define cortical matter
The cerebral cortex is the cerebrum 's (brain) outer layer of neural tissue in humans and other mammals. It is divided into two cortices, along the sagittal plane: the left and right cerebral hemispheres divided by the medial longitudinal fissure.n large mammals, the cerebral cortex is folded, giving a much greater surface area in the confined volume of the skull. A fold or ridge in the cortex is termed a gyrus (plural gyri) and a groove or fissure is termed a sulcus (plural sulci).