Barrel Cortex
Over the past two decades, the barrel cortex has emerged as a major model system for the analysis of the structure, function, and experience-dependent plasticity of neocortical circuits. Driven by the availability of transgenic animals expressing fluorescent proteins and protein effectors in specific cell types, circuit studies of the barrel cortex are now mostly performed in mice. The cortical layers, cell types, and the intralaminar connectivity are similar in mice and rats. This chapter combines information gained from experiments in both species, but all quantitative data pertain to the mouse barrel cortex. We summarize current knowledge about the inputs, outputs and local circuits of the barrel cortex. Special emphasis is placed on the structure and function of layer 4, which may currently be the best understood cortical circuit. Circuit principles derived from layer 4 likely apply to cortical circuits in general.