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Updated: Apr 19, 2026
High-definition Transcranial Direct Current Stimulation over Right Dorsolateral Prefrontal Cortex to Enhance Metacognitive Sensitivity
Published on: September 26, 2025
Transcranial direct current stimulation based metaplasticity protocols in working memory
Sandra Carvalho1, Paulo S Boggio2, Óscar F Gonçalves3
1Neuropsychophysiology Laboratory, CIPsi, School of Psychology (EPsi), University of Minho, Campus de Gualtar, 4710-057 Braga, Portugal; Spaulding Neuromodulation Center, Department of Physical Medicine and Rehabilitation, Spaulding Rehabilitation Hospital, Harvard Medical School, Boston, MA, USA; Department of Physical Medicine and Rehabilitation, Massachusetts General Hospital, Harvard Medical School, Boston, MA, USA.
Background:
It has been already shown that delivering tDCS that are spaced by an interval alters its impact on motor plasticity. These effects can be explained, based on metaplasticity in which a previous modification of activity in a neuronal network can change the effects of subsequent interventions in the same network. But to date there is limited data assessing metaplasticity effects in cognitive functioning.
Objectives:
The aim of this study was to test several tDCS-based metaplasticity protocols in working memory (WM), by studying the impact of various interstimulation intervals in the performance of a 3-back task.
Methods:
Fifteen healthy volunteers per experiment participated in this study. Experiments 1 and 2 tested an anodal tDCS-induced metaplasticity protocol (1 mA, 10 + 10') with 3 interstimulation intervals (10, 30, and 60 min). Experiment 3 determined the effects of a similar protocol-with a 10-min interval between two sessions of cathodal tDCS or anodal plus cathodal tDCS (1 mA, 10 + 10').
Results:
Two consecutive sessions of anodal tDCS delivered with a 10 min interval between them did not improve WM performance (P = .095). This effect remained the same if the interval was increased to 30 or 60 min. In contrast, when a 10 min interval was given between two consecutive cathodal tDCS sessions, performance in the 3 back task increased (P = .042).
Conclusions:
These results suggest that the polarity effects of tDCS on working memory are dependent on the previous level of activity of the recruited neural population.
