Saul, R.D., Wiest, M.K., & Brady, A.M.  (2006, April).  Effect of a neonatal ventral hippocampal lesion on working memory in rats.  Poster session presented at the Symposium for Young Neuroscientists and Professors of the Southeast (SYNAPSE), Davidson, NC.

Abstract

Patients with schizophrenia have deficits in spatial working memory, a function dependent on the hippocampus and its target structures.  Post-mortem analyses of schizophrenic brains have shown pyramidal cell disarray in the hippocampus.  We used the neonatal ventral hippocampal lesion (NVHL) rat model of schizophrenia to determine if spatial working memory is disrupted in two radial arm maze tasks.  In the non-delayed random foraging (NDRF) task, rats were required to forage for sucrose pellets in 4 arms of the 8-arm maze without re-entering any arms.  In the spatial delayed win-shift (SDWSh) task, rats were first given a training trial in which 4 arms were baited and 4 were blocked.  In the test trial, rats were required to enter only the 4 previously blocked arms, after either a 5 or 30 min delay.  Rats were also tested for prepulse inhibition (PPI) of the acoustic startle response.  Lesioned and sham-treated rats acquired the NDRF task in the same number of days, and did not differ on any behavioral measures on this task.  However, lesioned rats took longer than sham rats to acquire the SDWSh task, as measured by days to criterion performance, at both the 5 min and the 30 min delay.  Lesioned rats also exhibited a deficit in PPI, indicating impaired sensorimotor gating.  These results suggest that the NVHL model reproduces some of the working memory and sensorimotor gating abnormalities observed in patients with schizophrenia.  However, spatial navigation impairments are limited to task conditions which place higher demands on working memory.

View the poster (pdf format, 422KB)