UBC Theses and Dissertations
Ventral hippocampal lesion volume does not predict working memory deficits in the neonatal ventral hippocampal lesion model of schizophrenia Badiudeen, Mohamed Thariq
The neonatal ventral hippocampal lesion (NVHL) is the most well-characterized neurodevelopmental animal model of schizophrenia. NVHL animals are known to display marked deficits in cognitive flexibility and working memory (WM), which are largely reminiscent of cognitive deficits seen in human patients. Though WM deficits are a well-characterized feature of the NVHL model, our study was the first to use magnetic resonance imaging (MRI), on live rats, to determine the relationship between lesion extent and the WM deficit in a variable delayed non-match to sample (vDNMS) task. Similar to the existing literature, NVHL animals showed a significant deficit in performance when compared to sham operated animals. Interestingly, however, the magnitude of deficit in WM performance in NVHL animals was stable, regardless of delay length. We suggest that this delay-independent WM deficit reflects inefficiency during the encoding stage of WM processes in NVHL animals. Additionally, we found no evidence of a relationship between ventral hippocampal (VH) lesion volume and the magnitude of WM deficit, suggesting that there may be a threshold level of VH damage, beyond which no further WM impairment is produced.
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