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Cerebral Cortex

E8 · The Neuro Power Hour

36 Plays20 days ago

Let's learn about the brain! In this episode, Dr. Michael Powers introduces the cerebral cortex including the four main lobes (and wait, is there maybe a 5th lobe?), differences between the left and right hemispheres, and the importance of the limbic system. If you've ever wondered where in the brain language is processed, memories are stored, commands for movement are generated, where incoming sensation is interpreted, or the role of emotions in memory consolidation then this episode is for you!

References

All music courtesy of Free Music Archive and used via attribution 4.0 international license.

Intro and Outro: Stylin' by JMHBM
Transitional: Our Reality by Ketsa

Transcript

Introduction to the Cerebral Cortex

00:00:10

Speaker

Welcome to the NeuroPowerHour. I'm your host and neurological navigator, Dr. Michael Powers, physical therapist, board-certified in neurologic physical therapy and clinical electrophysiology.

00:00:20

Speaker

Let's get started. Today I'll be talking about the cerebral cortex, that big beautiful brain that makes us uniquely human, allows us to do so many things in terms of movement, language comprehension, but then also the parts of the brain that really are involved with emotions, fight, flight, or freeze.

Overview of Cerebral Cortex Lobes

00:00:39

Speaker

we're be talking about multiple different areas of the brain, focusing on the four major lobes of the cerebral cortex, but also talking about the fifth lobe, which is known as the insular cortex, and a functional system that's not really a lobe, but warrants consideration within the cortex, and that is the limbic

Neuron Anatomy and Matter Types

00:00:57

Speaker

system.

00:00:57

Speaker

Before we dive into talking about the cerebral cortex and the lobes, we should have a good understanding of the foundational layer, so neuron anatomy, and also have an understanding of what we're talking about when we say cerebral cortex versus cerebrum. So we're going to start out there.

00:01:16

Speaker

Then we'll move on to talking about the lobes of the cerebral cortex, including hemispheric differences. These will be very important when you're in the clinic, especially when you're working with individuals after stroke, because there are significant differences between hemispheres that'll show up clinically.

00:01:32

Speaker

Then finally, we'll conclude with a discussion of the insular lobe and the limbic system. Let's start then by talking about the neuron, which is the functional unit within the central nervous system, both brain and spinal cord. And I think having an understanding of the neuron will provide a better grasp of what we're talking about down the road when we talk about white matter and gray matter.

00:01:56

Speaker

The neuron then, we're thinking about three main structural parts. We've got the cell body. You may also hear the term soma. Soma is a Greek word meaning body, so anytime you hear soma, you're thinking body.

00:02:08

Speaker

We've got the cell body, we've got the dendrites, and then we've got the axon. The cell body is going to be the core section containing the nucleus. Around the cell body, you're going to have the dendrites.

00:02:20

Speaker

These branch out from the cell body and essentially act as receptors. They're reaching out, trying to gather information from other neurons. So incoming signals will be coming into the dendrites processed by the cell body, and then the axon is a long, thin projection that is conducting impulses away from the cell body.

00:02:42

Speaker

If we think about this then conceptually, as we stack neurons together, the dendrites are going to be receiving signals from other areas, information is processed in the cell body, and then pertinent information and impulses is sent out from the cell body via the axon. A key consideration on that axon is whether it's myelinated or unmyelinated. Remember that myelin is kind of that fatty covering that wraps around the axon.

00:03:10

Speaker

There's little gaps called the nodes of Ranvier, but those nodes allow for saltatory conduction and essentially increased speed of transmission. So anytime we see that an axon's myelinated,

00:03:22

Speaker

we know that there's going to be quicker conduction. And within the central nervous system, if you look at anatomical slices, myelinated axons show up

Structural Features of the Cortex

00:03:32

Speaker

as white. So next we're going go into a discussion of gray matter and white matter and why this is important. Let's start then with white matter. White matter, again, is those myelinated axons. Here we're prioritizing speed of conduction.

00:03:46

Speaker

If you hear white matter, an easy mnemonic or way to remember this is think wire. So we've got the W for white, we've got the W for wire. White matter is essentially a wire that's sending information quickly to other areas.

00:04:02

Speaker

Within the central nervous system, you're going to see white matter in the subcortical areas of the brain, so the areas below the cortex, and in the spinal cord we'll see white matter outside of the central area. The central area the spinal cord has this butterfly or H-shaped area that's gray matter and white matter is going to be surrounding that area.

00:04:23

Speaker

Key take home here is if you hear white matter think wires and really speed of transmission of signals. Gray matter by contrast is going to be primarily cell bodies dendrites, and possibly unmyelinated axons. When we hear gray matter, think groups, gray groups, groups of cell bodies, groups of dendrites.

00:04:44

Speaker

Really the key here is we want processing power and processing ability. So we're sacrificing some speed in terms of neural conduction because what we're prioritizing here is we want to do some processing.

00:04:59

Speaker

Within the central nervous system, we're going to see gray matter in the cerebral cortex. And in the spinal cord, we're going to see it in that central butterfly or H-shaped area. Now that we have an understanding of gray matter versus white matter, let's talk about the brain and the importance of gray matter as it relates to the cerebral cortex. First though, let's talk about the cerebrum. The cerebrum is the entire largest part of your brain responsible for high level functions.

00:05:26

Speaker

So we're not talking about the brainstem or other areas there. We're talking about the cerebrum, kind of that entire brain area. And this area split into two hemispheres. We'll talk later about hemispheric differences. If we use an analogy of, let's say, an orange, the entire orange is going to be the cerebrum, but the orange peel is going to be the cerebral cortex.

Frontal Lobe Functions

00:05:52

Speaker

The cerebral cortex, then, is that thin outer layer covering the cerebrum, and this is going to be gray matter. And we should remember and think back, okay, gray matter is groups, this is cell bodies, this is dendrites, unmyelinated axons.

00:06:08

Speaker

So the goal here is really all about processing. There's a lot of processing that we do in the cerebral cortex. So a big key here is to increase the surface area to pack as many neurons and ability to create connections as possible within the physical confines of the skull.

00:06:27

Speaker

So towards that end, we have a few terms we need to get comfortable with. One is a gyrus. Gyri would be plural. These are the ridges or bumps on the surface of the brain that massively increase the brain's surface area.

00:06:41

Speaker

Also want to know this term because anatomically you'll hear certain areas of the cortex be defined by being located, let's say, in a precentral gyrus or in certain areas. So gyrus is these ridges or bumps. Then we also have what's called the sulcus. Plural would be sulci or sulci.

00:06:58

Speaker

These are the shallow grooves that separate the gyri and they function as landmarks between the lobes. We can also think that the gyri are going to be the ridges.

00:07:09

Speaker

while the sulci are the valleys. You may also hear the term fissures. Very deep sulci are fissures. So gyri are the ridges and bumps that really increase the surface area.

00:07:21

Speaker

Sulci are the shallow grooves that function as landmarks, and very deep sulci are known as fissures. Now that we've got a basic understanding of the building blocks, which are the neurons and what the cerebral cortex is, which is that outer covering, the gray matter, and we've heard the terms gyri and sulci, we can move on then to talking about the four main lobes of the cerebral cortex.

00:07:52

Speaker

Let's talk about the foremane lobe. The frontal lobe is our largest lobe, located right behind the forehead. Within the frontal lobe, we have our primary motor cortex.

00:08:02

Speaker

Primary motor cortex is involved with voluntary motor control. And also we're going to have in the frontal lobe Broca's area. This is typically located in the dominant hemisphere, and it's heavily involved with language production.

Motor Planning Areas

00:08:16

Speaker

Let's talk more about the primary motor cortex.

00:08:20

Speaker

It's located in the precentral gyrus, and it houses the upper motor neurons that then project out to the spinal cord and brain stem for movement. We'll talk in future episodes much more about upper motor neurons. Key to think about, though, is that you want an understanding of upper motor neurons because you will see in certain conditions when you have damage to upper motor neurons, stereotypical findings on your clinical exam. You may hear upper motor neuron syndrome.

00:08:47

Speaker

And key in an exam is determining, well, is my patient's presentation consistent with upper motor neuron or lower motor neuron problems? And so the origination of upper motor neurons that start everything are going to be in the primary motor cortex. The arrangement for movement, we've got what's called a homunculus. This is an arrangement of body parts within a map. If you see in some anatomy textbooks, it's a pretty interesting drawing where certain body parts look bigger than others.

00:09:16

Speaker

And those maps are typically displayed to show the size of the body parts representing the amount of cortex devoted to each area. So areas that maybe have greater fine motor needs or just need more cortical representation are going to show up bigger within the homunculus.

00:09:34

Speaker

Now the primary motor cortex is going to get some help. So the primary motor cortex has the upper motor neurons and those ultimately send the signal for voluntary movement. But we want to understand that within the frontal lobe, there's a premotor cortex and a supplemental motor area.

00:09:51

Speaker

These are both located anterior to the primary motor cortex and they're involved in motor planning and sequencing. They're going to select movements based on sensory input and environmental context.

Prefrontal Cortex and Behavior

00:10:03

Speaker

And then they're going to communicate with the primary motor cortex to generate and refine motor commands. An analogy I sometimes think of here is that the primary motor cortex houses the bosses. Those upper motor neurons are the ones that are ultimately going to send out the signal.

00:10:20

Speaker

However, the premotor cortex and supplemental motor areas, these are assistants. These are maybe they're reading the room, getting the pulse of the organization, getting a sense of how things are really going.

00:10:32

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And so they provide invaluable information to the bosses, really helping to modulate the motor output to ensure it's appropriate for the task, the situation, and the environment.

00:10:43

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There's a very simplistic way I think about this is instead of the boss sitting in an office firing out angry emails, the premotor cortex and supplemental motor areas are plugged into what's going on, maybe help with, okay, maybe we should say it this way, or here's what's happening. So messaging coming out from the upper motor neurons is appropriate for the task, the situation, and the environment. Within the frontal lobe, we also have the prefrontal cortex.

00:11:09

Speaker

This is at the very front of the frontal lobe, a lot of fronts there, so prefrontal, front and front. This is evolved with executive functions. The prefrontal cortex is a top-down regulator, inhibitor of automatic reactions in favor of goal-directed and what are considered socially appropriate behaviors and impulse control.

00:11:29

Speaker

Some of you may have heard about Phineas Gage. If you have not, I recommend you look up his case. It's a very interesting case. He had a rod that went through his skull and he survived. This was recognized as maybe the entry point for a lot of people in the medical community to consider, well, what role does the brain and certain brain areas have on executive functioning and personality?

00:11:52

Speaker

The prefrontal cortex develops from childhood to the mid-20s. It's the last brain region to fully mature. So those of us that have children, we recognize that, yeah, during this time of development, the executive functioning is not going to be on the same level as adults, which is sometimes easy to forget as a parent.

00:12:13

Speaker

But it's key to know that the prefrontal cortex, if there's damage in adult neurologic conditions, This can be very impactful and significant because you may see then some disinhibition.

00:12:25

Speaker

You may see socially inappropriate behaviors. This could come about from trauma or damage from stroke, traumatic brain injury. You can also see this happening under duress or if someone is stressed, you may see that people who normally act reasonable all of a sudden are acting maybe socially inappropriate or are not able to manage their emotions, that can be due to stress.

00:12:48

Speaker

Definitely due to substances, some people may choose to use alcohol willingly as a little bit of a social lubricant or a little bit of disinhibition because that helps take the prefrontal cortex offline.

Parietal Lobe and Sensory Processing

00:12:59

Speaker

Let's move on to the parietal lobe. When you hear parietal lobe, you want to think perception. The parietal lobe is located behind the frontal lobe and above the ears. Key functions in the parietal lobe are receiving and processing somatosensory information. Note that somatosensory, we have the soma word again, so that's body, so that's body sensations.

00:13:20

Speaker

Touch, temperature, proprioception, and the processing of pain. Keep in mind, pain is an experience, not a signal. There's no such thing as a pain nerve.

00:13:30

Speaker

But the parietal lobe is involved in processing pain. It's applying and helping to put these signals into context and meaning. So I think it's appropriate to say the parietal lobe is processing pain. Parietal lobe is also going to help with spatial awareness and navigation, sensory integration of somatosensory, visual, and auditory input, and some cognitive functions. Within the parietal lobe, we have our primary somatosensory cortex, and very similar to the primary motor cortex, this is arranged somatotopically within a map like homunculus. And what we'll see then in cases of

00:14:08

Speaker

chronic pain, and or stroke, that that homunculus can get what's called smudged. So instead of having a very clear mental map of the body, some areas get smudged, and this can create decreased function and increased pain. So there are some treatments that are designed to really work on improving the homunculus after stroke and or situations of chronic pain.

00:14:34

Speaker

These would be treatments such as patients identifying hand laterality, mirror treatment, etc.

Temporal Lobe Functions

00:14:41

Speaker

And I find these fascinating because on the surface, you might look at some of these treatments and think, well, there's not much happening, but it's actually helping with neuroplasticity and improving any smudging of the homunculus that may have happened.

00:14:54

Speaker

Moving on to the temporal lobe, temporal lobe is located behind the ears, below the parietal lobe. Very convenient that it's located right by the ears because it's going to be involved with auditory processing and language understanding.

00:15:07

Speaker

You may have heard of Wernicke's area. This area is involved in language processing, and it's located in the temporal lobe. So we think, let's take a pause here and think about speech. Speech production, Broca's area is in the frontal lobe. Speech understanding, language understanding, is Wernicke's area in the temporal lobe. These are two areas you want to make sure you have a good understanding of because these will come up again quite frequently in clinical practice. And we'll talk a little bit later about hemispheric differences and which hemisphere for most people language production and understanding is located on.

00:15:45

Speaker

Temporal lobe also involved with object and face recognition, some interpretation of visual input, and the temporal lobe is going to have a role in memory management and emotional regulation because the hippocampus and amygdala are physically embedded within the temporal lobe. They're in the medial temporal lobe, inner region closest to the midline. So from an anatomic perspective,

00:16:05

Speaker

Memory management and emotional regulation is part of the temporal lobe. Functionally, though, you may hear memory management, emotional regulation being talked about more as functions of the limbic system, and we'll talk about the limbic system later. So anatomically, the hippocampus and amygdala are technically within the temporal lobe, but functionally and conceptually, most people consider that to be part of the limbic system.

00:16:29

Speaker

Finally, we have the occipital lobe. This is the smallest of the four main lobes located at the rear of the skull. Functions here are going to be visual perception. The occipital lobe contains the primary visual cortex.

00:16:42

Speaker

Occipital lobes involved with color recognition, motion detection, and depth distance of objects. And there's going to be some memory role here. There's memory formation related to vision, including mapping of the visual world, remembering objects and faces. And occipital lobe is going to interact with other brain regions to convert visual perceptions into memories.

00:17:02

Speaker

So to recap, we've got frontal lobe, parietal lobe, temporal lobe, occipital lobe, frontal lobe's voluntary movement, language production, executive functioning, Parietal lobe is going to be perception, primarily sensory perception. Temporal lobe is going to be auditory processing and some role in memory, although a lot of people will say memory is part of the limbic system.

Occipital Lobe and Visual Processing

00:17:25

Speaker

And occipital lobe is vision. And again, that is a 30,000 foot view. We could go into greater much greater detail with each lobe, but that should give you a general roadmap of what's happening in the four major lobes of the cerebral cortex.

00:17:39

Speaker

What about hemispheric differences? Our brain is split into two cerebral hemispheres. These hemispheres are connected via the corpus callosum. This is white matter. So white matter, you should be thinking, okay, that's myelinated axons prioritizing speed of conduction. And that corpus callosum is going to serve as a bridge connecting the hemispheres.

00:17:58

Speaker

The hemispheres show up or they look like mirror images, but they don't function necessarily as mirror images. There are some important functional differences. From a general motor and sensory perspective, motor control and the sensory perception cross midline. So essentially, right hemisphere is going to control the left side of the body.

00:18:18

Speaker

Right hemisphere is going to receive sensory signals from the left side of the body, and it's going to be the opposite for the left. Most of you that have seen or worked with people who've had a stroke recognize this, a right-sided stroke. You're going to notice that there's difficulty with movement on the left side of the body and difficulty with sensory perception on the left side of the body as well.

Hemispheric Differences

00:18:38

Speaker

Language and perception, there's going to be some differences here. Big picture, language for most people is left side.

00:18:45

Speaker

Perception, visual perception is on the right side. Broca's area, recall that Broca's area is in the frontal lobe. Wernicke's area, recall, is in the temporal lobe.

00:18:56

Speaker

Broca's is speech production, should be easy to remember because frontal lobe is voluntary movement. That includes speech production. Wernicke's is language comprehension, and we know that the temporal lobe is auditory information. These are going to be lateralized and most often located within the left hemisphere.

00:19:15

Speaker

The left hemisphere is dominant in about 95% of people. I'll attach the reference for this in the show notes. Even if you're left-handed, apparently 70% of left-handers have a left-dominant hemisphere.

00:19:28

Speaker

And because left-handers make up such a small subset of the population, when you look at big picture general population, 95% of us have a left-dominant hemisphere. So if you have someone who's had a left-sided stroke, again, it will depend on where the lesion is. You need to be on alert that they may have trouble with either expressive aphasia and or receptive aphasia.

00:19:51

Speaker

In contrast, visual perceptual deficits are more common with right hemisphere lesions, specifically right parietal lobe injuries. Big picture, left hemisphere is more involved with spoken and written communication, Left hemisphere is more analytical, going through stepwise processes, breaking things down into pieces, whereas the right hemisphere looks more at the big picture. It's more holistic, more creative.

00:20:19

Speaker

For those of you that are interested in further reading, I highly recommend my Stroke of Insight. This was a neuroanatomist who sustained a stroke herself and documents her recovery. And what I find fascinating is, I believe as she was recovering, she had more access to her right hemisphere. And she just talked about feeling more holistic, feeling grateful. And so she was kind of looking at the possible benefits of not being so left side dominant for a while.

00:20:46

Speaker

But also her book is excellent as it relates to talking about her recovery, especially over multiple years. And I think her book really pushes back on the idea that recovery is limited to a finite timeline if you're able to put in the work. So her book is is excellent, but I really like also that it talks about hemispheric differences, especially right-sided being more big picture, holistic, creative. Having said that, there's patterns of what we'll observe in injuries or damage to the left hemisphere versus the right

Effects of Hemisphere Damage

00:21:17

Speaker

hemisphere. So left-sided or left hemisphere damage, here's what we're looking for.

00:21:22

Speaker

Difficulties with language if it's affected Broca and or Wernicke's area. Left-sided is going to be more cautious and hesitant. Difficulty with processing sequential information. And we're going to note right-sided sensory information.

00:21:36

Speaker

and movement issues. The two big ones here outside of the the motor and sensory problems is the language challenges and more cautious and hesitant. So if I get someone with a left-sided stroke, I'm already thinking about, okay, let's check communication.

00:21:52

Speaker

And I may have someone that I need to push on the gas pedal with. I may need to try and get them moving because they're going to be more cautious and hesitant. In contrast with right-sided lesions, if I use that pushing on the gas analogy, I'm not pushing on the gas with someone with the right-sided lesion. I'm pumping the brakes.

00:22:10

Speaker

Reason for this is people with right-sided lesions tend to display poor insight, poor safety awareness, and they're impulsive with difficulty grasping the big picture.

00:22:22

Speaker

So these are people that you don't leave them alone sitting in the chair if they're not safe to get up on their own. These are people that think they can do much more than they can and don't perceive some of the issues. So these could be spatial and or visual deficits. You may observe a left neglect. So right-sided, we're thinking perceptual problems, poor safety awareness.

Insular Cortex Functions

00:22:42

Speaker

You're going to need to really emphasize safety for many of these individuals. And obviously, if it's a right-sided hemisphere problem, we're going to see left-sided sensory and motor control difficulties.

00:23:01

Speaker

Let's close out then by talking about what's commonly known as the fifth lobe and the limbic system. So we previously covered the four major lobes of the cerebral cortex. The insular cortex is sometimes called the fifth lobe and it's tucked deep within the lateral sulcus.

00:23:17

Speaker

You may hear the term sylvean fissure, which separates the temporal lobe from the parietal and frontal lobes. Insular cortex, think interoception. You know how I like to link my letters together. So insular cortex, interoception.

00:23:30

Speaker

Interoception is the awareness of our internal state. And here the insular cortex is really helping us in terms of recognizing pain, hunger, autonomic functions, and self-awareness. It's also involved with sensory processing for taste and smell.

00:23:47

Speaker

So it contributes to emotion and particularly disgust. So if you smell something and you are completely grossed out by it, that's probably your insular cortex at work. Insular cortex is going to categorize smells as pleasant and or unpleasant, and it contributes to that odor-induced taste. So if you smell something that smells good to you,

00:24:06

Speaker

and it augments or improves the taste, that's also the insular cortex adding some context to what you're

Limbic System and Emotions

00:24:13

Speaker

smelling. The limbic system, this is not a lobe of the cerebral cortex per se. It's more an aggregation of brain structures, but it's so heavily involved in communicating with the cortex And it's so involved with memory and emotion and has a big impact on how we engage with the world and our surrounding as humans that i felt I wanted to put it here within this discussion. So the limbic system is an aggregation of brain structures located underneath the cerebral cortex above the brainstem. And it's going to include the thalamus.

00:24:46

Speaker

And then the other structures are lateral to the thalamus, including the hypothalamus, hippocampus, and amygdala. The limbic system is one of the oldest structures in the brain. Here we're thinking natural instincts. We can also think of the limbic system as our emotional nervous system.

00:25:01

Speaker

The limbic system is really focused on survival via triggering of behavior such as eating or drinking, reproduction, caring for young, responding to threats.

00:25:12

Speaker

Now, keep in mind, responding to threats, these threats could be tangible, physical, real. These could also be perceived threats. These could be, oh my gosh, I have a presentation tomorrow, or how so-and-so going to respond to the email I just sent?

00:25:28

Speaker

And that's key to remember because later on in discussions about chronic pain, pain neuroscience, autonomic nervous system, this threat response can really have a an adaptive output for us. It can make us adapt and rise to the occasion, but prolonged triggering responses to perceived threats can also be maladaptive and can produce some outcomes maybe that we don't want. These responding to threats is really going to engage the autonomic nervous system, primarily the sympathetic nervous system, and get us to move towards fight, flight, or freeze.

00:26:03

Speaker

Limbic system then main functions are emotions, behaviors, motivations, memory, and again, this interaction with the autonomic

Thalamus and Hypothalamus Roles

00:26:13

Speaker

nervous system. An additional thing I wanted to mention about the limbic system is its role in smells.

00:26:19

Speaker

So we have a primary olfactory cortex that's located in the temporal lobe, but it communicates directly with the amygdala and the hippocampus. And we're going to talk about both of those. When you hear amygdala, think emotion and threat detection. When you think hippocampus, think memory. So the smells from the primary olfactory cortex go directly to a emotion and memory formation. These smells aren't processed the same way other sensations are in the thalamus.

00:26:46

Speaker

And this is why if you've ever smelled something, and you feel like you're transported in time or it triggers a strong emotion, that's why. So I just thought that's an interesting note if you've ever wondered, well, why do smells seem to hit me much harder or they take me to a place in time where I can close my eyes, I smell those cookies, and I'm back in grandma's house. That's why, because of the way the smells go from the primary olfactory cortex to the amygdala and hippocampus.

00:27:12

Speaker

Let's start our discussion of the limbic system by talking about the thalamus. Thalamus is located in the middle of the brain, superior to the brainstem, and I call the thalamus the middle manager.

00:27:23

Speaker

It's going to relay incoming sensory information to the appropriate areas of the cerebral cortex, and it's going to process motor signals, those coming in from the cerebellum and basal ganglia, before sending them to the cortex, and So you essentially have this middle manager maybe scanning emails, looking at mail, sorting things out, determining, okay, what's appropriate for me to send out or where should I route this information? So really the Thalamus serves as a relay center.

00:27:51

Speaker

Thalamus is also involved in regulating arousal, alertness, and sleep stages, and it's going assist in processing emotions and memory. The hypothalamus is located below the thalamus. That should be pretty apparent from the name hypo below. So hypothalamus is below the thalamus. When you hear hypothalamus, think homeostasis. So we've got our H and H, hypothalamus, homeostasis.

00:28:14

Speaker

The hypothalamus is the gatekeeper to the autonomic nervous system, and it's also controlling cycles such as sleep-wake cycles, eating, body temperature, reproductive cycles, and sex drive.

Hippocampus and Memory

00:28:26

Speaker

And it also has a significant role in endocrine system control.

00:28:30

Speaker

The hypothalamus then is seeking an ongoing stage of homeostasis. I don't think we can really say we're ever fully in balance. This is a dynamic process. But the hypothalamus is looking at, okay, where are we at within our homeostasis window? Do I need to dial up or dial down certain things to make sure we're within this homeostasis area we want to be in?

00:28:52

Speaker

The hippocampus is heavily related to memory. The hippocampus is a curved structure deep within the medial temporal lobe, and there's one located in each hemisphere. The hippocampus is going to consolidate short-term memories into long-term permanent memories, and it's going to link emotions to specific memories. What we'll see as we discuss the amygdala as well is there's just a key role with emotion and memory. And this is interesting because if you've ever experienced a traumatic event or a negative memory, we know those are pretty much hardwired into our nervous system. We remember those. There's also, if you've had a very happy memory, those are wired within the central nervous system as well. You remember those very well. But to me, what's interesting is if emotions are vital to really embedding and then consolidating memories, if we're actively trying to learn something, if we can include some emotion there, maybe some amount of stress, not overwhelming stress, but some amount of emotion, something that takes it from, I've just, I'm turned off in terms of emotion, I don't really care, versus there's an emotional component, we're going to consolidate the memory a little bit better. And this is why i'll just speak from an educator perspective. It's challenging because on the one hand, I don't want my students extremely stressed.

00:30:12

Speaker

But from a neuroscience perspective, some amount of stress is needed for neuroplasticity. Some amount of stress is needed to provide an emotional component to

Amygdala and Stress Responses

00:30:22

Speaker

form a memory. And some amount of stress is needed because that's the nervous system's cue to tap into neuroplasticity.

00:30:29

Speaker

So I suppose this is my sales pitch to any students listening. I understand school is stressful, but some amount of stress is necessary to actually learn and remember. This brings us to the amygdala, the last part of the limbic system I want to discuss.

00:30:44

Speaker

The amygdala is located deep within the brain's temporal lobes. This is a pair of almond-shaped structures. The amygdala modulates the stress response in humans. We're talking fear and threat detection.

00:30:55

Speaker

The amygdala collaborates with the hypothalamus and has a role in dialing up the sympathetic nervous system. The hypothalamus is looking at sympathetic and parasympathetic versus the amygdala. You you get that amygdala going. It's sending a message straight to the sympathetic nervous system.

00:31:12

Speaker

And if you've ever had a moment of intense fear, something unexpected has happened, you know it's almost instantaneous. That amygdala is sending a shooting an email straight to the sympathetic nervous system. It's go time.

00:31:24

Speaker

The amygdala is also going to collaborate with the hippocampus to store memories, especially those tied to strong emotions. It's outside the scope of today's podcast to talk about PTSD, trauma, strong emotions with memory formation, but previously alluded to this, When there's emotional components, we're going to remember things a little bit better, and that can be both positive emotions, negative emotions. But anytime there's an emotion linked to a memory, the memory formation is going to be stronger.

00:31:53

Speaker

The amygdala is also going to be involved in procedural learning. Recall that procedural learning is that kind of automatic learning below the level of conscious thought. And the amygdala is involved with associative or trial and error learning because there's strong emotions attached when you're trying to learn something and using trial and error, you feel a great sense of accomplishment when you've figured it out. And you also feel disappointment, maybe embarrassment when you've made some mistakes. So there's strong emotional attachments or components to trial and error learning.

00:32:24

Speaker

So the amygdala is involved in that procedure learning involving trial and error. This is why in many cases, I feel trial and error learning is very powerful as long as it's done safely.

00:32:36

Speaker

There's some cases as we're working with our patients that we want to do a visual demo or explain what's happening. But if you provide an opportunity for people to learn via trial and error, the sense of satisfaction when they get it right, and or their ability to figure out what they did wrong and also experience some frustration when they get it wrong, that's going to help with procedural learning because there's emotions attached to

Cerebral Cortex Recap

00:33:01

Speaker

it.

00:33:01

Speaker

There's much more learning that happens versus if I just gave feedback at every trial and said, this is how you need to do it, the memory formation and the learning is not going to be as strong.

00:33:12

Speaker

To summarize then, our cerebral cortex is the covering of the cerebrum. It's that outer layer. It's the orange peel of the orange consisting of gray matter, which is designed to emphasize integration and processing of information.

00:33:25

Speaker

We have four main lobes, frontal lobe, parietal lobe, temporal lobe, and occipital lobe. The insular lobe is sometimes called the fifth lobe. And then we also discuss the limbic system, and that's not a lobe per se, but I wanted to include it in discussions of the cerebral cortex because of its role in emotion and memory. Knowing the anatomy and function of the cortical areas is going to assist in planning and executing examination and treatment for patients with conditions such as stroke.

00:33:53

Speaker

Thanks for listening to the NeuroPowerHour. I'm your host, Dr. Michael Powers, and I hope to catch you next time to continue learning.