Electrical stimulation and visual network plasticity.

The visual system has the most complex circuitry of all the sensory systems and it also possesses the ability to undergo induced and spontaneous neuroplastic changes. Most of what we know about the functional organization of the visual system is derived from animal experiments or by correlating circumscribed anatomical lesions in patients and their visual perceptual deficits or dysfunctions. However, in the past years, significant achievements have been made in characterizing visual information processing in the human using non-invasive neurophysiological techniques, such as electrical stimulation of the brain. Transcranial direct (tDCS) and alternating current stimulation (tACS) applied through the skull was shown to directly modulate the excitability of the motor and visual cortices in human subjects. This review article focuses on these stimulation methods and summarizes the latest results with regard to the application of these method over the visual areas in healthy subjects and clinical populations.