cerebral cortex

Question 1

how is the neocortex grouped

Answer 1

layers (lamina) and columns

Question 2

how many cortical layers, and what are these designated by; what are cortical laminae in neocortex grouped by

Answer 2

3-6, designated by Roman numerals and letters for laminar subdivisions (e.g. IVa, b and c in visual cortex); grouped by function and anatomical features (neocortex is 6 layered bulk of cerebral hemispheres)

Question 3

cortical laminae in neocortex: features of layer 1 (dorsal surface)

Answer 3

contains mainly neuropril so acellular with association fibres and glial cells; mainly cortico-cortical connections

Question 4

cortical laminae in neocortex: features of layer 2 and 3

Answer 4

generally smaller pyramidal neurones with primarily cortico-cortical connections

Question 5

cortical laminae in neocortex: features of layer 3

Answer 5

generally smaller pyramidal neurones

Question 6

cortical laminae in neocortex: features of layer 4

Answer 6

rich in stellate neurones with locally ramifying axons; in primary sensory cortices, receive input from thalamus

Question 7

cortical laminae in neocortex: features of layer 5 (and 6 (ventral surface) to a lesser degree)

Answer 7

output layers so have pyramidal neurones with axons leaving cortex to connect with subcortical, brainstem and spinal cord

Question 8

cortical laminae in neocortex: cells in layer 5, and significance on motor vs sensory cortex size

Answer 8

Betz cells (large motor neurones, hence larger motor cortex vs sensory)

Question 9

how are columnar structures grouped and connected

Answer 9

functionally related (neurones with similar properties connected in same column), with dense vertical column connections (basis for topographical organisation)