FENNSI Group, Hospital Nacional de Parapléjicos, SESCAM, Toledo, Spain.
J Physiol. 2011 Oct 15;589(Pt 20):4949-58. doi: 10.1113/jphysiol.2011.211953. Epub 2011 Aug 1.
The aim of the present study was to investigate in healthy humans the possibility of a non-invasive modulation of motor cortex excitability by the application of static magnetic fields through the scalp. Static magnetic fields were obtained by using cylindrical NdFeB magnets. We performed four sets of experiments. In Experiment 1, we recorded motor potentials evoked by single-pulse transcranial magnetic stimulation (TMS) of the motor cortex before and after 10 min of transcranial static magnetic field stimulation (tSMS) in conscious subjects. We observed an average reduction of motor cortex excitability of up to 25%, as revealed by TMS, which lasted for several minutes after the end of tSMS, and was dose dependent (intensity of the magnetic field) but not polarity dependent. In Experiment 2, we confirmed the reduction of motor cortex excitability induced by tSMS using a double-blind sham-controlled design. In Experiment 3, we investigated the duration of tSMS that was necessary to modulate motor cortex excitability. We found that 10 min of tSMS (compared to 1 min and 5 min) were necessary to induce significant effects. In Experiment 4, we used transcranial electric stimulation (TES) to establish that the tSMS-induced reduction of motor cortex excitability was not due to corticospinal axon and/or spinal excitability, but specifically involved intracortical networks. These results suggest that tSMS using small static magnets may be a promising tool to modulate cerebral excitability in a non-invasive, painless, and reversible way.
本研究旨在探索在健康人体中，通过头皮施加静态磁场，是否有可能非侵入性地调节运动皮层的兴奋性。我们使用圆柱形 NdFeB 磁铁产生静态磁场。我们进行了四组实验。在实验 1 中，我们在清醒受试者中，在经颅静磁刺激（tSMS） 10 分钟前后，记录了单次经颅磁刺激（TMS）诱发的运动电位。我们观察到运动皮层兴奋性平均降低了 25%，这是 TMS 揭示的结果，这种降低持续了 tSMS 结束后的几分钟，并且与磁场强度（磁场强度）有关，但与极性无关。在实验 2 中，我们使用双盲 sham 对照设计证实了 tSMS 引起的运动皮层兴奋性降低。在实验 3 中，我们研究了调节运动皮层兴奋性所需的 tSMS 持续时间。我们发现，10 分钟的 tSMS（与 1 分钟和 5 分钟相比）是必需的，以产生显著的效果。在实验 4 中，我们使用经颅电刺激（TES）证实，tSMS 诱导的运动皮层兴奋性降低不是由于皮质脊髓轴突和/或脊髓兴奋性，而是具体涉及皮质内网络。这些结果表明，使用小的静态磁铁的 tSMS 可能是一种有前途的工具，可以非侵入性、无痛和可逆的方式调节大脑的兴奋性。
