Foveal effects of transcranial direct current stimulation on visual psychophysical performance

Introduction: In the primary visual cortex, transcranial direct current stimulation (tDCS) is able to induce upward and downward excitability shifts of the primary visual cortex measured by an altered TMS phosphene threshold in V1 (Antal et al. 2006). Anodal tDCS enhances V1 excitability, while cathodal stimulation diminishes it (Antal et al. 2003). In the present study we investigated to which degree tDCS can induce changes in psychophysical performance. Therefore, detection sensitivity was examined in a visual discrimination task by measuring d' (=z-transformed hit rate minus false alarm rate) in order to indi…