Primary Afferent Depolarization Evoked by a Painful Stimulus

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Science  11 Jul 1969:
Vol. 165, Issue 3889, pp. 184-186
DOI: 10.1126/science.165.3889.184


Pulses of intense radiant heat applied to the plantar pad of unanesthetized spinal cats produced negative dorsal root potentials, increased excitability of cutaneous A fibers, and marked activation of ipsilateral flexor motoneurons. The same effects were obtained during cold block of A fiber conduction in the appropriate peripheral nerve. We conclude that adequate noxious activation of cutaneous C fibers depolarizes cutaneous A fibers.

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