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Biomedical subjects

J M Fuster

Publications and source records attributed to J M Fuster.

At least 73 records · Page 4Linked to original sources
PubMed1978

Effects of d-amphetamine and prefrontal cortical cooling on delayed matching-to-sample behavior.

The interaction was examined between d-amphetamine (s-A) and dysfunction induced by localized cooling of the dorsolateral prefrontal cortex. Saline or d-A(0.1,0.2 or 0.4 mg/kg) was administered to monkeys in two conditions; normal cortical temperature (no cooling -NC) and frontal cooling (FC). Errors, reaction time (RT), eye movements, and motor activity were recorded during performance of a delayed matching-to-sample task with intratrial delays of 1-32 sec. Although d-A and FC had little effect on percentage of correct responses at the shortest delay, each of the two treatments significantly decreased correct responses, at longer delays; drug and FC combined produced a significantly greater decrease than either treatment alone. Motor activity and eye movements were increased by either d-A or FC; the two treatments combined had an even greater effect. In the NC condition, two-choice RT was decreased by the drug; it was increased by drug-FC combinations. These findings indicate that d-A and FC potentiate each other in their behavioral effects.

Animals↗
PubMed1976

Woodpeckers and head injury.

The woodpecker is an experiment in Nature, a model for the investigation of mechanisms of basic importance for head injury and its prevention. A preliminary anatomical study of the woodpecker's head suggests that it may be fruitful to explore impact protective systems which are radically different from those in common use.

Animals↗
PubMed1976

Delayed-matching and delayed-response deficit from cooling dorsolateral prefrontal cortex in monkeys.

The hypothesis that the functional integrity of the dorsolateral prefrontal cortex is important for short-term memory of both spatial and nonspatial information was examined. Monkeys were tested in delayed matching-to-sample (DMS) and delayed-response (DR) tasks with delays of 0-32 sec. Testing was carried out under three different conditions: frontal cooling (FC), parietal cooling (PC), and normal temperature (noncooling, NC). Errors, reaction time, and motor activity were recorded. The proportion of correct responses decreased in NC as a function of the delay. This decrease was significantly accentuated by FC, whereas it was not modified by PC. At each delay, the decrement elicited by FC was as large in DR as in DMS. Reaction time and activity normally increased as a function of delay; these changes were enhanced by FC. The FC-induced decrements in proportion of correct responses suggest a faster loss from short-term memory of both spatial and nonspatial information.

Animals↗
PubMed1971

Neuron activity related to short-term memory.

Nerve cells in the monkey's prefrontal cortex and nucleus medialis dorsalis of the thalamus show changes of firing frequency associated with the performance of a delayed response test. Most cells increase firing during the cue presentation period or at the beginning of the ensuing delay; spike discharge highler than that in intertrial periods is present in some cells throughout the delay. These changes are interpreted as suggestive evidence of a role of frontothalamic circuits in the attentive process involved in short-term memory

Action Potentials↗
PubMedDate not supplied

Distributed memory for both short and long term.

Neuropsychology points to the wide distribution of cortical memory networks. Electrophysiology and neuroimaging indicate that working memory, like long-term memory, is a widely distributed function, largely neocortical. Most of the evidence available from those three methodologies suggests that both working memory and long-term memory share the same substrate: a system of broad, partly overlapping and interconnected neocortical networks. Working memory appears mostly, if not completely, characterized by the sustained activation of one widely distributed network of long-term memory. That activation is at least in part sustained by reentrant excitatory loops through the different neuronal assemblies that constitute the network and that represent the associated features of the memorandum.

Animals↗
PubMedDate not supplied

Effects of ethanol on eye movements in the monkey.

Ethanol (0.25-2.0 g/kg) was administered by remotely controlled intravenous infusion to monkeys engaged in performance of a short-term memory task which required attention to and retention of visual stimuli. Eye movements were monitored and measured by recording the electrooculogram with implanted periorbital Ag/AgCl electrodes. Ethanol induced the following dose-dependent changes of ocular motility: (a) diminution of the frequency of saccades; (b) prolongation of fixation (immobility) periods, though stimulus-elicited fixations became shorter; (c) increase in saccade excursion; (d) increase in saccade duration; and (e) decrease in saccade velocity (preceded at low doses by a transient increase). These changes were correlated with an impairment of behavioral performance. The results of eye movement analysis complement the results obtained on studies of human subjects by oral administration of ethanol. The findings of the present study in the nonhuman primate are interpreted as a reflection of the deleterious effects of alcohol on the cerebral substrate of visual attention.

Animals↗