Movement-related cortical potential during dual tasks with distinct load levels

We investigated movement-related cortical potential (MRCP) during dual-task performance under different levels of secondary task load. This study included 20 healthy young, right-footed adults. MRCPs were measured under three conditions. The single task (ST) involved internal-paced dorsiflexion of the right ankle joint, whereas in the simple dual task (DT-S) and complex dual task (DT-C), participants engaged in the ST along with a visual number counting and memorizing task, with varying levels of cognitive load. These conditions represented no-, low-, and high-load divided attention tasks, respectively. Although the coefficient of variation (CV) in movement interval was higher during DT-C compared to ST and DT-S, the negative peak amplitude of MRCPs, recorded from the Cz electrode using the international 10/20 system, was lower in DT-S and DT-C compared to ST. Although no significant differences in CV were observed, DT-S resulted in a significant decrease in MRCP amplitude. Our findings indicate that MRCPs may serve as a biomarker for assessing divided attention capacity during dual-task performance, even in the absence of observable differences in task performance. These results suggest that the MRCP amplitude is an indicator of supplementary motor area activation, highlighting the crucial role of attention division in movement preparation and execution when performing dual tasks.