Centrifugal regulation of task-relevant somatosensory signals to trigger a voluntary movement
Centrifugal regulation of task-relevant somatosensory signals to trigger a voluntary movement
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DOI：
10.1007/s00221-005-0141-8
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发表时间：
2006-03-01
影响因子：
2
通讯作者：
Kakigi, R
中科院分区：
文献类型：
--
作者：
Kida, T;Wasaka, T;Kakigi, R
先前的许多论文报道了随意运动期间体感诱发电位（SEP）的调节，但由任务相关体感刺激引起的运动诱导的 SEP 离心调节的轨迹和机制仍不清楚。我们研究了由任务相关体感刺激引起的 SEP 的离心调节，该刺激在预先警告的反应时间任务中触发自愿运动。一对警告（S1：听觉）和命令性刺激（S2：体感）以 1 秒的刺激间隔呈现。受试者被指示通过移动同侧或对侧的手来响应引起 SEP 的体感刺激。在四个实验中，分别检查了 SEP 调节的轨迹和选择性、皮肤传入的贡献以及收缩幅度的影响。将受试者没有任务执行的控制条件与几种任务条件进行比较。与对照条件相比，当体感刺激触发受刺激手指的随意运动时，额叶 N30、顶叶 P30 和中央 P25 的振幅降低，长潜伏期 P80 和 N140 的振幅增加。 N60 随着任何手指的移动而减小。这些结果被认为是由体感命令性刺激之前发生的神经元活动的离心影响引起的。目前的研究结果并不支持以下假设：下行运动命令对传入输入的抑制可能发生在皮质下水平。较高的收缩幅度导致额叶 N30 的振幅进一步衰减，同时降低了 P80 的增强。此外，神经元反应的调节似乎主要来自皮肤传入的调节，尤其是来自移动的身体部位的调节。总之，来自运动身体部位的与任务相关的上行传入神经元引起的短潜伏期和长潜伏期体感神经元活动在这些传入输入之前受到运动相关神经元活动的不同调节。后一种活动可能与感觉增益调节有关，该调节与将注意力集中到参与该动作的身体部位相关。
Many previous papers have reported the modulation of somatosensory evoked potentials (SEPs) during voluntary movement, but the locus and mechanism underlying the movement-induced centrifugal modulation of the SEPs elicited by a task-relevant somatosensory stimulus still remain unclear. We investigated the centrifugal modulation of the SEPs elicited by a task-relevant somatosensory stimulus which triggers a voluntary movement in a forewarned reaction time task. A pair of warning (S1: auditory) and imperative stimuli (S2: somatosensory) was presented with a 1 s interstimulus interval. Subjects were instructed to respond by moving the hand ipsilateral or contralateral to the somatosensory stimulation which elicits the SEPs. In four experiments, the locus and selectivity of the SEPs' modulation, the contribution of cutaneous afferents and the effect of contraction magnitude were examined, respectively. A control condition where subjects had no task to perform was compared to several task conditions. The amplitude of the frontal N30, parietal P30, and central P25 was decreased and that of the long latency P80 and N140 was increased when the somatosensory stimuli triggered a voluntary movement of the stimulated finger compared to the control condition. The N60 decreased with the movement of any finger. These results were considered to be caused by the centrifugal influence of neuronal activity which occurs before a somatosensory imperative stimulus. The present findings did not support the hypothesis that the inhibition of afferent inputs by descending motor commands can occur at subcortical levels. A higher contraction magnitude produced a further attenuation of the amplitude of the frontal N30, while it decreased the enhancement of the P80. Moreover, the modulation of neuronal responses seems to result mainly from the modulation of cutaneous afferents, especially from the moved body parts. In conclusion, the short- and long-latency somatosensory neuronal activities evoked by task-relevant ascending afferents from the moved body parts are regulated differently by motor-related neuronal activities before those afferent inputs. The latter activities may be associated with sensory gain regulation related to directing attention to body parts involved in the action.