束旁核、中央中核对皮层体感觉区伤害性反应单位的影响

实验在清醒麻痹的猫上进行。先用记录诱发电位的方法,证明大脑皮层第 I 体感觉区(SI区)同一部位可接受来自外周神经、丘脑束旁核(Pf)和中央中核(CM)的上传信号;然后在这一皮层部位寻找在强电流刺激腓总神经时出现伤害性反应的神经元。在所观察的24个单位中,有20个单位如果先给予 Pf 刺激,可看到上述伤害性反应明显增强,增强的百分率平均在90.0%以上;在这同一组皮层单位,如果预先刺激 CM,有21个单位的伤害性反应明显减弱,反应抑制都在-55.6%以上。Pf 刺激本身对所观察单位的自发放电影响不明显,但 CM 刺激可明显抑制它们的自发放电。

EFFECTS OF STIMULATION OF PARAFASCICULAR AND CENTROMEDIAN NUCLEI ON NOCICEPTIVE DISCHARGES OF CORTICAL SOMATOSENSORY NEURONS IN CATS

Evoked potentials were recorded at the same sites of the somatosensory cortex(SI)following stimulation of either peroneal nerve or parafascicular nucleus(Pf)or centromedian nucleus(CM)in waking and flaxedil-immobilized cats.Thenociceptive discharges of 24 SI neurons at these sites were recorded extracellularlyand the effects of Pf and CM stimulation on the nociceptive discharges of theseneurons were tested.The results showed that nociceptive discharges of 20 SI neu-rons could be markedly enhanced,with an increasing percentage of more than 90%of the control rate when conditioned by Pf stimulation;while,upon conditioning CMstimulation,nociceptive discharges of 21 neurons in the same group were inhibitedat least 55.6%.Pf stimulation did not enhance the spontaneous discharges of theseneurons while CM stimulation could inhibit these discharges markedly.