Spatial and associative learning deficits induced by neonatal excitotoxic hippocampal damage in rats: further evaluation of an animal model of schizophrenia

Neonatal ventral hippocampal lesions in the rat result in post-pubertal ons et of behavioural abnormalities, modelling some aspects of schizophrenia. W e further assessed the behavioural effects of neonatal lesions in rats in a variety of cognitive tasks and in the prepulse inhibition (PPI) of startle response paradigm. Prepubescent, lesioned rats exhibited startle responses and PPI similar to controls whereas, at adulthood, they showed a deficit i n PPI. Lesioned rats acquired both passive and active avoidance responses. However, compared to controls, they showed a deficit in passive avoidance r etention and in acquisition of active avoidance responses. In a cued Morris water-maze task, lesioned rats demonstrated adequate sensorimotor function s and appropriate motivation to escape from water. However, they were impai red in place learning and in remembering the location of a submerged platfo rm. In conclusion, neonatal ventral hippocampal lesions result in the post- pubertal emergence of long-lasting deficits in sensorimotor gating and in t he capacity to acquire and retain information in tests of spatial and avoid ance learning. Therefore, this neurodevelopmental model of schizophrenia se ems to exhibit an interesting degree of validity in possibly simulating som e cognitive impairments and sensorimotor gating deficits frequently observe d in psychotic patients. (C) 2000 Lippincott William & Wilkins.