Can you Enhance Visual Learning with Stimulation of the Medial-Frontal Cortex?

Previous research suggests that applying anodal transcranial direct-current stimulation (tDCS) to the medial-frontal cortex can improve how quickly subjects learn to make simple discriminations (i.e., red from blue). Here, we tested the idea that this superior learning is due to superior encoding into the long-term memory of images. Thirty subjects completed an anodal stimulation session and a sham session, with order counterbalanced across subjects, before performing recognition-memory tasks using pictures of real-world objects and visually presented words or nonwords. These tasks allowed us to detect potential memory differences across types of memoranda. Contrary to the hypothesis that the medial-frontal cortex helps control encoding veracity, we found that 20 minutes of tDCS at 2.0 mA did not significantly improve participants’ memory, regardless of stimulus type, JZS Bayes Factors < 0.4. Our findings show that although medial-frontal cortex stimulation can change how quickly we learn stimulus-response mappings, this is not simply due to superior memory for the items.