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July 1959

Effect of Spatial Summation on Action of Nociceptive Stimuli on the Cerebral Cortex

Author Affiliations

Laboratory of Neurophysiology, Department of Physiology, University of Minnesota.

AMA Arch Neurol. 1959;1(1):68-73. doi:10.1001/archneur.1959.03840010070008

Hardy, Wolff, and Goodell1 found in extensive studies that the threshold of pain in man was independent of the size of the cutaneous area that was stimulated. Whereas temporal and spatial summation processes have a profound influence on the sensory threshold of touch and temperature sensations, the investigations of Hardy and others showed that the pain threshold was lowered by temporal but not by spatial summation. On the contrary, it is well known that both forms of summation influence the intensity and duration of the reflex reactions resulting from nociceptive stimulation. Since this statement is based largely on spinal reflexes, it appeared desirable to investigate the effect of spatial and temporal summations on cerebral reactions induced by nociceptive stimulation.

Method  Experiments were performed on lightly anesthetized cats prepared under thiopental (Pentothal) and local anesthesia, later supplemented by chondodendron tomentosum extract, purified (Intocostrin). Artificial respiration was used routinely. The

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