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Biomedical subjects

T R Bashore

Publications and source records attributed to T R Bashore.

27 records · Page 2Linked to original sources
PubMed1982

Left visual field superiority in a letter-naming task for both left- and right-handers.

Subjects identified on the basis of sex, handedness, and handwriting posture performed a letter-naming task. Single letters were shown briefly in the left or right visual field and the subject was required to name the letter as quickly as possible. Both left- and right-handers had shorter response latencies when the stimulus was presented in the left visual field. Response latency decreased across trials, however, the decrement was largest to right visual field stimuli. In addition, males produced significantly faster reaction than did females.

Discrimination Learning↗
PubMed1981

Differential actions of classical and atypical antipsychotic drugs on spontaneous neuronal activity in the amygdaloid complex.

Classical antipsychotic drugs such as haloperidol produce akinesia and catalepsy, whereas clozapine and related atypical antipsychotics fail to elicit these behaviors even at relatively high doses. Despite these behavioral differences, a cataleptic dose of haloperidol (2.0 mg/kg) produces changes in neuronal activity in the neostriatum and nucleus accumbens comparable to those produced by a non-cataleptic dose of clozapine (20.0 mg/kg). To further elucidate the brain mechanisms underlying the differential behavioral response to these drugs, an electrophysiological analysis was extended to neurons in the rat amygdaloid complex. Whereas an intraperitoneal injection of 2.0 mg/kg haloperidol generally failed to alter the firing rate of amygdaloid neurons, 20.0 mg/kg clozapine typically produced a prolonged increase in activity. Similarly, clozapine, but not haloperidol, reversed the depression of firing rate produced by 1.0 mg/kg d-amphetamine. The results suggest that neurons in the amygdaloid complex are more responsive to antipsychotic drugs devoid of extrapyramidal side effects than to antipsychotics which elicit parkinsonian-like motor dysfunctions.

Amygdala↗
PubMed1979

"Classical" and "atypical" antipsychotic drugs: differential antagonism of amphetamine- and apomorphine-induced alterations of spontaneous neuronal activity in the neostriatum and nucleus accumbens.

The ability of clozapine and haloperidol to antagonize the depression of firing rate produced by d-amphetamine and apomorphine in the neostriatum and nucleus accumbens was tested in immobilized, locally anesthetized rats. In the neostriatum, an intraperitoneal injection of 2.5 mg/kg d-amphetamine or 1.0 mg/kg apomorphine produced a prolonged inhibition of neuronal activity that was reversed by a subjsequent injection of either 20 mg/kg clozapine or 2.0 mg/kg haloperidol. An analysis of the onset and magnitude of the blockade revealed that clozapine was more effective than haloperidol in reversing the amphetamine response but that both antipsychotic drugs produced a comparable blockade of the apomorphine-induced depression. Similar results were obtained in the nucleus accumbens. The data indicate that although clozapine acts equieffectively in the neostriatum and nucleus accumbens, this atypical antipsychotic drug, aside from blocking postsynaptic dopamine receptors, may exert at least some of its effects by preventing dopamine release.

Amphetamine↗
PubMed1978

Alterations of spontaneous neuronal activity in the caudate-putamen, nucleus accumbens and amygdaloid complex of rats produced by D-amphetamine.

Changes in spontaneous neuronal activity in the caudate-putamen, accumbens nucleus and amygdaloid complex of immunobilized, locally anesthetized rats were recorded following intraperitoneal injection of 2.5 mg/kg d-amphetamine sulfate. In each site, d-amphetamine typically produced a prolonged depression of firing rate which, in most cases, occurred after an inital, brief potentiation of activity. However, the onset of the amphetamine-induced depression occurred signficantly later in the amygdala. Subsequent IP administration of either 5.0 mg/kg chlorpromazine or 2.0 mg/kg haloperidol reversed, to varying degrees, the amphetamine-induced depression of neuronal activity in each area. These results are discussed in terms of the known biochemical effects of amphetamine on catecholaminergic transmission and the alleged role of the nigro-neostriatal mesolimbic dopamine systems in the amphetamine behavioral response.

Amygdala↗
PubMedDate not supplied

Dynamics of brain electrical activity.

In addition to providing important theoretical insights into chaotic deterministic systems, dynamical systems theory has provided techniques for analyzing experimental data. These methods have been applied to a variety of physical and chemical systems. More recently, biological applications have become important. In this paper, we report applications of one of these techniques, estimation of a signal's correlation dimension, to the characterization of human electroencephalographic (EEG) signals and event-related brain potentials (ERPs). These calculations demonstrate that the magnitude of the technical difficulties encountered when attempting to estimate dimensions from noisy biological signals are substantial. However, these results also suggest that this procedure can provide a partial characterization of changes in cerebral electrical activity associated with changes in cognitive behavior that complements classical analytic procedures.

Brain↗
PubMedDate not supplied

Discovery of the P300: a tribute.

The significant and enduring contributions made to cognitive psychophysiology by Samuel Sutton and his colleagues in the first two papers on the P300 component of the event-related brain potential are discussed. The remarkable quality of these contributions is revealed in the fact that the issues that motivated the series of experiments reported by these investigators continue to be of core importance to the field.

Acoustic Stimulation↗