Experience-Dependent Bimodal Plasticity of Inhibitory Neurons in Early Development

•Experience-dependent plasticity identifies two groups of inhibitory neurons•The two groups display opposite bimodal plasticity to dark and visual experience•Experience potentiates visually evoked E and I inputs and E/I is maintained•Functionally antagonist inhibitory neurons maintain stability in nascent circuits

SummaryInhibitory neurons are heterogeneous in the mature brain. It is unclear when and how inhibitory neurons express distinct structural and functional profiles. Using in vivo time-lapse imaging of tectal neuron structure and visually evoked Ca2+ responses in tadpoles, we found that inhibitory neurons cluster into two groups with opposite valence of plasticity after 4 hr of dark and visual stimulation. Half decreased dendritic arbor size and Ca2+ responses after dark and increased them after visual stimulation, matching plasticity in excitatory neurons. Half increased dendrite arbor size and Ca2+ responses following dark and decreased them after stimulation. At the circuit level, visually evoked excitatory and inhibitory synaptic inputs were potentiated by visual experience and E/I remained constant. Our results indicate that developing inhibitory neurons fall into distinct functional groups with opposite experience-dependent plasticity and as such, are well positioned to foster experience-dependent synaptic plasticity and maintain circuit stability during labile periods of circuit development.