What Stops Synchronized Thalamocortical

The axons of thalamocortical cells, in turn, give rise toSection of Neurobiology axon collaterals within the thalamic reticular nucleus asYale University School of Medicine the parent axon passes through en route to the cerebralNew Haven, Connecticut 06473 cortex (Friedlander et al., 1981; Harris, 1987). The peri-geniculate nucleus (PGN) is interconnected with the dor-sal lateral geniculate nucleus and is functionally equiva-Summary lent to the thalamic reticular nucleus. Burst firing in the GABAergic neurons of the thalamicSlow-wave sleep as well as generalized absence sei-reticular/perigeniculate nuclei during the generation ofzures are characterized by the occurrence of synchro-spindle waves results in GABAA receptor–mediated in-nized oscillations in thalamocortical systems that hibitory postsynaptic potentials (IPSPs) in thalamocorti-spontaneously appear and disappear. The spontane-cal cells (Steriade and Deschênes, 1984; Bal et al.,ous appearance of synchronized oscillations results 1995a, 1995b). These phasic IPSPs in thalamocorticalfrom the initiation by one or a small number of cells cells result in the removal of inactivation of the low-followed by the progressive recruitment of large threshold Ca21 current. The rising, or repolarizing, phasenumbers of neighboring neurons into the synchro