Increased EMG-EMG coherence in the theta and alpha bands during bimanual force modulation

During the execution of movements, error correction processes have been inferred by EEG activation at oscillation frequencies in the theta (4-8 Hz) and alpha (8-12 Hz) bands. The current study examined whether evidence for error detection and correction could be found at the muscular level through the use of EMG-EMG coherence, which quantifies the amount of synchronous EMG activity between limbs in the frequency domain. Participants (n = 13) performed a bimanual force production task involving either wrist flexors or extensors under conditions in which the force was to be held constant or continuously modulated. As predicted, the modulation of changing force output resulted in significantly greater force variability and increased EMG-EMG coherence throughout the theta and alpha band for both flexor and extensor responses. These results are consistent with EEG activation frequencies associated with error correction, motor reprogramming and sustained attention and indicate that evidence for these cortical processes can also be observed at the muscular level in the form of correlated EMG frequency content between limbs.