Siegel J, Morton C R, Sandkühler J, Xiao H M, Zimmermann M
Exp Brain Res. 1986;62(2):363-72. doi: 10.1007/BF00238856.
In cats anaesthetized with sodium pentobarbital and 70% N2O, single lumbar dorsal horn neurons were excited by controlled noxious radiant heating of glabrous hindpaw skin. The EEG was recorded from the pericruciate cortex and posterior lateral gyrus. Subcortical forebrain sites where electrical stimulation inhibited dorsal horn neuronal heat-evoked responses contralaterally were identified by mapping the caudate nucleus, internal capsule, septum, nucleus accumbens and basal forebrain regions. Inhibitory sites were mainly located in the ventral forebrain (ventral septum, diagonal band, basal forebrain). The caudate nucleus and internal capsule had a low incidence and effectiveness of inhibitory sites. In the basal forebrain, the incidence and effectiveness of inhibitory sites decreased from caudal to rostral regions. There was a rostral limit of inhibitory sites, both medially and laterally. The magnitude of inhibition increased with graded increases in brain stimulation intensity. The mean incremental increase in inhibition was greater for caudal than for rostral basal forebrain sites. Mean stimulus currents for threshold of inhibition and for inhibition to 50% of control heat responses were lower for caudal than for rostral sites. Responses of the dorsal horn neurons to increasing temperatures of noxious skin heating were monotonic linear functions over the temperature range studied (48-53 degrees C). Stimulation in both rostral and caudal basal forebrain decreased the slope of this stimulus-response function, with a greater decrease for caudal sites. Cortical EEG synchronization was evoked by stimulation in the caudate nucleus and rostral basal forebrain. For both regions, most synchronogenic sites did not produce descending inhibition of dorsal horn neurons. The significance of these findings in relation to descending inhibition from other brain regions and stimulation-produced analgesia is discussed.
在用戊巴比妥钠和70%氧化亚氮麻醉的猫中，通过对无毛后爪皮肤进行可控的有害辐射加热，可兴奋单个腰段背角神经元。从十字周皮层和后外侧回记录脑电图。通过绘制尾状核、内囊、隔区、伏隔核和基底前脑区域的图谱，确定了电刺激对侧抑制背角神经元热诱发反应的皮层下前脑部位。抑制部位主要位于腹侧前脑（腹侧隔区、斜角带、基底前脑）。尾状核和内囊的抑制部位发生率和有效性较低。在基底前脑，抑制部位的发生率和有效性从尾侧向头侧区域降低。抑制部位在中线和外侧都有一个头侧界限。抑制程度随脑刺激强度的分级增加而增加。尾侧基底前脑部位的平均抑制增量大于头侧部位。尾侧部位抑制阈值和抑制至对照热反应50%的平均刺激电流低于头侧部位。在所研究的温度范围内（48-53摄氏度），背角神经元对有害皮肤加热温度升高的反应是单调线性函数。刺激头侧和尾侧基底前脑均降低了该刺激-反应函数的斜率，尾侧部位的降低幅度更大。尾状核和头侧基底前脑的刺激诱发了皮层脑电图同步。对于这两个区域，大多数同步位点并未产生背角神经元的下行抑制。讨论了这些发现与来自其他脑区的下行抑制和刺激产生的镇痛作用的关系。
