The supportive association of inhibitory control with working memory updating among individuals with mild cognitive impairment: An empirical study based on event-related potentials and transcranial direct current stimulation.

OBJECTIVES This study aims to examine how inhibitory control affects working memory updating and investigate the neuromodulation effect of transcranial direct current stimulation (tDCS) on inhibitory control in individuals with mild cognitive impairment (MCI).

METHODS Experiment 1 included 15 MCI and 16 cognitively normal (CN) participants performing a Flanker-Nback task with low-conflict and high-conflict conditions (LCT/HCT). Experiment 2 employed a randomized, single-blind, sham-controlled tDCS study design (7 MCI/group).

RESULTS In Experiment 1, frontal P3 showed lower amplitude in the HCT than LCT, while CN individuals demonstrated smaller congruency effect of amplitude (CE-AM) in the HCT than LCT under the Flanker-2back condition. Frontal P2 exhibited prolonged latency in the HCT than LCT, while MCI group showed smaller CE of latency (CE-LA) in the HCT than LCT for the Flanker-1back condition. Parietal N2 demonstrated lower amplitude in the HCT than LCT, and both groups demonstrated smaller CE-AM in the HCT during the Flanker-2back condition. In Experiment 2, compared to sham tDCS group, active group showed higher post-stimulation P3 amplitude for the Flanker task, with reduced N2 amplitude in congruent trials and trends toward an increased P3 amplitude in incongruent trials after stimulation.

CONCLUSIONS Baseline cognition and task load modulated inhibitory control's impact on working memory updating, with MCI individuals demonstrating an "optimized inhibitory control - maintained or improved working memory updating" pattern. TDCS modulated the general attention control instead of inhibition based on the CE, which further corroborated this supportive function as evidence by the "synchronized non-optimization" of both inhibition and updating.