grape, one-- and
goes through a list of 16 of these, one
every second or so. And they finish. And they say. OK, do you happen to remember
what I bought at the market today? Oh my God, it is so stressful. So you manage to get out like
maybe seven of them correct. And the person says,
OK, that's very good. Let's do that again. Today, I went to the market. And I brought one tomato, one
hammer, one box of Cheerios, one box of-- and goes
through this list again, and seeing each time how
many of them you remember, beginning to see your
memory acquisition thing as you're getting closer
and closer to remembering all 16. It's not until you're maybe
in the third or fourth round of doing this that
you begin to notice something, which is of the 16
items four of them are fruits. Four of them are hardware items. Four of them are
bread cereal things. Four of them are who knows what. And they're
scattered throughout. What the people
typically start doing by the third or fourth
one is you begin to group them by categories. And instead of remembering back
OK, tomato, hammer, cereal, fruit, whatever, you first
tell the three out of the four fruits that you remember. Then you tell the two out
of the four hardware items. You are beginning to
group the information. And what that is called
is executive function. Executive organizing
strategy, it is sheer memory systems that are
remembering these 16 factoids. It is executive organizing
that's telling you, do you notice some
patterns there? Don't just remember
it in sequence. Don't try to just
remember it in sequence. Stop for a second. And try to keep track
of the categories, because that's
going to be a better strategy in the long run. That's what the
frontal cortex does. You get someone with
frontal cortical damage, and their capacity to
remember, the learning curve is not all that different
from anyone else. But they never start
doing the grouping. They never start doing what
we might think of as almost cognitive strategizing. Oh, I see a pattern here. And I suspect if I put
the effort into exploiting that pattern, it's going to
make it more productive for me to try to remember things
rather than just trying to do it in sequence. So the frontal cortex
is good for that. Where else do you get
in the cognitive realm the frontal cortex getting
you to do the harder thing? Where you get all
this information in the cognitive realm
is when you study people with frontal damage-- either
people with accidents, or very often older individuals
who have strokes there. There's a very distinctive
type of dementia that takes out the
frontal cortex called frontotemporal dementia. And all sorts of cognitive
tests in those cases showing in the
cognitive realm what happens when you're not
having this going on throughout all the circuitry. One thing that
would be given-- OK, so you sit down this individual. And you say, OK, you
recognize this, don't you? Even though most of you
guys don't by now growing up in the digital era. But this is the face of a clock. And it comes with a little
hand and a big hand. And they point in
informative directions. So you ask the person,
OK, you recognize this. Of course, this is a clock face. Now, where would
you draw the hands if I said the time was 11:10? 11:10, so sit for a minute,
and think about where. And, of course, it's
10 minutes after 11:00. And that's that where
the hands would go. Someone with frontal damage,
instead, would draw the hands at 11 and 10. What are the rest of us doing? We're saying, OK,
the easier thing is to just get gummed
up on the number 11 and the number 10-- wait,
wait, don't do that. Hold on, remember,
10 is a coding for multiples of five
minutes, because that's the way clocks are organized. So 10 is actually two of these. So it's 11:10. 10 is a shorthand for
saying 10 minutes after. And you put your hands
in the right place. Somebody with frontal
damage can't hold off. And they get pulled by
the easiest interpretation of the sound 11:10. They draw the
hands at 11 and 10. So this is what you would see. More examples-- what the
frontal cortex is good at is getting you to
inhibit the easier route when it is a
very well-learned, very well-conditioned one. Here's what you would do. Now you take the
person who you think may have some frontal damage. And you say, OK, here's
a task I want you to do. Starting with December,
tell me the months of the year backwards. What have we all learned
since way back in first grade or whatever? That this is an easy
thing going forward. This is the harder
thing right now. And you will see a person
with frontal damage will say OK, December, November,
October, September, October, November, December. They manage to pull
it off for a while. And then they just slip on the
ice back into the easier way. It is, you normally
have December followed by January, not by November. It takes more work
to do it that way. People with frontal damage,
they have this intrusion. They can't hold off the
over-learned response, the more habitual response. You would then see with
frontal damage something that's termed intrusions. Now you would say to the same
person, OK, that's great. That's great. Now what I want you to do
is start with the number 20 and count backwards. And the person will say, OK, 20,
19, 18, 17, September, October, November, December. And they've slipped back
into the previous task. They don't have the
effort here to say, we've stopped it with
the months already. Now we're doing numbers. Don't slip back into
that month stuff. But, yet, that's
exactly what occurs. You take somebody
with frontal damage. You give them would be
called a verbal fluency test. You say, OK, one minute,
tell me as many words as you could think of starting
with the letter F. Great. Now tell me as many
words as you could think of starting with the
letter M, with the letter P, so on. And you go with the letter
M. And by the fifth word, they're back to words with
F. The previous task intrudes in there. It has trouble
organizing, strategizing, we're done with
the letter F. We're done with doing the months. Concentrate now,
we're doing the letter M. We're doing
numbers backwards. Don't fall for the easy
version of just saying 11:10. This is the stuff the
frontal cortex does. This is what it looks like
when you are getting damage to the frontal cortex. So cognitive aspects
of that-- what's the frontal cortex particularly
good at in the cognitive realm? It is making you work, and work,
and work for a cognitive reward way down the line. And that's the entire world
of all of you guys already gunning for the perfect
GPA that will get you into a good nursing
home someday. That is your frontal cortex
working to your advantage. That's your frontal cortex
doing that, this task of gratification postponement. Do the harder thing. Where am I going to
get the energy for it? It's these frontal
inputs that's just biasing so I could do the harder
pathway rather than the easier. You find this also when you're
doing electrophysiological, when you're recording, you're
sticking in electrodes, and seeing when
neurons are excited. Suppose, for example,
you've got a monkey. And you are recording. You have electrodes both
in the visual cortex and some other ones
in the frontal cortex. And, again, this is one
of those tasks where when the bell sounds--
bells don't beep, when some buzzer beeps, it
means to the monkey, now, OK, every time
the light goes on, you have to press a
lever three times. And you get a reward. That's the rule. Buzzer means we're starting
one of those testing sessions again. Light comes on, hit lever,
light comes on, hit lever. So you record from
the visual cortex. And here's what's happening. This is when the
buzzer comes on saying, oh, we've just started
one of these test periods. And now the light flashes. And the visual cortex
activates each time. What's going on in
the frontal cortex? The second the buzzer goes off,
the frontal cortex activates. And it stays up the whole time. What is the visual
cortex coding for? Individual examples
of this task. What's the frontal
cortex coding for? It's remembering the rule. OK, the buzzer went on. That means-- now,
remember, remember, remember for the next whatever
period of time, get ready. Every time the light
flashes, hit the lever there. The task of the
frontal cortex is to maintain the rule
throughout, transcending the individual examples of it. So you can already
see where we're heading with moral
development in kids, and frontal maturation. And all of that's
going to fit in really well, the frontal cortex
doing stuff like that. What you should begin to notice
is intrinsic in all of this, the frontal cortex is
sending these projections all over the brain. The frontal cortex does not
code for individual examples of rules, but instead maintains
rules for long, long periods. The frontal cortex
works really hard. Frontal cortical neurons have
very high metabolic rates. And a whole world of neurology,
thus, is built around the fact that frontal cortical
neurons are very fragile. They die very readily. All sorts of
neurological disorders damage the frontal cortex
with behavioral changes that go along with that. So you've got the wiring,
the patterning, all of that. But then at some point
you wonder, well, I learn all sorts of rules. Back when I was about
three years old, I learned this rule having
to do with no more diapers. And if you go to the
potty, you get M&Ms. And, in fact, I sort of
have internalized this. And same does that mean the,
you need to go to the bathroom now is internalized that there's
a frontal cortical neuron that got excited when I
was three years old and got toilet trained, and has
been firing ever since then? No, what you see after a while
is the frontal cortical realm of remember. Remember, you go to the bathroom
when you need to do this. Remember, remember, you
say the months forward. Remember all these
sorts of things. At some point, it
becomes automatic. It becomes reflexive. And what is seen
is at that point, the frontal cortex stops
being the area that is active. At some point,
instead, it becomes implicit procedural pathways. It gets stored
elsewhere in the brain. What you see in individuals
with Alzheimer's disease where you get a lot of
damage to the hippocampus and the cortex-- particularly
the frontal cortex-- what you see is all sorts of things
that were learned way back when, and learned enough
to just be habitual, people can still do. You will have somebody who
is demented enough that they cannot tell you what decade it
is, the name of their spouse, the name of their children,
how many children they have, whatever. But this is someone who
still knows how to knit. They learned when they were
seven years old how to knit. And now 80 years later,
they can still do that. This is not the frontal cortex
remembering the knitting rules for the last 70 years or so. This is, it became automatic
and got moved elsewhere. And a whole bizarre
world you see with frontal damage
in individuals with these dementias where
some of the things that become automatic are remarkable,
suggesting that you've got storage capacity in
other places in the brain when you don't
have to consciously think about it, when something
has become so automatic. You go to the bathroom when
you need to void your bladder. OK, we don't have to
think about that anymore. It has now gotten to
a pathway like this. Other brain regions
particularly, the cerebellum, seems to play a
larger role in that. Stay tuned. We are going to be getting
to a very interesting point about moral development in kids. When do certain moral
rules stop having to be coded in the
frontal cortex, and instead become as
habitual as toilet training? We'll see some really
interesting implications of that. OK, so what do you see when
you get frontal damage? You get all these
cognitive problems there, and these problems with doing
the harder but more correct thing cognitively. You see it as well
in terms of doing the harder but more
correct thing in terms of behavior, social behavior. First classic
example of this, they take away your
neurobiology license if you don't mention
this guy at some point. How many of you have
heard to Phineas Gage? How many of you have not
heard of Phineas Gage? OK, time for Phineas Gage. OK, but the ones who
have heard of him, let's all say this in unison. OK, Phineas Gage was the
first identified individual to have massive frontal damage. Phineas Gage was a foreman
on a railroad construction line in Vermont in the 1840s. One day, thanks to somebody or
other doing something wrong, there was an explosion
of some dynamite, which blew a large metal rod
through his forehead and out the other side,
taking out his frontal cortex in the process. And this was rather dramatic. And this was this
large metal pole that went through fast enough
that, in fact, cauterized all the blood vessels. And you can see that metal pole
at the museum in the Harvard Med School Library,
where you can also see his skull, which
is very interesting, because the rest of Phineas
Gage is about 20 miles from here buried in Colma. So I don't quite know
how his skull wound up at that end of the country. But in the either case, he
was buried in San Francisco, minus-- well, I guess the Dean
of Harvard Med School swooped in. And before you knew it,
the skull was on its way east there with the metal rod. But in any case,
OK, so Phineas Gage had his frontal cortex
splattered 15 feet behind him. And what happened
was, amazingly, because it went through
with such force and so fast, that it cauterized
all the blood vessels, he was actually, like, able
to get up at that point. And, most remarkably, with
a bunch of people from work, he was able to walk
a mile and a half to the nearest doctor, who
being a good diagnostician, took a look at Phineas Gage,
and tilted his head back. And looked, and he
said, whoa, you've got a hole there in
your head, and was sort of looking in more
detail, and saying, whoa, you've got frontal cortex
got blown out of your head there. And this was sort of the peak of
diagnostic skills at the time. But what happened was the boss
there on the railroad line said, Gage, you know what? Take the rest of the day off. See you tomorrow. So Gage goes home. And the next day he returns, not
just figuratively but literally transformed overnight. Gage, who was this
sober, sobrietous, religious man, highly reliable
foreman of this entire work place, et cetera. Gage was never able
to work a day steadily for the rest of his life. He became this brawling,
abusive, sexually predatory, out of control individual. And that original doctor,
seeing what he turned into, was the first one
who said, well, whatever that part of the brain
was that got taken out there, whatever it was, that
part of the brain reigns in our animal energies. And 170 years later, there's
not a hugely better definition out there as to what the
frontal cortex is about. So Phineas Gage being
the official first one, and you learn all
about this guy. But very interestingly,
about a year ago somebody found the very first
photograph of Phineas Gage. And go look at that online. What's interesting is he looks
like a perfectly normal guy. The pole took out his eye
along with the frontal cortex. And, obviously, there
was that problem. But this is, like, the face
of somebody from the 1850s. And there's something,
I don't know, I found very moving
about seeing this face that everybody learns
about Phineas Gage. And everybody has seen his
skull, and the reconstruction of the accident. And that's right. This was, like, a
regular old person whose life was
completely destroyed when the frontal
cortex scattered all behind him there--
remarkable first example of that. Since then, most of the evidence
for what frontal cortex is about from damage
is older individuals who have stroke damage
to the frontal cortex. And what I mentioned, I
think, in the limbic lecture, one example of what
this looks like was a horrifying case in a
facility in the East Bay some years ago where
an 80-year-old man who had had extensive frontal
damage due to a stroke was found to have raped
an 80-year-old woman with Alzheimer's disease. This is what frontal damage
looks like in an 80-year-old. Here's something very
interesting to consider, and seeing exactly
the terrain we're heading into here with
this sort of information, approximately 25% of men on
death row in this country have a history of
concussive head trauma to the front of their head. Front of the head,
where you wind up damaging the front of the
brain, frontal cortical damage. And what we enter into
here is this whole realm where this stuff is stupefyingly
relevant to making sense of criminal behavior in
humans-- possibilities of frontal damage. Currently, there
is one law that's on the books in the majority
of states in this country for deciding when somebody is so
organically impaired that they count as having an
insanity defense, rather than being criminally
culpable for their acts. And this is something
called the McNaughton rule. McNaughton rule,
everybody gets taught. What the McNaughton rule
is, can the individual tell the difference
between right and wrong? This is the gold
standard in courts as to whether or not somebody
gets a organically impaired insanity defense ruling or not. McNaughton, whose work was
all of this cutting edge neurobiology was based on,
McNaughton was most probably a paranoid schizophrenic,
a guy in 1840 who attempted to assassinate
the Prime Minister of England, and was so clearly,
clearly psychotic that this was the
first case of the jury formally saying that,
no, there is something too sick about this man to hold
him responsible for his acts. And the clearest thing that
came through in that trial was, he could not
distinguish right from wrong. And the sort of
thing that absolutely does in somebody attempting
to a McNaughton defense in a criminal trial
is if there's evidence that they tried to cover
their tracks afterward, that they were aware that
they had done something which was unacceptable. What you see with
people who can't tell the difference
between right and wrong, there is no evidence
of them trying to cover up their tracks. Where do you see the McNaughton
rule standardly applied? Severe, severe schizophrenics. And, for example, John
Hinckley, the person who tried to assassinate
Reagan in the 1980s, and he was found
innocent-- or guilty with an insanity
defense, because he failed a McNaughton ruling,
severe schizophrenic. So this has been the gold
standard in most of the courts, in most of the states,
in this country. The only way you could
be held not accountable for your criminal actions
because of organic impairment would be if you can't
tell the difference between right and wrong. But then you've got a problem,
because you get people with frontal cortical damage. And they can tell the difference
between right and wrong. They know the rules. They can state them for you. Yet, they can't control
their behaviors. And this comes through
with all sorts of tests. But you could show this now
with people with frontal damage. And, for example, here's the
M&M test that you give them. And what you've got is
something desirable. In this hand, you have
five M&Ms. In this hand, you have one. And the rule is, if the person
reaches for the five M&Ms, you pull your hand away quickly. And they get one
M&M as a reward. If they reach for the one
M&M, you pull your hand away. And you give them five M&Ms. In other words, can they
be disciplined enough to not reach for the
five M&M, and instead hold out and go for one? You get more of a
reward that way. By doing the harder thing,
you will get more of a reward. Extensive frontal
damage, they never, ever, ever are able to
reach for the one M&M. They always get pulled
towards the easier solution-- the easier, more
superficial way. There's five M&Ms.
That's what I want. Instead of being able to
do the executive stepping back, and saying, if I go for a
one right now, I will get five. What is remarkable is you get an
individual with frontal damage. And they will tell
you what the rule is. They will sit there
and say, I know. I know what you're up to. You want me to grab the five. But then I'll only get one. What I need to do is grab the--
and then they go for the five. They can verbalize
the rule right there. They know the difference
between right and wrong. This is not organic impairment
of knowing the rules. This is organic impairment of
being able to follow the rules. And it is extraordinary
what this one feature of what the frontal cortex does,
the difference between knowing that there is a difference,
and being able to activate this pathway
instead of that. This is hugely, hugely
challenging in the courts. At the time that Hinckley
attempted to kill Reagan, every single state
in the country that had a McNaughton
ruling in place-- yeah? So for those people that
just have the damage and know the rules,
would they cover up the tracks in court case so
they would be deemed not worthy of the McNaughton rule? OK, yeah, would fail the
McNaughton ruling, absolutely, because they know the difference
between right and wrong. So they would carry
out the action, then realize it was
wrong, so try and hide it? Yeah, exactly. Or if they're disturbed
enough-- OK, for our purposes, yes, the person will
know the difference between right and wrong. But they still cannot
regulate their behavior. And this is a huge problem. What you wind up seeing
is the McNaughton rule has generally been accepted in
most states in this country. At the time that the Reagan
assassination attempt was made, federal criminal rulings
had McNaughton ruling in it. Almost all the states
had McNaughton. And something, about
10 or 11 of them, also had organic impairment of
volitional control recognizing realms of frontal damage. And what was very
interesting was in the aftermath of Hinckley
being found criminally insane instead of
guilty, there were these neanderthal bellowings
all over the country, editorials everywhere, about how Hinckley
had gotten away with it. Within a month, the
federal government Congress revoked the ability to
have a McNaughton ruling in any federal criminal trial. The vast majority of
states in this country, their legislatures
promptly leapt into action to repeal McNaughton. And along the way, I think
in all but one or two states, the volitional
impairment rulings went down the tubes also. And at this point,
the vast majority of states in this country, you
could have your frontal cortex blown out of the water and
you've got one half neuron still functioning there. And that is not relevant
in a court of law-- an area that desperately,
desperately needs some reform. To give you a sense of how
bizarre this could look, this dissociation
here between knowing the difference between
right and wrong and being able to
regulate your behavior, this is what it would look like
in terms of criminal behavior with frontal cortical damage. And, bizarrely,
this was actually a law case I was involved
with some years ago, where this was an
individual who had just been convicted of his
eighth and ninth murders. And this was a serial murderer. And he was like a nightmare
beyond imagination, what this man was. And this eighth and
ninth one had just been two boys he had abducted,
kept captive for a week, sexually raped, sexually
mutilated, then strangled. And this was number
eight and nine. And he had been brought
out of a maximum security prison in Florida, were
we serving a whole bunch of other life sentences. And this was a case
down in San Diego that he was brought
out for that one. And the defense consisted of
three minutes of the defense attorneys getting up and
saying, yes, he did it. He absolutely did it. This was the defense. So this was now in the
penalty phase deciding, was this person going to
get the death penalty? Or was he going to
get life in prison without the chance for parole? And the relevant
thing about him was when he was six years old he had
had a massive car accident that destroyed his frontal cortex. He spent two months in
a coma, no prior history of anti-social behavior, no
family history of any of it. Came out of it extremely
behaviorally disinhibited. By age 11, he had assaulted his
first individual, first murder by age 13-- a completely
broken machine. Here's what behavior
looks like in somebody with no frontal
cortex in this realm. One of the things he
also did, in addition to his string of murders,
were kidnapping, and rape, and aggravated
assault. And this was one woman who had managed to,
fortunately, survive this. And she'd been abducted
by him, where he took her to his apartment and kept
her there for a week, repeatedly raping her,
beating her senseless, days and days of this going on. And, eventually, whatever it
is that shifted in him shifted. He had, of course, her wallet in
the process of kidnapping her, and seeing her name,
where she lived, he finally says, OK, time to
go, bundles her into his car, and drive her home. And as he lets her out, he
says, I had a really good time. I hope you did too. Here's my phone number. Maybe we can get together again
sometime, and drives away. And no surprise, he was
arrested within an hour or so, and eventually sort of
pinned to a whole bunch of these other ones. This is what it looks like when
you've got no frontal cortex. What's interesting there is
he's obviously made no attempt to cover his tracks. He was able to verbalize
some of these rules, and say it was inappropriate. And he was able even to be told
the specifics of his own case with other names used,
and be able to say, whoa, that's not
something you should do. That against the law. At these junctures, though,
completely going off the rails. He had an interesting
combination, though, which is that there
were some elements of the difference between
right and wrong aspect of it. The fact that he had his frontal
cortex damage so early in life, what you tend to see is
around age 5 or 6 or younger, the person tends to never quite
incorporate the rules either. It's not till you
get-- say, adults who get frontal
damage that you get the absolutely pure dissociation
between this is not OK to do. This is a wrong thing to do. I am not going to do it. And then goes and does it. He, instead, had this much
more mixed case there. When you get the frontal
damage around ages five, or six, or younger,
you get what is now termed acquired sociopothy. You don't do a great
job of incorporating the rules themselves. And you certainly
can't act on it. So this is what it
looks like with someone who is that broken in
this part of the brain. Ironic ending, first
jury was hungry. We got one person to hold
out for organic impairment and give him life
without parole. So that was a mistrial. And second jury went through
the whole thing all over again. And it took them three hours
to give him the death penalty. So what's very
interesting there is, like, 25% of men
on death row have a history of concussive trauma
to their frontal cortex-- really, really interesting. But now we begin to see some
of those if-then clauses. Here's another individual with
a history of frontal damage. And this is a relative of
a close friend of mine. And this was someone who
when he was being born there was a birth complication. And they had to use calipers,
and something slipped, and caused frontal damage. And frontally disinhibited. This is an individual who is now
an adult who is unconstrained by the laws of society. This is an individual who
cannot regulate his behavior. What does he do? Whenever there's
family get-togethers, he plays the piano way
longer than anybody else wants to listen to. He can't pick up the cues
that everybody has had enough and wants to go eat dinner. Well, that was great. I think the pot roast is
getting a little cold by now. Wasn't that great everyone? Wasn't that-- and
just keeps, oh my God. He's out of control. No less frontal damage
than this guy did. So here we have this puzzle. We do not have the simple
machine output there, of, oh, massive frontal
damage, this person is a serial murderer. Massive frontal
damage, this person plays Scott Joplin
for hours and hours until even his grandmother
can't stay in the room anymore. What's the difference? I think we begin to see
some of our if-then clauses perhaps relevant. The Scott Joplin playing one,
upper middle class family, tremendous family support. This guy coming from
a family anything but that, we begin to see the,
if you have no frontal cortex but you have tremendous
amounts of family support, lots of opportunities, blah, blah,
it is going to look different than the massive case of it. OK, so now looking
at that, what we see is there's just a
couple of states and the couple of juries
in this country that could deal with the
implications of somebody having 99% of their
frontal cortex destroyed. All you need to do to see the
problem we're up against is, what happens if
you've got somebody who's got 97% of their frontal
cortex, destroyed or 94%, or 85? Or finally in our realm, where
we all just have different sized ones. And the person next to you
has 5% more synapses there, or 3% fewer re-uptake
pumps, or whatever. That is beginning to get into a
realm that is very challenging. OK, so legal implications
there-- enormous ones, and ones where reform
is desperately needed. This reminds me. Here is an example
which strikes me as historically quite amazing. So we have this
system saying, yes, it is possible to be responsible
for your criminal behavior. But here's this one exception. If you happen to have all
of these neurons destroyed and you're in Oregon, you can
have this criminal defense. And it's effective. Oh yeah, there's this footnote. Every now and then,
something can happen so that you get into a
different category than people who have done
something awful because soul, or evil, or whatever
terms are coming in there. Really interesting
piece of history-- 16th century, during
the period where if you had an epileptic seizure,
you were virtually guaranteed to be burned at the
stake as a witch, because there was a
medical explanation for epilepsy at the time,
which was demonic possession. And you were obviously a
witch of some sort or other. And, OK, so that was the
medical knowledge of the time. And if someone was
accused of a witch in most Western European countries where
the Inquisition was occurring, the rule of the law
at the time was, how do you confirm if
somebody is a witch or not? You read them the story
of the crucifixion. And if they don't cry,
they are obviously a witch. And that was the test. That was the legal test. If somebody was
not moved to tears by the story of Christ
being crucified, they were obviously a witch,
and would very quickly be burned at the stake. At that point, one very,
very progressive physician who was up on the top of
behavioral biology insights at the time wrote a pamphlet
saying, well, yes, of course, we need to get rid of witches
because they're bad news. And of course we
should burn them. And this is very good test. You have to remember,
though, that every now and then in some elderly
women the lacrimal glands can atrophy. So they can't cry. So this would be someone who
is involuntarily unable to cry, rather than they're a witch. You just need to
keep that in mind when you do some of that
witch sentencing stuff. Sometimes it could be due
to this organic impairment business. But the overall structure, yeah,
let's get rid of those witches. And that's a very good
way of getting at it. That makes no sense at all. I suspect ultimately saying that
in a small handful of places, if you have no
frontal cortex at all, we're talking about neurology. If you've got any
frontal cortex, we're talking about morality,
and soul, and even all of that. I suspect it will eventually
make as little sense as lacrimal glands drying up. OK, I'm obviously just
on the edge of tirading. So let's take a
five minute break. And we will continue. Frontal cortex [? of ?]
[? viewers, ?] keeping track of all those different rules,
and keeping you from belching loudly in the
middle of a lecture, and all those other frontal
cortical sort of tasks. What's the time of day when your
frontal cortex is least active? Any guesses? OK, wait somebody
say something clear. Late at night. Late at night,
when late at night? When you're sleeping. When you're sleeping,
when when you're sleeping? REM sleep-- REM sleep,
your frontal cortex basically shuts down entirely. That's why your
dreams make no sense. That's where your
dreams you're doing all sorts of things you would
never want to do in real life. The thing about
the frontal cortex is that it keeps you from doing
and saying the sort of stuff that all of us contemplate
at various times, but we would die if anybody
knew we were thinking that. You wipe out the frontal
cortex, and you do it. Or you take the
frontal cortex offline in the middle of dreaming. And, suddenly, that seems like
a wonderfully prudent thing to be doing with yourself
in the middle of a dream. That's when the frontal
cortex is least active. OK, so now frontal
cortex, looking at one of its most
distinctive, interesting things about its function,
its development. When does it
develop after birth? And I think what I've
already mentioned is the frontal
cortex is interesting because it's the last part of
your brain to fully develop. It is the last part of
your brain to fully form all of the myelin on its axons. It's the last part to get
its full large complement of synapses, and branching
connections, and such. It's the last part of
the brain to develop. When does the frontal cortex, on
the average, completely mature, go online for the first time? Around age 25, which
is astonishing, which among other things
should be reckoned in the context that,
probably, all sorts of you guys still have a whole lot
more myelin to lay down there in the frontal cortex. It is the last part of the
brain to fully develop. Some immediate implications
of that-- if it is the last part of the
brain to develop, it is, by definition, the
part of the brain least constrained by genes. And it is the part of the brain
most sculpted by environment and experience, which is
real interesting, given that it is the most definedly
human part of the brain. So frontal cortical development
in kids-- what we've already heard is by age 5 or
younger, get frontal damage, and you get this
acquired sociopathy. You don't get as clear of a
disassociation between you know what the rules are, you
simply can't carry them out. It's more of a mixed
bag at that point. Frontal development after
that-- the frontal cortex works in a very interesting,
perfectly logical way in teenagers, as follows. When you look at
frontal activity, and the extent to
which it is being driven by dopamine with one
of these brain scanners, take an adult, and
take a teenager. And they each have circumstances
where they're doing some task and they get a reward. And some of the time,
they get a smaller reward than they think they deserve
from the amount of effort they put in. And some of the time, they get
an unexpectedly large reward. Circumstance where the
individual gets a bigger reward than anticipated,
dopamine goes up in adults and drives frontal metabolism
to a certain extent. Dopamine goes up much
higher in the teenager. Now a circumstance where the
task is being carried out. And you don't get the reward. Dopamine goes down in the
adult, frontal metabolism goes down a bit. Dopamine goes down much
more in the teenager. The gyrations are
much more extreme. The dopamine-driven metabolic
changes in the frontal cortex are more dramatically
large for reward, are more dramatically
having the floor fall out under it for lack of
reward, for disappointment. It's a system that is
simply less regulated. And this, this fact that the
frontal cortex is the last maturing part of the brain, had
to do with one of the wisest things the Supreme Court
has done in a long time, which was about 10 years ago,
when they made a ruling that individuals who
are under age 18, when they carry out
a capital crime, you cannot have the death
penalty applied to someone for a crime they did
between ages 16 and 18, because explicitly stated
in the court decision, the brain and the regulatory
areas of the brain are not fully mature at that point--
the most neurologically informed the Supreme Court has
been in a long time. Again, the McNaughton rule--
the McNaughton rule, which is the backbone of the criminal
defense and legal system in this country, is based on
170-year-old neurobiology. So this was a major leap
forward in jurisprudence meets neurobiology in this
country with the Supreme Court ruling. Of course, what
one might ask is, so what exactly happens in
the brain on the morning of your 18th birthday
that now makes it OK to put you to death,
where the science simply doesn't back it? But at least that recognition,
the Supreme Court actually dealing with the fact that
a 17-year-old does not have a normal frontal cortex yet. What else goes on? Thus, by the time you get a
fully online frontal cortex, around age 25 or so, one of
the truly depressing things out the other end of it
is the frontal cortex is the third most vulnerable
brain region to normal aging-- bummer. That is a drag. What that winds up meaning is
you have spectacular impulse control for about
three and a half weeks on your 25th birthday. And it's all
downhill from there. There's a motor system in the
brain called the substantia nigra which loses most of
its neurons with aging. That has something to do
with the tremor of old age, Parkinson's disease. The hippocampus lose substantial
percentage of its neurons with age. That has something to do with
some of the memory problems. Number three on the list
is the frontal cortex. Frontal cortex loses
lots of neurons over the course of aging. And what you see, then,
is all of those tests of cognitive function,
of frontal functioning, they all have to be
age-adjusted because people as they get older have more
trouble doing this, inhibiting the over-learned response,
preventing something from intruding previously. There's fewer of these
projections coming in there. And what does this
begin to explain? This is this whole world
of grandmothers telling you exactly how hideous they
think your new hairdo is. That's the world of disinhibited
80-year-olds speaking. And what has always been
the case in that literature, it has always been interpreted
in a social, psychological maturation framework. By the time you get
to a certain age, you finally accept,
this is who I am. I'm not in middle school anymore
just trying to be popular. If I need to march to
a different drummer, so be it, because I am
at peace with who I am. I accept myself. It's not that. It's the brain damage. It's the brain damage that kicks
in at that point, that being a feature of normative aging. Now, where else do you wind
up seeing abnormalities and frontal function? Other individuals,
individual differences-- one personality
style where you see elevated frontal metabolism. And this is people
with what's called repressive personalities. These are individuals who
are highly regimented, highly disciplined, highly capable
of controlling their behavior. These are individuals who do not
express emotions very readily. They're very bad at reading
emotions in other people. They're not depressed. They're not anxious. In order to be labeled with
a repressive personality, those are rule-outs. You have an extremely
structured life. These are the people
who can tell you everything they're planning to
do for the next three years. And it's already scheduled out. This is the roommate who
always has all the work done three weeks
before the due date. This is the person
who makes you crazy because you wish you could
be half as disciplined as they are. People with
personalities like this, elevated resting metabolism
in the frontal cortex. So which sort of people have
far lower than normal metabolism in the frontal cortex? Any guesses? Shout out. Thrill seekers. Thrill seekers,
yeah-- thrill seekers, it seems to be more at the
dopamine end of things. And the zebra book considers
that at one point in there. When it's more
manifest in, how are you going to pull
off stuff like this, sociopaths have much lower
than normal metabolic rates in the frontal cortex. In fact, in a couple
of weeks there is a guy coming to
give a lecture-- and I'll announce in
here when and where-- who is one of the
people doing the most interesting work with this. What this guy has is a
functional MRI machine on a trailer, which
he drives around from one maximum security
prison to another throughout this country--
really interesting research on violent individuals who
are or aren't sociopathic, decreased frontal metabolism. But now something interesting. You take a sociopath whose
resting metabolic rate in the frontal cortex
is lower than normal. Now you give them a task
which demands a certain degree of frontal function. Not, oh, be a law abiding
citizen in society, but something like the
tell the months of the year backwards as fast as you can go. And what you see is
in order to generate the same level of
performance, they have to activate more
of the frontal cortex than other people do. In other words, under
resting circumstances, there is a hypometabolism
in the frontal cortex. And in the rare, relatively
unemotional circumstances where a sociopath does want to
pull off a lot of regulation of behavior, they've got
to recruit a lot more of the frontal cortex to do it. It takes more work to do. Other aspects of
frontal cortex-- not only are kids not
dealing with a whole lot of frontal cortex. Other species are not
dealing with a whole lot of frontal cortex. Again, humans have more
frontal cortex proportionately than any other species. There is no chimpanzee
on Earth who could master the five
M&M, one M&M task. And that is regularly used as
a test for frontal function on them. Chimps cannot do it because it
is simply too tempting to reach for the five M&Md
because it's right there. Interesting assay of how many
frontal neurons a chimp does have, though, which is now
instead of 5 M&Ms and 1 M&M, five chips of wood
and one chip of wood. Reach for the five chips
of wood, you get one M&M. Reach for the one chip of
wood, you get five M&Ms. Every chimp can do it now. They can all do it now
because they're just looking at these pieces of wood. And they can remember,
that's right. Don't go for the
five pieces of wood. Go for the one piece of wood. When it's chocolate,
though, in front of them, it's smells so great. And how can you expect them
to keep track of the rules? And it's just the five. And before you know it,
they've done the wrong thing. If you take away some
of the viscera of it, if you step back sensorially,
if you substitute this in your face chocolate
for these little bits of wood, chimps on the average have
enough frontal function to be able to pull
that task off. Kids, again, could
never do this. And this is one classic
sort of developmental test. You take a kid. And they're in a room. And you put a marshmallow there. And you say, OK, does
people know this one? OK, so do people
now know this one? OK, so here's what you do. You put the marshmallow there. And you tell the child,
OK, I've got to go out of the room for a little bit. You can have a marshmallow
whenever you want. But if you haven't had it
by the time I come back, you can have two marshmallows. In other words,
how many synapses do you have in your
frontal cortex? Because that is
spectacularly predictive of frontal metabolism
in these kids. How long can they hold out
doing the harder thing that gets more of a reward? What those studies
also were showing is the length of time
a kid could hold out on the marshmallow test
when they're five years old is predictive of SAT
scores many years later, is predictive of all sorts
of aspects of the trajectory of that frontal development. Here's an even better assay
for frontal function in a kid. And this one, I think this
is even more informative than the marshmallow test. Here's what you do. You've got your five-year-old. And you play hide
and seek with them. And the deal is you're
the one who counts first while they go and hide. And what you do is
you finish counting. And then you loudly,
excitedly say, here I come. Here I come. I'm going to get you. Here I come. Oh, where are you? And then they instantly say,
right here under the piano, because they don't have
enough frontal neurons to keep themselves from saying that. They can't stop themselves
from saying, here I am. Here I am, falling for that. Now, they switch. And it's their turn to count. And they count. You count up to 10. And they go 7, 8, 9,
10, 11, 12, 13, 14, because they're so excited
to have discovered recently there's all these numbers, that
why not count all of them off? And they've long forgotten
you're supposed to stop at 10. They can't inhibit
that response. This is what frontal function
looks like in a kid-- so marshmallow tests
and hide and seek tests. How's this, though, for
taking that charming world of five-year-old
regulation and putting it into a much more depressing
developmental context? Studies by now showing at age 5,
already kindergarten-aged kids, there is a relationship between
your socioeconomic status and the thickness of
your frontal cortex and its resting metabolic rate. What's the part
of the brain that has some of the highest
levels of receptors for glucocorticoids? The frontal cortex. What do glucocorticoids
do to the frontal cortex? They atrophy neurons there. So what you are
already seeing is, get yourself an unfortunate,
imprudent decision in terms of which family
you got yourself born into. And be raised with
the stress of poverty. And by age 5, already there
are socioeconomic differences in the size and the activity
of the frontal cortex. And that is, I think, one
of those factoids that should have people rioting
at the barricades in terms of how screwed you are, how
early on in life in the most straight forwardly
neurobiological way by some of these oddities of
experience and bad luck. OK, so looking finally at the
frontal cortex-- one thing to ask at the end of the day
is, so, frontal disinhibition? Why don't you see with people
with massive frontal damage, instead of them becoming
serial murderers, why don't they become like
serial people getting married? Why aren't they serial standing
on street corners giving away their money and announcing
their love to the whole world, and doing equally disinhibited
things in that realm? It's not clear. It's not clear why this is
so much more tightly involved in regulation of stuff
going on in the amygdala. OK, so as implied,
though, by this arrow, it is not one direction
of inputs there. It is bidirectional. What you also see is a lot of
ways in which the amygdala can regulate the frontal cortex. And what you already can
guess is the projection from the frontal cortex to
the amygdala is inhibitory. The projection from the
amygdala to the frontal cortex is inhibitory. The frontal cortex is
trying to get the amygdala to restrain itself. The amygdala is trying
to get the frontal cortex to stop sermonizing at it. And what you wind up seeing
is in rats, in primates, and humans there is
an inverse correlation under resting conditions
between the metabolic level in the amygdala and
the frontal cortex. They move in opposition. And what you see is, what
are the circumstances where, in effect, the amygdala is going
crazy enough to be silencing the frontal cortex? That's the world
in which you are making astonishingly bad
decisions about things during moments of great
duress and arousal that you spend the rest
of your life regretting. That's the world of the amygdala
getting very inaccurate, rapid fire information, and being able
to silence the frontal cortex. And then out comes behavior
that is really unregulated. The frontal cortex and
the amygdala, in a sense, constantly wrestling in
terms of their reciprocity. So what happens when
somebody has learned to be afraid of something? And slowly, over time, they
learn that, in fact, this thing is not fearful? They habituate to this
fear-conditioned response. They habituate to yoking. This buzzer means I'm
going to get a shock. They extinguish the behavior. That's the term given for that. You gradually see the amygdala
activates less and less. Oh, play the buzzer,
play the tone, that you've been conditioned
to associate with a shock. Amygdala goes crazy. No shock this time,
do the buzzer again, no shock, not quite as active. Next time, not quite as active,
and it slowly habituates away. Destroy the frontal
cortex, and the amygdala never habituates to
a learned response, a fear-conditioned response
which is no longer fearful. It can't learn to
stop being afraid-- so another realm of this
reciprocal inhibitory relationship between the
frontal cortex and the amygdala. OK, final bit here in terms
of their interactions-- the easiest way to frame it
is, each inhibits the other. They work reciprocally. There are circumstances, though,
where both the frontal cortex and the amygdala will activate
because all you have to think are of some circumstances
where whatever your cultural conditioning is,
doing the harder thing, which is the right thing, is
also the scarier thing. Just think what it takes to
have somebody blow a whistle. And you leap up over the top
of your trench in World War I. And you're going
to be dead 10 steps into running towards
the other trench line. At some point,
the frontal cortex is, in fact, stimulating
the amygdala very strongly to produce its behaviors. That's showing a circumstance
where that is, indeed, the harder behavior. It is simplifying to say that
they always work in opposition. But as a general rule,
that's happening. OK, what this allows us
do now is step back a bit and now look at another
brain region, one which is in effect
working in opposition to the amygdala in another
realm, which is the septum. And you remember the septum. The hippocampus sends its
loop through the fornix down to that septum thing. In some manner, the septum
inhibits aggression. In the same way that,
simplistically, the amygdala mediates it, the exact
same sort of evidence, lesion studies, stimulation
studies, recording studies. For reasons I don't
fully understand, the septum has never
been really a hot spot for a lot of research. Nonetheless, it, in some
ways, works in opposition to the amygdala. You could now sit with
one of those circuit diagrams of the limbic system
seeing who's connecting to who. And you could see
what sort of wiring there must be for
the septum to try to silence the amygdala, what
the circuitry there would be. Back to that limbic rule,
all these limbic structures are trying to yell
at the hypothalamus and get it to listen to them
and not to the other regions. Another area implicated
in aggression-- the lateral
hypothalamus, subject of a huge amount of research
in the 1960s, people interested in aggression. And then people acted
like ethologists and learned the thing
that we've already talked about a bit in here,
which is, oh, actually the lateral hypothalamus has
nothing to do with aggression. It's got to do with
predatory behavior. When a rat leaps on a
mouse and shreds it, that's not an act of aggression. That's an act of foraging. Oh, lateral hypothalamus, food
acquisition, not aggression. Tons of research in the
'60s went down the tubes when people began
to figure that out. Now flipping to the other
side of all of this stuff rather than the aggression
realm, the empathy realm, the compassionate realm-- where
are the structures coming in? And we already know
one area from the sex lectures that is
pertinent, which is the anterior
cingulate, sitting just behind the frontal cortex. And we already know about some
of the things that it does. Remember, that's the
part of the brain, somebody pokes your finger, it
activates, along with your pain receptor pathways. You watch the finger of your
loved on gets poked with a pin, anterior cingulate
activates as well. That is the part of the brain
where, literally and not just metaphorically, you feel the
pain of other individuals. How is this? Now, a study-- this was done
recently by a guy at Harvard named Josh Green. What he does is he puts people
in brain scanners, functional MRIs. And he gives them one of
the great, horrifying moral decisions that ever
sort of actually occurred in history, which
was the old scenario that and a bunch of people are hiding
from the Nazis who are nearby. And there is a baby with you. And the baby who keeps crying. And it is clear
if the baby keeps crying you are all going
to be caught and killed. Is it OK to smother the child? And this wonderfully
hypothetical, let's write a doctoral
thesis dissertation on this problem
here, was one which was a human sort
of decision that had to be made endless
number of times. What would you do in
that circumstance? And what he shows
in these studies are that people who activate
the anterior cingulate less when they are
contemplating this decision are more likely to reach
the decision that it is OK to smother the child. You see that in these studies,
something about the feeling the pain element,
the empathizing, something about that,
when it is not as extreme, that it is a predictor in these
studies of the individuals who will vote for
the smothering. All of this has given
rise to this view that a lot of what's
happening between the cortex and the limbic system is a
whole lot more complicated than this old dichotomy
between thought and emotion. And the cortex is about thought. And the limbic system
is about emotion. What is clear is, instead,
they are inseparable. This whole notion
brought up already, that Guy Damasio, major figure
in the field, this book of his called Descartes'
Error, where he goes over Descartes' notion
of the separability of thought and emotion, and how in
terms of brain function that is not remotely the case. In some realms,
you can partially separate frontal cortical
function from limbic function. One example of this-- and
this was a classic study done by that same guy, Josh Green. And this was when he was
still a graduate student. It involved making use of
people with a brain scanner with what's apparently
a classic test in, or a classic
puzzle in, philosophy-- the runaway trolley problem. Here's the scenario. There is a trolley
which is somehow broken loose from its brake. It is rolling down
the tracks, where it is going to roll over
there and kill five people. First scenario,
you have a choice. You can pull a lever, which
will cause the trolley to be diverted onto a
different track, where it will kill one person. Is it OK to pull the lever,
saving these five people, and one person getting killed? Second scenario, you
have the option-- you're standing behind
this big beefy person. And you can push him onto the
track, where the trolley will hit them and kill them. But it will stop it from
hitting the five people. Are you willing to kill one
person in order to save five? And something that is shown
in these studies over and over is 75% of people are
willing to pull the lever. 25% of people or so or
willing with their own hands to push somebody onto the track. The math, the logic,
is absolutely equal. But this is always
interpreted as how we make different
sorts of decisions when it is a much more
visceral, in your face, you are going to have to
push this person to his death with your own hands,
versus something as impersonal as
pulling a lever sitting in a cockpit in a military
base in Las Vegas, and killing people on the
other side of the globe. How salient, in your face is it? You get very
different responses. And what Green showed
in his study was, have people contemplating
whether or not to pull the lever, it's the
cortex that's activating-- predominantly frontal cortex. Have people decide whether or
not to push with their hands, it's predominately
limbic activation. Another version of this--
this has been researched by a guy at Dartmouth named
Oliver Goodenough-- again, brain imaging. And he is both a neurobiologist
and also on the law school faculty there. And here's the sort
of study he does. You will see the
equivalency of it. Put people in a scanner. And they've been going
through a mock jury trial. And what they now
receive on the scanner are the judge's
orders to the jury before they go and deliberate. First version, the judge says,
remember what you are here for. You may have your feelings. You may have your feelings about
the person, and what they did, or what they didn't do. But at the end of the day, your
job as a juror now deliberating is simply to decide, was
this law violated or not? This is not for you to decide
if it's a good law or not. This is simply, was
this law broken? Second scenario, the judge
stands there and says, OK, as you go and
deliberate, remember, of course, what the law is. But, remember, at the end of the
day, what is this system about? It is about protecting the
weak from the powerful. And you are a decision
maker at this point-- two totally different. One is rule bound. On is empathy bound. People get the first sets of
rules, cortex is activating. Second set of rules, limbic
system is activating. So those are some domains
where, in fact, they are quite separable. What you see,
though, is that there are all sorts of domains
in which it is a completely ridiculous dichotomy
to make between, oh, pure abstract cognitive
decisions, and these messy, yucky, emotive limbic
sorts of ones-- instead, tremendous amounts of
interactions between the two. One domain where
you see this, which is what happens when
you begin to damage some of these structures? You change the flavor of
the decisions that are made. Get people with frontal damage. And give them the
runaway trolley problem. And they are far more
likely to say, yes, it is OK to push
somebody onto the tracks. They get a far more
utilitarian decision. Equally interesting, and
the same sort of punch line, studies where a technique
that's now just being worked out called transmagnetic
stimulation, were you can
decrease the activity of certain cortical regions for
a couple of minutes at a time. Turn off one sub region of
the frontal cortex in people, in volunteers. And in various game theory
games that they're doing, they become a lot
more utilitarian. They become a lot more selfish. So modulating interactions
between there, cross talk between the two. In some ways the most
interesting demonstration for me of the ways in which
these are not separable, this thought from
emotion stuff, is this really interesting
domain of how the human brain does metaphor. OK, so we get to symbols. We get to abstract things. We get into a world where
we have a legal system where not only can we judge
that somebody has done something wrong to somebody else, if they
have murdered them, or stolen their possessions. But they can be viewed as having
done something transgressive if they've ruined the
reputation of somebody else, if they've stolen the ideas
of somebody else, plagiarism. This is a very abstract
world of judgments we have. These are very symbolic
realms of decision making we are often into. Yet, we have this
problem that we have this very old evolutionary
brain that did not necessarily evolve for doing
symbols and metaphors. And one of the things
you wind of seeing is when the brain
evolved the ability to do some of this more
metaphorical stuff, it had to make use of the
old circuitry that was there. And, thus, what
you wind up seeing is very often when dealing
with extremely abstract issues of decision making,
we treat some of the metaphorical
components as if they were absolutely real. What would be an
example of this? Here's one very cool study
that was done recently. So your body and your
brain is very wired up for doing
temperature regulation. Oh, this is hot. This is cold. These are different
temperatures. There's a whole metric,
in temperature-sensitive receptors. And there's a whole
circuitry thing. And it's going about
the very physical task in the very real world
of telling something about temperature oscillation
of ions, or whatever. Get a hold of this study. Somebody is coming
up through what they believe is some
sort of psych testing that they have volunteered for. They get in the
elevator to go up. And the actual experiment
has started in the elevator. Somebody working on the
experiment comes in. And they're holding a
whole bunch of books, and barely holding on to them. And they're having
a cup of something. And they ask the person,
can you do me a favor? I'm about to drop this. Could you just hold
this cup until we get up to the fourth floor? In one case, the
cup is iced tea. The cup is cold. In the other case, the
cup is warm tea, warm. So the person spends
about 15 seconds holding either this cold
cup or this hot cup. And the person thanks
them afterward. And out they go. And then they are
asked to evaluate the personality of the
person they just interacted with in the elevator. And hold the warm cup,
and you rate the person as having a warmer, more
expressive personality. No, no, no, temperature
we're talking about, like how fast molecules
are oscillating. That's what temperature is. Warmth, that's just a metaphor. They get intermixed. When brains had to invent
dealing with things like how warm of a
personality somebody has, or even something
as nutty as how warm is the color of the
carpeting in this room, where are you going to stuff it? In some way, it
is hijacking some of the far more literal
pathways of storage of information in the brain. Another example-- here
is a wonderful one. We already know that the same
part of the brain, the anterior cingulate that will tell
you that your finger was just poked, is telling you
that somebody else's finger was poked. You are feeling their pain in
the same part of the brain that is doing pain in the
literal sort of way, another case of the brain
kind of mixing metaphor and symbol with the real thing. Here's a particularly
interesting version. Go get yourself exposed
to some totally rotting, smelly carcass, or
inadvertently take a bite into some truly rotten food. And you will have an area
of the brain activate called the insular cortex. And what that does in
every species looked at is it processes foul,
disgusting stimuli-- disgusting spoiled food, or rotten,
smell all of that. That's what the
insular cortex does. And, no doubt, there's
tongue receptors telling you bacterial loads, or acidity
of this rotten food, or some such thing. And that's what this
part of the brain does. Now, sit down a person. And tell them a story of
somebody being totally, totally mistreated by somebody powerful,
and some completely exploited of horrible circumstance. And the insular
cortex will activate. Have somebody play some
game with somebody else, one of the prisoner's
dilemma type games, where the person
totally stabs him in the back, the person
they're playing against. And gets away with it, and
make a really exploitative, rotten gesture. And the insular
cortex activates. Sit somebody down and
say in the control group, tell me about some
event that happened when you were growing up. Versus the experimental
group, tell me about a time when you were growing up that
you did something really awful to somebody else. And the person describes
that circumstance. And the insular
cortex activates. What does this part
of the brain do? It's saying, oh, yes, this
food is full of maggots and does not taste very well. But it also does moral disgust. When you are feeling
disgusted with how someone has been treated, when how you
have been treated it activates. When you are having
moral self-disgust recounting something
awful you did to somebody, this part of the
brain activates. My God, don't they realize
up there this is a metaphor? You're not really
eating rotten food. And every language on
Earth has words referring to moral failures
with words denoting gustatory, repellent stimuli. I am disgusted by what you did. The fact that they did
this, when I hear about what they did, it makes me nauseous. Something about
this smells rotten. Every culture has
terms that intermixes literal sensory disgust
with moral disgust. And what that's telling you
is that when humans came up with something as fancy
as moral transgressions, where are you going to
stick the sense of outrage you feel when there is
a moral transgression? I know. Let's hijack the part
of the brain that tells you you're eating
some rotten food, shoehorning into there. Now what you see is
it is possible for us to begin to confuse on which
level those areas are working. Another study, amazing
one a couple of years ago-- here's what was
done in the study. You take people. And you put them
through their paces of either telling me
something wonderful you did when you
were a kid, something neutral, or some moral
transgression you once had. Tell me all about it. And then afterward,
saying, well, thanks for
participating in this. And tell you what? We can't pay you. But we can either
give you this pen set. Or we can give you
this nice flash drive. Or we can give you this little
soap set of scented soaps, or whatever. And have people talk about
their moral failings, and they're more likely to
choose the soap afterward. People want to wash their
hands of their sins. And starting with [? pilot ?]
washing his hands of whatever, this is in intermixing of
metaphor with reality, showing how clearly this was the case. Now what they next did in the
study was have people wallow in recounting something awful
they had done to somebody else. And then they were allowed
to go to the bathroom. And I don't quite
remember how they did this, if they had cameras
in the bathroom, which I kind of suspect they didn't, or if
they weighed the soap afterward or something. But people who had just gone
through the moral transgression recounting were much more
likely to go in the bathroom and washed their
hands at that point. But now what they
had were people who had done the moral
transgression recounting. Either they were
given the opportunity to wash their hands
afterward of it. Or they were not
given the opportunity. Now sitting in the
test room, what happens is the staged thing. One of the people
working on the project comes in holding a
whole bunch of books, and accidentally drops them. And a bunch of pencils
scattered all over the floor. If you were allowed to wash your
hands of your metaphorical sins in the previous few minutes,
what they showed was you were less likely to
jump up and help the person. People translating
a sense of being morally soiled into being an
imperative of helping somebody else. Let somebody go wash their hands
of recounting the awful thing they did to somebody
else, and they're less likely to help
people afterward. What I think we're
seeing here is this amazing intertwining
of doing some of our most abstract judgments, and
decision making, and decisions about behaviors or not
where we just got these old, ancient, mammalian brains
that those rotten food, doesn't do rotten ethics. You've got the systems confused. What this begins to speak to is
work by very prominent person in the field, a guy University
of Virginia Jonathan Haight, whose work emphasizes just how
much moral decision making is not decision making, how much
it is affective decisions, showing first with brain imaging
how often you are getting the affective, the limbic,
the disgusted cortical levels of response before you
have the decision making. Argument being,
there it is affect driving the decision making,
rather than the other way around. But what he also points
out is the frequency you give people
scenarios-- and he's doing really interesting
work with this-- where you give somebody a
scenario where it just strikes you as wrong. Here are three of
the ones that he uses very often in the studies. First one, you describe
a pair of siblings. They are grown up. They are post-reproductive. She has gone through menopause. He's had a vasectomy, whatever. And they are in love, and not
in the platonic sibling way. And they want to have a sexual
incestuous relationship. Is it OK for them to do
it completely in private? Second scenario-- your
elderly grandmother says it is absolutely fine with
her to slap her in the face right now. Do you feel like it is OK to do? Third scenario, one
that he brings up having to do with burning
a flag and stomping on it, something laden with symbolism,
but at the end of the day is nothing more than
just some cloth. Another one he brings
up is, you're hungry. Your pet has just died. Why not cut him up and eat him? And in all these cases, what you
have is exactly the responses all of you just had in there. And these insular,
cortical neurons are popping out of people's
ears all over this room. And then what he does is say,
well, what's wrong with that? And people really
have a hard time giving a rational explanation,
this whole framework that he has developed, which
most of the imaging research agrees with, that people make
their affective decisions long before their more
cognitive ones. The cognitive ones are catching
up afterward trying to figure out, well, why is it so
important that you cannot step on some cloth that has
this pattern on it? But it's OK to step on
the cloth with-- why is that something worth
putting people in jail for? It just doesn't feel right. And I think what
that has much to do with is how much of the
coding of the abstract stuff has to be stuffed into ancient
brain pathways that's telling you about very cold
things, instead of cold personalities,
very disgusting foods rather than
disgusting moral acts. We are dealing with a very
ancient brain, and one that's not very good yet at
separating the limbic world from a more cortical one. OK, couple more pieces
of this-- final piece in terms of making sense of the
neurobiology, which is now you look at parts of the
brain when somebody is committing an aggressive act. And you show neurons
get activated there. Well, that's kind
of interesting, all sorts of hypothalamus
nuclei, mid-brain, brain stem, those reptilian parts of the
brain from the other day. You see that happening. You say, well, someone
does something aggressive. And they activate. That seems to be interesting. That seems to be pertinent. And it winds up being not
pertinent in the slightest, because what you see is those
are the same neurons that would activate if you are
running for your life. Those are the same
neurons that would activate if you were running
joyfully to meet someone. Those are neurons
that are just doing the nuts and bolts sympathetic
nervous system stuff. If you were running
for your life, or if you were running
towards someone you love, and those are totally
different emotional states, nonetheless your heart
has to be beating faster. And your diaphragm has to be
doing something different. These are nonspecific
pathways of activation in the sympathetic
nervous system. As has been stated, if you are
recording from some of these sympathetic nuclei
in the mid-brain, if you were recording from them,
you cannot tell the difference whether a person has just
murdered someone or just had an orgasm. In both of those
cases, neurons have to be doing very similar things. There's a whole realm of
non-specificity to arousal. And this brings up a
really important quote, and one that I think will run
through all of these aggression sections here, a quote
from Elie Wiesel, concentration camp survivor,
Nobel Laureate for his writing, Elie Wiesel,
extraordinary man, who has this famous quote,
which goes as follows. The opposite of
love is not hate. The opposite of love
is indifference. And the way that he
uses it is in sort of a historical framework. The opposite of
love is not hate. The greatest harm
you can do to someone who has been a
victim of something is to be indifferent
to their history, to deny that it has happened,
to see it not be an imperative to make sure it never
happens to anyone else again, et cetera, et cetera. The opposite of hate
is indifference. Applied to physiology here,
it is absolutely the case. When you look at what the
sympathetic nervous system is doing, when you look at
some of the stress hormones, love and hate are not
opposites in the slightest. They are physiologically
very, very similar. What I think that
also tells you is how readily some humans
psychopathologically can confuse the two states. When you look at
some of these brain stem hindbrain spinal
areas during these acts, love and hate are not opposites. They are very related
to each other. OK, jumping forward in the last
couple of minutes, what we now have is looking at
what hormones are doing to this-- hormones in terms
of the short-term hormonal environment, not early in
life, the short-term hormonal environment. And what we have to deal
with, of course, instantly if we're going to
bring up hormones is, so what's the deal
with testosterone? What does testosterone
have to do with aggression? Why is it that in virtually
every species out there, males are more aggressive
than females, males have more testosterone than females do? All you need to do to make
sense of this whole section here is take everything
from last week concerning testosterone and sexual
behavior and just substitute aggressive
behavior for sexual behavior. It's the same exact rules. Yes, testosterone is required
for the full expression of aggressive behavior
in males of most species. How do you tell? Subtract it out, the
castration stuff. After castration, do levels
of aggression go down to zero? No, same thing as last
week, the more prior experience one has
being aggressive, the less of a drop
in aggression there is after testosterone
levels are removed. Put back 100% the normal levels,
aggression is reinstated. Put back 10% the normal levels,
reinstated to the same extent, 200%, same extent, same
exact rule-- testosterone is needed for the normal
expression of behavior. But it is not necessary
or sufficient. And your brain,
your limbic system, can't tell the
difference between moderate, medium, and very
high levels of testosterone. There is no way you could
look at an individual's testosterone levels,
and because it's two units higher than
it was last week, or higher than the person
sitting next to them, to make any sort of prediction about who
is going to be more aggressive. When you see a correlation
between the levels of aggression and
levels of testosterone, it's the behavior driving the
testosterone, not the other way around. How does this translate
into physiology? Here's one example of
this in terms of studies. Take five rhesus monkey
males-- and this was a classic study that was done. Put them together, and they
form a dominance hierarchy. Number run beats
two through five, number two beats three
through five, so on. Take number three and pump
him up with testosterone. Pump him up with insane
amounts of testosterone. And what you will see is he will
now be involved in more fights. Does that mean that number
three is now threatening number two and number one? Absolutely not, what's
going on, number three is being a nightmare to
numbers four and five. Is testosterone
changing the structure of aggression in this group? No, it's exaggerating the
pre-existing social structure. What testosterone
does is modulate. It amplifies. It does not turn on a
radio of aggressive music. It increases the
volume if and only if it is already turned on. What does this look like
in terms of the biology, getting down to the
neurobiology level? That whole business,
raise testosterone levels, and the amygdala gets
a lower threshold for deciding that a
face looks threatening. Put somebody in a brain
scanner, and flashing up subliminal faces, and it takes
less of a scary face, one that would be border line higher
testosterone levels in someone, amygdala activates more. How would this look like
on a cellular level? Back, remember,
with that business about action potentials, the
neuron has an action potential. And then for a while afterward,
it enters a refractory period. It is silent for
a while afterward. What does testosterone do on
the level of single neurons in the amygdala? It shortens the
refractory period. It makes it possible
for the neurons to fire more times
per unit time, thus asking the
question, what does testosterone do to
electrical activity in neurons and the amygdala? It does nothing. If and only if the neurons
are already excited, testosterone will increase
the numbers of them. Testosterone does not cause. It amplifies. And what it mostly amplifies is
preexisting social structures. OK, you noticed
there that I was also being very careful in
saying on the average, males are more aggressive than
females in all sorts of species out there. On the average, males have
higher testosterone levels than females do. The one great exception
to this, which is briefly touched on in the
zebra book, which is one of the great topics
in all of endocrinology these days, is spotted hyenas. Hyenas are weird animals. Hyenas have a totally
different worldview thanks to a bizarre neurobiology. Among spotted hyenas, females
are dominant to males. Females are bigger than males. Females are more
muscular than males. Females are more
aggressive than males. Females have higher testosterone
levels than males do. And you look at the
private parts of a hyena, and you cannot tell
who is which sex. Female hyenas have
androgenization. They have enlarged clitoris's
the size of penises in males. They have something that looks
like a scrotum, which turns out to be compacted fat cells that
form these scrotum-like things. And they look just
like the males. And over the years as
part of my field work, I spent some years sharing
camp with a guy who is without question the world's expert
on, like, hyena clitoris's. And this guy would bring
in some anesthetized hyena. And he would have to
look at this thing for 15 minutes with like
calipers, and like night viewing goggles and stuff to
finally decide its gender. Hyenas are this very interesting
case of a sex reversal androgenization. Females producing
very high levels of androgens in their ovaries. And you've got this
sex reversal system with the following thing, unlike
in most species of carnivores. What happens in the
lions, for example, males eat first, followed by
females, followed by cubs. Most lion cubs starve to death
in the first year of life. Among hyenas because of
the sex reversal system, cubs eat first, followed by
females, followed by males. The kids survive that
way, a wonderful mutation in terms of doing that. And what you get as a
result is, unavoidably, you get a masculinization of the
genitalia in the females. And what you wind up doing
is it winds up having a different signaling purpose. In most species, what
happens among male primates, for example when
males are trying to display their dominance,
they get an erection and wave their penis, and
look how tough and scary I am. And that's due to
a certain wiring of the autonomic nervous system. In hyenas, it works
just the opposite. Males get erections
when they're terrified, because you think about it. Males are lower
ranking than females. Females spend all their
time ripping off the males who have just hunted something. Females terrorize the males. So you're some
male sitting there. And here comes this
terrifying female. What do you do? You say, don't hurt me. I'm one of these males. I'm not threatening,
or whatever. In males, what you get
is you get erections when you are under stress
as a subordination gesture. What do females do? Low ranking females
get clitoral erections when they are being threatened
by high ranking females, a total sex reversal system. So hyenas can either
wind up telling you, we are breaking out of
these stereotypical role gender expectations, in that
you can have a species where females are dominant, and more
muscular, and more aggressive. But at the end of the
day, they are like that because they are even
more hormonally like males than males are. Final amazing thing
about them-- and this is a story of this
friend of mine, this guy who's been studying
hyenas for 30 years. And he's incredibly
knowledgeable about hyenas. And this was
something that really makes you stunned at
what sort of people there are in the government
thinking about things here. So one day-- he's from Berkeley. One day, he's in
his office there. And he gets a call. And it's from some army colonel. And the army colonel says,
oh, we're having a conference. And we're having a whole bunch
of carnivore biologists coming to it. We're going to
have a great time. We're having this conference
of carnivore biologists. And we want you to come to it. My friend says, um,
you're from the army? What are you talking about? Do you know what I study? And the guy proceeds to show him
that he knows exactly what he studies, and what his
social security number is, and how many, like, cavities he
has, and how much unpaid taxes. And he says, so all of
America's carnivore biologists are coming to this meeting. So come to this meeting. We're going to
have a great time. It's going to be at
this hotel in Arizona. Come, you're going to
have a terrific guy. So my friend decides, why not? And goes to this, and
winds up in this place. And here's this
conference with all of America's
carnivore biologists, and these three army
colonels sitting in the back with
these sunglasses on. So all the carnivore biologists
are fairly confused about what's up here. But, nonetheless, they
sort of settle down. And they start doing
their scientist thing, giving talks to each other. And the Army guys are
sitting in the back there. And there's two days
worth of them just sitting in the back saying nothing. And, finally, all the
carnival biologists get all upset, and say, what
are you guys doing here? What are we doing
at a conference paid for by the US Military? And they finally say, OK,
OK, you're such great guys. We're going to tell you actually
what we're really up to here. You know, we're
from the military. We're actually from
the tank corps. And what we have is we're
designing these new walker things. Do you remember in the Star
Wars movie, in the second one, they had those machines that
looked like the elephants that could walk and all of that? Well, we want to build them. In order to build
them, we have to know how animals locomote, locomate,
how they move, how they walk. And you guys study carnivores. And carnivores run around a lot. So we want to hear you guys. Tell us how your animals
move when they're doing things like hunting. And America's carnivore
biologists listen to this, and say, this makes
no sense at all. You want to learn about
locomotion in animals. You get bioengineering people. You don't get zoologists. What's going on here? So all of America's
carnivore biologists proceed to go and sort of
huddle there, and decide they're going on strike. They are not going to
give any more talks until people explain what's up. They eat all the donuts that
are left, go to the bar, start drinking. And they're going to
refuse to have anything to do until these
colonels explain what's actually going on. So the colonels, obviously,
need to get on the phone to Washington, and call
up, and get permission. They come back and say, OK,
OK, because you guys are all our best friends, we're going
to tell you what's really going. We're really not making
Star Wars walkers. Here's what we're really doing. We're from the tank corps. And we've built this
new tank recently and it was what was
called the Sherman tank. And apparently for
all of history, what you do if you're in the
tank corps, is what you do is you just bash the
hell out of everything, and drive your tank
to the highest spot around, and just shoot
anything that moves. But the Sherman tank apparently
was like the greatest tank that had ever been built. It could drive like
60 miles an hour. And it could fire missiles when
it was bouncing upside down out of ditches, and
gyroscopic this and that. And it was the greatest,
most mobile tank. And they were having
a problem, which was they would put in
their tank corps in there. And what they would do was bash
the hell out of everything, and drive to the highest
spot around, and just shoot anything that moved. So the US Army Corps
decided that they needed to teach their troops,
their army, their tank corps, how to hunt like carnivores. And, thus, here they
invited all of America's carnivore biologists
to come in and teach us how to teach our tank crews
how to hunt like carnivores. How do you figure
out who's going to cut corners on the prey? How do you communicate if you're
out of sight with each other? What do your hyenas do? What do your wolves do? What do your coyotes do? So at that point, like, all of
America's carnivore biologists say, whoa, we are way
in over our heads here. So a third of them
instantly march out shouting about Ho Chi
Minh or whatever, given the age group of most of
America's carnivore biologists. And the rest of
them huddle there. And they come back. And they say, well,
these are very difficult questions to answer. So the military guys say,
well, yes we will give you money for your research. So at that point, all of
America's carnivore biologists decide they're now best friends
with these Army Corps guys. They go through the rest of
the conference telling them all about the hunting
techniques of their animals, and with careful instructions
as to who to submit grants to. They all immediately go back to
the universities, write grants. My friend writes this grant
for like four Sherman tanks, and night viewing goggles
for like a Death Star and flamethrowers for his
hyenas, and all of that. All of America's
carnivore biologists send in their grant proposals
to this PO Box at the Pentagon. And nobody has ever heard from
any of these Army guys again. And this was about 15 years ago. And to this day,
none of them know what were these people
really trying to find out from us at this meeting? This was this totally
bizarre incident showing that somebody or
other in the tank corps is sitting around
trying to figure out what it is that the coyotes,
and marmots, and hyenas do. For more, please visit
us at Stanford.edu.
man I love his lectures
Thanks for reminding me to continue watching his lecture. He's so great at them.