ABSTRACT
Within the CNS, neurons that share a common function are usually grouped together; such groupings are called
nuclei
(singular
nucleus
, which is somewhat confusing as it does not refer to the part of a cell). In other parts of the brain, the neurons are grouped at the surface, forming a
cortex
. In a cortical organization, neurons are arranged in layers and the neurons in each layer are functionally alike and different from those in other layers. Older cortical areas have three layers (e.g., the cerebellum); more recently evolved cortices have six layers (the cerebral cortex) and sometimes sublayers.
