Making the rich richer: Frontoparietal tDCS enhances transfer effects of a single-session distractor inhibition training on working memory in high capacity individuals but reduces them in low capacity individuals

• Published in: NeuroImage (Orlando, Fla.) Vol. 242; p. 118438
• Main Authors: Schmicker, Marlen, Menze, Inga, Schneider, Christine, Taubert, Marco, Zaehle, Tino, Mueller, Notger G.
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 15.11.2021; Elsevier Limited; Elsevier
• Subjects: Adolescent; Adult; Attention; Brain; Cognition; Cognitive ability; Cognitive training; Cortex (parietal); Distractor inhibition; Education; Electrical stimulation of the brain; ESB; Female; Frontoparietal network; Humans; Individual differences; Individuality; Inhibition, Psychological; Investigations; Male; Memory; Memory, Short-Term - physiology; Neural networks; Neuropsychological Tests; Parietal Lobe - physiology; Prefrontal Cortex - physiology; Short term memory; tDCS; Transcranial Direct Current Stimulation - methods; Working memory capacity; Young Adult; Cognitive training; LCI; tDCS; Working memory capacity; WM; Individual differences; DIIN training; Distractor inhibition; WMC; Frontoparietal network; HCI
• ISSN: 1053-8119; 1095-9572
• DOI: 10.1016/j.neuroimage.2021.118438

Working memory (WM) performance depends on the ability to extract relevant while inhibiting irrelevant information from entering the WM storage. This distractor inhibition ability can be trained and is known to induce transfer effects on WM performance. Here we asked whether transfer on WM can be boosted by transcranial direct current stimulation (tDCS) during a single-session distractor inhibition training. As WM performance is ascribed to the frontoparietal network, in which prefrontal areas are associated with inhibiting distractors and posterior parietal areas with storing information, we placed the anode over the prefrontal and the cathode over the posterior parietal cortex during a single-session distractor inhibition training. This network-oriented stimulation protocol should enhance inhibition processes by shifting the neural activity from posterior to prefrontal regions. WM improved after a single-session distractor inhibition training under verum stimulation but only in subjects with a high WM capacity. In subjects with a low WM capacity, verum tDCS reduced the transfer effects on WM. We assume tDCS to strengthen the frontostriatal pathway in individuals with a high WM capacity leading to efficient inhibition of distractors. In contrast, the cathodal stimulation of the posterior parietal cortex might have hindered usual compensational mechanism in low capacity subjects, i.e. maintaining also irrelevant information in memory. Our results thus stress the need to adjust tDCS protocols to well-founded knowledge about neural networks and individual cognitive differences.