Cerebral cortex

A large part of the brain's activity takes place in a layer of grey matter several millimetres thick which is situated at its surface, the cerebral cortex. It is an assembly of nerve cells, over 10 billion of them in an adult male. The cortex has numerous convolutions, which considerably increases its surface area. The cortex has activities in each of the general categories: motor, sensory and associative, each one having its specific region.