Berardelli A, Inghilleri M, Gilio F, Romeo S, Pedace F, Currà A, Manfredi M
Dipartimento Scienze Neurologiche, Università di Roma La Sapienza, Rome, Italy.
Exp Brain Res. 1999 Mar;125(1):82-6. doi: 10.1007/s002210050661.
The effects of repetitive transcranial stimulation (rTMS) on brain activity remain unknown. In healthy subjects, we studied the effects of rTMS on the duration of the cortical silent period (SP). Repetitive stimuli were delivered with a Cadwell High Speed Magnetic Stimulator and a figure-of-eight coil placed over the hand motor area. rTMS was delivered in trains of 11 or 20 stimuli at frequencies of 3 and 5 Hz and at stimulation intensities of 110 and 120% of motor threshold. The SP was recorded from the forearm muscles during a voluntary contraction (20% of maximum effort). rTMS delivered at a frequency of 3 and 5 Hz and intensities of 110 and 120% motor threshold prolonged the duration of the SP, without modifying either the size or the latency of the muscle-evoked potentials (MEP). A conditioning train of 11 stimuli at 3 Hz had no effect on the duration of the SP evoked by a single magnetic shock delivered 600 ms after the train. These findings show that rTMS increases the duration of the cortical SP, but does so only during the train of stimuli. rTMS probably changes the duration of the SP by facilitating cortical inhibitory interneurons.
重复经颅磁刺激（rTMS）对大脑活动的影响尚不清楚。在健康受试者中，我们研究了rTMS对皮质静息期（SP）时长的影响。使用Cadwell高速磁刺激器和置于手部运动区上方的八字形线圈施加重复刺激。rTMS以11次或20次刺激的序列，在3Hz和5Hz的频率以及运动阈值的110%和120%的刺激强度下进行。在自愿收缩（最大用力的20%）期间从前臂肌肉记录SP。以3Hz和5Hz的频率以及110%和120%运动阈值的强度施加rTMS可延长SP的时长，而不改变肌肉诱发电位（MEP）的大小或潜伏期。在3Hz下施加11次刺激的条件刺激序列对在该序列后600ms施加的单次磁刺激所诱发的SP时长没有影响。这些发现表明，rTMS增加了皮质SP的时长，但仅在刺激序列期间如此。rTMS可能通过促进皮质抑制性中间神经元来改变SP的时长。
