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Visual activity enhances neuronal excitability in thalamic relay neurons
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The dorsal lateral geniculate nucleus (dLGN) has long been held to act as a basic relay forvisual information travelling from the retina to cortical areas, but recent findings suggest alargely underestimated functional plasticity of dLGN neurons. However, the cellularmechanisms supporting this functional plasticity have not been yet explored. In particular, itremains to elucidate whether intrinsic neuronal excitability change upon visual stimuli. Weshow here that monocular deprivation for 10 days reduces the intrinsic excitability of dorsalLGN relay cells. Furthermore, dLGN neurons exhibit long-term potentiation of their intrinsicexcitability (LTP-IE) when suprathreshold afferent retinal inputs are stimulated at 40 Hz orwhen spikes are induced with direct somatic current injection to reproduce patterns of retinalactivity. LTP-IE is observed after eye opening and requires calcium influx mediated by L-typecalcium channels. It involves activation of PKA and is expressed through the down-regulationof Kv1 potassium channels. In conclusion, our study provides the first evidence for intrinsicplasticity in dLGN relay cells, thus further pointing the role of thalamic neurons in activity-dependent visual plasticity and amblyopia.
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