NMDA receptors participate differentially in two different synaptic inputs in neurons of the zebra finch robust nucleus of the archistriatum in vitro.

Intracellular recordings were made from neurons of the zebra finch song control nucleus, the robust nucleus of the archistriatum (RA), in slice preparations to examine synaptic responses. RA neurons receive two separate inputs from the lateral magnocellular nucleus of the anterior neostriatum (1MAN) and the caudal nucleus of the ventral hyperstriatum (HVc). Excitatory postsynaptic potentials (EPSPs) elicited by stimulation of the fibers of the 1MAN were greatly reduced by 2-amino-5-phosphonopentanoic acid in many cells, whereas EPSPs elicited by stimulation of the fibers of the HVc were greatly reduced by 6-cyano-7-nitroquinoxaline-2,3-dione in all cells. It is concluded that RA neurons receive inputs mediated mostly by N-methyl-D-aspartate (NMDA) receptors from the 1MAN, and inputs mediated mostly by non-NMDA receptors from the HVc.