Separable global and local beta burst dynamics in motor cortex of primates
Sensorimotor beta band oscillations are known to modulate during normal movement control and abnormal beta modulation is linked to pathological bradykinesia. However, the functional differences between beta localized to one brain area versus beta synchronized across brain areas remains unclear. We monitored beta bursts in non-human primates, both neurotypical and stroke- impaired, during the performance of complex motor tasks. Across both groups of animals, we identified two distinct beta burst types: global bursts that tend to be synchronized across cortical and subcortical areas, and local bursts that tend to be confined to cortex. These two types exhibited distinct neural dynamics, with global bursts linked to reduced firing variability and overall slowed movements. In contrast, local bursts often occurred during the execution of complex behaviors, particularly during prehension. We found evidence for changes in the distribution of global and local bursts during recovery after stroke. In impaired animals early after stroke, global bursts predominated and were associated with reduced speed and impaired grasping. Notably, recovery of grasping was associated with a reduction in global bursts and an increase in local bursts, suggesting that local bursts may play an important role during prehension. Our findings reveal distinct roles of global and local beta bursts and indicate that the normalization of global and local burst timing tracks recovery of dexterity.