Behavioural facilitation following brain stimulation: implications for neurorehabilitation.

Studies showing facilitation of behavioural performance by transcranial magnetic stimulation (TMS), and transcranial direct current stimulation (tDCS) in sensory and perceptual domains, spatial attention, working memory, and executive and emotional tasks are reviewed. In these domains the performance of neurologically unimpaired participants may be modulated, with behavioural facilitation or interference, by TMS, and by tDCS. The mapping of the frequency-dependent effects of TMS, and of the polarity-dependent effects of tDCS on behaviour does not systematically and mechanistically result in an increase or decrease of behavioural performance. Factors such as the parameters of the cerebral stimulation (localisation, duration, intensity), and the features of the task (complexity, phase of training) contribute to determine the final net effect on the participants' performance. Non-invasive brain stimulation (NIBS), which modulates learning, and appears to have, under some conditions, long lasting effects, is a promising tool to be used in the rehabilitation of a variety of neurological and cognitive disorders, that typically involve repeated behavioural training sessions.