Calhoon, G.G., & Brady, A.M.  (2006, October).  The effects of cognitive intervention in adolescence on behavioral abnormalities in a neurodevelopmental rat model of schizophrenia.  Poster sessio to be presented at the Society for Neuroscience Annual Meeting, Atlanta, GA.

Abstract

Clinical data suggest that schizophrenic patients who achieve high levels of education prior to onset of psychotic symptoms have better prognoses than patients who accomplished lower levels of education.  This raises the possibility that cognitive stimulation in adolescence may protect against the development of schizophrenic symptoms in adulthood.  The present study assessed the effects of cognitive intervention in adolescence on disrupted adult behaviors in the neonatal ventral hippocampal lesion (NVHL) model, a neurodevelopmental model of schizophrenia in rats.  At postnatal day (PD) 7, neonatal rats received bilateral infusions of the excitotoxin ibotenic acid (NVHL, n=12) or artificial CSF (sham-lesioned, n=8) into the ventral hippocampus.  In adolescence (beginning at PD 28), NVHL rats and sham-lesioned rats were trained in an attentional set-shifting task in a T-maze, which served as the cognitive intervention.  Rats in the intervention control condition were given equivalent time to explore the T-maze, but were not trained in the set-shifting portion of the task.  Adolescent NVHL and sham-lesioned rats did not differ in their performance on the set-shifting task (p=.83).  In adulthood (beginning at PD 56), rats were assessed on a number of behaviors known to be disrupted in the NVHL model.  Compared to sham-lesioned rats, NVHL rats displayed impaired prepulse inhibition of the acoustic startle response (p=.003), decreased social interaction behaviors (p=.001), and hyperlocomotion in response to amphetamine (p=.015).  These adult abnormalities were not alleviated by the adolescent cognitive intervention.  As adults, NVHL rats also performed worse than sham-lesioned rats in a working memory task in an 8-arm radial arm maze, as indicated by total errors over 16 daily trials.  However, the performance of NVHL rats that had received cognitive intervention in adolescence was markedly improved compared to NVHL rats that did not receive the intervention (p=.032).  The results of the present study are consistent with previous findings of abnormalities in the NVHL paradigm, and suggest that premorbid cognitive intervention may protect against the cognitive symptoms of schizophrenia.