NEOCORTICAL DAMAGE ALTERS SYNAPTIC RESPONSES OF NEOSTRIATAL NEURONS IN-VITRO

The present experiments were designed to investigate the physiological impact of a partial decortication upon neostriatal synaptic responses using intracellular recording techniques in the in vitro brain slice preparation. In the intact rat, the locally evoked neostriatal synapti c response is primarily mediated by excitatory amino acid receptor act ivation. Following neocortex damage, the contributions of both N-methy l-D-aspartate and non-N-methyl-D-aspartale receptor activation were si gnificantly diminished, although responses remained robust in amplitud e and duration. Components of the locally evoked synaptic response med iated by activation of GABA(A) receptors were relatively unchanged, wh ile presynaptic inhibition mediated by activation of GABA(B) receptors was markedly reduced. Furthermore, the normally minimal acetylcholine contribution to the synaptic response was significantly increased aft er neocortical damage. This enhanced cholinergic role in the generatio n of the synaptic response appeared to be mediated primarily by activa tion of nicotinic receptors. Thus, neocortical damage leads to novel p hysiological relationships between intrinsic neostriatal cholinergic i nterneurons and the GABAergic projection neurons. One possibility is t hat cholinergic interneurons have the potential for substituting for t he loss of excitation created by the absence of neocortical glutamater gic input. Copyright (C) 1996 IBRO.