Transcranial direct current stimulation facilitates category learning
Highlights
- •
A novel classification task was created to test the generality of learning effects seen with F10 anodal tDCS.
- •
Learning in the anodal tDCS group was enhanced by greater than a factor of 4 compared with sham.
- •
This tDCS protocol may offer a method to accelerate learning and improve performance in a variety of tasks.
Abstract
Background
After two decades of transcranial direct current stimulation (tDCS) research, it is still unclear which applications benefit most from which tDCS protocols. One prospect is the acceleration of learning, where previous work has demonstrated that anodal tDCS applied to the right ventrolateral prefrontal cortex (rVLPFC) is capable of doubling the rate of learning in a visual camouflaged threat detection and category learning task.
Goals
Questions remain as to the specific cognitive mechanisms underlying this learning enhancement, and whether it generalizes to other tasks. The goal of the current project was to expand previous findings by employing a novel category learning task.
Methods
Participants learned to classify pictures of European streets within a discovery learning paradigm. In a double-blind design, 54 participants were randomly assigned to 30 min of tDCS using either 2.0 mA anodal (n = 18), cathodal (n = 18), or 0.1 mA sham (n = 18) tDCS over the rVLPFC.
Results
A linear mixed-model revealed a significant effect of tDCS condition on classification accuracy across training (p = 0.001). Compared to a 4.2% increase in sham participants, anodal tDCS over F10 increased performance by 20.6% (d = 1.71) and cathodal tDCS by 14.4% (d = 1.16).
Conclusions
These results provide further evidence for the capacity of tDCS applied to rVLPFC to enhance learning, showing a greater than quadrupling of test performance after training (491% of sham) in a difficult category learning task. Combined with our previous studies, these results suggest a generalized performance enhancement. Other tasks requiring sustained attention, insight and/or category learning may also benefit from this protocol.