Integration of Feedforward and Feedback Information Streams in the Modular Architecture of Mouse Visual Cortex

Radial cell columns are a hallmark feature of cortical architecture in many mammalian species. It has long been held, based on the lack of orientation columns, that such functional units are absent in rodent primary visual cortex (V1). These observations led to the view that rodent visual cortex has a fundamentally different network architecture than that of carnivores and primates. While columns may be lacking in rodent V1, we describe in this review that modular clusters of inputs to layer 1 and projection neurons in the layers below are prominent features of the mouse visual cortex. We propose that modules organize thalamocortical inputs, intracortical processing streams, and transthalamic communications that underlie distinct sensory and sensorimotor functions.