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 β-rhythm (15-29 Hz) is associated with inhibitory signalling within the fronto-basal ganglia network. Recent evidence suggests that transient β-bursts support inhibitory performance but are often masked by conventional trial-averaged β-power analyses. A recently developed analysis approach, combining linear mixed-effects modelling and threshold-free cluster enhancement (LMM-TFCE), was applied to examine trial-by-trial β-bursting activity associated with response inhibition and initiation in older adults. Twenty healthy older adults (9 female) performed a bimanual anticipatory response inhibition task, while electroencephalography and electromyography were recorded to capture β-activity (β-burst rate/volume; averaged β-power) and muscle bursting dynamics, respectively. Our analysis revealed distinct β-bursting signatures absent in averaged β-power data. During bimanual response inhibition, parieto-occipital β-bursting preceded bilateral fronto-central β-bursting, consistent with initial attentional processes prior to broader inhibitory network engagement. Moreover, a link was established between right sensorimotor β-bursting and muscle bursts during stopping, indicating rapid cortical suppression of initiated motor output. β-burst volume proved uniquely sensitive to response withholding, with early left frontal activity supporting preparatory suppression mechanisms. A further link between increased parieto-occipital β-burst volume and muscle bursts aligned with top-down inhibitory signalling to support visuomotor stabilisation and prevent premature response release. These results underscore the sensitivity of β-bursting to both the timing and context of inhibitory demands in healthy ageing. Future research will help establish the potential of β-bursting, combined with LMM-TFCE analysis, as a clinically relevant marker of impulse control dysfunction. Significance statement: Our novel application of an advanced statistical framework revealed distinct spatiotemporal β-bursting patterns during response inhibition and response withholding in healthy older adults, which were not captured by averaged β-power. Identifying a further link between cortical β-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 β-burst measures in general, as well as inhibitory control across aging and clinical populations.