A MODEL FOR 8-10 HZ SPINDLING IN INTERCONNECTED THALAMIC RELAY AND RETICULARIS NEURONS

We investigated a simplified model of a thalamocortical cell and a ret icular thalamic cell interconnected with excitatory and inhibitory syn apses, based on Hodgkin-Huxley type kinetics. The intrinsic oscillator y properties of the model cells were similar to those observed from si ngle cells in vitro. When synaptic interactions were included, spindle oscillations were observed consisting of sequences of rhythmic oscill ations at 8-10 Hz separated by silent periods of 8-40 s. The model sug gests that Ca2+ regulation of l(h) channels may be responsible for the waxing and waning of spindles and that the reticular cell shapes the 10-Hz rhythmicity. The model also predicts that the kinetics of gamma- aminobutyric acid inhibitory postsynaptic potentials as well as the in trinsic properties of reticular cells are critical in determining the frequency of spindle rhythmicity.