Chapman C E, Jiang W, Lamarre Y
Centre de Recherche en Sciences Neurologiques, Université de Montréal, Québec, Canada.
Exp Brain Res. 1988;72(2):316-34. doi: 10.1007/BF00250254.
Modulation of sensory transmission in the lemniscal system was investigated in 2 monkeys trained to perform a simple elbow flexion in response to an auditory cue. Evoked responses to peripheral stimulation were recorded in the medial lemniscus, sensory thalamus (ventral posterior lateral nucleus, caudal division, VPLc) and somatosensory cortex. Simultaneous recordings were made from the cortex and either the medial lemniscus or VPLc. At all recording sites, evoked responses to natural (air puff) or electrical, percutaneous stimulation were depressed prior to and during active movement. The time course of the depression was similar at all three levels; the magnitude of the decrease during movement was most pronounced at the cortical level. Cortical evoked responses to central stimulation of effective sites in either the medial lemniscus or VPLc were decreased during, but not before, the onset of movement. The decrease was less than that seen for peripheral evoked potentials. Passive movement of the forearm significantly decreased all but the lemniscal evoked potential. The results indicate that there is a centrally mediated suppression of somatosensory transmission prior to, and during movement, occurring at the level of the first relay, the dorsal column nuclei. During movement, reafferent signals from the moving arm decrease transmission at the thalamocortical level.
在2只经过训练能根据听觉提示做出简单肘部弯曲动作的猴子身上，研究了内侧丘系系统中感觉传导的调制情况。记录了内侧丘系、感觉丘脑（腹后外侧核，尾侧部，VPLc）和体感皮层对周围刺激的诱发反应。同时从皮层与内侧丘系或VPLc进行记录。在所有记录部位，在主动运动之前和期间，对自然（吹气）或经皮电刺激的诱发反应均受到抑制。在所有三个层面上，抑制的时间进程相似；运动期间下降的幅度在皮层层面最为明显。在运动开始期间而非之前，皮层对内侧丘系或VPLc中有效部位的中枢刺激的诱发反应降低。这种降低小于外周诱发电位所见的降低。前臂的被动运动显著降低了除内侧丘系诱发电位之外的所有诱发电位。结果表明，在运动之前和期间，在第一级中继站即背柱核水平存在中枢介导的体感传导抑制。在运动期间，来自运动手臂的再传入信号在丘脑皮质水平降低传导。
