刺激家鸽上纹状体对丘脑背中腹前核神经元电活动的影响

在氨基甲酸乙酯麻醉的55只鸽上,记录和分析了丘脑背中腹前核(nueleus dorsalis inter-medius ventralis anterior thalami,DIVA)对桡神经传入冲动发生反应的88个躯体感觉单位的放电其中一部分单位还对刺激坐骨神经发生反应。电刺激上纹状体的躯体传入投射区,可引致上述DIVA躯体感觉单位的自发放电和对桡神经传入的反应发生明显抑制。对自发放电抑制的程度与上纹状体的刺激频率和刺激强度呈正相关的关系;对桡神经传入反应的抑制则是使反应潜伏期增长和锋电位减少。以上结果提示,DIVA确实隶属于躯体感觉系统,而上纹状体躯体传入投射区对其躯体感觉单位有下行的抑制性影响,这种下行抑制可能使上纹状体得以对感觉输入进行反馈控制。看来中枢神经系统高级部位与丘脑之间的这种功能联系,在鸟类和哺乳类具有相似之处。

EFFECT OF ELECTRICAL STIMULATION OF HYPERSTRIATUM ON NUCLEUS DORSALIS INTERMEDIUS VENTRALIS ANTERIOR THALAMI SOMATOSENSORY UMTS IN PIGEON

Discharges of 88 somatosensory units in the nucleus dorsalis intermedius ventralisanterior thalami (DIVA) in response to afferent impulses of radial nerve on 55 ure-thane anesthetized pigeons were recorded and analysed. Among the 88 units, Part ofthem also responded to the stimulation of sciatic nerve. Following electrical stimula-tion of somatic projecting area of hyperstriatum, the spontaneous discharges and the re-sponses of DIVA somatosensory units to radial inputs were obviously inhibited and thedegree of inhibition was linearly correlated with the frequency and intensity of stimula-tion. The inhibitory effect on the responses to radial inputs may cause an increase inlatency and a decrease in number of spikes. These results indicate that the DIVA cer-tainly belongs to somatosensory system, and the somatic projecting area of hyperstria-tum has a descending inhibitory effect on the DIVA somatosensory units. The hypers-triatum may thus exert feedback control over its sensory inputs through descending in-hibitibn. It appears that the functional connection between the highest region of cen-tral nervous system and thalamus in avian is similar to that of mammal.