Paint it black (or red, or green): optical and genetic tools illuminate inhibitory contributions to cortical circuit function.

Visual responses in the cortex are generated by the interactions of feedforward thalamic inputs with local inhibitory and excitatory circuitry, but the exact roles of different cell types in establishing response selectivity are unclear. Two papers in this issue of Neuron (Kerlin et al. and Runyan et al.) combine two-photon imaging with guided electrical recordings to measure orientation tuning in molecularly defined groups of interneuron types.