Lecture 1 - The Human Brain Flashcards
What is the cerebrum covered by?
a layer of cells called the cerebral cortex
4-6mm
outer layer
grey matter
What changes as you go from simpler to most complicated mammal?
the forebrain develops faster than any other part of the brain.
simpler=more smooth
increasing in complex= relative amount of the forebrain increases
in doing so, the cerebral cortex folds to accommodate
What is the basic principle of the brain’s organisation?
Right side of the brain controls the left side of the body
Left side of the brain controls the right side of the body
What makes up the brainstem?
2x sections
- upper= midbrain
- lower= pons + medulla
What is the relative placement of the brain stem and cerebellum?
cerebellum is behind the brain stem
What is the role of the cerebellum?
co-ordinates movement
small convolutions
What makes up the hindbrain?
all red
cerebellum
pons
medulla
What are the four areas of the brain from medial view?
brain stem
forebrain
midbrain
hindbrain
What does Pons mean?
bridge
What is the role of the forebrain?
responsible for making us higher order animals
conscious cognitive thoughts
movement and sight
What is a gyrus?
folds of the forebrain
What is a sulcus?
border/gap between each gyrus
a. sulci=shallow grooves
b. fissures= deep grooves
What is the major fold present in everyone and separates lower and upper forebrain?
lateral sulcus (fissure) (deep crevasse)
What is the general principle pattern of folding?
consistent + slight variations (like a face)
- lateral fissure (deep, separates lower part of hemisphere from rest)
- central sulcus (lies roughly in centre)
- parietal-occipital sulcus (top/upper –> lateral/stops just short)
when joined, separate the brain into four lobes
What is the principle pattern of naming?
Geography
- Frontal Lobe
- Parietal Lobe
- Occipital Lobe (under the occipital bone of skull)
- Temporal Lobe (under temporal bone of skull)
Where is the parietal-occipital sulcus more apparent?
Medial view of hemisphere
What is the role of the longitudinal fissure?
separates the right and left hemispheres
What is present in the lower aspect of the brain?
Pre-occipital Notch
What is the role of the frontal lobe?
behavioural control
executive thinking
What does the Frontal Lobe consist of?
central sulcus + lateral fissure
- Pre-central gyrus
(3x longitudinal gyri) Superior frontal gyrus
Middle frontal gyrus
Inferior frontal gyrus - Triangular part of the inferior frontal gyrus
- Pre-central sulcus
superior frontal sulcus
inferior frontal sulcus
Describe longitudinal gyri
complicated
vary between people
- consistent upper
-convoluted and variable middle
What does the Temporal Lobe consist of?
Lateral fissure + pre-occipital notch
- 3x longitudinal gyri
- 2x sulci
- HESCHI’S Gyrus
- transverse temporal gyrus,
- located in 1 primary auditory area
- percusses sound
What does the Parietal Lobe consist of?
Complex folds
Central sulcus + parieto-occipital sulcus
- Post-central gyrus
2x lobules
- inferior lobule has a distinct pattern of lobule within it –> Supra Marginal Angular Gyrus
What does the Occipital Lobe consist of?
parieto-occipital sulcus + pre-occipital notch
What is the function of the pre-central gyrus?
functional name: primary motor cortex
in the frontal lobe
-primary function is to control the muscles on the opposite side of the body
control: very organised
What does gyri consist of?
gray matter + white matter
- outer layer of gray matter = 4-6mm
- under layer of white matter
Electrical stimulation of pre-motor areas
Lower–> upper
at any point of motor cortex causes contraction of specific skeletal muscle fibres on opposite side of the body
- face, eyes, vocalisation (head neck lips)
- fingers, head, arms
- small: trunk - thorax, abdomen
- large(large control): leg, thigh
- foot (medial side)
What does the pre-motor areas represented?
distorted representation of the area relative to amount of control
How is the pre central gyrus organised?
Somatotopically
according to body map
(somites/sequence of body)
What is the function of the post central gyrus?
Primary Somatosensory Cortex
primary function is the conscious perception of sensation (e.g. touch, pain, heat)
sensation - termination/end of all touch and pressure pathways from skin
Describe the post central gyrus
each region of the primary somatosensory cortex receives nerve impulses for touch, pressure, vibration,temperature,pain and joint+muscle position
size of cortical area which receives impulses from a particular part of the body depends on # of receptors (x not size of body)
–> larger region for lips and fingertips
can pinpoint somatic sensations
- similar somatopical organisation
Which regions are relatively larger in the pre-central gyrus?
leg and thigh
Which regions are relatively larger in the post-central gyrus?
lips and fingetips
How is the post-central gyrus organised?
Somatotopically
according to body map
(somites/sequence of the body)
How the central cortex organised?
Somatotopically
What is the name of the area of the superior temporal gyrus?
Primary Auditory Area
extends deep into the fissure
- extension of the superior temporal gyrus which goes deep
Transverse gyrus of heschl
primary area which receives sound
What is the role of the Primary Auditory area?
receives information for sound
auditory perception
organised Tonotopically
- according to tone/freq./pitch
–> front -> low freq.
back -> high freq.
Which cortex is located in the occipital lobe?
Primary Visual Cortex
located on the POSTERIOR tip of the occipital lobe, on the MEDIAL SURFACE next to the LF
Arranged around the Calcarine Sulcus
What is the role of the Primary Visual Cortex?
functional relationship with vision
processing information related to vision
receives visual information
Which cortex is viewed better from the Medial Side?
Primary Visual Cortex
extend
Which sulcus is the primary visual cortex arranged around?
Calcarine Sulcus
How is the primary auditory area organised?
Tonotopically
How is the Primary Visual Cortex organised?
Visuotopically according to map of visual field Retinotopically organised according to retina
Describe the visual field
- Tip of cortex = central part of visual field = discriminative, upside down
- Deep section of cortex = peripheral vision = Right vision goes to left part of the brain
vision is highly acute
Which part of the visual field do you use the most?
Central part of visual field at the tip/outer part of the cortex
=2/3 of primary visual field
=impulses passing through optic nerve
=discriminative reading
What is a Lesion?
hole in the visual field opposite
How are the right and left sides of the visual field connected?
By fibres from either sides which cross the midline
They combine to give a 3D Panoramic Vision
What are the main Primary Motor and Sensory areas
Motor: Primary Motor Cortex
Sensory: Primary Somatosensory Cortex - Skin Sensations
Primary Auditory Area - Ear Sensations
Primary Visual Cortex - Eye Sensations
What is the role of the Supplementary/Secondary Visual Cortex?
Processes the visual information in complicated ways
Adds to the image via:
a. colour b. recognises movement c. 3D analysis
What is the Primary Visual Cortex Helped by?
Supplementary/Associated Visual Cortex
- can be quite complex
What is the role of the Supplementary/Secondary Motor Area?
Plans movements
Stimulates cells to produce movements
What is the Primary Motor Cortex helped by?
Supplementary/Secondary Motor Cortex
- can be quite complex
Which hemispheres are dominant?
Left handed people= RH hemisphere is dominant
Right handed people= LH hemisphere is dominant
What is another name for the Left Hemisphere?
Verbal Language Area
Dominant side of RH people
Describe the Left Hemisphere
- Verbal Language Area
- is the Dominant side of RH people (99% of people)
- all functions regions which are related to SPEECH and LANGUAGE are present in ONE hemisphere ONLY
- speaking, hearing, reading, writing
Who and how was Wernicke’s Area Discovered?
by Kyle Wernicke
by studying patients with stroke in this area
even though people could hear what was being said to them, but COULDNT UNDERSTAND
What is the role of Wernicke’s Area?
- UNDERSTANDING
- speech recognition
- comprehension
- gives meaning
- sensory analysis of speech: translates words into thoughts
- fluent
- ASSOCIATION AREA
Superior Temporal Gyrus
damage = Sensory/Fluent aphasia = unable to understand spoken word
What is an Aphasia?
A disorder of speech associated with the brain
Which muscles are used for smooth speech?
Pharynx
Larynx
Lung muscles
Respiratory Muscles
What is Broca’s Area?
Triangular Area
Contains all Information which STIMULATION of muscles to pronounce words
- ARTICULATION of speech (motor speech area)
-relatively small
-more present in more complex beings
damage (tumour) = still pronounce (noise) but NOT CLEAR = Motor/Non-fluent/Speech/Expressive Aphasia = muscles aren’t co-ordinated for speech
What is the Arcuate Fasciculus ?
the pathway which connects Wernicke’s and Broca’s Area
damage(tumour)= Individual will understand spoken word, but REPLY UNRELATED to the question = NOT CONNECTED= disconnection aphasia
Where does a Motor Aphasia Occur?
In Broca’s Area
Where does a Sensory Aphasia occur?
In Wernicke’s Area
What is a stroke on the left side of the brain more likely to involve and why?
Speech Disorder
Motor Disorder
as Broca’s area is located on the left side of the brain and is related to speech pronunciation
What is stroke on the right side of the brain more likely to involve and why?
Sensory Disorder
Fluent Disorder
as Wernicke’s Speech area is located in the right side of the brain and is related to understanding the spoken word
What is another name for the Right Hemisphere?
Non-Verbal Language Area
Non-Dominant Side (for RH people)
Describe the Right Hemisphere
NON-verbal Language Area NON-dominant side supra marginal angular gyrus 1. BODY Language =90% of language/communication between people 1. non-verbal language (body language) 2. Emotional Expression (language) 3. Spatial Skills (identify 3D objects 4. Conceptual Understanding 5. Artistic Skills 6. Musical Skills
What is the role of the SupraMarginal Angular Gyrus?
Reading + Writing
Input from = visual cortex + Wernicke’s Area
See the words in the back and transferred to the inferior parietal lobule
writing = 1. Transfers visual representation (stored) of WRITTEN words –> Exner’s Area –> 2. Motor Cortex (conveys muscles of right hand to write the word)
reading = 1. receiving input from primary visual cortex 2. processing visual information
What are Association Areas?
Supplementary Areas which Process information that is received by primary cortexes
They are connected to each other via Association Tracts
Large remaining parts which are involved with complicated/high order brain functions
What does the Frontal Association Cortex have a critical function in?
lies in front of the motor etc area this large area is involved with a variety of functions (doesn't have simple mapping like 1 motor cortex) intelligence-idea,movement personality behavioural profile mood cognitive function
What does the Parietal Association Cortex have a critical function in?
spatial skills
3D Recognition
- shapes, faces, written word, concepts, abstract perception
What does the Temporal Association Cortex have a critical function in?
wide expanse and goes down deep
memory-most important-past,present,future
mood
aggression
intelligence -each feature is not specifically localised (complicated relationship, 1 neuron has multiple outputs)
lesion: people become aggressive - alsiemers patients
What is a stroke?
CerebroVascular Accident (CVA)
characterised by an abrupt onset, or persisting neurological symptoms e.g. - paralysis or loss of sensation
*intracerebral haemorrhage (from blood vessel)
*blood clots
*atherosclerosis: formation of cholesterol (contain plaques which block blood flow)
Which three biological conditions can cause strokes?
intracerebral haemorrhage (from blood vessels)
blood clots
atherosclerosis (formation of cholesterol - containing plaques that block blood flow)
Which side of the brain is affected when there is a stroke on the right side of the body?
opposite side of brain effects opposite side of body
left side of brain
What are the four risk factors of strokes?
high blood pressure
high blood cholesterol
diabetes
smoking
What affect does a stroke have on the primary motor cortex?
lesion would PARALYSE MUSCLE MOVEMENT(spastic) on the opposite side of the body
the muscles paralysed would depend on where (according to the homunculus) on 1/primary motor cortex
What affect does a stroke have on the primary somatosensory cortex?
lesion would result in the LOSS OF SENSATION on the opposite side of the body
dependant on the mapping of the sensory cortex (according to the homunculus)
What affect does a stoke have on the primary auditory area?
lesion would result in a LOSS OF HEARING in the opposite ear
What is Ataxia?
a disorder in muscle co-ordination due to damage in cerebellum, such as trauma or disease
resulting in - uncoordinated movements or a loss in balance
What can Ataxia result in?
uncoordinated movements
loss in balance
What does Embryonic Development consist of?
increase in brain size GRAY matter (functions/cell bodies) increase MORE than white matter (axons)
What does the cerebral cortex consist of?
region of gray matter
is 2-4mm thick
contains billions of neurons (cell bodies)
increases more than white matter
What happens when gray matter enlarges?
causes the cortical regions to fold and roll upon itself
How do we know that Association areas are involved in higher order brain functions?
Due to how they are affected by injury
What do association areas do?
Association areas bring together complicated functions
