β-bursting as a sensitive neural marker of inhibitory control in healthy older adults: a linear mixed-effects modelling and threshold-free cluster approach
Inhibitory control is essential for adaptive behaviour and declines with age, yet the underlying neural dynamics remain poorly understood. The {beta}-rhythm (15-29 Hz) is thought to reflect inhibitory signalling within the fronto-basal ganglia network. Recent evidence suggests that transient {beta}-bursts support inhibitory performance, often masked by conventional analyses of trial-averaged {beta}-power. To reveal the link between trial-by-trial {beta}-bursting and inhibition, we applied a recently developed analysis framework combining linear mixed-effects modelling (LMM) with threshold-free cluster enhancement (TFCE) during response inhibition and initiation in older adults. Twenty healthy older adults performed a bimanual anticipatory response inhibition task, while electroencephalography and electromyography were recorded to capture {beta}-activity ({beta}-burst rate/duration; averaged {beta}-power) and muscle bursting dynamics, respectively. Our analysis revealed distinct {beta}-bursting signatures absent in averaged {beta}-power data. Following the stop-signal, parieto-occipital {beta}-bursting presented before a temporal cascade from attentional to inhibitory processes. In addition to expected right fronto-central and bilateral sensorimotor activity, we observed left prefrontal {beta}-bursting, indexing broader inhibitory network engagement during bimanual response inhibition. Moreover, we established a functional link between right sensorimotor {beta}-bursting and muscle bursts during stopping, indicating rapid cortical suppression of initiated motor output. These results help clarify the mechanistic role of {beta}-oscillations and underscore the sensitivity of {beta}-bursting to both the timing and context of inhibitory demands in healthy older adults. Future research will help establish the potential of {beta}-bursting, combined with LMM-TFCE analysis, as a clinically relevant marker of impulse control dysfunction. Significance statementOur novel application of an advanced statistical framework revealed distinct spatiotemporal {beta}-bursting patterns during response inhibition and response withholding in healthy older adults, which were not captured by averaged {beta}-power. Identifying a further link between cortical {beta}-bursting and muscle-level suppression, the findings offer a mechanistic account of how the brain halts action in real time in older adults. This work provides a sensitive, trial-level framework for studying {beta}-bursting measures in general, as well as inhibitory control across aging and clinical populations.