Fig. 12.

Highly schematic summary of the micromodularity of layers 1 and 2 of the rat visual cortex. Honeycomb walls in layer 2 (darker shading) are preferentially occupied by somata and proximal dendrites of layer 2 pyramids. These comingle with PV-ir GABAergic terminals and zinc-enriched corticocortical terminals. The zinc-enriched terminals extend into layer 1b, where they are likely to target the dendrites from layer 2 pyramidal neurons. Apical dendrites of deeper pyramidal neurons preferentially occupy honeycomb hollows (lighter shading) and colocalize with VGluT2-ir thalamocortical terminals. Other markers related to the honeycomb mosaic are listed. The degree of segregation and precise microcircuitry organization will need to be investigated further.