Intra- and inter-hemispheric coupling of electroencephalographic 8-13 Hz rhythm in humans and force of static finger extension.

The coupling of electroencephalographic (EEG) 8-13 Hz oscillations during static right finger extension performed under four different force levels was analyzed in 12 right-handed subjects. Increases in force of static muscle contraction were accompanied by increases in the 8-13 Hz band coherence between the contralateral sensorimotor area (S1/M1) and the ipsilateral S1/M1, frontal and parietal cortex, between supplementary motor area and bilateral S1/M1, and between posterior parietal cortex and bilateral S1/M1. The results suggest increased functional coupling between primary and higher-order motor areas during increased motor effort.