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Emotions: cerebral hemispheres and prefrontal cortex


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Created by Jeffrey Walsh.

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  • blobby green style avatar for user Lukas Vasionis
    Who is talking in this video? Does he/she have a degree in neuro, biology or psichology sciences?
    (0 votes)
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    • blobby green style avatar for user Jessica Supp
      His name is Jeffrey Walsh. Here's his bio from the Content Specialists page: Dr. Jeffrey P. Walsh earned his M.D. from The George Washington University School of Medicine and Health Sciences in 2014. He is currently completing his psychiatry residency at Kaiser Permanente in Southern California.
      (77 votes)
  • blobby green style avatar for user Jackie Wooley
    When talking about R/L hemispheres, does this truly mean R/L or is it a simplification of dominant/nondominant hemispheres?
    (7 votes)
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    • mr pink red style avatar for user doctor_luvtub
      When neuroscientists and physicians categorize cerebral hemispheres, right means anatomic right, and left means anatomic left. ("Anatomic" means the designation is based on sidedness from the perspective of the patient or subject.) The examples of sidedness discussed in the video are consistent with anatomic designation. Hope this helps.
      (7 votes)
  • blobby green style avatar for user Bmeizok
    What does it take to damage the brain? As kids play and fall and knock their heads really hard all the time, does that cause damage to the brain? And does the brain heal?
    (3 votes)
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    • piceratops tree style avatar for user Alexander Zeisberg
      It depends on what was injured, how bad, and a multitude of other factors. However some functions can be rerouted to other areas of the brain. Such as a blind person learning to read Braille, the brain area dedicated to that finger expands the sense of touch into the visual cortex. (barinaga, 1992) And this is called Plasticity. The ability to change, with the best results in children, and reorginize after damage by building new pathways. I saw a man in his late 20's bonk his head pretty hard and he went unconcious, when he woke up, he could barely walk, talk, or survive without help from others, that was in 2010 when this happened and now, he is back at it, talking and walking, taking care of his kids and back to pretty decent functioning, however he seems different. He was a really rough tough guy and now he is alot more mellow. I was the medic on scene at the time of his accident.. It was so interesting to see his recovery.
      Also, i think interesting is the newer idea of Neurogenesis, which is the production of new brain cells. It is believed they devolop deep within the brain and migrate outward to form new connections with neighboring neurons. PRETTY WILD STUFF!
      (14 votes)
  • starky tree style avatar for user Alexa Jones
    Can you refer me to the sources that talk about the studies conducted by researchers that lead to the conclusion that the left hemisphere was more positively active than the right? As well as the right hemisphere being more negatively, active in terms of emotions, than the left? Thanks
    (6 votes)
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  • piceratops ultimate style avatar for user Shekinah
    Does this happen to have anything to do with the hand you use? Is it true that left-handed people tend to use the right side of their brain? Would this, therefore, make left-handed people more isolated and more likely to be alone? :o
    (6 votes)
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  • leaf green style avatar for user hlinee
    What does the prefrontal cortex have to do with emotion?
    (3 votes)
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  • blobby green style avatar for user Lisa Hunter
    Who was the study with the children conducted by?
    (5 votes)
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  • winston default style avatar for user jazzybenigno11
    Do psychology and nuerology connect somehow?
    (4 votes)
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  • starky ultimate style avatar for user natureforever.care
    What is meant by the word 'feeling' in context of emotions?
    (4 votes)
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  • blobby green style avatar for user Timothy J. Calcara Jr.
    I thought the story about Phineas Gage was wonderfully fascinating. It also explains why some folks fly off the handle while others are able to control themselves. What makes the difference is the development of the prefrontal cortex. Is the brain damage irreversible? What I mean is, could Phineas Gage redevelop his prefrontal cortex and get things back the way they used to be? Hope I made sense.
    (2 votes)
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    • leaf blue style avatar for user Kevin D. Fettel
      The brain has some plasticity allowing it to reroute and reintegrate neurological pathways. This ability to do so becomes much more limited as we age. Further, while in the case of Phineas Gage, there may have been little rerouting and reintegration by the brain to compensate, it's understood that gross damage in a mature brain may never be 100% back to normal.
      (4 votes)

Video transcript

So what we have here is a brain. And this is like we're above the person, looking down into their brain. To orient you, let me draw two eyes here. And this is the front of the brain and this is the back of the brain. And we're looking at it, like I said, from the top. Now, why are we looking at a brain? Well, I want to talk about a certain area of the brain known as the cerebral cortex and how it plays a role in emotions. And there's a number of different ways that you can divide up the cerebral cortex and organize it. So we're going to look at a few in terms of emotion. So one way that you can view the brain is in terms of hemispheres. And in your brain, you have two hemispheres. You have a left hemisphere and a right hemisphere. And the way you think of hemispheres, it's as if you draw the line down the brain. And you can split it into two different hemispheres. You have the left hemisphere and the right hemisphere. And there's actually some differences between the left and right hemisphere. Researchers actually found that positive emotions evoke more electrical activity on the left side of the brain than on the right. Whereas negative emotions tend to elicit more activity in the right hemisphere. Now, you might be wondering how did they figure that out? Well, what they did is they had participants in the research study watch a TV screen. So let's draw a TV here. And this was several years ago. So I bet TVs had bunny ears back then. So we'll draw some bunny ears here. So what this research study did was they had their participants watch films, either evoked pleasure or disgust. And pleasure films were things like the kind of videos that people share with each other on YouTube. I mean obviously YouTube back then didn't exist. So they just got films of things that evoked positive emotions, like puppies playing in flowers and actually a gorilla taking a bath at the zoo. I guess that does bring quite a bit of pleasure. But that wouldn't be the first thing that came to my mind. And they had them watch other videos that evoked feelings of disgust. And these were like shock films, like videos of third-degree burns and very like gory leg amputations, things that would evoke negative emotions. And while these participants were watching these films, the researchers videotaped their facial expressions and also recorded their brain activity through something called an EEG recording. And EEG recordings basically measure the electrical activity of your brain. And what they found was that pleasure films increase activity in the left hemisphere because the pleasure films are associated with positive emotions. Now, it's not to say that there wasn't any activity in the right hemisphere. There's just more activity in the left hemisphere because positive emotions increase activity in the left hemisphere. And the same could be said for the disgusting shock films. On EEG recording, they found that participants had more activity in the right hemisphere and these disgusting films are more associated with negative emotions, like fear and disgust. So I think it's pretty neat that while the brain is such a complicated structure, is that you can actually just split it down the middle and think of it in terms of left and right. So you can associate the left hemisphere with positive emotions and the right hemisphere with negative emotions. But that's not all in terms of hemispheres. This concept of left and right hemispheres becoming more active in certain situations can also be applied to social interaction and how outgoing and sociable you are. And in a different study, researchers observed a group of four-year-olds playing in a group. So I'm going to draw some little kids here. So you have someone here. The researchers watched the kids interacting in groups and saw how they interacted with each other. So here are two guys. And you can see them sharing in a cool toy here. And check out their expression. They're smiling and they look like they're having a great time. And some kids, that's how they act. Other kids tend to be more isolative. Some kids like to isolate a little bit more and be alone. And here's an example. Here's one kid here. He's just kind of sitting. He's all alone. He's frowning. He's kind of isolating over here. So after observing and noting how these children behaved, they did a similar experiment to what we mentioned above. And they took EEG recordings. And notice something kind of interesting. That the kids who were more sociable, playing in a group, they tended to have an increased level of activity in their left hemisphere. So I'll put "sociable." On the other hand, they noticed that the children who isolated more, like this guy here, they tended to have more activity in the right hemisphere. And to represent that, I'll write "isolative." And of course there's been other studies as well. And other research shows that people with more active left hemispheres, they tend to be more interested, joyful, and enthusiastic about things. Whereas those with more active right hemispheres, tend to be more timid, fearful, avoidant, and even depressed. So that's the basic overview of emotions in terms of brain hemispheres. Now another way you can look at the cerebral cortex is by dividing it into functional divisions. So I'm going to erase these structures up here. And some of these functional divisions you can already see in different colors here. But the one that I want to focus on is the prefrontal cortex. And the prefrontal cortex is basically this area right here, this area all the way in the front of your brain. And it's actually right behind your forehead. And this area of the brain is responsible for many high order functions, like language, information processing, all the things that you think of that make humans, humans-- the ability to solve math problems, think through philosophical issues. Sometimes these are referred to as very like cerebral activities. And where do you think that term comes from? Well, the cerebral cortex and the prefrontal cortex, a part of the cerebral cortex. And like I said, the prefrontal cortex is really what distinguishes humans. And because of that, it's extremely well developed in humans. And it undergoes the greatest amount of development after birth. I mean think of how you become more mature as you get older, or so they say. In terms of the prefrontal cortex, you use this part of the brain when you're trying to solve problems, make decisions, and manage how you behave in social situations. For instance, you probably behave differently during a job interview than you do during a wild sporting event. And even if you don't, you know that there are certain norms and expectations in job interviews than there are in sporting events. And the ability to know that comes from your prefrontal cortex. And I mention this because in another video, we talked about the amygdala. And the amygdala causes fear, anxiety, anger, and aggression. And I'm sure you've had the experience in your life where you felt very angry at someone. And when you have those sorts of feelings, maybe your primal reaction is to attack the person or physically hit them. But of course, many people don't do that. And why is that? Well, because they have a well-developed prefrontal cortex and the ability to understand, well, violence isn't the answer. You shouldn't attack someone, no matter how you feel. And that thinking that you have your mind where you say no, no, I should restrict my behavior, I should walk away, all those thoughts that you have come from the prefrontal cortex because that helps to manage how you behave in social situations. One question that's interesting to consider is what would happen if you damaged your prefrontal cortex? How would you act? Well, there's a famous example of this where someone actually did have that happen to them. And his name was Phineas Gage. Now, Phineas Gage was 25 years old, back when it was 1848. And he was a railroad worker. So I'll draw some train tracks here. And as part of building this railroad, they had to do controlled explosions to make way for it. And Phineas Gage was responsible for overseeing that. So here he is. And he was just overseeing these explosions. Now during one of these explosions, an iron rod was sent flying through the air. And it actually penetrated through his skull. It went in one side and out the other. And during its course through his skull, it destroyed much of his prefrontal cortex. The man that Phineas Gage was after the accident was not the same man he was before. You see before, his friends and coworkers known as a hard working and well-liked guy. After he experienced this trauma to his head, he became rude and gruff. He swore a lot and just behaved inappropriately overall. And that's because he no longer had a functioning prefrontal cortex. So that's the cerebral cortex. So if you ever wonder what makes a human, human, well, a lot of it's actually right behind your forehead, in the area known as the prefrontal cortex.