Anodal online transcranial direct current stimulation (tDCS) facilitates
visual motion perceptual learning
Visual perceptual learning (VPL) has great potential implications for
clinical populations, but adequate improvement often takes weeks to
months to obtain; therefore, practical applications of VPL are limited.
Strategies that enhance visual performance acquisition make great
practical sense. Transcranial direct current stimulation (tDCS) could be
beneficial to VPL, but thus far, the results are inconsistent. The
current study had two objectives: (1) investigate the effect of anodal
tDCS on VPL and (2) determine whether the timing sequence of anodal tDCS
and training influences VPL. Anodal tDCS was applied on the left human
middle temporal (hMT+) during training on a coherent motion
discrimination task (online), anodal tDCS was also applied before
training (offline), and sham tDCS was applied during training (sham).
The coherent thresholds were measured without stimulation before, 2 days
after and one month after training. All participants trained for 5
consecutive days. Anodal tDCS resulted in more performance improvement
when applied during daily training but not when applied before training.
Additionally, neither within-session improvement nor between-session
improvement differed among the online, offline and sham tDCS conditions.
These findings contribute to the development of efficient stimulation
protocols and a deep understanding of the mechanisms underlying the
effect of tDCS on VPL.