Valzania F, Quatrale R, Strafella A P, Bombardi R, Santangelo M, Tassinari C A, De Grandis D
Divisione di Neurologia, Ospedale Bellaria, Università di Bologna, Italy.
Electroencephalogr Clin Neurophysiol. 1994 Aug;93(4):312-7. doi: 10.1016/0168-5597(94)90034-5.
The changes in motor pathway excitability, induced by pairs or trains of transcranial magnetic stimuli, were studied. The motor evoked potential (MEP) pattern depended on the interstimulus interval (ISI), the stimulus intensity and the type of coil employed. At low intensity, using either an 8-shaped or a circular coil, there was a test MEP inhibition at ISIs of 50-150 msec. During trains of stimuli, this inhibition showed a periodic trend with an interval of 250-300 msec. At high stimulus intensity we observed a progressive disappearance of test MEP inhibition which was incomplete with an 8-shaped coil and complete, reaching an MEP facilitation, with a circular coil. The inhibition observed at low intensity might be due to cortical inhibitory mechanisms. The effect found at high intensity and with the circular coil could depend on the activation of deeper and at higher threshold cortico-spinal structures. This hypothesis, however, does not explain the simultaneous delay of the test MEP latency which might depend on the activation of different cortico-spinal pathways.
研究了经颅磁刺激成对或成串刺激所诱发的运动通路兴奋性变化。运动诱发电位（MEP）模式取决于刺激间隔（ISI）、刺激强度和所用线圈类型。在低强度时，使用8字形或圆形线圈，在ISI为50 - 150毫秒时会出现测试MEP抑制。在成串刺激期间，这种抑制呈现出间隔为250 - 300毫秒的周期性趋势。在高刺激强度下，我们观察到测试MEP抑制逐渐消失，使用8字形线圈时抑制不完全，而使用圆形线圈时抑制完全消失并达到MEP易化。在低强度时观察到的抑制可能归因于皮质抑制机制。在高强度且使用圆形线圈时发现的效应可能取决于更深层且阈值更高的皮质脊髓结构的激活。然而，这一假设无法解释测试MEP潜伏期同时出现的延迟，这可能取决于不同皮质脊髓通路的激活。
