Figure 2.

From three-layer to six-layer cortical microcircuits. (A) Simplified basic cortical module of ancestral three-layer olfactory cortex, hippocampus and reptilian dorsal cortex. Based on Kriegstein and Connors (1986) and Shepherd (2011). PC, pyramidal cell. Abbreviations of functional actions: ffexc, feedforward excitation; ffinh, feedforward inhibition; fbexc, feedback excitation; fbinh, feedback inhibition; lexc, lateral excitation; linh, lateral inhibition. (B) Olfactory cortex: lamination of basic circuit modules. (C) Mammalian neocortex: lamination of basic circuit modules. Abbreviations as in (A). Laminae for the cell types are indicated. Presumed excitatory cells shown in red, inhibitory cells shown in blue. Based on Shepherd (1988) and Rowe and Shepherd (2016).