Pre-movement EEG microstates reflect intended lifted load of volitional movement.

Introduction: Load estimation is one of the essential parameters for assistive robotic control in cases of rehabilitation. The high temporal resolution of the Electroencephalography (EEG) technique makes it the best tool to resolve the temporal dynamics of movement intention and planning. The quasi-stable scalp electrical potential topography represented by the EEG microstates could assess the real-time information processing in the brain for controlling assistive devices. We hypothesize that the EEG microstate preceding the movement could reflect the increasing load during a biceps curl movement. Methods: Ten healthy participants performed biceps curl movements, while their brain activity and muscle activation was recorded using EEG and EMG. Results: Eight microstate maps were found to represent the functional brain state before the movements. Two pre-movement microstate maps were found to reflect the load increments. The source maxima of these two reflective microstates maps were localized at the right insula and cingulate gyrus. Discussion: Our results imply that the load increments of volitional movement could be reflected by the pre-movement EEG microstates.