[Influence of stimulation of cerebral anterior lateral association area on cortical potentials evoked by C-fiber inputs in saphenous nerve].

The effect of stimulation of cerebral anterior lateral association area (ALA) on evoked potentials recorded in the primary somatosensory cortex (SI), elicited by C-fiber inputs of saphenous nerve (C-CEP) was investigated in cats anesthetized with chloralose and immobilized by Flaxedil. Following 1 min electric stimulation of ALA (0.1 mA, 100 Hz, duration 0.2 ms), the amplitudes of C-CEP were obviously decreased, indicating that ALA had an inhibitory effect on C-CEP. In order to explore the neural pathway underlying the inhibition of C-CEP by ALA stimulation, a vertical section between ALA and SI was made. It was shown that the inhibition of C-CEP produced by ALA stimulation was reduced considerably and the time course of the inhibition was shortened after the section. Moreover, the ALA stimulation-produced inhibition was also blocked partially 7 min after the intraventricular injection of naloxone (25 micrograms/50 microliters). The results suggest that ALA may exert an inhibitory effect on C-CEP, which is mediated by endogenous opiate like substances and through the nervous connection between ALA and SI. The cerebral association area may play a role in the modulation of C-CEP.