5 Things You Should Know About Your Brain

[Music] one of our favorite things here at scishow is to use our brains to debunk myths and pseudoscience so I bet you can deduce what's really fun that's right debunking junk science about our brains here are three videos that break down long-held totally ridiculous theories about our brains and then two videos that shine some light on just how amazing our brains are first up victorian-era fake science because why did people ever put any stock in phrenology a lot of exciting neuroscience was happening in 19th century England Victorian scientists were figuring out that certain parts of our brains are connected with certain parts of our bodies like different senses or muscles mixed in with the legitimate research with some pseudoscience or misleading ideas that spread without rigorous scientific backing like one theory from Viennese physician Franz Joseph gall who thought that character traits like religiousness or curiosity were also linked to specific brain regions this theory became the basis of phrenology a field of study that claimed that you could determine someone's personality by the shape of their skull phrenologist believes that all human brains were made up of many distinct organs that could be mapped to various personality traits they claimed that the more you used a certain brain region the bigger it got and the less you use it the smaller it got kind of like how muscles work and they assumed that the skull conformed to the shape of the brain revealing where these bigger and smaller organs were so theoretically you could inspect someone's skull to figure out parts of their personality chronology became enormous ly popular in the UK around the early 1800s and spread to places like America France and Germany it was pretty much a load of garbage and guesswork and many scientists were vocal critics but at the time there wasn't enough evidence to thoroughly debunked the theory researchers would of course dissect the brains of dead people not living people and the human body changes a lot after death so even if living brains were different shapes dead brains probably looks pretty much the same plus the public thought phrenology was really compelling just like horoscopes people tend to love things that tell them something about themselves so phrenology thrived on subjective validation which is the idea that people tend to believe in something if it's personally true or meaningful for them but as the ideas spread they started being used to justify race and class inequalities upper classes use phrenology to reassure themselves that they were supposed to be on top because of the ideal shapes of their brain the lower classes on the other hand accepted the pseudoscience because it claims that these brain organs could be developed so they could improve themselves with hard work the American physician Samuel Morton made even more sweeping claims about skull shape in a book crania Americana Morton argued that Caucasians were superior or to other races like Africans and Native Americans because of craniometry or different school and supposedly brain sizes which is just racism under the guise of science some phrenologist use these ideas to rationalize slavery and colonization while others were anti-slavery because they thought these inferior races ought to be protected eventually all of this scientific racism was acknowledged and fern ologies legitimacy took a nosedive in the mid 1800s as we continue to learn more about how the human brain actually worked first of all the brain conforms to the shape of the skull not the other way around and secondly the brain does not physically grow or shrink like our muscles in ologists were also wrong that the brain was made up of discrete chunks it's one organ with a bunch of networked cells but there was something to the idea that the brain was spatially organized and different regions were linked with different functions which we call functional specialization the French physician Paul Broca contributed some evidence to support this idea in the 1860s he found that damage to the left frontal lobe in humans was linked to speech impairment without affecting someone's ability to understand what other people were saying in the 1870s Gustav rich and JL hetsig were experimenting with stimulating different parts of the cerebral cortex of a dog which produced movement in different areas of its body new experiments like these scientists were able to develop a better understanding of different regions of the brain by the start of the 20th century unlike phrenological maps which assigned arbitrary brain areas to personality traits our current brain maps are based on experiments that show different functions of each region with the development of technologies like magnetic resonance imaging and computed tomography and is the ability to do careful brain surgery our understanding of neuroscience continues to grow nowadays we are positive that phrenology was junk science the shape of someone's head doesn't say anything about their personality character or moral depth but we can still see it's echoes in language we use today like highbrow lowbrow and well rounded phonology may have lacked scientific merit and was definitely used to justify harmful ideas but it did cause scientists to think more critically about how biology is intertwined with thoughts and emotion those silly Victorians we modern intellectuals would never blow something so stupid right well have you ever heard that we only use 10% of our brain that's still a pretty common myth here's Hank to rip it apart the notion that's been propagated by movies magazines and motivational speakers and repeated by well-meaning folks and shysters alike tell you that you're only using 10% of your brain if you're only able to access a fraction of your brain power just imagine what you could do if you tapped into all that unused potential read other people's stuff clay the stock market crush cans with your mind and levitate I'll have to write on your brain parade but that 10% stuff is so far off that it would be laughable if it weren't so widespread and it kind of can't believe I'm still talking about it so like many myths it's hard to pinpoint exactly where it began there's no definitive source though some have linked it back to American psychologist William James and even Albert Einstein who both suggested in so many words that we were only using part of our mental potential the fact is we use pretty much every part of our brains a lot of it is active most of the time whether you're reading a book or listening to music or walking around town or even sleeping how can we be so sure well for one thing neural imaging techniques like PET scans and MRIs actually let us see the brain in action these images show us that nearly every region of the brain lights up during even simple tasks like walking and talking well we don't use all of our brain at once just like we don't engage every single muscle at the same time those scans prove that over the course of any given day you use just about all of your brain it also stands to reason that if 90% of your brain was useless you could remove large portions of it as you might an appendix or tonsil and carry on as usual brain damage and disease wouldn't be as much of a concern if only 10% of the organ was actually functional but in reality there isn't a single area of the brain that can be damaged or diseased without resulting in some kind of physical or mental consequence small or big you may have heard of the case of Phineas Gage the 19th century railroad worker who wound up with a spike through his head because of an accident it didn't actually stay at his head it went all the way through and then kept going for quite a while it didn't kill him somewhat surprisingly and he still had his memories and his skills but many of his friends reported that he had changed personalities now we don't actually know a ton about gage because a lot of people used him to try and prove a lot of different points over the years but there's little doubt that you can have a rod go through your brain and not have some things mess with members Clive wearing the British pianist who conducted a viral infection that destroyed his hippocampus the part of the brain that controls the storage of memories as a result he's no longer able to recognize anyone but his wife and he can't retain a memory from within 30 seconds at a time every part of your brain has a function and you need it in order to keep being you and finally we know that our brains are working all the time because we have to constantly feed them literally the average human brain accounts for about 3% of a person's body weight but it demands at least 20% to the body's energy to keep all those neurons firing we're talking hundreds of food calories every day just so your brain can remind your heart to beat or help you solve for X or remember where you left your phone our constant needs for food especially foods rich in fats and sugars has a lot to do with our brains and it wouldn't make much evolutionary sense for us to expend so much energy feeding a useless wet lump so in the end while telekinesis would be pretty awesome our brains are already capable of truly incredible things in fact if anything we only understand a fraction of what's really going on up there so instead of insulting its function be thankful for all the cheer brain does which is more than you know you know I bet you're so smart that you use both sides of your brain so why don't we still try to compartmentalize people into being right-brained or left-brained it's kind of complicated and cool here's an in-depth video about it there are plenty of personality tests out there that claim to tell you which side of your brain controls how you think what you're good at basically who you are they might say that you're creative right brain ur doomed to perform poorly in math and science guess we better give up on getting into MIT or they might tell you that your logical left brain ur a regular mr. Spock terrible in the arts so so much for Juilliard but you may have noticed that there are more than just two types of people in the world and they're not all either scientists or artists so that'd be some flaw and that whole left-brain right-brain thing even if you've never bought into the myth your high school textbooks probably taught you that the right half of your brain processes creative tasks and the last half can handle math or form language and that is a real thing different sides of the brain are often responsible for different tasks it's just that pop psychology has taken the idea a little too far it all started way back in the 19th century when doctors realized that the two halves of the brain might not be identical they noticed that when someone injured one side of their head it affected some brain processes like language or emotion more than others so it wasn't until 1961 that a neurobiologist named Roger Walcott Sperry set out to fill in the blanks along with a graduate student he was working with at the time Michael Gazzaniga Ferries research of the next few years would completely change the way the neuroscience community thought about the human brain but in the process he also accidentally created a myth that would plague popular culture for decades Barrie studied patients with severe epilepsy who had elected to undergo a surgery called a commissure Adami this involves completely severing the corpus callosum a bundle of nerve fibers that connects the two hemispheres of the brain and allows them to communicate with each other you'd think that effectively chopping their brains in half would be a big deal and it was but the side effects like problems with memory were relatively minor compared with the benefit of not having seizures anymore since the brain hemisphere is in these patients basically went about their business independently it's very figured that studying them would be a great way to find out what happened on each side of the brain all I needed were some simple tests he already knew that the right hemisphere controlled the left side of the body and the left hemisphere had controlled the right so he and Gazzaniga devised an experiment in which they display an object on the screen to the subjects in such a way that it would only be processed by their right hemispheres the best way to do that was just to make sure that only their left half visual field was seeing the way the optic nerves are set up that's not the same as just covering the patient's right eye instead Barry had the patients focus on the center of a screen and then flash the image on the left or right hand side of the screen the flash went by too quickly for them to follow it with both fields of vision so once Barry showed an object of a picture on the left side of their screens he found that the subjects noticed it but they couldn't name it if that object was let's say a picture of a key their right hemispheres knew that they were seeing a shiny object but they couldn't come up with a word key since the subjects were lacking that connection between two hemispheres Sperry concluded that language had to be processed by the left side of the brain which his subjects couldn't connect to he kept testing the patients with similar tasks that tested other basic processes and eventually found a pattern language and calculations seemed to be done on the left and spatial reasoning on the right over time that's been simplified to logic on the left and creativity on the right but simplifying it's not a great idea when dealing with something as complicated as a brain fairy himself describes the results as highly statistical districting a general pattern and not an absolute rule there even turned out to be some people who show the reverse pattern usually left-handed people and their mental capabilities aren't any worse for wear still his research was a huge deal at the time in Sperry was eventually awarded a Nobel Prize for his work and understanding the specialization of the two hemispheres of the brain but even though he cautioned against generalizing his research too much an article appeared in 1973 in the New York Times Magazine titled we are left-brained or right-brained describing Sperrys research in oversimplified terms then there was an article in Time magazine that did the same thing the rest is popular psychology history a bevy of self-help books and personality tests soon popped up claiming that some people were guided by the logical left brain and some by the creative right brain so now there were two new ideas going around one the different processes occurred exclusively on different sides of the brain and to that people were more prone to one side strength than the other but only one of those concepts that each hemisphere controlled different processes was actually based on Sperrys research known as brain lateralization the concept basically became neuroscience cannon and evolutionarily there were a lot of reasons that it made like it's not efficient for both hemispheres to be required for us to perform every single task split up the functions between two hemispheres and you can multitask scientists were even able to test is using baby chicks they found that chicks that tended to use their brain hemispheres separately managed to forage for food and give an eye out for predators but the ones with more distributed brain function couldn't do both at once and evolutionary terms not being able to watch your back is bad news for species there's also the matter of brain traffic jams the corpus callosum is something of an information bottleneck which means that the brain has to be selective about what information it sends back and forth between hemispheres just like delegating tasks within a group of people it's much more efficient to let each hemisphere take responsibility for a particular job and finally putting one hemisphere in charge of certain things just helps keep the peace in the brain if both sides tried to process the same situation all the time each would come up with completely different responses which would be confusing so the concept of brain lateralization itself made perfect sense but turning the concept of delegating processes into the idea that some people could be left-brained or right-brained Sperry never suggested that at all which is why when in 2013 a group of American researchers set out to analyze over a thousand brain scans they figured it might be time to debunk that myth once and for all researchers analyzed a type of brain scan called functional magnetic resonance imaging or fMRI fMRI shows the parts of the brain that are active by tracking the flow of oxygenated blood through different regions the blood brings oxygen and nutrients to the more active parts of the brain and areas with more blood flow show up as bright webs on the scan the researchers looked at scans of over a thousand healthy uninjured brains and what's known as the resting state where the subjects aren't asked to perform any particular task but there's still brain activity because they're not dead certain areas showed up brighter on the scan it would mean that those parts of the brain were more active and interconnected and if one whole hemisphere showed more bright areas than the other while the subject was basically doing nothing that meant they probably had a dominant hemisphere it would be evidence that some people were left-brained or right-brained now the researchers were expecting that certain areas would light up more brightly than others at rest there are brain regions that are associated with things like language and paying attention and those did light up more what seemed that even in the rest state-specific processes were divvied up between hemispheres confirming Sperrys findings but the stands didn't show that any one hemisphere was consistently showing up any more or less brightly than the other in subjects and over a thousand brain scans they didn't find a pattern of people who had more strongly connected right hemispheres than the left or left over right as far as the authors of the study could tell there are no Vulcans among us in other words there is no such thing as an inherently left or right brained person now the idea of brain lateralization is still a really important development in our understanding of our brains but it too is probably a lot more complicated and it's often been made out to be like even though particular tasks tend to be handled by different hemispheres the whole point is that the two are constantly talking to each other to make even simple jobs possible ask someone to do something like invent a new word for instance and they'll need creativity from the right hemisphere but also language from the left so people can still have particular intellectual talents obviously but being good at math doesn't necessarily make you bad at writing fanfiction I mean it can't have Sherlock without Watson or Bert without Ernie your brain is a dynamic duo and it's incredibly versatile and you might as well give it the credit it deserves okay so skulls don't form around brains we use our whole brains and people aren't left or right brained really but our brains are plastic it turns out that brains learn in pretty fascinating ways check out this video about it you would not be here if you weren't interested in learning and neither would i but here's something we haven't learned about together learning the ways in which we acquire and retain knowledge which is the very definition of learning is really a science in itself and like any other discipline that involves the study of the human brain is practically still in its infancy just twenty years ago most scientists believe that once we reached adulthood our brains were pretty much fixed not that we were incapable of learning anything new exactly but the assumption was that our brains development phase was over and now it's pretty much there to remind our hearts to keep beating and occasionally let us remember where we left our phone but thanks to huge advances in things like functional brain imaging we have a clearer picture than ever of how our brains work and we're beginning to observe some wonderful things for one we now know that the process of learning actually alters the structure of our brains at the cellular level and once more it turns out that our brains never stop changing to make room for new information people often compare the human brain to a computer but imagine a computer that can actually grow new circuits as it acquires new facts in associations and you have a much more awesome comparison this is the gift known as neural plasticity you might think of plastic as being stiff and cheap but in biology plasticity refers to the capacity of living things to mold themselves to new conditions and our brains are great at it for one thing your brain cells or neurons are always changing their connections to one another to meet changing demands each of your neurons consists with a central body with spindly dendrites and a long axon stemming from it the neuron transmits electrochemical signals to other brain cells through its axon and receive signals through its dendrites via connections where the cells meet called synapses when you're born each neuron in your brain has about 2,500 synapses connecting it to other cells but by the time you're three and you've become just a sponge of fascinating new information like what sound the piggy makes and where your mom's face goes when she hides it behind her hand you have 6 times as many up to 15,000 synapses for each neuron in your brain in this regard it's kind of true that your brain hits its peak when you're young because by the time you're an adult your brain cells have about half as many synapses as when you were three but it turns out that's okay because we now know that synapses just shrink up when they're no long needed like you know now that pigs go oink and that people still exist when you can't see their faces so you don't need to keep those connections to remind you this process of winnowing down unused connections is known as synaptic pruning meanwhile your neurons experience all kinds of new growth as you continue to soak up new information like how to drive how to solve for X and how to get through that one really hard level in your favorite castle smashing game here the key to learning is memory because you need to retain that information in order to apply it in the future so your brain cells can change in different ways depending on how long you remember what you've learned as you stockpile data in your short-term memory for example the structure of your existing synapses has been found to change with more and stronger dendrites growing to reinforce them so for info that you retain for just a short time like how to destroy digital castles using rocks and fire you don't need to sprout whole new connection just beefing up the existing ones you've used so far will help you map the game just fine well when it comes to important stuff like the learning we do at school or hopefully the stuff you learn here on scishow your neurons actually Forge entirely new synapses over time as you relearn re-remember and reuse the information this is how your brain builds the long-term memory you need to retain the learning you're doing right now at work and at school and turn it into a lifetime of applied knowledge so I said it before and I'll say it again take care of your brain and odds are it'll take care of you ok one more video about some of the amazing things brains can do this time the three senses you might not even know you have at some point you've probably learned about the five senses sight sound smell taste and touch but these five don't explain all of our sensations how can we tell how hot or cold we are keep ourselves as balanced now scientists are beginning to add more senses to that classic list here are three of it's probably no surprise that sensing temperature is pretty important which we call thermo ception it helps us keep our body temperature constant and lets us know when our environment is too hot or too cold so we can avoid tissue damage like from burns or frostbite so how do we do it scientists have found a couple of potential mechanisms connected with the transient receptor protein channel or trip family there are lots of these channels and they react to lots of different stimuli we're still trying to figure out what they all do the woman for sure a lot of them help us respond to changes in temperature scientists aren't exactly sure how these channels work but with the physical stimuli of the environment getting warmer or colder depending on the channel they're more likely to open one of those channels that trip v1 plays a role in the sensation of painful heat the receptor is activated when temperatures get uncomfortably warm around 40 degrees Celsius rip and eight on the other hand response to cold stimuli below 20 degrees Celsius so pretty much anything below room temperature these channels and others can be found throughout our bodies but when they're on nociceptors or pain sensing nerves activation of the channel triggers a rush of calcium into the cell and sends a signal to the brain about painful temperature all that information goes to the primary somatosensory cortex a six fold of tissue on the top of the brain where most of the mechanical sensations like cuts pain and vibration are processed then you can consciously process the temperature and yank your hand away from that campfire or decide whether you want to put on the jacket now have you ever thought about how you just know where your body is in space well that's proprioception the word comes from the latin for one's own grasp it's how you can type without looking at a keyboard and walk without looking at your feet and there are a bunch of specialized receptors in our skin joints and muscles that help us do it for example muscle spindles response to changes in muscle length and the speed of muscle movement while Golgi tendon organs send signals about muscle tension and exertion and then cutaneous McCann receptors respond to stretch and pressure in the skin and joint all of these receptors work together to provide the brain especially the cerebellum with information about your movement and the positions of your limb the cerebellum is responsible for coordinating things like balance posture and voluntary movement weirdly though if I just recently discovered a case of a woman born without a cerebellum who has some balance and movement issues but seems to be doing relatively fine so there is still a lot to understand about how our brains process proprioceptive information separately we have equilibria ception our sense of balance and we need balance whenever we move like walking and run years are important for our sense of hearing but they're also a key part of equilibria ception especially the inner ear it contains the vestibular system which includes three fluid-filled semicircular canals lined with tiny hair cells when your head moves these hair cells are sloshed around by the fluid and send signals to the brain specifically to the vestibular nuclei in the brainstem each canal is responsible for a different kind of movement one for up and down one for left and right and one for side-to-side odorless organs located just below the semicircular canals are similar but in addition to liquid they have tiny crystals made of calcium carbonate as the head moves these crystals rub against the hair cells attached to the membrane which send information to the brain stem your brain men send information out to your eyes and joints and muscles so they can respond accordingly and help you navigate the world now problems with this system can lead to issues with balot vertigo for example can be caused by loose stones in the otolith oregon they can also fall into the semicircular canals disrupt the normal fluid movement and put unexpected pressure on the hair cell that pressure conflicts with what your eyes are seeing which can make you feel dizzy when you move your head together these three senses are really important in helping us navigate our environment successfully and safely so even though they don't make the list of our traditional senses I think we do ourselves a disservice by forgetting about thanks for watching this collection of videos on our incredible brains if you want to learn more about the human mind and how it affects everything in our lives check out our new channel scishow site and special thanks to our patreon patrons who make this channel possible and brought scishow psych into the world [Music]

Channel: SciShow

Views: 1,442,457

Rating: 4.845489 out of 5

Keywords: SciShow, science, Hank, Green, education, learn, 5 Things You Should Know About Your Brain, Neuroplasticity, Brains, Neuroscience, Pseudoscience, Victorian, Senses, Phrenology, 10% of my brain, Left Brained, Right Brained, Myth, Fact, Learning, Cranium

Id: tO8Kk0wIsrI

Length: 24min 55sec (1495 seconds)

Published: Wed Mar 22 2017

Reddit Comments

[u/Striped_Monkey]

I love sci-show

[u/FireData]

8 minutes in and I finally found it.