Frontal Lobe | Cerebral Cortex

Summary

In this educational video, Dr. Mike explores the frontal lobe, the 'action lobe' of the brain, detailing its anatomical divisions and functional roles. He explains the central and lateral sulci that demarcate the frontal lobe from other lobes and delves into the primary motor cortex, motor association cortex, Broca's area for speech production, and the frontal eye field for tracking objects. The prefrontal cortex's role in cognition, emotion, and behavior is highlighted, emphasizing its importance in social interactions and decision-making.

Takeaways

• 🧠 The frontal lobe is one of the four main lobes of the brain, responsible for a variety of functions, including movement, emotions, and cognition.
• 📏 The central sulcus is the anatomical marker that separates the frontal lobe from the parietal lobe.
• 🔍 The lateral sulcus, also known as the Sylvian fissure, delineates the boundary between the frontal and temporal lobes.
• 🏋️‍♂️ The pre-central gyrus contains the primary motor cortex, which initiates voluntary movement.
• 🤲 The motor homunculus is a map of the body's skeletal muscles on the primary motor cortex, with more area dedicated to muscles requiring fine motor skills.
• 🎼 The motor association cortex, including the pre-motor cortex and supplementary motor cortex, is responsible for planning and sequencing motor activities.
• 🗣️ Broca's area, located in the frontal lobe, is crucial for language production and speech.
• 👀 The frontal eye field is involved in tracking objects and rapid eye movements.
• 🧐 The prefrontal cortex, which makes up most of the frontal lobe, plays a significant role in cognition, behavior, emotion, and social interactions.
• 🛠️ Damage to the prefrontal cortex can result in changes to an individual's behavior and emotional responses, as illustrated by the case of Phineas Gage.
• 🧠 The frontal lobe is often referred to as the 'action lobe' because it is involved in initiating and executing actions.

Q & A

What are the four main lobes of the brain?

The four main lobes of the brain are the frontal lobe, parietal lobe, occipital lobe, and temporal lobe.

What is the anatomical marker that separates the frontal lobe from the parietal lobe?

The central sulcus is the anatomical marker that separates the frontal lobe from the parietal lobe.

What is the term for the fissure that separates the frontal lobe from the temporal lobe?

The fissure that separates the frontal lobe from the temporal lobe is called the sylvian fissure or lateral sulcus.

What is the primary motor cortex and where is it located?

The primary motor cortex is the area of the brain responsible for initiating voluntary movement, and it is located in the pre-central gyrus, in front of the central sulcus.

How is the skeletal muscular system represented on the primary motor cortex?

The skeletal muscular system is represented on the primary motor cortex through a map known as the motor homunculus, which organizes muscles based on the amount of fine motor control they require.

What is the role of the motor association cortex in relation to the primary motor cortex?

The motor association cortex, which includes the pre-motor cortex and supplementary motor cortex, is responsible for planning and sequencing motor activities, working in conjunction with the primary motor cortex to execute complex movements.

What is Broca's area and what function does it serve?

Broca's area is a region within the frontal lobe that is responsible for language production and speech. Damage to this area can result in a type of aphasia characterized by difficulty in speaking.

What does the frontal eye field contribute to in terms of visual processing?

The frontal eye field is important for tracking objects and rapid eye movements, allowing for the smooth following of moving objects in the visual field.

What is the prefrontal cortex and what are its main functions?

The prefrontal cortex is the largest part of the frontal lobe and is involved in higher cognitive functions, emotion, behavior, and understanding context to guide appropriate actions.

What historical case illustrates the importance of the prefrontal cortex in behavior and cognition?

The case of Phineas Gage in the 1800s demonstrated the importance of the prefrontal cortex. After an accident that damaged his prefrontal cortex, Gage's personality and social behavior changed dramatically.

How can the frontal lobe be described in terms of its overall function in the brain?

The frontal lobe can be described as the 'action lobe' because it is responsible for initiating, planning, and executing motor activities, including those related to speech and complex behaviors.

Outlines

00:00

🧠 Introduction to the Frontal Lobe

Dr. Mike introduces the frontal lobe of the brain in this video, providing an anatomical orientation by comparing it to other lobes: the parietal, occipital, and temporal lobes. He explains the sulci and gyri, which are the anatomical features that help delineate the frontal lobe from its neighboring areas. The central sulcus is identified as the boundary between the frontal and parietal lobes, while the lateral sulcus separates the frontal lobe from the temporal lobe. The video aims to explore the frontal lobe's functional divisions, emphasizing its role as the 'action lobe' responsible for initiating voluntary movements and behaviors.

05:02

🏃‍♂️ Motor Functions of the Frontal Lobe

This paragraph delves into the motor functions of the frontal lobe, specifically highlighting the primary motor cortex located in the pre-central gyrus. The primary motor cortex is responsible for initiating voluntary movements, and a somatotopic map, known as the motor homunculus, represents the body's skeletal muscles in this area. The motor homunculus illustrates that muscles requiring fine motor skills, such as those in the hands and face, have a larger representation in the brain due to the complexity of their movements. Additionally, the motor association cortex, which includes the pre-motor cortex and supplementary motor cortex, is discussed as the area responsible for planning and sequencing motor activities, such as writing or playing an instrument.

10:02

👁️‍🗨️ Cognitive and Emotional Roles of the Frontal Lobe

The final paragraph discusses the prefrontal cortex's role in cognition, behavior, and emotion. It emphasizes the prefrontal cortex's importance in understanding and responding appropriately to social contexts, as well as in language production, particularly through Broca's area. Damage to this area can result in changes to behavior and emotional responses, as historically illustrated by the case of Phineas Gage. The prefrontal cortex is also involved in tracking objects and rapid eye movement, as managed by the frontal eye field. Overall, the prefrontal cortex is portrayed as a critical area for executive functions and social interactions.

Keywords

💡Frontal Lobe

The frontal lobe is a region of the brain located at the front of the cerebral cortex and is involved in a variety of functions including reasoning, planning, emotions, and motor control. In the video, the frontal lobe is the main focus, with the script detailing its anatomical location and its functional divisions, emphasizing its role as the 'action lobe' of the brain.

💡Sulcus

A sulcus is a shallow depression or groove in the brain's surface, separating different areas of the cerebral cortex. The script mentions the central sulcus as a key anatomical marker that separates the frontal lobe from the parietal lobe, highlighting the importance of sulci in defining brain regions.

💡Gyrus

A gyrus is a ridge of gray matter in the brain that forms the bumps between sulci. The script describes the presence of a sulcus and the subsequent gyrus as a common pattern in brain anatomy, with the pre-central gyrus being specifically identified as the location of the primary motor cortex.

💡Central Sulcus

The central sulcus is a prominent sulcus that runs longitudinally down the brain, serving as the boundary between the frontal and parietal lobes. The script explains its role in anatomical demarcation and its proximity to the pre-central gyrus, which is crucial for voluntary movement.

💡Lateral Fissure

The lateral fissure, also known as the sylvian fissure, is a cleft in the brain that separates the frontal lobe from the temporal lobe. The script uses this term to further illustrate the anatomical boundaries of the frontal lobe.

💡Primary Motor Cortex

The primary motor cortex, located in the pre-central gyrus, is the region responsible for initiating voluntary movements. The script describes its role in the motor homunculus, a map of the body's muscles on the cortex, and how damage to this area can affect movement.

💡Motor Homunculus

The motor homunculus is a representation of the body's musculature on the primary motor cortex, with areas dedicated to different body parts. The script explains that muscles requiring fine motor skills, such as the hands and face, have larger areas on this map, reflecting their complexity.

💡Motor Association Cortex

The motor association cortex, which includes the pre-motor cortex and supplementary motor cortex, is involved in planning and sequencing complex movements. The script describes its role in coordinating muscle movements for activities like writing or playing an instrument.

💡Broca's Area

Broca's area, named after the French physician Pierre Paul Broca, is a region of the brain involved in speech production and language. The script explains that damage to this area can result in Broca's aphasia, characterized by difficulty in speaking.

💡Frontal Eye Field

The frontal eye field is a region of the frontal lobe that is responsible for tracking moving objects and rapid eye movements. The script emphasizes its role in visual tracking and the coordination of eye movements.

💡Prefrontal Cortex

The prefrontal cortex is a part of the frontal lobe that is involved in higher cognitive functions such as decision-making, social behavior, and understanding context. The script discusses its importance in emotional and behavioral regulation, using the case of Phineas Gage to illustrate its significance.

Highlights

Introduction to the frontal lobe and its anatomical position among other brain lobes.

Explanation of sulci and gyri as anatomical features of the frontal lobe.

Identification of the central sulcus as the anatomical marker separating the frontal and parietal lobes.

Description of the Sylvian fissure, which separates the frontal lobe from the temporal lobe.

Overview of the functional divisions of the frontal lobe and its role as the 'action lobe'.

Discussion on the pre-central gyrus and its function as the primary motor cortex for voluntary movement initiation.

Explanation of the motor homunculus, a map of the body's skeletal muscles on the primary motor cortex.

Importance of fine motor skills and their representation in the size of the motor homunculus.

Role of the motor association cortex in planning and sequencing motor activities.

Localization of motor skills in the motor association cortex, such as hand skills for playing the piano or juggling.

Introduction of Broca's area and its critical role in language production and speech.

Consequences of damage to Broca's area, leading to a type of aphasia characterized by difficulty in speech production.

Function of the frontal eye field in tracking objects and rapid eye movement.

The prefrontal cortex's extensive role in cognition, behavior, emotion, and language processing.

Historical case of Phineas Gage illustrating the impact of prefrontal cortex damage on personality and social behavior.

Summary of the frontal lobe's anatomical and functional divisions and its significance as the action lobe.

Transcripts

hi everyone dr mike here in this video

we're going to take a look at the

frontal

lobe now to orientate ourselves let's

look at the other lobes of the brain we

know that we've got the frontal lobe

here

the parietal lobe the occipital lobe and

the temporal lobe and if you were to

pull that away you would see the insula

underneath

we're focusing in this mini lecture on

the frontal lobe

now a couple of things we need to know

some of the anatomical divisions so

how do we know that the frontal lobe

sits here what sits under it being the

temporal

and parietal behind it how do we

delineate between those particular lobes

so first thing is

with the frontal lobe what you're going

to find is that there is

a dip down that we call a sulcus and

then there's a bump

up called a gyrus and then another dip

down called a sulcus so

if i've got a sulcus here there's always

going to be a gyrus the bump up right

next to it and then there's going to be

another

sulcus for example what you're going to

find is that there is a sulcus

sitting pretty much in the middle of the

brain going straight down like that and

we call this the central

sulcus

now the central sulcus this central

sulcus is actually the delineating

marker anatomically

that separates the frontal lobe from the

parietal lobe

now inferiorly we've got this fissure

that sits here called the sylvanian

fissure or

called the lateral sulcus and that

separates the frontal lobe

from that of the temporal lobe so

central sulcus

separates the frontal from the parietal

and the lateral sulcus separates the

frontal

from the temporal lobe so now that we've

identified

the anatomical barriers lateral sulcus

write that down

what we can now talk about are the

functional divisions of the frontal lobe

now

functionally they're not as defined as

you know

here's a sulcus and this is where this

function starts and ends

but i can tell you whereabouts these

functions predominantly sit

now this as you can see there's five

different functions i want to go through

that basically make up what the frontal

lobe does

but the way i want you to think about is

this the frontal lobe is the action lobe

we want something done we recruit the

frontal lobe

it may be motor movement it may be

talking it may be some sort of

emotional behavior that we need to

demonstrate

it all needs to come from the frontal

lobe so what we're going to do is we're

going to start centrally and move

anterially and we're going to start with

we've got the central sulcus

which means there must be a gyrus in

front of it which we can see here

which we call the pre-central gyrus so

that's

this area here pre-central gyrus this is

actually the site

of the primary motor cortex now the

primary motor cortex is important

it is the area in which we initiate

voluntary

movement the area that we initiate

voluntary movement so

that's worth writing down

initiate voluntary or conscious

movement

now if i want to move my mouth for

example it needs to initiate be

initiated from here if i want to move my

arm again

the signal needs to start from here and

so forth

so how does it know just move my arm or

move my mouth or move my feet

well importantly there's actually a map

of all the muscles

of the body or at least all the

voluntary or consciously moved muscles

so skeletal muscles

there's a map of the skeletal muscular

system

on the brain specifically on this motor

cortex

and if i were to cut down the central

sulcus and have a look in

this is what we'll see right and this is

how the map

works so i'll just wipe this off here

so what you'll find is that the muscles

of the foot

are mapped here then the muscles of the

leg are mapped here and the muscles of

the bum and the back

and the arm and the hand and the neck

and the face and the eyes and the mouth

and the pharynx larynx and tongue this

is how

we map the muscle skeletal muscles of

the body onto the primary

motor cortex this is called our motor

homunculus and as you can see some

muscles

have not much area of the primary motor

cortex dedicated to it and some have a

lot

so for example our back doesn't have

much area dedicated to it but the hand

and the face does why is this what's

because

muscles that require a lot of fine skill

or fine motor movement

so for example our hand if i were to

pick up a pen it requires a lot of fine

motor movement same with our lips for

speech for example and our face so

what that means is those areas have a

larger part of the brain dedicated to it

because you need more neurons to allow

for a nice pattern sequence of firing

so that you can articulate that movement

better right

so this is how we map those skeletal

muscles onto the primary motor cortex

so if i were to translate this onto

here for example what you're going to

find is that

the foot's going to be a little bit

around the corner but then we're going

to have the

leg then we're going to have the

bum back

arm hand

neck

face eyes

mouth pharynx

larynx

tongue

and so this is moving around like that

and so it's moving around like that

so the way that this primary motor

cortex works if i just want to move the

mouth

contract those muscles that gets

activated move the arm contract those

muscles

this area gets activated but we don't

just move those muscles

in isolation we usually move them

because we want some sort of planned

patterned and sequenced motor activity

so for example if i need to write it

needs to be a planned pattern sequence

motor activity if i want to juggle or

play the piano the same thing

so we need to recruit another part of

the frontal cortex

to help this area we need a part of the

brain that says okay

fire this muscle this time and then this

muscle at this time and then this muscle

at this time

so it plans and sequences that motor

firing and this is what we now call the

motor association cortex

this sits just in front of this primary

motor cortex

in this area here just immediately

in front of it and it's made up of the

pre-motor cortex and the supplementary

motor cortex

we're going to talk about them together

and what happens is this

if i want to grab a pen and start

writing

i need to tell certain muscles to

contract in a certain sequence

it needs to be planned in sequence like

i said and this is going to begin

here at this motor association cortex

now

where are the muscles or where's the

area of the primary motor cortex for the

muscles of the hand

it's all here so the motor association

cortex

for hand skills are going to be here

could be playing the piano or juggling

or whatever it may be

so i've got hand skills here

and again that's going to fire off and

then tell

the primary motor cortex what the fire

what moment if i want to

turn or move my head for example it's

going to fire here

it's going to be head tilt

or head turning

if i want to speak produce language

articulate words or sounds that come out

of my mouth this is going to happen in

this area

here language production

but this language production area

actually has a name it's called brocco's

area b-r-o-c-a-s

area and this is actually important

enough to have its own

function so broca's area is actually

there for

language production

language and speech production

to be able to speak now importantly

again this motor association cortex here

it's there

for planned

sequenced motor skills

that's what that motor association

cortex does and again that's the same

with language because it's planned

it's sequenced it's a motor skill but

specifically it's for language

production and it's called brocco's

area if you have damage to broca's area

what do you think you have aphasia

inability speaks with broca's aphasia

inability to produce

words now we're going to talk about the

frontal eye field and the frontal eye

field sits around about here

and the frontal eye field

is important for following objects

so if you see an object jump into your

vision and you can follow it and track

it

this is the frontal eye field it's

important also for rapid

eye movement so let's write this down

tracking

objects and

rapid eye movement right

the last part i want to talk about makes

up most

of the frontal lobe it's called the

pre-frontal cortex

pre-frontal

cortex and again i said that the whole

frontal lobe is the action lobe

right so the prefrontal cortex is about

demonstrating

these actions in regards to emotions and

behaviors

and understanding and cognition all

right so for example this is why i like

to because

the front prefrontal cortex does a whole

bunch of stuff but the way i like to

think about is like this

how do you know how to behave in a

particular scenario how do you know what

to say

in this context as opposed to this

context what you say in a job interview

may not be what you say to your friends

and family

for example how do you know not to walk

up and just slap somebody in the face

or yell profanities at them it's because

you can cognitively understand and

process a situation

and then behave a pope appropriately in

that situation all because of the

prefrontal cortex

and we know this because for example

individuals who have damage to the

prefrontal cortex their behaviors

change their emotions change their

processing of how to behave in motion

in context change an individual called

phineas gage back in the 1800s working

on the railway

an explosion put a metal spike through

his prefrontal cortex

and his behavior totally changed he went

from being this calm and placid person

to quite a crude and crass person in

social contexts

so that's the prefrontal cortex so again

it's important when it comes to

cognition

cognition behavior

emotion but also things like

language as well processing

and so forth so what you can see here is

the frontal lobe the action lobe and the

way we've divided it anatomically

and functionally