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The Role of Biological Processes in Perceiving Emotion: Brain Regions and the Limbic System – Emotion (PSY, BIO)

by Tarry Ahuja, MD
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    00:01 Okay, now let's get into how emotion and biology play a role together.

    00:09 So what we want to figure out is, is there a place in the brain that is dealing with all of our emotion?.

    00:14 Is there a place in the brain that is allowing us to experience our emotion? Is there a place in your brain right now that is saying, "I'm completely stressed out about this MCAT exam." And the answer really is, "No." So we know there is no specific brain region associated with a specific emotion.

    00:30 Therefore, for example, there is no discussed center of the brain.

    00:34 There is, "No, I'm scared center of the brain." But what we have instead is this really unique way to express several different emotions through emotional circuits that would involve different brain structures.

    00:45 It's kind of makes much more sense and think about it, is that you want to have sometimes a different component from each or more than just one emotion.

    00:52 Because there's a lot of scenarios I think you can think of where you're kind of happy, you're kind of sad, you're kind of scared, you're kind of excited.

    01:00 And all that's put into a blender and you experience that emotion that you are experience.

    01:04 And it's hard to say, "I'm feeling just fear." "I'm feeling just happiness." So by having these emotional circuits we are allowed to pull and draw from a bit of those emotions to create the ultimate final emotional experience that you're getting.

    01:18 And that's done through all these networks and circuits that are happening within the brain.

    01:22 Now that being said, you will have some brain structures that are involve in that process.

    01:28 And we've highlighted some of them here on this diagram.

    01:30 And you can see we have things like the thalamus, the hypothalamus, the frontal lobe, the amygdala, the hippocampus.

    01:37 Even olfactory bulb which is a part of your brain dealing with this smell of things that actually really contribute to emotions that you feel.

    01:46 But a lot of times you've heard of how scent or smell can trigger a memory or can trigger an emotion.

    01:53 Which is why when you go to your local candle shop and you have, your calming candle and then you'll have your chill candle.

    02:00 Have your, you know, different types of candles based on scent that's because we have established that smell can impact emotion.

    02:06 So what we're going to do, we're going to highlight some of these brain structures.

    02:09 And we'll talk about what they do and how they contribute to our perception of emotion.

    02:14 So the first one we will look at is the limbic system.

    02:17 And the limbic system is going to come up and several lectures we are going to have.

    02:21 And it is quite important for your MCAT exam.

    02:23 So you should be quite familiar with the components of the limbic system.

    02:26 How they are involved with emotion.

    02:27 And we're going to talk about how they are involved in other processes as well.

    02:30 So the limbic system is a collection of structures found on both sides of the thalamus, okay.

    02:36 So if you go back to the previous slide, we'll look at that and you can refer that diagram.

    02:40 And you can have one in front of you looking at, okay, here's a thalamus and here the limbic system is.

    02:44 The structures within the limbic system are appear to be primary responsible for emotional experiences.

    02:50 So we're going to get into how when you are presented with an emotional experience.

    02:56 Parts of the limbic system are activated.

    02:59 And there's different neurotransmitters which will release within the limbic system, dopamine being one of them.

    03:05 Which provides pleasure.

    03:07 And therefore, we know the limbic system is quite involved with things like reinforcing positive behavior.

    03:13 We'll get into that in more detail.

    03:14 So the first specific structure we are going to talk about is amygdala.

    03:18 This is the main structure involved with emotion found in the limbic system.

    03:22 And it's surprisingly small.

    03:24 So it's, about the size of an almond or nothing much more than an almond may be a kidney bean.

    03:31 And it's found deep, deep within your brain.

    03:33 So this is something very superficial on the top.

    03:35 This is deep, deep within the brain.

    03:37 And we know that if you activate this structure, if it is stimulated, that we are going to activate the expression of fear and aggression.

    03:46 We also know in studies and experiments where the amygdala amygdala is damaged or removed that you see a removal of this fear and aggression.

    03:54 Okay, so this is an example in research, in health research where we look at damaged to see the impact on function.

    04:03 So great example of it is you remove again amygdala you see this direct impact which change in our expression of fear and aggression.

    04:13 So here you can see a visual diagram looking at where you would see the amygdala.

    04:19 And you can see that it is quite small and it is found deep within the brain.

    04:22 And this is what I meant by, it's not found on the corticular layers on the top.

    04:25 Convoluted layers expand deeper in the brain.

    04:31 Now, let's talk about the hypothalamus.

    04:33 The hypothalamus is also a very small structure and it is very involved with the amygdala.

    04:38 So it communicates with the amygdala and prefrontal cortex.

    04:41 Or the PFC, it's lot of times you see it abbreviated.

    04:44 These three structures have this straight relationship and they communicate a lot.

    04:48 And that makes sense if we're dealing with emotion.

    04:50 You want this cross-talk.

    04:51 So we know that the hypothalamus controls a lot of the body functions associated with emotion.

    04:57 So we say the physiological aspects of emotion.

    05:00 Things like when you saw that bear, or you had your surprise MCAT party, the increase in your heart rate is sweating, those changes are attributed to changes in functions or stimulation of the hypothalamus.

    05:14 And the prefrontal cortex is very, very important.

    05:16 And it is involved with a lot of different functions.

    05:19 Now in terms of where it's located, it's found at the brain.

    05:23 That's the name pre.

    05:24 Frontal which should be in front of your head, right here.

    05:27 Cortex.

    05:28 It controls a lot of behavioral aspects of emotion.

    05:32 So how do you approach things.

    05:34 How do you thinking about things.

    05:36 How do you avoiding different things.

    05:38 Obviously all things directly related to emotion.

    05:40 And it also helps regulate emotion.

    05:44 And it plays a role in an executive function.

    05:46 So, I'm throwing a lot of terms around.

    05:48 Let's walk through a couple of those.

    05:49 So an important term I want you to understand is executive function.

    05:53 So what are we talking about when we say executive function.

    05:55 So let's break that down, executive.

    05:58 When you think of executive, you think of somebody that's higher up in the rungs of say an organization.

    06:03 So the big boss or the executive brass at a company, your company is somebody that kind of runs the show and makes the big decisions.

    06:11 And related to function.

    06:13 So executive function is referring to as an individual, these broad important choices are being made by the prefrontal cortex.

    06:21 And so in terms of the emotion, it's going to modulate what you're experiencing.

    06:26 And it's going to therefore, direct what are the functional roles that you're going to do based on that emotion.

    06:32 So how do we understand what the prefrontal cortex does.

    06:36 I'm going to bring forth an example.

    06:38 And this is a classic MCAT style example that you would need to know.

    06:43 And this is about are good friend Phinease Gage.

    06:46 So you may have heard this story before.

    06:48 We are going to really quickly bring you up to speed on that.

    06:51 This is an example of us understanding the function of the brain based on damage.

    06:56 So you got to backtrack a little bit and think of you know, fifty hundred years ago, we didn't have the bio-technology that we have today.

    07:03 Today you have headaches and you have an issue, you go to your local hospital, and you get an MRI or CAT scan and they can look at all these different ways to bio-image your brain.

    07:13 And we can use so many different ways to examine changes and function and what's happening inside your body.

    07:19 You got to think a 100 years ago we didn't have access to these types of tools.

    07:24 So how would you figure out what this portion of the brain is doing versus that portion.

    07:28 Really it's kind of barbaric but what we would do is look at an individual before.

    07:33 If you had some type of record and you looked at damage that happened, hopefully you didn't apply that damage versus what happens after the damage.

    07:40 So Phineas Gage was a railroad worker.

    07:44 And he was a very well liked guy, very bright.

    07:47 And he was sort of a foreman and he was able to manage his troops laying down tracks.

    07:52 And one day while working on the railway track, there was an explosion.

    07:57 And they have something called a tampering rod which is the long metal rod.

    08:00 You know, I'm not a big railway guy so I can't get into the specifics of what those are for.

    08:04 But basically there was an explosion and that explosion caused that tampering rod go fly in the air.

    08:10 But on it's way to go through the air, decided to go through Phineas Gage's head.

    08:15 So you can see from the diagrams here.

    08:17 I have 4 diagrams, A, B, C and D.

    08:21 A is showing a diagram of where the tampering rod actually entered his brain and exited his brain.

    08:26 And B is showing what that would look like if he had skin in hair.

    08:30 And you can see, this is pretty significant trauma and damage that had happened to him.

    08:35 And it actually entered his, it actually entered below his cheek and exited up through the top of his frontal, temple and frontal lobe.

    08:45 That's got to hurt.

    08:48 That's got to hurt a lot.

    08:49 Now that's not something you want happening to you hopefully on a regular basis.

    08:52 But this happened to our friend Phineas.

    08:54 And this brought forth a really unique situation, is we understood Phineas's personality and behavior prior to the accident and post accident.

    09:04 And prior to the accident, we know behaviorally speaking, he was a great guy.

    09:08 He was very well liked, personable, intelligent.

    09:11 And after the accident they noticed these huge changes.

    09:15 So they track these changes and post hoc or afterwards they realized where was the damage to his brain.

    09:22 And they realized that was in his frontal lobe.

    09:24 More specifically in the prefrontal cortex.

    09:26 And they are able to attribute the behavioral change to the damage that we saw in those areas.

    09:32 So again just to summarize.

    09:33 We know what he was like before.

    09:35 Tampering rod enters his brain.

    09:38 Destroys and really damages his prefrontal cortex and the frontal lobe.

    09:42 And then we see the resultant personality change.

    09:44 So we can make this indirect relationship and say, well that must mean that is prefrontal cortex is involved with these types of behaviors because they've been impacted by a metal rod through the head.


    About the Lecture

    The lecture The Role of Biological Processes in Perceiving Emotion: Brain Regions and the Limbic System – Emotion (PSY, BIO) by Tarry Ahuja, MD is from the course Responding to the World.


    Included Quiz Questions

    1. Pons
    2. Amygdala
    3. Prefrontal lobe
    4. Hypothalamus
    5. Cingulate gyrus
    1. Limbic system
    2. Pituitary gland
    3. Occipital lobe
    4. Temporal lobe
    5. Motor cortex
    1. Amygdala
    2. Prefrontal cortex
    3. Frontal lobe
    4. Hippocampus
    5. Medulla
    1. Hypothalamus
    2. Cingulate gyrus
    3. Amygdala
    4. Prefrontal cortex
    5. Caudate
    1. Prefrontal cortex
    2. Postfrontal cortex
    3. Cingulate gyrus
    4. Amygdala
    5. Temporal lobe

    Author of lecture The Role of Biological Processes in Perceiving Emotion: Brain Regions and the Limbic System – Emotion (PSY, BIO)

     Tarry Ahuja, MD

    Tarry Ahuja, MD


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