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Biomedical subjects

H E Rosvold

Publications and source records attributed to H E Rosvold.

At least 19 recordsLinked to original sources
PubMed1982

Spatial memory impairments following damage to the mediodorsal nucleus of the thalamus in rhesus monkeys.

The present study assessed whether the mediodorsal nucleus (MD) of the primate thalamus subserves some of the same learning and memory functions mediated by its prefrontal cortical projection areas. Behavioral effects of MD lesions were evaluated in 14 young adult rhesus monkeys, using tests known to be sensitive to damage in different regions of the prefrontal cortex. Performance on a spatial delayed alternation task was significantly (P less than 0.01) impaired by MD lesions, and this impairment was significantly correlated (rs = 0.52) with damage to the posterior half of the mediodorsal nucleus. Such damage was also correlated significantly (rs = 0.51) with performance on another spatial memory task, delayed response; monkeys that sustained the largest lesions of the posterior mediodorsal nucleus were significantly (P less than 0.05) impaired on this task relative to operated animals suffering the least posterior MD damage. In contrast to their performance on spatial memory tasks, operated animals were not impaired on tests of object reversal or visual pattern discrimination. These results indicate that lesions of the mediodorsal nucleus can elicit a specific syndrome of spatial memory loss qualitatively similar to that observed after damage to the dorsolateral prefrontal cortex.

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PubMed1981

Time discrimination with positional responses after selective prefrontal lesions in monkeys.

Monkeys with ablations of the cortex in the principal sulcus who were impaired on a spatial delayed reaction test were unimpaired on a time discrimination test in which length of time since the last trial signalled the spatial position of the correct foodwell. The finding undermines the view that the classical delayed reaction deficit after lateral prefrontal lesions reflects the loss of temporal structuring of the stream of sensory input. The result is consistent instead with the alternative view that the classical deficit reflects a spatial memory disorder. Monkeys with inferior prefrontal ablations were impaired on both spatial tasks, and on object discrimination reversal as well; analysis of their deficits indicated that they were instances of perseverative interference. Finally, monkeys with ablations of the cortex in the arcuate sulcus were not consistently impaired on any of the tasks. There is no evidence from these results that prefrontal cortex plays any role in time perception.

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PubMed1979

Cognitive deficit caused by regional depletion of dopamine in prefrontal cortex of rhesus monkey.

Depletion of dopamine in a circumscribed area of association cortex in rhesus monkeys produces an impairment in spatial delayed alternation performance nearly as severe as that caused by surgical ablation of the same area. This behavioral deficit can be pharmacologically reversed with dopamine agonists such as L-dopa and apomorphine. These data provide direct evidence that dopamine plays an important role in a specific cortical function.

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PubMed1976

Postnatal maturation of subcortical projections from the prefrontal cortex in the rhesus monkey.

Orbital and dorsolateral prefrontal lesions were performed on a series of rhesus monkeys at 2, 6, or 24 months of age. The consequent degeneration in the efferent pathways from these cortical regions to the caudate nucleus, the dorsomedial nucleus of the thalamus and adjacent structures was studied at 5- and 15-day survival times by a modification of the Nauta-Gygax method for tracing degenerating fibers. Following dorsolateral lesions, considerable numbers of black-impregnated degenerating fibers were found in the parvocellular division of the dorsomedial nucleus and in the fiber bundles of the internal capsule and the subcallosal fasciculus at all ages.

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PubMed1975

Primate drinking system as defined by electrical stimulation of the brain (ESB).

Four rhesus monkeys were examined by ESB for drinking sites in structures that had been previously demonstrated to support drinking behavior. Three yielded a significantly greater proportion of drinking sites than expected from the earlier study, and one yielded significantly less. As the exploration proceeded, the proportion of sites yielding drinking greatly increased in the drinkers and decreased in the nondrinker, and the ratio of stimulus-bound to nonstimulus-bound drinking sites increased in the drinkers but decreased in the nondrinker. Orienting responses decreased in both drinker and nondrinker as exploration proceeded. Two sites that had reliably supported drinking in the restraint chair failed to do so when telestimulated in a free environment, but instead yielded turning, walking, and climbing behavior. The results suggest that ESB-elicited drinking is determined by stimulation of several overlapping neural systems. These probably include ascending dopaminergic and cholinergic systems which are relatively thirst specific, and a nonspecific, cholinergic component of the reticular activating system which triggers the animal to execute a prepotent response which is specific to a given animal with a given history of stimulation under particular enviromental constraints. The learning of stimulus bound drinking is proposed to have its neural locus within the system which mediates the prepotent response, rather than in a thirst system or general activation system.

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PubMed1975

Dissociation of deficits on auditory tasks following partial prefrontal lesions in monkeys.

Separate groups of normal monkeys were trained either in Pavlovian differentiation or in positional responses, and with either auditory frequency or auditory location cues. After reaching criterion, half the animals in each group were given a dorsal prefrontal lesion and the other half, a ventral prefrontal lesion. The dorsal removal produced a strong impairment on the positional response tasks but none on Pavlovian differentiation, whereas the ventral removal produced a severe impairment on Pavlovian differentiation and only a mild deficit in the positional response tasks. This dissociation of deficits after prefrontal lesions is discussed within the framework of the neural theory of conditioning elaborated in Konorski's "Integrative Activity of the Brain".

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PubMed1973

Delayed recovery of function following orbital prefrontal lesions in infant monkeys.

Monkeys given orbital prefrontal lesions at 1, 4, or 8 weeks of age exhibited a severe learning disability when they were tested at 1 year of age, but showed substantial recovery by the time they were 2 years old. These results suggest that the protracted maturation of intact cortical regions is important in recovery of function after early brain injury.

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PubMed1972

The frontal lobe system: cortical-subcortical interrelationships.

The prefrontal cortex in the monkey is related structurally and functionally to several subcortical structures in such a way as to suggest that they constitute a neural system. Both anatomical and behavioral evidence justify implicating in such a system the prefrontal cortex itself, the head of the caudate nucleus, the globus pallidus, the substantia nigra, the subthalamic nucleus, the septal nuclei, the hippocampus, the centromedian nucleus, and the hypothalamus. There is, furthermore, an indication that this system is organized into at least two well-defined subsystems: a "dorsal" system originating in the dorsolateral prefrontal cortex involving the anterodorsal sector of the caudate, the lateral pallidum, the subthalamic nucleus, and the hippocampus; an "orbital" system originating in the orbital prefrontal cortex and involving the ventrolateral sector of the caudate nucleus, the medial pallidum, the centrornedian nucleus, the hypothalamus and the septal nuclei. While the anatomical and behavioral dissociation between these two systems is emphasized, attention is also drawn to the many possibilities for the two systems to converge upon one another.

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