Organization of Cerebral Cortex

Question 1

Describe the 9 stages of neuroembryological development

Answer 1

1. Neural induction and patterning: The neural plate forms from surface ectoderm,
   then patterned into dorsoventral and anteroposterior domains
2. Neurulation: The neural plate folds up and the lateral edges fuse dorsally forming the
   neural tube
3. Vesicle formation: The neural tube bends and expands to form characteristic
   swellings called vesicles
4. Neuronal proliferation: Neuroblasts undergo mitosis in an area adjacent to
   ventricles
   2
5. Neuronal migration: Post-mitotic neurons travel from the subventricular zone to their
   proper position within the maturing brain
6. Axon outgrowth and pathfinding: Neurons extend axons to innervate targets,
   establishing roles in cell-cell signaling
7. Neuronal differentiation: Discrete populations of neurons acquire their unique
   characteristics
8. Myelination
9. Post-natal development

Question 2

Explain the concept of synaptic pruning and how this process refines neural networks during life

Question 3

Describe the cytoarchitecture of the cerebral cortex and distinguish histologically and functionally between pyramidal and non-pyramidal granule cells

Question 4

Describe the characteristics of the six cortical layers, noting the layers associated with short-, long-association, commissural, spindle, and corticofugal projection fibers

Question 5

Describe the major long association bundles and commissural fibers and the areas these interconnect

Answer 5

Short (layer 2; intrahemispheric)

Long (layer 3; interhemispheric)
1. superior longitudinal fasiculus
- frontal with parietal & occipital
2. arcuate fasciculus
- connects Wernicke’s area to Broca’s
- connects superior temporal gyrus to
inferior frontal gyrus
3. inferior longitudinal fasciculus
- “what” pathway occipital lobe to the
temporal pole
4. uncinate fasciculus
- temporal pole to the PFC
- limbic circuits
5. cingulum
- cingulate cortex to parahippocampal
gyrus
6. inferior fronto-occipital fasiculus
- lower orbital frontal vmPFC to both
temporal and occipital lobe

Commissural fibers (layer 3; connect homologous parts of opposite hemispheres)
1. corpus collosum (all lobes except
temporal)
2. anterior commissure (temporal lobe
interconnections)

Question 6

Consider evidence for the potential role of Von Economo spindle neurons and the enigmatic claustrum in maintenance of consciousness

Question 7

Note layers targeted by corticopetal (thalamocortical) neurons and explain how cortico-thalamo-cortical connections allow one cortical area to control the thalamic gating of information to connected cortical areas

Question 8

Describe the columnar organization of cortical neurons and modules and relate this to function

Question 9

Explain how dysynaptic recurrent inhibition in the cortex sharpens cortical responsiveness

Question 10

Describe the organization of the cortex into primary and association areas and note the responsibilities of each

Question 11

Explain what is meant by ‘lateralization of cortical function’ and why this concept is difficult to explain