Knecht S, Sommer J, Deppe M, Steinsträter O
Department of Neurology, University of Münster, Albert-Schweitzer-Strasse 33, D-48129 Münster, Germany.
Clin Neurophysiol. 2005 Aug;116(8):1988-93. doi: 10.1016/j.clinph.2005.04.016.
To assess the impact of the scalp site on the biological effects of TMS.
We performed high-resolution, three-dimensional whole head magnetic resonance imaging (MRI) in a healthy subject, systematically measured the scalp-to-cortex distance across the head and calculated the resulting electric field in the superficial cortex.
The variability in scalp-to-cortex distance led to differences in calculated cortical electric field strengths of a factor of two. A major portion of this variability was explained by a lateral to medial gradient with scalp-to-cortex distances being greatest close to the midline and smallest towards the temporal coordinates.
Because of the medio-lateral gradient in scalp-to-cortex distance interventions tailored on the basis of effects of TMS in the motor system will systematically induce stronger than expected electric currents when performed laterally to the motor spot.
The biological effects of TMS outside the motor spot may be markedly different from those observed in the motor system and this should be taken into account to optimize TMS for the evaluation or treatment of neuropsychiatric disorders.
评估头皮部位对经颅磁刺激（TMS）生物学效应的影响。
我们对一名健康受试者进行了高分辨率三维全脑磁共振成像（MRI），系统测量了全脑头皮至皮质的距离，并计算了浅表皮质中的电场。
头皮至皮质距离的变异性导致计算出的皮质电场强度相差两倍。这种变异性的主要部分可由从外侧到内侧的梯度来解释，头皮至皮质距离在靠近中线处最大，在颞部坐标处最小。
由于头皮至皮质距离存在从内侧到外侧的梯度，基于TMS在运动系统中的效应而定制的干预措施，在运动点外侧进行时，将系统性地诱发比预期更强的电流。
运动点以外区域的TMS生物学效应可能与运动系统中观察到的效应明显不同，在优化TMS用于评估或治疗神经精神疾病时应考虑到这一点。
