Cerebral cortex is gray matter covering the cerebral hemisphere. Cortex outside of the rhinencephalon, so-called neocortex, has six horizontal layers.

The labeled image illustrates the six cortical layers. On the left side, Golgi silver precipitation of selective neurons is shown. The right side shows a Nissl stain.

Pyramidal cells (neurons) and granular cells predominate in the cerebral cortex (layer 6 has multiform cells). Pyramidal cells send axons into the underlying gray matter. Granular cells are interneurons that remain within the cortex.

The six layers are:
    I = molecular layer
    II = outer granular layer
    III = outer pyramidal layer
    IV = inner granular layer
    V = inner pyramidal layer
    VI = multiform layer

The outer layers receive non-specific afferents which serve to keep the cortex awake. Layer IV receives specific afferents, which bring the specific information that activates the particular cortical cell column.