Cerebral cortex
The
Cerebral cortex is the extensive outer layer of
gray matter of the cerebral hemispheres, largely responsible for higher
brain functions, including
sensation, voluntary
muscle movement,
thought,
reasoning, and
memory. The
human brain's wrinkled texture results in substantially more cortex than is present in other brains of similar size.
Cerebral cortex is typically 1-4mm thick.
Laminar pattern
The standard areas of cortex (isocortex) is characterized as having six distinct layers. From outside inward:
- Molecular layer
- External granular layer
- External pyramidal layer
- Internal granular layer
- Internal pyramidal layer
- Fusiform layer
Classification
Based on the differencies in lamination the cerebral cortex can be classified into two major groups:
- Isocortex (homotypical cortex), the part of the cortex with six layers.
- Allocortex (heterotypical cortex) with variable number of layers, e.g., olfactory cortex and hippocampus.
Auxilliary classes are:
- Mesocortex, classification between isocortex and allocortex where layers 2, 3 and 4 are merged.
- Proisocortex, Brodmann areas 24, 25, 32.
- Periallocortex is cortical areas adjacent to allocortex.
Based on supposed developmental differencies the following classification also appears:
- Neocortex that corresponds to isocortex.
- Archicortex
- Paleocortex
See also