Brief Communications Improving Visual Sensitivity with Subthreshold Transcranial Magnetic Stimulation

We probed for improvement of visual sensitivity in human participants using transcranial magnetic stimulation (TMS). Stimulation of visual cortex can induce an illusory visual percept known as a phosphene. It is known that TMS, delivered at intensities above the threshold to induce phosphenes, impairs the detection of visual stimuli. We investigated how the detection of a simple visual stimulus is affectedbyTMSapplied tovisual cortexat orbelow thephosphene threshold.Participantsperformed thedetection taskwhile the contrast of the visual stimulus was varied from trial to trial according to an adaptive staircase procedure. Detection of the stimulus was enhanced when a single pulse of TMSwas delivered to the contralateral visual cortex 100 or 120ms after stimulus onset at intensities just below the phosphene threshold. No improvement in visual sensitivity was observed when TMS was applied to the visual cortex in the opposite hemisphere (ipsilateral to the visual stimulus). We conclude that TMS-induced neuronal activity can sumwith stimulus-evoked activity to augment visual perception