Danish Research Centre for Magnetic Resonance, Centre for Functional and Diagnostic Imaging and Research, Copenhagen University Hospital Hvidovre, Hvidovre, Denmark; Department of Neurosciences, Reproductive Sciences and Odontostomatology, University Federico II of Naples, Italy.
Danish Research Centre for Magnetic Resonance, Centre for Functional and Diagnostic Imaging and Research, Copenhagen University Hospital Hvidovre, Hvidovre, Denmark; INSERM, U1216, Grenoble Institut des Neurosciences, GIN, F-38000 Grenoble, France.
Neuroimage. 2017 Sep;158:37-47. doi: 10.1016/j.neuroimage.2017.06.063. Epub 2017 Jun 29.
Using the short-latency afferent inhibition (SAI) paradigm, transcranial magnetic stimulation (TMS) of the primary motor hand area (M1) can probe how sensory input from limbs modulates corticomotor output in humans. Here we applied a novel TMS mapping approach to chart the spatial representation of SAI in human hand-knob. We hypothesized SAI is somatotopically expressed in M1 depending on both the site of peripheral electrical nerve stimulation and the cortical spot targeted by TMS within M1. The left index or little finger was stimulated 23 ms before focal single-pulse TMS of the right M1. Using frameless stereotaxy, we applied biphasic-TMS pulses at seven stimulation positions above right M1 and recorded the motor evoked potentials (MEPs) from relaxed left first-dorsal-interosseous (FDI) and abductor-digiti-minimi (ADM) muscles. Homotopic stimulation of the finger close to the muscle targeted by TMS revealed a somatotopic expression of afferent inhibition matching the somatotopic representation of unconditioned MEPs (homotopic SAI). Conversely, heterotopic stimulation of a finger distant to the muscle targeted by TMS induced short-latency afferent facilitation (SAF) of MEPs in M1. Like homotopic SAI, heterotopic SAF was somatotopically expressed in M1. Together, the results provide first-time evidence that fast sensorimotor integration involves centre-inhibition and surround-facilitation in human M1.
利用短潜伏期传入抑制（SAI）范式，经颅磁刺激（TMS）刺激初级运动手区（M1）可以探测肢体感觉输入如何调节人类皮质运动输出。在这里，我们应用了一种新的 TMS 映射方法来描绘人类手 knob 中 SAI 的空间表达。我们假设 SAI 根据外周电神经刺激的部位和 TMS 在 M1 内靶向的皮质点在 M1 中具有躯体定位表达。在对右侧 M1 进行单次聚焦 TMS 刺激之前 23 毫秒，刺激左侧食指或小指。使用无框架立体定向技术，我们在右侧 M1 上方的七个刺激位置施加双相 TMS 脉冲，并记录来自放松的左侧第一背间骨间肌（FDI）和小指展肌（ADM）的运动诱发电位（MEP）。接近 TMS 靶向肌肉的手指同部位刺激显示出与未调节 MEP 的躯体定位表达相匹配的传入抑制的躯体定位表达（同部位 SAI）。相反，远离 TMS 靶向肌肉的手指异部位刺激会在 M1 中引起 MEP 的短潜伏期传入易化（SAF）。与同部位 SAI 一样，异部位 SAF 在 M1 中具有躯体定位表达。总之，这些结果首次提供了证据，表明快速感觉运动整合涉及人类 M1 中的中心抑制和周围易化。
