Gangitano Massimo, Valero-Cabré Antoni, Tormos José Maria, Mottaghy Felix Manuel, Romero Jose Rafael, Pascual-Leone Alvaro
Laboratory for Magnetic Brain Stimulation, Division of Behavioral Neurology, Department of Neurology, Beth Israel Deaconess Medical Center, Harvard Medical School, 330 Brookline Avenue, Boston, MA 02215, USA.
Clin Neurophysiol. 2002 Aug;113(8):1249-57. doi: 10.1016/s1388-2457(02)00109-8.
Exploring the modulatory effects of different frequencies of repetitive transcranial magnetic stimulation (rTMS) on the excitability of the motor cortex as measured by the input-output curve technique (I-O curve).
Sixteen healthy subjects participated in this experiment. On two different sessions, conducted 1 week apart, rTMS was applied either at a frequency of 20 or 1 Hz at 90% of individual motor threshold (MT) for a total of 1600 pulses each. Before and after rTMS, the cortical excitability was assessed by measuring MT and the size of motor evoked potentials (MEPs) collected at different intensities of stimulation.
The analysis on the whole population showed a significant decrease of cortical excitability after 1 Hz rTMS and an increase after 20 Hz rTMS. A subsequent cluster analysis pointed out the presence of two distinct groups of subjects with opposite responses at the same frequency of stimulation. Significant variations on MT were found for both groups only for the facilitatory effect irrespective of the frequency of stimulation.
The results provide further insight into interindividual differences in the effects of rTMS and suggest the existence of subpopulations with specific patterns of response to rTMS.
采用输入-输出曲线技术（I-O曲线）探究不同频率重复经颅磁刺激（rTMS）对运动皮质兴奋性的调节作用。
16名健康受试者参与本实验。在间隔1周进行的两次不同实验中，分别以20Hz或1Hz的频率、在个体运动阈值（MT）的90%强度下施加rTMS，每次共1600个脉冲。在rTMS前后，通过测量MT以及在不同刺激强度下收集的运动诱发电位（MEP）的大小来评估皮质兴奋性。
对全体受试者的分析显示，1Hz rTMS后皮质兴奋性显著降低，20Hz rTMS后皮质兴奋性升高。随后的聚类分析指出，在相同刺激频率下存在两组反应相反的不同受试者群体。两组仅在促进作用方面，无论刺激频率如何，MT均有显著变化。
研究结果进一步揭示了rTMS效应的个体差异，并提示存在对rTMS有特定反应模式的亚群体。
