Figure 1. The structure of the cerebral cortex. The human cerebral cortex is made up of distinct functional areas. Sensory cortices (visual, auditory and somatosensory) process information received from peripheral sense organs, motor areas plan and instruct motor output and association areas integrate cortical inputs to create meaningful motor outputs and cognitive and emotional constructs.

Figure 2. Cells and circuitry of the cerebral cortex. (a) Image of a cortical area stained with the Golgi technique showing several cortical neurons and their dendrites (A – dendrites of the apical tuft; B – basal dendrites). (b) Reconstructions of Golgi-stained neurons. Top panel: layer 3 pyramidal neuron. Lower panel: layer 4 spiny stellate neuron. (c) New imaging techniques allow the visualization of cortical neurons and the monitoring of the function of these neurons in live tissue. Left panel: Two-photon image of a layer 2/3 pyramidal neuron filled with calcium-sensitive dye through whole-cell recording in an acute slice. Pyramidal neuron dendrites are characterized by the presence of protusions called dendritic spines (right panel) which receive excitatory inputs from other neurons. (d) Cortical microglia stained with an antibody against Iba1. (e) Cortical astrocytes stained with an antibody against glial fibrillary acidic protein (GFAP). Photo (a) and camera lucida drawing (b) by Grazyna Gorny, provided by Terry Robinson. Image (e) provided by Maiken Nedergaard.

Figure 3. Circuitry of the cerebral cortex, Neurons in different layers have stereotyped projections including feedforward, feedback and lateral connections. Neurons with similar properties are arranged in a columnar fashion suggesting that single columns containing canonical circuits may be the basic unit of processing in the cerebral cortex.