Inhibition of somatosensory-evoked cortical responses by a weak leading stimulus
Inhibition of somatosensory-evoked cortical responses by a weak leading stimulus
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DOI：
10.1016/j.neuroimage.2014.07.035
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发表时间：
2014-11-01
期刊：
影响因子：
5.7
通讯作者：
Kakigi, Ryusuke
中科院分区：
文献类型：
--
作者：
Nakagawa, Kei;Inui, Koji;Kakigi, Ryusuke
我们以前证明，神经刺激诱发的皮层反应被抑制的方式类似于惊吓反射的前脉冲抑制（PPI）的微弱的领先刺激。本研究的目的是调查是否存在类似的现象在躯体感觉系统，以及是否这种抑制反映了抑制过程。我们记录了体感诱发磁场刺激正中神经和评估的程度，他们被抑制插入领先的刺激强度为2.5-，1.5-，1.1-，或0.9倍的感觉阈值（ST）在健康的参与者（实验1）。结果表明，刺激侧对侧半球（cSII）的次级躯体感觉皮层的活动被强度大于1.1倍ST的弱先导刺激显著抑制。这一结果表明，躯体感觉系统具有类似于PPI的抑制过程。然后，我们提出了两个连续的领先的刺激前的测试刺激，并比较了测试刺激诱发的反应和第二个前脉冲单独和两个前脉冲（第一和第二）（实验2）之间的抑制程度。当两个预脉冲之前，cSII响应第二预脉冲被抑制的第一预脉冲，而第二预脉冲抑制测试刺激的能力保持不变。这些结果表明存在至少两个单独的途径;反应产生和抑制途径。(C)2014爱思唯尔公司All rights reserved.
We previously demonstrated that auditory-evoked cortical responses were suppressed by a weak leading stimulus in a manner similar to the prepulse inhibition (PPI) of startle reflexes. The purpose of the present study was to investigate whether a similar phenomenon was present in the somatosensory system, and also whether this suppression reflected an inhibitory process. We recorded somatosensory-evoked magnetic fields following stimulation of the median nerve and evaluated the extent by which they were suppressed by inserting leading stimuli at an intensity of 2.5-, 1.5-, 1.1-, or 0.9-fold the sensory threshold (ST) in healthy participants (Experiment 1). The results obtained demonstrated that activity in the secondary somatosensory cortex in the hemisphere contralateral to the stimulated side (cSII) was significantly suppressed by a weak leading stimulus with the intensity larger than 1.1-fold ST. This result implied that the somatosensory system had an inhibitory process similar to that of PPI. We then presented two successive leading stimuli before the test stimulus, and compared the extent of suppression between the test stimulus-evoked responses and those obtained with the second prepulse alone and with two prepulses (first and second) (Experiment 2). When two prepulses were preceded, cSII responses to the second prepulse were suppressed by the first prepulse, whereas the ability of the second prepulse to suppress the test stimulus remained unchanged. These results suggested the presence of at least two individual pathways; response-generating and inhibitory pathways. (C) 2014 Elsevier Inc. All rights reserved.