D G Dotov1, S Bayard2, V Cochen de Cock3, C Geny2, V Driss4, G Garrigue5, B Bardy6, S Dalla Bella7. 1. EuroMov, Université de Montpellier, Montpellier, France; Centro de Ciencias de la Complejidad (C3), Universidad Nacional Autónoma de México, Mexico. Electronic address: dobri.dotov@gmail.com. 2. EuroMov, Université de Montpellier, Montpellier, France; CHRU, Hôpital Gui-de-Chauliac, Montpellier, France. 3. CHRU, Hôpital Gui-de-Chauliac, Montpellier, France; Clinique Beau Soleil, Montpellier, France. 4. CHRU, Hôpital Gui-de-Chauliac, Montpellier, France. 5. Clinique du Parc, Montpellier, France. 6. EuroMov, Université de Montpellier, Montpellier, France; Institut Universitaire de France (IUF), Paris, France. 7. EuroMov, Université de Montpellier, Montpellier, France; Institut Universitaire de France (IUF), Paris, France; International Laboratory for Brain, Music, and Sound Research (BRAMS), Montreal, Canada; Department of Cognitive Psychology, WSFiZ, Warsaw, Poland.
Abstract
INTRODUCTION: Rhythmic auditory cueing improves certain gait symptoms of Parkinson's disease (PD). Cues are typically stimuli or beats with a fixed inter-beat interval. We show that isochronous cueing has an unwanted side-effect in that it exacerbates one of the motor symptoms characteristic of advanced PD. Whereas the parameters of the stride cycle of healthy walkers and early patients possess a persistent correlation in time, or long-range correlation (LRC), isochronous cueing renders stride-to-stride variability random. Random stride cycle variability is also associated with reduced gait stability and lack of flexibility. METHOD: To investigate how to prevent patients from acquiring a random stride cycle pattern, we tested rhythmic cueing which mimics the properties of variability found in healthy gait (biological variability). PD patients (n=19) and age-matched healthy participants (n=19) walked with three rhythmic cueing stimuli: isochronous, with random variability, and with biological variability (LRC). Synchronization was not instructed. RESULTS: The persistent correlation in gait was preserved only with stimuli with biological variability, equally for patients and controls (p's<0.05). In contrast, cueing with isochronous or randomly varying inter-stimulus/beat intervals removed the LRC in the stride cycle. Notably, the individual's tendency to synchronize steps with beats determined the amount of negative effects of isochronous and random cues (p's<0.05) but not the positive effect of biological variability. CONCLUSION: Stimulus variability and patients' propensity to synchronize play a critical role in fostering healthier gait dynamics during cueing. The beneficial effects of biological variability provide useful guidelines for improving existing cueing treatments. Copyright Â
INTRODUCTION:Rhythmic auditory cueing improves certain gait symptoms of Parkinson's disease (PD). Cues are typically stimuli or beats with a fixed inter-beat interval. We show that isochronous cueing has an unwanted side-effect in that it exacerbates one of the motor symptoms characteristic of advanced PD. Whereas the parameters of the stride cycle of healthy walkers and early patients possess a persistent correlation in time, or long-range correlation (LRC), isochronous cueing renders stride-to-stride variability random. Random stride cycle variability is also associated with reduced gait stability and lack of flexibility. METHOD: To investigate how to prevent patients from acquiring a random stride cycle pattern, we tested rhythmic cueing which mimics the properties of variability found in healthy gait (biological variability). PDpatients (n=19) and age-matched healthy participants (n=19) walked with three rhythmic cueing stimuli: isochronous, with random variability, and with biological variability (LRC). Synchronization was not instructed. RESULTS: The persistent correlation in gait was preserved only with stimuli with biological variability, equally for patients and controls (p's<0.05). In contrast, cueing with isochronous or randomly varying inter-stimulus/beat intervals removed the LRC in the stride cycle. Notably, the individual's tendency to synchronize steps with beats determined the amount of negative effects of isochronous and random cues (p's<0.05) but not the positive effect of biological variability. CONCLUSION: Stimulus variability and patients' propensity to synchronize play a critical role in fostering healthier gait dynamics during cueing. The beneficial effects of biological variability provide useful guidelines for improving existing cueing treatments. Copyright Â