Figure 6.

A canonical microcircuit for mammalian visual cortex. P2 + 3 represent pyramidal cells of the superficial 2 and 3 layers of visual cortex. Also included are the stellate cells of layer 4, indicated by (4), whose properties resemble those of the superficial pyramidal cells. P5 + 6 represent pyramidal cells of the deep five and six layers. GABA cells represent inhibitory interneurons of all types. Strength of functional connection is indicated by thickness of line. The thalamic input is relatively limited in terms of numbers of synapses, but is amplified by the strong recurrent excitatory connections. From Douglas et al. (1989).