刺激家兔扣带回前部对丘脑腹后外侧核痛敏神经元放电的作用

131只家兔在三碘季铵酚麻痹下,用玻璃微电极在腹后外侧核(VPL)记录对伤害性刺激有反应的单位。在786个 VPL 单位中,对伤害性刺激有反应的单位共128个,占总数16.3%.其中116今对伤害性刺激呈兴奋效应,占90.6%。其余12个呈抑制效应,占9.4%。静脉注射吗啡可以取消这些神经元对伤害性刺激的放电反应。78次的测试结果表明扣带回前部的刺激可以抑制32%VPL 神经元的自发放电活动。同样,也可以抑制由于伤害性刺激而引起的 VPL 神经元的放电反应。这种抑制程度和扣带回的刺激频率有关;8Hz 的刺激频率所引起的抑制效应最佳。上述实验结果说明,扣带回可以通过其下行纤维的活动;影响伤害性冲动在丘脑 VPL水平上的传递。

EFFECT OF CINGULATE GYRUS STIMULATION ON NOCICEP TIVE DISCHARGES OF NEURONS IN THALAMIC VENTRO POSTERIOR LATERAL NUCLEUS OF RABBITS

Experiments were performed on 131 rabbits immobilized with Flaxedil.Unitdischarges of ventroposterior lateral nucleus(VPL)responsive to nociceptive sti-mulation were recorded with glass microelectrodes.Of the 786 units of VPL,128units were found to be responsive to noxious stimuli,among which 116 units showedexcitatory effect and 12 units,inhibitory effect.The unit discharges evoked bynoxious stimuli could be abolished by intravenous injection of morphine(4 mg/kg).The spontaneous discharges as well as the evoked nociceptive discharges were in-hibited to some extent in 32% of VPL neurons by direct repetitive stimulation ofthe anterior region of cingulate gyrus.Eight Hz stimulation seemed to be optimal.These results indicated that the cingulate gyrus could modulate the nociceptive im-pulses in VPL nucleus through some descending pathway.