Article

Transcranial direct current stimulation (tDCS) is attracting increasing interest
as a therapeutic tool for neurorehabilitation, particularly after stroke, because
of its potential to modulate local excitability and therefore promote functional
plasticity. Previous studies suggest that timing is important in determining the
behavioural effects of brain stimulation. Regulatory metaplastic mechanisms exist
to modulate the effects of a stimulation intervention in a manner dependent on
prior cortical excitability, thereby preventing destabilization of existing
cortical networks. The importance of such timing dependence has not yet been
fully explored for tDCS. Here, we describe the results of a series of behavioural
experiments in healthy controls to determine the importance of the relative
timing of tDCS for motor performance. Application of tDCS during an explicit
sequence-learning task led to modulation of behaviour in a polarity specific
manner: relative to sham stimulation, anodal tDCS was associated with faster
learning and cathodal tDCS with slower learning. Application of tDCS prior to
performance of the sequence-learning task led to slower learning after both
anodal and cathodal tDCS. By contrast, regardless of the polarity of stimulation,
tDCS had no significant effect on performance of a simple reaction time task.
These results are consistent with the idea that anodal tDCS interacts with
subsequent motor learning in a metaplastic manner and suggest that anodal
stimulation modulates cortical excitability in a manner similar to motor
learning.
CI - Copyright (c) 2011 Elsevier Ltd. All rights reserved.

Langue : ANGLAIS