Visual activity enhances neuronal excitability in thalamic relay neurons
Résumé
The dorsal lateral geniculate nucleus (dLGN) has long been held to act as a basic relay for
visual information travelling from the retina to cortical areas, but recent findings suggest a
largely underestimated functional plasticity of dLGN neurons. However, the cellular
mechanisms supporting this functional plasticity have not been yet explored. In particular, it
remains to elucidate whether intrinsic neuronal excitability change upon visual stimuli. We
show here that monocular deprivation for 10 days reduces the intrinsic excitability of dorsal
LGN relay cells. Furthermore, dLGN neurons exhibit long-term potentiation of their intrinsic
excitability (LTP-IE) when suprathreshold afferent retinal inputs are stimulated at 40 Hz or
when spikes are induced with direct somatic current injection to reproduce patterns of retinal
activity. LTP-IE is observed after eye opening and requires calcium influx mediated by L-type
calcium channels. It involves activation of PKA and is expressed through the down-regulation
of Kv1 potassium channels. In conclusion, our study provides the first evidence for intrinsic
plasticity in dLGN relay cells, thus further pointing the role of thalamic neurons in activity-
dependent visual plasticity and amblyopia.
Origine : Fichiers produits par l'(les) auteur(s)