Unveiling the role of beta activity in motor motivation: an EEG study of effort using neurofeedback and pupillometry

International audience; A progressive desynchronization of beta-band power (β-desync; 13-30 Hz) has been consistently observed before movement initiation. Although mounting evidence demonstrate a significant relationship between this β-desync and subsequent motor vigor, a neurophysiological foundation to explain this finding is still lacking. In the present study, we proposed that this association might come from changes in motor motivation and perceived effort. This hypothesis will be tested by recording the signal from electroencephalography and using it as neurofeedback to decrease or increase β-desync in two distinct sessions, in an intra-subject and double-blinded design. First, participants will be screened based on their ability to up- and down-regulate their β-desync. The selected participants will then perform the experimental test, in which each trial comprised a neurofeedback phase directly followed by an effort phase. The effort will consist in squeezing a dynamometer with the right hand during an allocated time of 10 seconds. Participants will be asked to apply enough force to cross a defined threshold, and that the more time the exerted force would exceed the threshold, the more money they would earn. Subjective perception of effort will be evaluated afterwards using an analog scale. Because effort exertion is associated with increased pupil dilation, which is itself modulated by noradrenergic activity, we will further investigate the influence of noradrenergic activity on changes in β-desync due to neurofeedback and effort exertion. Besides the contribution to unraveling the neurophysiological and functional bases of beta activity, the present work is of special interest to the study of Parkinson’s disease by helping to better understand the association between beta activity and motor symptoms.