Neurophilosophy – Patricia Churchland

neural philosophy is kind of at the interface between neuroscience on the one hand and those grand old questions that have worried philosophers for a long time so the idea is that because science has developed so much and because neuroscience is really beginning to develop in rather extraordinary ways the idea was that there would be things from neuroscience particular kinds of discoveries that would help us understand things about the nature of the mind and on the assumption that our mental states and our capacity for learning and remembering for seeing for thinking that all of these are functions of the physical brain the idea really they're motivated neuro philosophy was that we will understand those functions much more deeply once discoveries are made in neuroscience that bear upon them and this is kind of turned out to be so so let me give you an example of what in the early days kind of motivated me to think that to understand the mind you need to understand the brain so the discovery that really motivated me I think was the discovery made in California a Caltech that in human patients who were treated for epilepsy surgically a very remarkable result was observed these are known as the split brain patients so they were epileptic but their epilepsy could not be treated by drugs so what happened was surgeons suggested that if you separated the two cerebral hemispheres let the right from the left that this might have the good effect for the patient of controlling the seizure so what they did was they separated the two phears bicep by cutting the nerve sheet that normally in us connects the two hemispheres and that keeps information on this side sent to information on this side and vice versa the deeper structures were not of course split so it was really just at this upper level where the cortex connects the result was that in a way consciousness was split consciousness itself which we think of as a very special kind of mental state was separated so that the things that the right hemisphere could see and was aware of were different from the things that the left hemisphere could see and be aware of and one of the surgeons Joe bogan tells the story of the very early post surgical days of one of the patients so the patient was a man who was sitting in a chair his right hand picked up a newspaper and the left hand put it down and the right hand picked up the newspaper and the left hand put it down and this was this was a transitory sort of disconnection effect but it showed that at least for a brief time these two hemispheres were behaving and controlling the body behavior in quite different ways and this result made me think a time that this was really a very new way of thinking about mental processes such as consciousness and strongly implied that consciousness is really a function of the physical brain itself but since the discovery of made by those working on split brain subjects and of course Michael Gazzaniga has written very extensively and very interestingly about these subjects since that time there have been many many other discoveries that have had an impact on how we think about the nature of learning and memory for example so again an early result which then launched a long long and very wonderful and very rich program of research involved again a human patient who on both sides of his brain lost certain structures related to the hippocampus and the hippocampus is quite deep but it sort of lives within the temporal lobe on each side and then the hippocampus and related structures in this patient were taken away and we learned a lot from this patient namely that the hippocampus is really really crucial for learning new things and we also learned then from rodent studies that the hippocampus is essential for spatial learning and we see now for example in a raft that if rat is allowed to wander around a room that very specific cells in the hippocampus always respawn whenever it's in one place another cell responds when it's in a different place and so forth and if the rat learns to navigate a maze for food one of the things you will also see is that when the rat rests it rehearses and you can see this from the electrical activity in the hippocampus that when the rat is resting it rehearses or replays or replan its route through the maze and I think it's a very striking result for two reasons it tells us about the nature of representations that the rat has a representation of its spatial world which is kind of like a map and it also tells us that the rat offline can replay a rehearse or as you might say can imagine its route through the spatial world so these are the kinds of discoveries that have told us really deep and interesting things that bear upon human representation upon human consciousness also and I think these are the kinds of examples where neuro philosophy that is to say philosophical questions and neuroscience questions have really intermeshed of course there have been many many discoveries in neuroscience and it's important to kind of realize that they happen at many different levels of organisations so there we can think of the level of molecules as being the deepest sort of level where we think that certain molecules can have a very important effect on learning and memory on reward on feelings of pleasure on feelings of connectedness to other people so the let the molecular level is very important and through manipulations and experiments we can see that but the level of the synapse where we can see that the connecting structure between nerve cells can change can in some cases deteriorate in some cases be pruned back and in some cases can flourish and we know that now that this has a really important role in the embodiments of information itself and above the level of the synapse is the whole neuron and many important discoveries had to be made about the nature of the neuron itself before we could really understand how the brain as a whole is organized and how the brain might solve certain kinds of problems like how to touch my nose or how to see in depth above the level of the neuron or circuits where groups of neurons are connected to each other and in some tasks are highly connected to each other and another tasks less so and part of the challenge facing neuroscience right now is how to access all of the elements in the neural kept in order to really understand how a neural circuit can work so how it can work so that when I ask you a question like did you ever fall off your bicycle you can immediately answer how does that happen well to answer those kinds of questions we really need to understand the circuit level but above the circuit level there are are levels of organization having to do with whole systems like the whole visual system or the whole system for smell or for taste and these systems also have been explored in quite a lot of detail but we don't yet have a picture that sort of puts it all together we have fragments and really important components of the story but there are many many fundamental unanswered questions in neuroscience and so that means that four really fundamental issues about the nature of the brain such as precisely what governs development or why is it that as humans and probably rodents and other and primates - as they enter adolescence there is a large pruning back of synapses and the question really has been why does that happen and what is achieved in the pruning back there's really extensive pruning back that we see in human adolescence and a related question is what happens if there is insufficient pruning back or if the pruning back the neuronal circuits and the structures that make up the neuronal circuits what happens if the pruning back is different from the normal case and one interesting hypothesis but let me say it's only a conjecture at this point is that it may be related to schizophrenia as you know schizophrenia is its onset is in late adolescence and early adulthood it's not a we don't see Timms by and large we don't see symptoms in childhood but it begins to happen a little while after this normal period where we see pruning back and so what conjecture has been that schizophrenia might be related in some way to pruning back that is either insufficient or that is disorganized or that fails to achieve the kind of streamlining that we think happens in normal pruning back so I mentioned that only to illustrate that there are really really important connections between research and neuroscience and these tremendously important issues in medicine such as what is the underlying cause of schizophrenia what might we do in order to be able to stop it but also related questions about Alzheimer's disease for example but there are something like 600 diseases of the nervous system all of them terrible and for none of which do we have really an adequate understanding that will allow us to intervene and prevent or to cure so I think that's a really important aspect of neuroscience but of course we also think that discoveries about how the brain can be so amazing how it can its elements can be so much slower than the elements of a computer by a factor of a thousandfold and yet we can do things much faster so we know that there's a lot of parallel processing and the idea that a parallel machine with the kind of organization of nervous systems might be amazingly efficient much more so than the kind of conventional computers that are pretty darn amazing in themselves so there may be tremendous technological spin-offs also from neuroscience and this is a reason that has motivated many governments to invest very heavily in neuroscience not just for health reasons not just because the questions are scientifically so exciting but also because it may open the door to conceptually very very new ways of computing and doing the kinds of things that we would like machines to have the flexibility and the complexity in order to be able to do

Channel: Serious Science

Views: 21,698

Rating: 4.8867927 out of 5

Keywords: science, lecture, Serious Science, neurophilosophy, brain, research, thinking, psychology, neuron

Id: U8epdBqRvPU

Length: 14min 5sec (845 seconds)

Published: Wed Jul 29 2015

Reddit Comments

[u/[deleted]]

Can't watch it yet, but just going by the title it's an interesting question.

I took a class called consciousness and machines, and I noticed the only other neuro student and I disagreed with the rest of the class (Comp Sci students) a fair amount. This happened in a lot of topics, stuff like qualia, what constitutes self-awareness, etc.

[u/Dirkef88]

Experiments with split-brain patients are truely some of the most interesting that I've read, and challenged many of my early assumptions about the mind and self-identity. Here is a great summary article about some of those early experiments and their implications. And an excerpt from that article:

On stage last May, delivering a keynote address at the Society of Neurological Surgeons' annual meeting in Portland, Oregon, Gazzaniga showed a few grainy film clips from a 1976 experiment with patient P.S., who was only 13 or 14 at the time. The scientists wanted to see his response if only his right hemisphere saw written words. In Gazzaniga's video, the boy is asked: who is your favourite girlfriend, with the word girlfriend flashed only to the right hemisphere. As predicted, the boy can't respond verbally. He shrugs and shakes his head, indicating that he doesn't see any word, as had been the case with W.J.. But then he giggles. It's one of those tell-tale teen giggles — a soundtrack to a blush. His right hemisphere has seen the message, but the verbal left-hemisphere remains unaware. Then, using his left hand, the boy slowly selects three Scrabble tiles from the assortment in front of him. He lines them up to spell L-I-Z: the name, we can safely assume, of the cute girl in his class. “That told us that he was capable of language comprehension in the right hemisphere,” Gazzaniga later told me. “He was one of the first confirmation cases that you could get bilateral language — he could answer queries using language from either side.”

Patricia Churchland was also one of my favourite guests on the Philosophy podcast, The Partially Examined Life. The interview is primarily about how neuroscience can inform us about moral philosophy, specifically how the science relates to Hume's concept of the moral sentiment and where it comes from.