FUNCTIONAL DYNAMICS OF GABAERGIC INHIBITION IN THE THALAMUS

The inhibitory gamma-aminobutyric acid-containing (GABAergic) neurons oi the thalamic reticular and perigeniculate nuclei are involved in th e generation of normal and abnormal synchronized activity in thalamoco rtical networks. An important factor controlling the generation of act ivity in this system is the amplitude and duration of inhibitory posts ynaptic potentials (IPSPs) in thalamocortical cells, which depend on t he pattern of activity generated in thalamic reticular and perigenicul ate cells. Activation of single ferret perigeniculate neurons generate d three distinct patterns of GABAergic IPSPs in thalamocortical neuron s of the dorsal lateral geniculate nucleus: Low-frequency tonic discha rge resulted in small-amplitude IPSPs mediated by GABA(A) receptors, b urst firing resulted in large-amplitude GABA(A) IPSPs, and prolonged b urst firing activated IPSPs mediated by GABA(A) and GABA(B) receptors. These functional properties of GABAergic inhibition can reconfigure t he operations of thalamocortical networks into patterns of activity as sociated with waking, slow-wave sleep, and generalized seizures.