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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)
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)
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)
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)
Disruption of prepulse inhibition (PPI) induced by NMDA receptor antagonists, such as MK801, has been used as an animal model of positive and negative symptoms of schizophrenia. Previous studies suggested that atypical, but not typical, neuroleptics can selectively restore MK801-induced PPI disruption and that such selectivity may depend on strain(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)
Organisms exposed to a stimulus which has no significant consequences, show subsequently latent inhibition (LI), namely, retarded conditioning to this stimulus. LI is considered to index the capacity to ignore irrelevant stimuli and its disruption has recently received increasing interest as an animal model of cognitive deficits in schizophrenia. Initial(More)
Maternal infections during pregnancy increase the risk for schizophrenia and related disorders of putative neurodevelopmental origin in the offspring. This association has been attributed to enhanced expression of pro-inflammatory cytokines in the fetal environment in response to maternal immunological stimulation. In contrast, the specific roles of(More)
Rearing rats in isolation has been shown to be a relevant paradigm for studying early life stress and understanding the genesis of depression and related affective disorders. Recent studies from our laboratory point to the relevance of studying the social isolation syndrome as a function of home caging conditions. Accordingly, the present series of(More)
Postweaning isolation rearing in rats is shown to have consequences for the expression of numerous behaviors. The present studies investigated isolation-induced disruptions of the prepulse inhibition (PPI) response in the Wistar rat strain, as a function of exposure of the animals to locomotor activity testing. Further, repeated testing of PPI was(More)