Male monogamous prairie voles vary in the way they use space, with some males intruding extensively on the territories of others, while others do not. We hypothesize that individual differences in the way males set up their territories is due to individual differences in their cognition and neural peptide receptor expression. Indeed, our lab has identified individual differences in vasopressin receptor expression in the retrosplenial cortex that are associated with differences in space use in the wild; this brain variation is predicted in part by sequence variants in the avpr1a gene. To test this hypothesis we first tested different behavioral paradigms that could be used to assess social cognition in the monogamous prairie vole. We tested the voles in a test of scent mark memory. We tried to establish conditioned place preference for male urine or postpartum estrus urine. Lastly, we developed a novel Barnes maze paradigm for looking at vi socio-spatial memory associated with escape. Male voles improved their performance in the Barnes maze over the course of 4 days, but did not respond to the overmark task or the conditioned place preference test. Next we used the Barnes maze to assess whether males of HI and LO RSC-V1aR genotypes perform differently in the task. Males of different genotypes did not perform differently in the Barnes maze. We also looked at V1aR expression levels in the brains of the animals that were tested in the Barnes maze. V1aR expression in the RSC did not correlate to Barnes maze performance. In addition to genetic influences, RSC-V1aR is known to be affected by neonatal exposure to oxytocin antagonist. Here we show preliminary results indicating that the RSC V1aR expression is reduced in LO animals, but not in HI animals. In addition, V1aR expression the anterior medial BNST was affected by neonatal exposure to OTA. The posterior lateral and ventral BNST, medial and lateral DT, and LS were not affected by neonatal exposure to OTA. / text