Cerebral Cortex

Question 0

Which structures of the brain connect the cerebral hemispheres ?

Answer 0

Corpus callosum - larger white matter region and anterior commisure

Question 1

How many neurons are present in human cerebral cortex ?

Answer 1

10 to the power of 10 neurons

Question 2

What is the function of the precentral gyrus?

Answer 2

It is important in motor control and is just in front of the central sulcus

Question 3

What is the function of the post central gyrus ?

Answer 3

It is important in somatosensory control and is just behind the central sulcus

Question 4

What is Brodmann areas ?

Answer 4

It is the histological analysis of the cortex based on the laminar distribution
The neocortex has 6 layers

Question 5

Which laminae are important for sensory input ?

Answer 5

Lamina 4

Question 6

What laminae is important for motor input ?

Answer 6

Laminar 5

Question 7

What are some of the key areas of the subdivisions of the cerebral cortex ?

Answer 7

Post central gyrus - for somatosensory input
Primary motor cortex/precentral gyrus- for fine motor control
Visual cortex- for conscious visual sensation
Auditory cortex - for auditory sensation
Broca’s area- for speech production

Question 8

What do the layers if the cerebral cortex look like ?

Answer 8

Layer 1- has few cells
Layer 2 and 3- contain small pyramidal cells which project to other cortical regions
Layer 4- contain large stellate cells which receive massive inputs from the thalamus telling us sensory info
Layer 5- contain large pyramidal cells with very long projecting axons which make them major output cells
Layer 6- contain pyramidal cells that project to the thalamus providing an output for the thalamus

Question 9

What are basket cells like ?

Answer 9

They can innervate different layers or can remain confined to a single layer
They are inhibitory

Question 10

What are EEGs and explain the different waves ?

Answer 10

They measure the electrical activity of a large group of neurons in the cortex

• delta waves = low frequency and are active during deep sleep (<4hz)
• theta waves = slightly higher frequency which are active during sleep (4-7hz)
• alpha waves = slighter higher frequency again and here are active when your awake but relaxed (8-13hz)
• beta waves = higher frequency again and these are active during mental activity (13-20hz)

Question 11

What is CT imaging ?

Answer 11

Uses x rays which are fired at several angles
Computer constructs a 3d image
Exposure to radiation
Non functional imaging

Question 12

What is MRI imaging ?

Answer 12

Uses strong magnetic fields and radio waves to produce images based on hydrogen content of body tissue- water
No radiation.
Non functional imaging

Question 13

What is PET pane fMRI imaging ?

Answer 13

Functional imaging

It detects changes in the brain metabolism and blood flow
Active neurons require more oxygen/glucose and so brain blood vessels work by increasing the blood flow to these neurons

Question 14

How much of the cerebral cortex is made up of the association cortex and what is it’s function ?

Answer 14

75%
Important for integrating info received from other brain regions
It is very large in humans
Inputs: main one is the CORTICO-CORTICAL CONNECTIONS. Others include primary/secondary sensory and motor cortices, other association areas in both hemisphere and the thalamus and brainstem
Outputs: hippocampus, basal ganglia/cerebellum, thalamus etc

Question 15

What is the flow of connections of cortical areas ?

Answer 15

Primary sensory areas 
Higher sensory areas 
Association areas 
Premotor areas
Primary motor area - these then activate the CORTICO-spinal outputs to innervate muscles

Question 16

What is contra lateral neglect syndrome ?

Answer 16

It is the inability to attend to objects in space

The patients deny the existence of the side of the body opposite to lesion

Question 17

What is prospognosia?

Answer 17

Face blindness - caused by lesions to the temporal lobe

Question 18

What are the symptoms of Broca’s aphasias ?

Answer 18

Halting speech 
Repetitive 
Disorder syntax 
Disordered grammar
Disordered structure of words

Question 19

What are the effects of wernickes aphasias ?

Answer 19

Fluent speech 
Little repetition
Syntax adequate
Grammar adequate
Contrived or inappropriate words 

They can understand the language spoken to them but struggled producing speech

Question 20

Explain bilingualism ?

Answer 20

If you learn more than one language while you are young then the speech areas overlapping for both languages I strongly lateralised

If you learn another language after about 8/9 years old then then the speech areas are non overlapping so there is less lateralisation

Question 21

What is “split brain” and what is it used to treat ?

Answer 21

It is the surgical separation of the right and left hemispheres of the brain
It is used to treat epilepsy to try and prevent the spread of seizures from one hemisphere to the other,

Question 22

Where is language specialisation mainly in the brain ?

Answer 22

It is mainly in the left cerebral hemisphere

Therefore if a person has “split brain” surgery for epilepsy they can easily name objects in heir right hands but struggle to name objects in their left hands