Imaging Experience-Dependent Plasticity in the Mouse Barrel Cortex

Abstract

Experience affects the development and function of somatosensory cortex circuits during specific time windows known as the critical period. However, the underlying circuit mechanisms are poorly understood. We used voltage-sensitive dye imaging and optogenetic circuit mapping to characterize experience-sensitive circuit changes occurring in the somatosensory cortex of whisker-deprived P30 mice. We found that deprivation weakened inhibitory circuits and reduced columnar specificity of excitatory circuits. To directly examine effects on parvalbumin (PV) expressing interneurons, we used a PV-Cre driver line, mated to another line with floxed-stop cassette controlling expression of the light-sensitive cation channel, Channelrhodopsin-2. Sensory deprivation decreased the range and amplitude of inhibitory postsynaptic input onto layer 2/3 pyramidal neurons. This effect on inhibitory circuits is age-sensitive, with the critical period closing around postnatal day 10. Our results provide a direct and quantitative measurement of the strength and spatial organization of this inhibitory circuit and its response to experience-dependent plasticity.