Beta bursts spatiotemporal profiles and their links to hemodynamic responses during movement and rest.

Both periodic and aperiodic components in the electroencephalography (EEG) signal are known to play a role in motor control. In particular, periodic beta oscillations and their associated transient bursts (beta bursts) have been linked to motor inhibition. While the occurrence of these bursts is well-documented during simple motor tasks, their spatiotemporal distribution during more complex movements remains largely unexplored. This gap in our understanding extends to the relationship between transient EEG events and Blood Oxygenation Level Dependent (BOLD) activity, typically measured with functional magnetic resonance imaging (fMRI). To better understand these and their hemodynamic and functional correlates, simultaneous EEG and fMRI recordings were obtained at rest and during hand movements in 11 healthy adults. The spatiotemporal distribution for both aperiodic components and beta bursts was mapped during different phases of a handgrip task (low-level, ramp, and high-level grip force conditions). Additionally, the modulation of hemodynamic responses by beta bursts was investigated during both conditions. To this end, the detected beta bursts were used to estimate a hemodynamic response function (HRF) and predict the corresponding BOLD fMRI activity. During movement transition phases, a significant increase in the exponent and offset of the aperiodic components, as well as an increase in beta burst amplitude and rate were observed, as compared to sustained contractions. Furthermore, beta bursts in the contralateral/dominant motor regions of the moving hand elicited positive hemodynamic responses during movement but negative responses during rest, although the HRF features did not differ significantly between the two conditions. Other brain regions showed consistent negative hemodynamic responses across both motor tasks and resting state. These findings reveal a directional dissociation in hemodynamic responses to beta bursts between movement and rest states in motor regions, though future studies with larger sample sizes are needed to further characterize the state-dependence of this relationship. This work advances our understanding of the relationship between transient neural events and hemodynamic responses during movement-related processes in healthy individuals.