The cerebral cortex, or gray matter, is the most external layer of the brain of vertebrates, constituting the largest portion of the nervous system. It is connected to the thalamus, forming the thalamocortical system, which, except by some sensory olfactory pathways to the cortex, constitutes the major two-way unit between sensory perception and intellectual functions in humans. The cortex is divided into several cortical areas, each responsible for separate functions, such as planning of complex movements, memory, personality, elaboration of thoughts, word formation, language understanding, motor coordination, visual processing of words, spatial orientation, and body spatial coordination.

Sensations received from peripheral sense organs by the primary motor and sensory cortical areas are detected as specific sensations (visual, somatic, auditory). The secondary sensory areas are activated in the process of recognition of these signals, and begin the analysis of sensory signals, such as the interpretation...