Frontal Lobe | Cerebral Cortex
Summary
TLDRIn 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
- đ§ The frontal lobe is one of the four main lobes of the brain, responsible for a variety of functions, including movement, emotions, and cognition.
- đ The central sulcus is the anatomical marker that separates the frontal lobe from the parietal lobe.
- đ The lateral sulcus, also known as the Sylvian fissure, delineates the boundary between the frontal and temporal lobes.
- đïžââïž The pre-central gyrus contains the primary motor cortex, which initiates voluntary movement.
- đ€Č 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.
- đŒ The motor association cortex, including the pre-motor cortex and supplementary motor cortex, is responsible for planning and sequencing motor activities.
- đŁïž Broca's area, located in the frontal lobe, is crucial for language production and speech.
- đ The frontal eye field is involved in tracking objects and rapid eye movements.
- đ§ The prefrontal cortex, which makes up most of the frontal lobe, plays a significant role in cognition, behavior, emotion, and social interactions.
- đ ïž 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.
- đ§ 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
đ§ 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.
đââïž 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.
đïžâđšïž 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.
Mindmap
Keywords
đĄFrontal Lobe
đĄSulcus
đĄGyrus
đĄCentral Sulcus
đĄLateral Fissure
đĄPrimary Motor Cortex
đĄMotor Homunculus
đĄMotor Association Cortex
đĄBroca's Area
đĄFrontal Eye Field
đĄPrefrontal Cortex
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
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