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Biomedical subjects

R W Sperry

Publications and source records attributed to R W Sperry.

At least 19 recordsLinked to original sources
PubMed1985

Interhemispheric communication after section of the forebrain commissures.

Cognitive information is shown to be transmitted interhemispherically through channels other than the neocortical commissures, presumably through subcortical pathways. What crosses through these subcortical channels does not appear to include the name or identity of stimuli but rather is more contextual or associative in nature. Results obtained with a technique for prolonged visual lateralization indicate that this information, when used in conjunction with cognitive strategies, allows the cortically disconnected left hemisphere under certain conditions to verbally identify stimuli projected to the right hemisphere or to cross-compare bilateral input. The presence of this subcortical communication would thus appear to help explain some of the increasing exceptions to characteristic disconnection symptoms reported among split-brain subjects. In particular, the present results challenge reports which have attributed oral naming of stimuli in the left visual hemifield to the typical disconnected right hemisphere.

Adolescent↗
PubMed1984

Left hemisphere involvement in left spatial neglect from right-sided lesions.

Current views of the unilateral neglect syndrome caused by right-sided focal lesions generally imply that the left hemisphere is lacking in awareness for the left half of the body and surrounding space. Questioning this assumption on the basis of previous split-brain and hemispherectomy observations, we applied lateralized tests for left hemineglect in three subjects with complete forebrain commissurotomy. Results for the left disconnected hemisphere revealed substantial awareness for the left side of the body and also for extrapersonal space, far greater than suggested by the unilateral lesion data. It is inferred that the left hemisphere, functioning independently, possesses the requisite cognitive mechanisms needed to prevent the appearance of the typical neglect syndrome as observed following right-sided lesions. It is proposed that the eventual explanation of this disorder must therefore account for the lack of left hemisphere compensation.

Attention↗
PubMed1983

Hemispheric specialization in nonverbal communication.

Subjects sustaining right hemisphere damage were impaired in the ability to evaluate emotional situations presented through nonverbal means, particularly through facial expressions. Left brain damage, even of considerable extent, led to significantly milder deficits. In agreement with these findings, a study in split-brain patients showed the isolated right hemisphere to be competent in evaluating facial expressions but less sensitive to body movements, while the left hemisphere showed the opposite pattern.

Adult↗
PubMed1981

Changing priorities.

In the context of today's mounting global problems the relative demand for medical, educational, and related social benefits that derive from the neurosciences is diminished. At the same time the human value spin-offs of brain research are thrust into a strategic position of top concern because of their key role as criteria or policy priorities and decision-making guidelines. Recent conceptual developments in the mind-brain sciences rejecting reductionism and mechanistic determinism on the one side, and dualisms on the other, clear the way for a rational approach to the theory and prescription of values and to natural fusion of science and religion. Science can be upheld as the best route to an increased understanding and report with the forces that made and move the universe and created man. The outlines of the value-belief system emerge that include an ultimate respect for nature and the evolving quality of the biosphere, which, if implemented, would set in motion the kind of social change needed to lead us out of the viscious spirals of increasing population, pollution, poverty, energy demands, etc. The strategic importance of neuroscience and the central role of prevailing concepts of the mind-brain relation to all of the foregoing remain evident throughout, as does also the direct relevance of efforts to bring added insight and substantiation of these mind-brain concepts through further advances in brain research.

Animals↗
PubMed1979

Capacity for holding sustained attention following commissurotomy.

To assess the relative capacities of the two cerebral hemispheres to sustain prolonged mental concentration, the performance of commissurotomized patients and normal controls was tested on monotonous sorting and signal detection tasks. The two series of tasks all required the maintenance of focused attention but differed in the amount of motor activity involved. Results showed that attentional capacity was different for active than for passive tasks in the patient group. During the active sorting tasks, commissurotomy patients were able to sustain continuous attention for periods of up to an hour while in the passive signal detection tasks, a decline in general levels of arousal was evident within ten to twenty minutes. The maintenance of generalized attention with minimal proprioceptive and external stimulation was thus found to be markedly weakened following commissurotomy. Neither hemisphere was consistently inferior to the other in sustaining mental concentration. The unique ability of commissurotomy patients to efficiently carry out mutually conflicting volitional decisions while sorting with the hands simultaneously points up the role of the intact commissures in unifying attentional components of cognitive processing.

Adult↗
PubMed1975

Test for left-right chemospecificity in frog cutaneous nerves.

Studies of the effects of competitive reinnervation by left and right cutaneous nerves were carried out in Rana pipiens in an effort to test for the existence of left-right biochemical differentiation of neural tissue. The dorsal cutaneous nerves were cut, transposed and allowed to regenerate under different conditions of denervation and competition and the resultant reinnervation and reflex patterns were determined by behavioral and electrophysiological mapping techniques. Contrary to earlier findings, there was no indication in the present investigation that the growth patterns were influenced by the laterality of the fibers. Other factors such as availability of terminal sites created by complete or partial denervation and the tendency of fibers to seek terminal connections seemed to override any qualifications imposed by the existence of lateral specificity on the formation of terminal contacts.

Action Potentials↗