Responses of nucleus accumbens (NAS) neurons to ventral pallidum (VP) stimulation were examined in anesthetized rats. Results demonstrated: (1) NAS to VP projection neurons reside primarily in the relatively lateral aspects of the NAS, and (2) substantial VP to NAS feedback also exists. These feedback projections are widely distributed throughout the NAS. Moreover, functionally identifiable NAS neuronal subpopulations were revealed by analysis of unit responses to concurrent VP and fimbria stimulation: (1) most, but not all NAS units responded to VP and fimbria stimulation in qualitatively divergent ways; (2) many NAS units demonstrated monosynaptic convergence of fimbria and VP terminations onto individual NAS units; and (3) in other cases, identified NAS-VP projection neurons were also monosynaptically activated by fimbria stimulation.