Tamburin S, Manganotti P, Zanette G, Fiaschi A
Department of Neurological Sciences and Vision, Section of Clinical Neurology, University of Verona, Ospedale Policlinico G.B. Rossi, piazzale Scuro, 37134 Verona, Italy.
Exp Brain Res. 2001 Nov;141(2):232-41. doi: 10.1007/s002210100859.
The aim of this study was to elucidate sensorimotor integration in human hand motor areas, its time course, somatotopy and the interaction of sensory fields arising from two different fingers. We studied the influence of different intensities of electrical digital stimulation of two different fingers on motor-evoked potentials elicited in hand muscles by transcranial magnetic stimulation (TMS). Single conditioning electrical stimuli were applied to the right second (D2) and fifth fingers (D5) individually and also to both fingers (D2+D5) simultaneously in six normal volunteers. Magnetic tests, adjusted to produce a response in the abductor digiti minimi muscle of the right hand, were delivered using a circular and a focal coil. The digital stimuli were delivered to the finger at the sensory threshold (ST), at 3 and 5 times the ST, and over the pain threshold at interstimulus intervals (ISIs) ranging from 10 to 100 ms. In order to define the anatomical level of the sensorimotor interactions, the effect of the digital stimulation on TMS was compared to the effect on transcranial electrical stimulation. When the peripheral stimulation was delivered at the ST a small inhibitory effect was found only when stimulating both fingers. At 3 times the ST we detected a topographic distribution of motor-evoked potential inhibition, which partially disappeared at higher intensity (5 times the ST); two types of convergence effects took place at different ISIs. When conditioning stimuli were painful, somatotopy and convergence were lost. Sensorimotor integration shows somatotopy and interaction of afferents at different sites. The intensity of the conditioning stimulus plays an important role in topography and sensory convergence. The importance of these mechanisms in physiology and physiopathology is discussed.
本研究的目的是阐明人类手部运动区域的感觉运动整合、其时间进程、躯体定位以及来自两个不同手指的感觉场之间的相互作用。我们研究了对两个不同手指进行不同强度的电指刺激，对经颅磁刺激（TMS）诱发的手部肌肉运动诱发电位的影响。在六名正常志愿者中，分别对右手的第二指（D2）和第五指（D5）单独施加单次条件电刺激，同时也对两个手指（D2 + D5）同时施加刺激。使用圆形线圈和聚焦线圈进行磁测试，以在右手小指展肌中产生反应。数字刺激在感觉阈值（ST）、ST的3倍和5倍强度下，以及超过疼痛阈值时，以10至100毫秒的刺激间隔（ISI）施加到手指上。为了确定感觉运动相互作用的解剖学水平，将数字刺激对TMS的影响与对经颅电刺激的影响进行了比较。当外周刺激在ST强度下施加时，仅在刺激两个手指时发现了轻微的抑制作用。在ST的3倍强度时，我们检测到运动诱发电位抑制的拓扑分布，在更高强度（ST的5倍）时部分消失；在不同的ISI下发生了两种类型的会聚效应。当条件刺激引起疼痛时，躯体定位与会聚消失。感觉运动整合显示了不同部位传入神经的躯体定位和相互作用。条件刺激的强度在拓扑结构和感觉会聚中起着重要作用。讨论了这些机制在生理学和病理生理学中的重要性。
