Mémoire numérisé par la Division de la gestion de documents et des archives de l'Université de Montréal.

Mémoire numérisé par la Division de la gestion de documents et des archives de l'Université de Montréal

Active allothetic avoidance task (AAPA) could be a useful tool to study cognitive deficit of schizofrenia. In this task two different reference frames are created. The subject should distinguish which oriental frame is relevant for navigation and is proper for the solution of the task. This ability is called cognitive coordination. It is proved that the process of cognitive coordination is impaired in schizophrenic individuals, which comes to light in a Stroop test. Schizophrenia-like behavior can be modelled on the rats by a non-competitive NMDA receptor antagonist dizocipline (MK-801). The aim of these thesis was to study the existence of alternative strategies and the influence of different habituation on the performance of rats within AAPA. Furthermore, we have been studying the influence of MK-801 at a dose of 0.15mg / kg on the cognitive coordination in this task. We have found that the rats are able to learn AAPA task after pre-training without distal orientation cues, using relatively efficient alternative strategies. In these alternative strategies the idiothetic navigation is applied. The performance of rats in AAPA task is influenced by different conditions during habituation. We have proved that MK-801 at this dosage has no effect on cognitive performance of the rats in AAPA task, but...

Schizophrenia is a severe neuropsychiatric disorder characterized by positive, negative and cognitive symptoms with poor functional outcomes, placing an enormous burden on the individual, caregivers and society. Although deficits in cognition are an integral part of the disease and the best predictor of functional outcomes, there is as yet no established treatment addressing them. Avoidance of a hidden place on a continuously rotating arena (Carousel) requires cognitive control and is a rodent model of cognitive coordination of information from dissociated spatial frames, which is impaired in acute pharmacological and neurodevelopmental model of schizophrenia. Cognitive training on the Carousel during adolescence alleviates adult cognitive deficit in a neurodevelopmental model of schizophrenia and improves neural coordination (oscilations in the beta and gamma band), which is thought to be necessary for cognition. We examined if cognitive training during adolescence eliminates the deficit in neuronal coordination observed in adult rats after acute systemic NMDA receptor antagonist MK-801 (0.15 mg/kg). During adolescence, rats were either trained in spatial avoidance on Carousel or merely handled. As adults, rats received two 5-min exploration sessions in the same (A/A) or in two distinct...