刺激大脑皮层联合区对C类纤维传入诱发皮层电反应的影响

电刺激猫大脑皮层前外侧回联合区(ALA)能使隐神经 C 类纤维传入引起的体感皮层(S(?)区)诱发电位(C-CEP)的幅值明显变小,并有后作用,表明 ALA 对 C-CEP 有抑制作用;切断ALA 与 SI 区之间的皮层内纤维联系后,ALA 对 C-CEP 的抑制作用明显减弱,抑制时程缩短;侧脑室微量注射阿片受体拮抗剂纳洛酮后,电刺激 ALA 对 C-CEP 的抑制作用明显减弱,表明 ALA 对 C-CEP 的抑制作用的作用途径之—可能是通过 ALA 与 SI 区之间的皮层内神经径路;可能与内源性阿片样物质的释放有关。提示大脑皮层联合区可能对体感皮层 C-CEP 有调制作用。

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.