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isocortex (neocortex)
The larger part of the mammalian cerebral cortex, distinguished from the allocortex by a larger number of cells, roughly arranged in 6 layers. The human neocortex is about 3 times as large as would be expected for a non-human primate of the same size. [3]
The isocortex may be further categorized:
1) homotypical isocortex (6 distinct layers)
a) unimodal association cortex
b) heteromodal association cortex
2) heterotypical (idiotypic) isocortex
a) 6 layer architecture is obscured by structural variations
b) primary visual, auditory, somatosensory & motor cortex
The 6 layers of the neocortex:
1) molecular layer (plexiform or tangential layer)
2) corpuscular layer (dysfibrous or extragranular layer)
3) pyramidal layer (suprastriate of external pyramidal layer)
4) granular layer (internal granular layer of external band of Baillarger)
5) ganglionic layer (internal pyramidal or interstriate layer, or internal band of Baillarger)
6) spindle layer (multiform, infrastriate of fusiform layer)
Cortical columns:
The basic unit of the mature neocortex is the minicolumn, a narrow chain of 80-100 neurons that extends from layers 2-6. Columns are formed through the binding together of minicolumns by dense, short-range connections. Each column is a complex processing & distributing unit.
Column size: 300-500 um in diameter
Related
allocortex
cortical column
layers of the neocortex
mesocortex
Specific
heterotypical (idiotypic) isocortex
homotypical isocortex
General
cerebral cortex
References
- Stedman's Medical Dictionary 27th ed, Williams &
Wilkins, Baltimore, 1999
- Clarke, D., UCLA Dept of Neurobehavior
- Arendt T.
Neurodegeneration and plasticity.
Int J Dev Neurosci. 2004 Nov;22(7):507-14. Review.
PMID: 15465280