Forebrain: Cerebral cortex

Question 1

What are the 2 cell types in the cortex?

Answer 1

Pyramidal
Granular
names on the basis of shape

Question 2

What are the distinguishing features of pyramidal cells

Answer 2

Quite large (10-70microm)
have apical and basal large dendrites
EFFERENT or Golgi I

talk to other areas of the cortex or out of the cortex

Question 3

What are the distinguishing features of granule or stellate cells

Answer 3

• very small, round cells
• Local circuit neurons: talk to other cells close by
• process sensory info
• “Golgi II”

Question 4

What layers of the neocortex are ‘efferent layers’ and what do they therefore contain?

Answer 4

Layer II: ‘Ext. granular’
Layer IV: ‘Int granular’

Both of these layers have a high concentration of granule cells.
These convey infor out

Question 5

What are the two types of fibres in layer III (pyramidal cells)? ‘External pyramidal’

Answer 5

Commissural Fibres: between hemispheres
Association Fibres: within cortex on the same side

Co-ordinate the brain WITHIN the cortex

Question 6

What are the two types of fibres in layer V (pyramidal cells)? ‘Internal pyramidal’

Answer 6

Projection fibres

Big, long efferent fibres that take a message OUT to co-ordinate the lower motor neurons in the spinal cord and brain stem etc

Question 7

What is special about the Internal Granular layer ‘IV’

Answer 7

Full of granule cells
Convey info from ‘specific sensory locations’; like the eye, ears, skin.
Specific afferents, the principal area they terminate and information is processed, before it goes to affect the output brain

Question 8

What is special about the Ext Granular layer ‘II’

Answer 8

If information is travelling from one area of the cortex to another it usually terminates in the top 3 layers, especially Layer II

Question 9

What is homotypical cerebral cortex and where is it found?

Answer 9

-where the 6x layers of granular and pyramidal cells is clearly distinguishable.

This is found in the association areas. ‘frontal, temporal, parietal’

Where they are getting equal amounts of input/output

Question 10

What is heterotypical; granular cerebral cortex and where is it found?

Answer 10

Granule cells dominate;
Layers 2 and ESPECIALLY 4 increase

For primary SENSORY input; primary somatosensory, visual and auditory cortex

Question 11

What is heterotypical; agranular cerebral cortex and where is it found?

Answer 11

Pyramidal cells dominate in layers 3 and 5

Non-distinguishable layers 2 & 4

for primary MOTOR cortex (efferent)