Department of Optometry and Vision Science, University of Auckland, Auckland, New Zealand.
PLoS One. 2012;7(5):e36220. doi: 10.1371/journal.pone.0036220. Epub 2012 May 1.
Transcranial direct current stimulation (tDCS) is a safe, non-invasive technique for transiently modulating the balance of excitation and inhibition within the human brain. It has been reported that anodal tDCS can reduce both GABA mediated inhibition and GABA concentration within the human motor cortex. As GABA mediated inhibition is thought to be a key modulator of plasticity within the adult brain, these findings have broad implications for the future use of tDCS. It is important, therefore, to establish whether tDCS can exert similar effects within non-motor brain areas. The aim of this study was to assess whether anodal tDCS could reduce inhibitory interactions within the human visual cortex. Psychophysical measures of surround suppression were used as an index of inhibition within V1. Overlay suppression, which is thought to originate within the lateral geniculate nucleus (LGN), was also measured as a control. Anodal stimulation of the occipital poles significantly reduced psychophysical surround suppression, but had no effect on overlay suppression. This effect was specific to anodal stimulation as cathodal stimulation had no effect on either measure. These psychophysical results provide the first evidence for tDCS-induced reductions of intracortical inhibition within the human visual cortex.
经颅直流电刺激（tDCS）是一种安全、非侵入性的技术，可暂时调节人类大脑内兴奋和抑制的平衡。有报道称，阳极 tDCS 可以减少人类运动皮层中的 GABA 介导的抑制和 GABA 浓度。由于 GABA 介导的抑制被认为是成人大脑内可塑性的关键调节因子，这些发现对 tDCS 的未来应用具有广泛的意义。因此，重要的是要确定 tDCS 是否可以在非运动脑区产生类似的效果。本研究旨在评估阳极 tDCS 是否可以减少人类视觉皮层内的抑制相互作用。作为 V1 内抑制的指标，使用环绕抑制的心理物理测量。作为对照，还测量了认为起源于外侧膝状体核（LGN）的叠加抑制。枕叶极的阳极刺激显著降低了心理物理环绕抑制，但对叠加抑制没有影响。这种效应是阳极刺激特有的，因为阴极刺激对这两种测量都没有影响。这些心理物理结果为 tDCS 诱导的人类视觉皮层内皮质内抑制减少提供了第一个证据。
