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This series of studies investigated the effects of predator exposure on working memory in rats trained on the radial arm water maze (RAWM). The RAWM is a modified Morris water maze that contains four or six swim paths (arms) radiating out of an open central area, with a hidden platform located at the end of one of the arms. The hidden platform was located(More)
Prolonged treatment with stress levels of corticosterone has been reported to produce changes in the hippocampus. In the experiments reported here, we examined for functional and morphological consequences of this treatment. First, young adult or mid-aged male Long-Evans rats were treated for either 1 or 3 months with corticosterone, at a dose sufficient to(More)
Stress blocks hippocampal primed-burst potentiation, a low threshold form of long-term potentiation, thereby suggesting that stress should also impair hippocampal-dependent memory. Therefore, the effects of stress on working (hippocampal-dependent) and reference (hippocampal-independent) memory were evaluated. Rats foraged for food in seven arms of a 14-arm(More)
Central mechanisms of sensory gating were assessed in Sprague-Dawley rats by an evoked potential technique similar to one that we have previously used to show diminished sensory gating in psychotic patients. Middle latency (15-50 msec) auditory evoked potential responses were recorded at the skull in unanesthetized freely moving animals. Gating mechanisms(More)
Diminished evoked response to repeated auditory stimuli, an example of sensory gating normally present in human subjects, is often absent in schizophrenics. To examine the mechanism of the normal response and to delineate possible sites of its abnormality in psychosis, it would be desirable to reproduce the phenomenon in laboratory animals. In this study,(More)
Nicotinic receptors containing alpha7 subunits are widely distributed in the central nervous system and are thought to be involved in a number of functions. However, it has been difficult to study alpha7-containing receptors in vivo because of a paucity of selective agonists. A new spirooxazolidinone compound, AR-R17779, was recently described as potent(More)
Studies have shown that peripheral levels of corticosterone correlate with the magnitudes of two well-described physiological models of memory, long-term potentiation (LTP) and primed burst (PB) potentiation. In the present experiments, the authors investigated the effects of experimenter-controlled manipulations of the levels of corticosterone on the(More)
One function of the hippocampus is to ascertain the novelty of incoming sensations and encode significant new information into memory. The regulation of response to repeated stimuli may prevent overloading of this function by redundant sensory input. Recent pharmacological studies implicate the role of alpha-bungarotoxin-sensitive nicotinic cholinergic(More)
Recordings were made from the dentate gyrus granule cell layer of freely-moving rats. The neurons recorded from the layer were divisible into 3 classes using a combination of electrophysiological and behavioral criteria; the duration of the extracellularly recorded unfiltered action potential provided the most reliable means of differentiating between cell(More)