Whisker experience modulates long-term depression in neocortical γ-aminobutyric acidergic interneurons in barrel cortex.

Long-term plasticity is believed to be an important mechanism that allows neural circuits to be modulated in an use-dependent manner. However, evidence regarding the role of sensory experience in modulating long-term plasticity of glutamatergic synapses in neocortical GABAergic interneurons is unavailable. Here, we focused on regular-spiking nonpyramidal (RSNP) interneurons and examined spike-pairing-induced plasticity of glutamatergic synapses and its modulation by sensory experiences ex vivo. In our previous studies, RSNP interneurons do not show experience-dependent plasticity of intrinsic properties or alteration of thalamocortical (TC) synapses and exhibit robust modulation by mGluRs. Here we report a spike-pairing-induced long-term depression (spLTD) of glutamatergic synapses in RSNP interneurons of barrels cortex. Using paired recording and thalamic-induced responses, we found that the spLTD was specific for intracortical but not TC synapses. The spLTD was mediated via presynaptic mGluRs. The spLTD was not modulated by chronic or acute administration of NMDAR antagonists but was enhanced by sensory deprivation (via whisker trimming) during a postnatal sensitive period ex vivo. The synapses specific spLTD to intracortical glutamatergic synapses in RSNP cells and their modulation by sensory deprivation may contribute to sensory-dependent remodeling of cortical circuits and redistribution circuit activity along the whisker-related columns.