Which factors modulate spontaneous motor tempo? A systematic review of the literature

Evoked and entrained pupillary activity while moving to preferred tempo and beyond

People synchronize their movements more easily to rhythms with tempi closer to their preferred motor rates than with faster or slower ones. More efficient coupling at one's preferred rate, compared to faster or slower rates, should be associated with lower cognitive demands and better attentional entrainment, as predicted by dynamical system theories of perception and action. We show that synchronizing one's finger taps to metronomes at tempi outside of their preferred rate evokes larger pupil sizes, a proxy for noradrenergic attention, relative to passively listening. This demonstrates that synchronizing is more cognitively demanding than listening only at tempi outside of one's preferred rate. Furthermore, pupillary phase coherence increased for all tempi while synchronizing compared to listening, indicating that synchronous movements resulted in more efficiently allocated attention. Beyond their theoretical implications, our findings suggest that rehabilitation for movement disorders should be tailored to patients' preferred rates to reduce cognitive demands.

From Sound to Movement: Mapping the Neural Mechanisms of Auditory-Motor Entrainment and Synchronization

BACKGROUND

Humans exhibit a remarkable ability to synchronize their actions with external auditory stimuli through a process called auditory-motor or rhythmic entrainment. Positive effects of rhythmic entrainment have been demonstrated in adults with neurological movement disorders, yet the neural substrates supporting the transformation of auditory input into timed rhythmic motor outputs are not fully understood. We aimed to systematically map and synthesize the research on the neural correlates of auditory-motor entrainment and synchronization.

METHODS

Following the PRISMA-ScR guidelines for scoping reviews, a systematic search was conducted across four databases (MEDLINE, Embase, PsycInfo, and Scopus) for articles published between 2013 and 2023.

RESULTS

From an initial return of 1430 records, 22 studies met the inclusion criteria and were synthesized based on the neuroimaging modality. There is converging evidence that auditory-motor synchronization engages bilateral cortical and subcortical networks, including the supplementary motor area, premotor cortex, ventrolateral prefrontal cortex, basal ganglia, and cerebellum. Specifically, the supplementary motor area and the basal ganglia are essential for beat-based timing and internally guided rhythmic movements, while the cerebellum plays an important role in tracking and processing complex rhythmic patterns and synchronizing to the external beat. Self-paced tapping is associated with additional activations in the prefrontal cortex and the basal ganglia, suggesting that tapping in the absence of auditory cues requires more neural resources. Lastly, existing studies indicate that movement rate and the type of music further modulate the EEG power in the alpha and beta frequency bands.

CONCLUSIONS

These findings are discussed in the context of clinical implications and rhythm-based therapies.

Spontaneous rates exhibit high intra-individual stability across movements involving different biomechanical systems and cognitive demands

Spontaneous rhythmic movements are part of everyday life, e.g., in walking, clapping or music making. Humans perform such spontaneous motor actions at different rates that reflect specific biomechanical constraints of the effector system in use. However, there is some evidence for intra-individual consistency of specific spontaneous rates arguably resulting from common underlying processes. Additionally, individual and contextual factors such as musicianship and circadian rhythms have been suggested to influence spontaneous rates. This study investigated the relative contributions of these factors and provides a comprehensive picture of rates among different spontaneous motor behaviors, i.e., melody production, walking, clapping, tapping with and without sound production, the latter measured online before and in the lab. Participants (n = 60) exhibited high intra-individual stability across tasks. Task-related influences included faster tempi for spontaneous production rates of music and wider ranges of spontaneous motor tempi (SMT) and clapping rates compared to walking and music making rates. Moreover, musicians exhibited slower spontaneous rates across tasks, yet we found no influence of time of day on SMT as measured online in pre-lab sessions. Tapping behavior was similar in pre-lab and in-lab sessions, validating the use of online SMT assessments. Together, the prominent role of individual factors and high stability across domains support the idea that different spontaneous motor behaviors are influenced by common underlying processes.

Resonance tuning of rhythmic movements is disrupted at short time scales: A centrifuge study

The human body exploits its neural mechanisms to optimize actions. Rhythmic movements are optimal when their frequency is close to the natural frequency of the system. In a pendulum, gravity modulates this spontaneous frequency. Participants unconsciously adjust their natural pace when cyclically moving the arm in altered gravity. However, the timescale of this adaptation is unexplored. Participants performed cyclic movements before, during, and after fast transitions between hypergravity levels (1g-3g and 3g-1g) induced by a human centrifuge. Movement periods were modulated with the average value of gravity during transitions. However, while participants increased movement pace on a cycle basis when gravity increased (1g-3g), they did not decrease pace when gravity decreased (3g-1g). We highlight asymmetric effects in the spontaneous adjustment of movement dynamics on short timescales, suggesting the involvement of cognitive factors, beyond standard dynamical models.