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Interneurons and pyramidal cells were identified electrophysiologically in the hippocampus of anesthetized rats. Paired tones were presented 500 ms apart, and the resulting neuronal response was compared to differences in the amplitude of an auditory evoked potential (N40) elicited by each of the tones. Generally, the N40 elicited in response to the second(More)
We have developed a unique computer model of the CA3 region of the hippocampus that simulates the P50 auditory evoked potential response to repeated stimuli in order to study the neuronal circuits involved in a sensory processing deficit associated with schizophrenia. Our computer model of the CA3 hippocampal network includes recurrent activation from(More)
Patients with schizophrenia often cannot respond to important features of their environment and filter out irrelevant stimuli. This dysfunction could be related to an underlying defect in inhibition--i.e., the brain's ability to alter its sensitivity to repeated stimuli. One of the neuronal mechanisms responsible for such inhibitory gating involves the(More)
BACKGROUND Altered sensory response is a prominent feature of schizophrenia. Inhibitory gatting mechanisms, shown by diminished P50 evoked responses to repeated auditory stimuli, seem to be deficient in schizophrenic persons. These inhibitory mechanisms usually are studied by averaging the electroencephalographic responses to many presentations of pairs of(More)
Schizophrenia can be partially characterized by deficits in sensory processing. Biochemical, molecular, and genetic studies of one such endophenotype, the P50 auditory-evoked potential gating deficit, suggest that one of the neuronal nicotinic receptors, the alpha 7 nicotinic receptor, may function in an inhibitory neuronal pathway involved in this(More)
The psychotomimetic drug 1-(1-phenylcyclohexyl) piperidine (PCP, phencyclidine) was found to cause a deficit in the gating of the response of the hippocampal neuron to repeated auditory stimuli, which is similar to a particular physiological feature observed in human psychosis. Other drugs, with sigma agonist and/or N-methyl-D-aspartate (NMDA) antagonist(More)
Neurons in the medial septal nucleus were recorded extracellularly in response to auditory stimuli in chloral-hydrate-anesthetized rats. Two populations of neurons were identified, both of which were localized to the nucleus by horseradish peroxidase labeling. The auditory-responsive population was characterized by slow axonal conduction velocity, as(More)
The trematode and cestode flatworms include numerous parasitic forms of major medical and economic importance. A better knowledge of the neuromuscular physiology of these animals could lead to development of new control measures against these parasites. Since these animals are near the stem from which all other animals have evolved, better knowledge of(More)
The consequence of long-term potentiation (LTP) of hippocampal commissural inputs was investigated in an auditory gating paradigm. Auditory evoked potentials (AEPs) were recorded in the CA3b region of the hippocampus of rats anesthesitized with chloral hydrate. Two tones were delivered 0.5 sec apart; in this paradigm, the second AEP is diminished compared(More)
Schistosoma mansoni muscle fibers contract in response to L-glutamate in a dose-dependent manner (10(-6)-10(-3) M). L-aspartate and D-aspartate are likewise effective in eliciting contraction of the fibers. Mammalian glutamate receptor agonists produce little or no contraction at concentrations as high as 1 mM. In addition, common glutamate receptor(More)