Spiking-bursting activity in the thalamic reticular nucleus initiates sequences of spindle oscillations in thalamic networks

Recent intracellular and local field potential recordings from thalamic ret icular (RE) neurons in vivo as well as computational modeling of the isolat ed RE nucleus suggest that, at relatively hyperpolarized levels of membrane potentials, the inhibitory postsynaptic potentials (IPSPs) between RE cell s can be reversed and gamma-aminobutyric acid-A (GABA(A))-mediated depolari zation can generate persistent spatio-temporal patterns in the RE nucleus. Here we investigate how this activity affects the spatio-temporal propertie s of spindle oscillations with computer models of interacting RE and thalam ocortical (TC) cells. In a one-dimensional network of RE and TC cells, sequ ences of spindle oscillations alternated with localized patterns of spike-b urst activity propagating inside the RE network. New sequences of spindle o scillations were initiated after removal of I-h-mediated depolarization of the TC cells. The length of the interspindle lulls depended on the intrinsi c and synaptic properties of RE and TC cells and was in the range of 3-20 s . In a two-dimensional model, GABA(A)-mediated 2-3 Hz oscillations persiste d in the RE nucleus during interspindle lulls and initiated spindle sequenc es at many foci within the RE-TC network simultaneously. This model predict s that the intrinsic properties of the reticular thalamus may contribute to the synchrony of spindle oscillations observed in vivo.