Self-sustained rhythmic activity in the thalamic reticular nucleus mediated by depolarizing GABA(A) receptor potentials

Intracellular recordings from reticular thalamic (RE) neurons in vivo revea led inhibitory postsynaptic potentials (IPSPs) between RE cells that revers ed and became depolarizing at the hyperpolarized membrane potentials that o ccur during sleep. These excitatory IPSPs can directly trigger low-threshol d spikes (LTSs). The oscillatory mechanisms underlying IPSP-triggered LTSs crowned by spike bursts were investigated in models of isolated RE networks . In a one-dimensional network model, external stimulation evoked waves of excitation propagating at a constant velocity of 25-150 cells per second. I n a large-scale, two-dimensional model of the reticular nucleus, the networ k showed transient or self-sustained oscillations controlled by the maximum conductance of the low-threshold calcium current and the membrane potentia l. This model predicts that the isolated reticular nucleus could initiate s equences of spindle oscillations in thalamocortical networks in vivo.