The cerebral cortex is the 2-4mm thick outer layer of the cerebrum, containing approximately 16 billion neurons organized in six layers. It is the seat of higher cognitive functions — perception, language, memory, planning, and consciousness. The cortex is divided into four lobes: the frontal lobe (executive function, motor control, language production), parietal lobe (spatial processing, attention, somatosensation), temporal lobe (auditory processing, memory, object recognition), and occipital lobe (visual processing).
Organization
Brodmann identified 52 cytoarchitecturally distinct areas, many of which correspond to functionally specialized regions. The cortex follows several organizational principles: topographic mapping (orderly representations of sensory surfaces), hierarchical processing (information flows from primary sensory areas to association areas), and hemispheric specialization (language typically left-lateralized, spatial processing right-lateralized). Cortical columns — vertical units spanning all six layers — are thought to be the fundamental computational units.
The cortex is remarkably plastic — it reorganizes in response to experience, learning, and injury. Musicians have enlarged auditory and motor cortical representations for their practiced hand. Blind individuals repurpose visual cortex for Braille reading and auditory processing. After limb amputation, neighboring cortical representations expand into the deafferented region. This plasticity underlies learning and recovery from brain injury but also contributes to phenomena like phantom limb pain.