Effect of Task Complexity on the Post-Movement Beta Synchronization in the Sensorimotor Cortex

We studied the effect of the complexity of the secondary task on event-related EEG dynamics over the sensorimotor cortex in primary task under multitasking conditions. 32-channel EEG was recorded from 24 healthy subjects during the performance of four tests combining Go/NoGo and N-back paradigms and differing in complexity. In contrast to the previous studies using the classical paradigm of N-back tasks requiring memorization of information about the stimuli itself, for this study we developed a variant of the N-back task, which requires memorization of the completed action. It was shown that an increase in the complexity of the N-back task leads to a decrease in the magnitude of beta synchronization observed after a movement in the Go condition of the Go/NoGo task over the left sensorimotor cortex (electrode C3). It can be assumed that an increase in working memory load, regardless of the type of information held in memory, leads to a deterioration in the processes of movement control necessary to perform the primary task. The obtained results support the assumption that the multitasking condition requires the distribution of attention resources and, due to this, decreases the quality of each task performance.