A model of different cognitive processes during spontaneous and intentional coupling to music in multiple sclerosis.

Evidence for using auditory-motor coupling in neurological rehabilitation to facilitate walking is increasing. However, the distinction between spontaneous and intended coupling and its underlying mechanisms is yet to be investigated. In this study, we include 30 persons with multiple sclerosis and 30 healthy controls (HCs) in an experiment with two sessions in which participants were asked to walk to music with various tempi, matching their preferred walking cadence (PWC) up to 10% above in incremental steps of 2%. In the first session, no instructions were given to synchronize. In the second, participants were instructed to synchronize steps to the beats. Spontaneous synchronization was possible at 0% and +2% of the PWC, and fewer persons with multiple sclerosis were able to do so compared with HCs. Instruction was needed to synchronize at above +2% tempo in all participants. In the instructed session, the +6% condition marked a cutoff for cognitively impaired persons, as they were no longer able to synchronize. Based on our findings, we constructed a model illustrating that spontaneous entrainment is limited, operating during spontaneous coupling at only 0% and +2% of the PWC, and that at a higher tempo, entrainment requires intentional synchronization, with an active cognitive control mechanism.