Understanding dual task performance in humans : electrophysiological correlates of interferences and costs between motor and working memory tasks at different levels of workload

The simultaneous execution of two different tasks is associated with interference processes that produce a decrease in the performance of one or both duties, a common phenomenon whose neural mechanisms are not yet understood. We recorded electroencephalographic activity (EEG) during cognitive-motor interference in 24 subjects, using a working memory N-back task concurrent with a finger movement both tests were performed on 3 different workloads (easy, medium and hard) resulting in 9 dual tasks of different difficulty levels. A time-frequency analysis of the EEG showed a midline decrease of theta band activity and an increase of alpha band activity when both tasks progressed to a motor workload medium level. The current study shows the development of an opposing oscillatory pattern of alpha and theta, which can be linked to the interferential effects of cognitive-motor task, determining the fall in the overall performance of the test. These effects are only a product of the increase in the difficulty of the motor task.The simultaneous execution of two different tasks is associated with interference processes that produce a decrease in the performance of one or both duties, a common phenomenon whose neural mechanisms are not yet understood. We recorded electroencephalographic activity (EEG) during cognitive-motor interference in 24 subjects, using a working memory N-back task concurrent with a finger movement both tests were performed on 3 different workloads (easy, medium and hard) resulting in 9 dual tasks of different difficulty levels. A time-frequency analysis of the EEG showed a midline decrease of theta band activity and an increase of alpha band activity when both tasks progressed to a motor workload medium level. The current study shows the development of an opposing oscillatory pattern of alpha and theta, which can be linked to the interferential effects of cognitive-motor task, determining the fall in the overall performance of the test. These effects are only a product of the increase in the difficulty of the motor task.The simultaneous execution of two different tasks is associated with interference processes that produce a decrease in the performance of one or both duties, a common phenomenon whose neural mechanisms are not yet understood. We recorded electroencephalographic activity (EEG) during cognitive-motor interference in 24 subjects, using a working memory N-back task concurrent with a finger movement both tests were performed on 3 different workloads (easy, medium and hard) resulting in 9 dual tasks of different difficulty levels. A time-frequency analysis of the EEG showed a midline decrease of theta band activity and an increase of alpha band activity when both tasks progressed to a motor workload medium level. The current study shows the development of an opposing oscillatory pattern of alpha and theta, which can be linked to the interferential effects of cognitive-motor task, determining the fall in the overall performance of the test. These effects are only a product of the increase in the difficulty of the motor task.