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doi: 10.1007/BF02324762pmid: 5422469
221 10 10 4 4 L. Rispal-Padel J. Massion Laboratoire de neurophysiologie générale, I.N.P. — C.N.R.S. Marseille France Summary In cats anesthetized with chloralose, a topographic study of the relations between the ventrolateral nucleus and the precruciate cortex has been performed. It has revealed a mediolateral topography inside the ventrolateral nucleus such that the medial neurones project to area 6 and the more lateral ones to area 4. Postsynaptic spikes were evoked in ventrolateral nucleus by stimulation of the precruciate cortex, with the same topography. The postsynaptic spikes are usually preceeded by an antidromic spike. The possible action of the cerebellum on axial musculature by way of the ventrolateral nucleus and the motor cortex is discussed.
Finger, Stanley; Scheff, Stephen; Warshaw, Ira; Cohen, Karen
doi: 10.1007/BF02324763pmid: 5422470
221 10 10 4 4 Stanley Finger Stephen Scheff Ira Warshaw Karen Cohen Department of Psychology Washington University St. Louis USA Summary Rats with histologically confirmed bilateral lesions of one or both somatosensory cortical areas, occipital cortex, or sham operations were tested in a T-maze for retention of 29° vs. 39° C and 29° vs. 34° C temperature discriminations, and for acquisition of a 29° vs. 31° C habit. Statistical analyses failed to reveal group differences on the three postoperative discriminations. The suggestion that thermal habits are mediated by a diffuse and redundant forebrain afferent system is discussed.
doi: 10.1007/BF02324764pmid: 4987208
221 10 10 4 4 Peter H. Schiller Department of Psychology Massachusetts Institute of Technology Cambridge Massachusetts USA Summary 1. Extracellular single unit records were obtained in the brainstem oculomotor complex of alert monkeys. 2. Maintained eye position, smooth pursuit and saccadic eye movement appear to be brought about by the same population of neurons. 3. Increasing deviation in eye position for fixation and for smooth pursuit movement is accomplished in two ways: (a) increase and decrease in firing rate and (b) change in the number of neurons discharging concurrently. 4. Saccadic eye movement is brought about by a rapid burst of firing in these same units. Saccade size is determined by the duration of the burst; the speed of the saccade appears to be influenced both by discharge frequency and the size of the neuronal pool discharging in synchrony. 5. A small population of units discharges specifically in association with vergence operations, increasing their firing rate to convergence and decreasing it to divergence.
doi: 10.1007/BF02324765pmid: 5422472
221 10 10 4 4 Whitman Richards Department of Psychology Massachusetts Institute of Technology Cambridge USA Summary Psychophysical tests reveal three classes of wide-field disparity detectors in man, responding respectively to crossed (near), uncrossed (far), and zero disparities. The probability of lacking one of these classes of detectors is about 30% which means that 2.7% of the population possess no wide-field stereopsis in one hemisphere. This small percentage corresponds to the probability of squint among adults, suggesting that fusional mechanisms might be disrupted when stereopsis is absent in one hemisphere.
doi: 10.1007/BF02324766pmid: 5422473
221 10 10 4 4 D. E. Joshua P. O. Bishop Brain Research Unit, Department of Physiology University of Sydney Sydney Australia Department of Physiology John Curtin School of Medical Research, Australian National University Canberra A.C.T. Australia Summary Of binocularly-activated striate neurons only a proportion have their two receptive fields in exactly corresponding positions in the contralateral hemifield. Those which are not corresponding are said to show receptive field disparity. Because the eyes diverge in the anaesthetized and paralyzed preparation, the binocular receptive fields are horizontally separate. With increasing retinal eccentricity there is a gradual decrease in this horizontal separation as well as progressive changes in the local receptive field disparities. With increasing horizontal retinal eccentricity there is a progressive increase in horizontal receptive field disparities together with a smaller decrease in vertical disparities. Receptive field disparities are relatively unaffected by increasing vertical retinal eccentricity. A neurophysiological theory for binocular single vision and depth discrimination is put forward as a theoretical framework for the construction of the horopter for the cat as well as a region analogous to Panum's fusional area in man. Observations have been made on the responses, particularly to moving slit stimuli, of units with peripherally-located receptive fields. For several binocular units it was possible to study the full range of the binocular interaction when the two receptive fields were moved from exact correspondence to positions of increasing non-alignment.
doi: 10.1007/BF02324767pmid: 5422474
221 10 10 4 4 H. McLennan Department of Physiology University of British Columbia Vancouver Canada Summary 1. Repetitive electrical stimulation of the surface of the cerebral cortex of cats, with current intensities less than those required to produce epileptiform after-discharges, elicited a suppression of discharge of many neurones within the same gyrus which may last many seconds. Such suppression was only rarely preceded by excitation of the cells. 2. Such inhibitions were observed in neurones tiring spontaneously, or in those activated by the iontophoretic application of glutamate, homocysteate or acetylcholine. 3. No alterations in the pattern of inhibition in individual neurones were observed after the iontophoretic administration of atropine or of strychnine to them; nor did the systemic administration of these drugs affect the production of the inhibition. 4. The inhibition produced by a given stimulation was generally considerably longer in neurones activated by glutamate than in the same cells excited by homocysteate. Quantitative examination suggested that this difference was most marked in cells lying in layers II and V of the cortex.
Bourke, R.; Nelson, K.; Naumann, R.; Young, O.
doi: 10.1007/BF02324768pmid: 4987209
221 10 10 4 4 Dr. R. S. Bourke K. M. Nelson R. A. Naumann O. M. Young Laboratory of Neurochemistry and Surgical Neurology Branch, National Institute of Neurological Diseases and Stroke, National Institutes of Health Bethesda USA Department of Neurosurgery Roswell Park Memorial Institute 666 Elm Street 14203 Buffalo New York USA Summary 1. The swelling of intact primate cerebral cortex perfused under isosmotic conditions in vivo , like swelling of slices of mammalian cerebral cortex incubated in vitro , is a linear function of the concentration of K + in the extracellular fluid over the range 20–120 mM. 2. The simultaneous presence of the Cl − ion is required for the development of K + -dependent swelling of cerebral cortex under various experimental conditions in vivo and in vitro . 3. The maintenance of previously established K + -dependent swelling of cerebral cortex both in vitro and in vivo requires the relative concentrations of both K + and Cl − in the extracellular fluid to remain constant. A reduction in the concentration of either ion is associated with an absolute loss of fluid of swelling of cerebral cortex. 4. The content of Cl − in cerebral cortex is a function of the magnitude of K + -dependent swelling even though the concentration of Cl − in the extracellular fluid is maintained constant. 5. The mechanism of swelling in primate cerebral cortex following cerebral circulatory arrest is discussed in the light of the experimental findings, as a model of the type of brain injury encountered in massive clinical stroke.
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