title: Dysrhythmia of timed movements in Parkinson's disease and freezing of gait.
abstract: A well-established motor timing paradigm, the Synchronization-Continuation Task (SCT), quantifies how accurately participants can time finger tapping to a rhythmic auditory beat (synchronization phase) then maintain this rhythm after the external auditory cue is extinguished, where performance depends on an internal representation of the beat (continuation phase). In this study, we investigated the hypothesis that Parkinson's disease (PD) patients with clinical symptoms of freezing of gait (FOG) exhibit exaggerated motor timing deficits. We predicted that dysrhythmia is exacerbated when finger tapping is stopped temporarily and then reinitiated under the guidance of an internal representation of the beat. Healthy controls and PD patients with and without FOG performed the SCT with and without the insertion of a 7-s cessation of motor tapping between synchronization and continuation phases. With no interruption between synchronization and continuation phases, PD patients, especially those with FOG, showed pronounced motor timing hastening at the slowest inter-stimulus intervals during the continuation phase. The introduction of a gap prior to the continuation phase had a beneficial effect for healthy controls and PD patients without FOG, although patients with FOG continued to show pronounced and persistent motor timing hastening. Ratings of freezing of gait severity across the entire sample of PD tracked closely with the magnitude of hastening during the continuation phase. These results suggest that PD is accompanied by a unique dysrhythmia of measured movements, with FOG reflecting a particularly pronounced disruption to internal rhythmic timing.
authors.affiliation: Dept of Neurology, Vanderbilt University, Nashville, TN, United States.
authors.forename: Christopher M
authors.initials: CM
authors.lastname: Tolleson
authors.affiliation: Psychology, University of Virginia, Charlottesville, VA, United States.
authors.forename: David G
authors.initials: DG
authors.lastname: Dobolyi
authors.affiliation: Dept of Neurology, Vanderbilt University, Nashville, TN, United States.
authors.forename: Olivia C
authors.initials: OC
authors.lastname: Roman
authors.affiliation: Dept of Neurology, Vanderbilt University, Nashville, TN, United States.
authors.forename: Kristen
authors.initials: K
authors.lastname: Kanoff
authors.affiliation: Music, Worcester Polytechnic Institute, Worcester, MA, United States.
authors.forename: Scott
authors.initials: S
authors.lastname: Barton
authors.affiliation: Dept of Neurology, Vanderbilt University, Nashville, TN, United States.
authors.forename: Scott A
authors.initials: SA
authors.lastname: Wylie
authors.affiliation: Psychology, University of Virginia, Charlottesville, VA, United States.
authors.forename: Michael
authors.initials: M
authors.lastname: Kubovy
authors.affiliation: Dept of Neurology, Vanderbilt University, Nashville, TN, United States. Electronic address: daniel.claassen@vanderbilt.edu.
authors.forename: Daniel O
authors.initials: DO
authors.lastname: Claassen
mesh_terms: D000368:Aged; D001696:Biomechanical Phenomena; D005260:Female; D020233:Gait Disorders, Neurologic / Q000150:complications*; D006801:Humans; D008297:Male; D008875:Middle Aged; D009068:Movement / Q000502:physiology*; D010300:Parkinson Disease / Q000150:complications*; D010468:Perceptual Disorders / Q000175:diagnosis / Q000209:etiology*; D010507:Periodicity; D011597:Psychomotor Performance / Q000502:physiology; D013997:Time Factors; D013998:Time Perception / Q000502:physiology*
keywords: Freezing of gait; Motor timing; Paced finger tapping test; Parkinson׳s disease