**Motor Delays and Variability in Movement Execution** The study explored whether stuttering is linked to difficulties in movement initiation due to a dysfunctional basal ganglia. Contrary to previous findings, this study found no significant differences between people who stutter (PWS) and people who do not stutter (PNS) in terms of average finger reaction time and its variability. Additionally, no correlation was found between reaction times and the severity of stuttering or synchronization accuracy. These results suggest that movement initiation difficulties are not a contributing factor to stuttering in externally triggered movements. The "dual premotor" model by Alm et al. was considered, which distinguishes between a medial premotor circuit (associated with self-triggered actions and potentially impaired in stutterers) and a lateral premotor circuit (associated with externally triggered actions and intact in stutterers). The study expected to see timing differences in tasks mediated by the medial premotor circuit but found no significant differences in periodicity error. However, significant differences in negative mean asynchrony were observed in tasks involving external triggers, suggesting reliance on the lateral premotor circuit. The study concluded that timing differences observed between PWS and PNS were not due to difficulties in initiating movements. The study also examined the hypothesis that motor impairments in PWS are related to inaccurate internal models or neural noise. Previous studies noted greater variability in movement amplitude and timing in PWS. This study observed increased timing variability in PWS during simple synchronization tasks but not in tapping force variability. More complex tasks revealed increased variability in both timing and force for PWS. The study found no correlation between timing and force variability, suggesting that the observed differences were not due to inaccurate internal models or neural noise. **Beat Perception and Reproduction** PWS demonstrated the ability to tap an isochronous sequence without external auditory reference and predict regular events, showing no significant acceleration or deceleration. They maintained acceptable levels of periodicity error and tapping variability, indicating accurate beat perception and transfer to motor actions. These findings suggest no strong deficit in tuning neuronal oscillations with the external beat in PWS. When compared to PNS, PWS showed no significant difference in periodicity error during beat reproduction tasks but exhibited greater tapping variability. This indicates that PWS can perceive the beat accurately but have difficulty reproducing it consistently. The study proposes that timing differences are not due to impaired motor execution but might be explained by the Oscillators Coupling Hypothesis. This suggests a deficit in coupling neuronal oscillators driving the motor system, leading to increased variability in beat reproduction. This coupling deficit appears intrinsic and long-lasting, as no improvement was observed with practice. PWS showed more errors in reproducing complex non-isochronous patterns, aligning with previous findings, but no difference in marking beat hierarchy compared to PNS. Both groups tapped stronger beats with greater force, indicating that beat hierarchy perception was intact. **Sensorimotor Integration and Learning** In synchronization tasks, PWS showed reduced accuracy and consistency, with greater negative mean asynchrony (NMA) and lower phase locking values (PLV). Variations in phase angles depended on beat strength, external auditory stimuli, and task complexity. These findings exclude the idea that NMA is a compensation for motor delays or an underestimation of intervals. The study supports the theory of slower processing of tactile and proprioceptive information in PWS, leading to increased integration delays between auditory and kinesthetic feedback. This delay might explain why PWS perform taps in advance of the beat to synchronize sensory inputs accurately. The "sensory accumulation" model suggests that NMA compensates for slower tactile feedback accumulation, supported by observations of reduced NMA with increased tapping force. PLV also varied with external auditory stimuli and task complexity, indicating that tapping variability in synchronization tasks involves additional sensorimotor variability. However, this was not significantly different between PWS and PNS, suggesting no deficit at this stage. Improvement in synchronization consistency was observed for both groups over time, but not in accuracy. This excludes a sensorimotor learning deficit in PWS for consolidating internal beat representations.