Caparelli Ec, Backus W, Telang F, Wang Gj, Maloney T, Goldstein Rz, Henn F
SCAN Center, Stony Brook University, Stony Brook, NY, USA.
Open Neuroimag J. 2012;6:69-74. doi: 10.2174/1874440001206010069. Epub 2012 Jul 17.
1 Hz repetitive Transcranial Magnetic Stimulation (rTMS) is considered to have an inhibitory effect in healthy people because it suppresses the excitability of the motor or visual cortex that is expressed as an increase in the motor or the phosphene threshold (PT), respectively. However, the underlying mechanisms and the brain structures involved in the action of rTMS are still unknown. In this study we used two sessions of simultaneous TMS-functional magnetic resonance imaging (fMRI), one before and one after, 15 minutes of 1Hz rTMS to map changes in brain function associated with the reduction in cortical excitability of the primary visual cortex induced by 1 Hz rTMS, when TMS was applied on the occipital area of healthy volunteers. Two groups were evaluated, one group composed of people that can see phosphenes, and another of those lacking this perception. The inhibitory effect, induced by the 1 Hz rTMS, was observed through the increase of the PT, in the first group, but did not lead to a global reduction in brain activation, instead, showed change in the activation pattern before and after rTMS. Conversely, for the second group, changes in brain activation were observed just in few brain areas, suggesting that the effect of 1 Hz rTMS might not be inhibitory for everyone and that the concept of inhibitory/excitatory effect of rTMS may need to be revised.
1赫兹重复经颅磁刺激（rTMS）在健康人群中被认为具有抑制作用，因为它分别抑制运动或视觉皮层的兴奋性，表现为运动阈值或光幻视阈值（PT）的增加。然而，rTMS作用的潜在机制和涉及的脑结构仍然未知。在本研究中，我们对健康志愿者的枕叶区域施加TMS时，使用了两次同步的TMS-功能磁共振成像（fMRI），一次在15分钟1赫兹rTMS之前，一次在之后，以描绘与1赫兹rTMS诱导的初级视觉皮层皮质兴奋性降低相关的脑功能变化。评估了两组，一组由能看到光幻视的人组成，另一组由缺乏这种感知的人组成。在第一组中，通过PT的增加观察到1赫兹rTMS诱导的抑制作用，但并未导致脑激活的整体降低，相反，显示出rTMS前后激活模式的变化。相反，对于第二组，仅在少数脑区观察到脑激活的变化，这表明1赫兹rTMS的作用可能并非对每个人都具有抑制性，rTMS的抑制/兴奋作用概念可能需要修正。
