大鼠背外侧索中各类上行纤维的电生理学特征

THE ELECTROPHYSIOLOGICAL CHARACTERISTICS OF THE ASCEN DING FIBERS OF THE DORSOLATERAL FUNICULUS IN RATS

在大鼠胸髓下段,用分离纤维细束法观察背外侧索(dorsolateral funiculus,DLF)中各类上行纤维的电生理学特征。在记录的251个单位中,144个主要接受A_β类纤维输入的单位对触毛和/或轻压皮肤反应,26个伤害性单位和毛压-伤害性会聚单位接受A_δ和C纤维的传入;这两类纤维主要沿DLF的中、浅层上行,且具有明显的会聚特点;提示其中部分单位可能属于脊颈束(spinocervicaltract,SCT)。在DLF的深、中层分离到61个对关节运动敏感的单位,它们可能属于脊髓小脑背束(dorsal spinocerebellar tract,DSST)。另有20个对各类自然刺激均无反应的自发单位。在DLF的浅层近背根处,还记录到38条来自对侧的交叉上行纤维,它们与同侧的非交叉上行纤维相混杂,其生理学特性与同侧上行纤维相似,本文结果提供了大鼠DLF中存在部分交叉上行纤维的生理学证据。

The electrophysiological characteristics of the ascending fibers of the dorsolateral funicu-lus (DLF) at the lower thoracic spinal cord of rats were studied with micro-dissection method. Of the 251 units, 144 responded to hair movement and/or light pressure to the skin. They received inputs from Aβ fibers. Twenty-six units were noxious units and hair-press and noxious convergent units. They wete excited by stimulating Aδ and C fibers. These units mainly ascended in the middle and superficial layer of the DLF and were characterized by convergence. The result suggests that these units might belong to the spino-cervical tract (SCT). Sixty-one units responded to joint movement and change of limb position. They were located in the deep and middle layer of the DLF. These units resemble dorsal spinocerebellar tract (DSCT). Twenty units with spontaneous discharges showed no response to natural stimulations. It was also found that thirty-eight crossed ascending fibers were isolated from the superficial layer of the DLF which was near the dorsal ro3t. They were mixed with the uncrossed ascending fibers. Their physiological characteristics were similar to those of the uncrossed fibers. This result supplied the physiological evidence for the crossed ascending fibers in the DLF of rats.