Verbal-manual interactions during dual task performance: An EEG study.

Everyday situations regularly require the performance of more than one task at the same time, such as walking and conversing. Here, a dual task approach was adopted for evaluating changes in neural activity associated with a motor assignment. To this end, participants performed a self-paced motor (tapping) task in a unimanual and bimanual context along with a verbal (counting) task. Neural dynamics was assessed by means of EEG coherence in the beta frequency band (13-30Hz) and included intrahemispheric, interhemispheric and midline connectivity profiles. Results showed that coherence intensified across the motor network during dual tasking for unimanual tapping, which permitted to preserve performance. For bimanual tapping, strengthening of functional connectivity was not observed for interhemispheric and midline regions, which associated with a degradation of coordinative output. The latter underlines the significance of these communication pathways for bimanual behaviour. Overall, the findings indicate that dynamic modulation of functional connectivity patterns provides a substrate for preserving behaviour in effortful circumstances such as dual tasking.