M. C. van der Steen

Sensorimotor synchronization with tempo-changing auditory sequences: Modeling temporal adaptation and anticipation

The current study investigated the human ability to synchronize movements with event sequences containing continuous tempo changes. This capacity is evident, for example, in ensemble musicians who maintain precise interpersonal coordination while modulating the performance tempo for expressive purposes. Here we tested an ADaptation and Anticipation Model (ADAM) that was developed to account for such behavior by combining error correction processes (adaptation) with a predictive temporal extrapolation process (anticipation). While previous computational models of synchronization incorporate error correction, they do not account for prediction during tempo-changing behavior. The fit between behavioral data and computer simulations based on four versions of ADAM was assessed. These versions included a model with adaptation only, one in which adaptation and anticipation act in combination (error correction is applied on the basis of predicted tempo changes), and two models in which adaptation and anticipation were linked in a joint module that corrects for predicted discrepancies between the outcomes of adaptive and anticipatory processes. The behavioral experiment required participants to tap their finger in time with three auditory pacing sequences containing tempo changes that differed in the rate of change and the number of turning points. Behavioral results indicated that sensorimotor synchronization accuracy and precision, while generally high, decreased with increases in the rate of tempo change and number of turning points. Simulations and model-based parameter estimates showed that adaptation mechanisms alone could not fully explain the observed precision of sensorimotor synchronization. Including anticipation in the model increased the precision of simulated sensorimotor synchronization and improved the fit of model to behavioral data, especially when adaptation and anticipation mechanisms were linked via a joint module based on the notion of joint internal models. Overall results suggest that adaptation and anticipation mechanisms both play an important role during sensorimotor synchronization with tempo-changing sequences. This article is part of a Special Issue entitled SI: Prediction and Attention.

Basic Timing Abilities Stay Intact in Patients with Musician's Dystonia

Task-specific focal dystonia is a movement disorder that is characterized by the loss of voluntary motor control in extensively trained movements. Musicians dystonia is a type of task-specific dystonia that is elicited in professional musicians during instrumental playing. The disorder has been associated with deficits in timing. In order to test the hypothesis that basic timing abilities are affected by musicians dystonia, we investigated a group of patients (N = 15) and a matched control group (N = 15) on a battery of sensory and sensorimotor synchronization tasks. Results did not show any deficits in auditory-motor processing for patients relative to controls. Both groups benefited from a pacing sequence that adapted to their timing (in a sensorimotor synchronization task at a stable tempo). In a purely perceptual task, both groups were able to detect a misaligned metronome when it was late rather than early relative to a musical beat. Overall, the results suggest that basic timing abilities stay intact in patients with musicians dystonia. This supports the idea that musicians dystonia is a highly task-specific movement disorder in which patients are mostly impaired in tasks closely related to the demands of actually playing their instrument.

Modeling effects of cerebellar and basal ganglia lesions on adaptation and anticipation during sensorimotor synchronization

This study addressed the role of subcortical brain structures in temporal adaptation and anticipation during sensorimotor synchronization. The performance of patients with cerebellar or basal ganglia lesions was compared with that of healthy control participants on tasks requiring the synchronization of drum strokes with adaptive and tempo‐changing auditory pacing sequences. The precision of sensorimotor synchronization was generally lower in patients relative to controls (i.e., variability of asynchronies was higher in patients), although synchronization accuracy (mean asynchrony) was commensurate. A computational model of adaptation and anticipation (ADAM) was used to examine potential sources of individual differences in precision by estimating participants’ use of error correction, temporal prediction, and the amount of variability associated with central timekeeping and peripheral motor processes. Parameter estimates based on ADAM indicate that impaired precision was attributable to increased variability of timekeeper and motor processes as well as to reduced temporal prediction in both patient groups. Adaptive processes related to continuously applied error correction were, by contrast, intact in patients. These findings highlight the importance of investigating how subcortical structures, including the cerebellum and basal ganglia, interact with a broader network of cortical regions to support temporal adaptation and anticipation during sensorimotor synchronization.