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Rats with complete excitotoxic hippocampal lesions or selective damage to the dorsal or ventral hippocampus were compared with controls on measures of contextually conditioned freezing in a signaled shock procedure and on a spatial water-maze task. Complete and ventral lesions produced equivalent, significant anterograde deficits in conditioned freezing(More)
The amnestic effects of hippocampal lesions are well documented, leading to numerous memory-based theories of hippocampal function. It is debatable, however, whether any one of these theories can satisfactorily account for all the consequences of hippocampal damage: Hippocampal lesions also result in behavioural disinhibition and reduced anxiety. A growing(More)
In the latent inhibition (LI) paradigm, nonreinforced preexposure to a stimulus retards subsequent conditioning to that stimulus. Three experiments investigated the effects of acute amphetamine administration on LI in rats. Experiments 1 and 3 used a conditioned emotional response (CER) procedure and Experiment 2 used two-way active avoidance procedure.(More)
Latent inhibition (LI) consists of retardation in conditioning to a stimulus as a consequence of its prior non-reinforced pre-exposure. In view of findings that LI is disrupted in acute schizophrenic patients and evidence from animal experiments pointing to the involvement of the mesolimbic dopamine (DA) system in this phenomenon, the present study(More)
Maternal infection during pregnancy is an environmental risk factor for the offspring to develop severe brain disorders, including schizophrenia and autism. However, only little is known about the neurodevelopmental mechanisms underlying the association between prenatal exposure to infection and the emergence of brain and behavioral dysfunctions in later(More)
The animal amphetamine model of schizophrenia has been based primarily on stereotyped behavior. The present study sought to demonstrate an amphetamine-induced deficit in attentional processes. To this end, the effects of acute and chronic (14 days) 1.5 mg/kg dl-amphetamine administration on the ability of rats to ignore irrelevant stimuli were examined(More)
Over the last decades of research there has been increasing interest in endocrine and behavioral effects of postnatal environmental manipulations. A manipulation procedure that has been widely used to date is that of maternal separation. Many studies have demonstrated that, in the rat, a single or repeated separation of the pups from the mother leads to(More)
Studies on the involvement of the rat hippocampus in classical fear conditioning have focused mainly on the dorsal hippocampus and conditioning to a context. However, the ventral hippocampus has intimate connections with the amygdala and the nucleus accumbens, which are involved in classical fear conditioning to explicit and contextual cues. Consistently, a(More)
The effects of electrolytic lesions of the medial prefrontal cortex (mPFC) or its subregions were investigated on two cognitive tests that may have relevance to the behavioral impairments of patients with schizophrenia. One task consisted of a delayed non-match-to-sample and reversal of the non-match-to-sample rule, in a Skinner box. The reversal component(More)
In the rat, both the medial and lateral prefrontal cortices (PFC; mPFC and lPFC, respectively) have direct connections with limbic structures that are important in the expression of fear and anxiety. The present study investigated the behavioral effects of excitotoxic lesions of either the mPFC or the lPFC on conditioned and unconditioned fear paradigms. In(More)