Auditory observation of stepping actions can cue both spatial and temporal components of gait in Parkinson׳s disease patients

Gait-modifying effects of augmented-reality cueing in people with Parkinson's disease

Introduction

External cueing can improve gait in people with Parkinson's disease (PD), but there is a need for wearable, personalized and flexible cueing techniques that can exploit the power of action-relevant visual cues. Augmented Reality (AR) involving headsets or glasses represents a promising technology in those regards. This study examines the gait-modifying effects of real-world and AR cueing in people with PD.

Methods

21 people with PD performed walking tasks augmented with either real-world or AR cues, imposing changes in gait speed, step length, crossing step length, and step height. Two different AR headsets, differing in AR field of view (AR-FOV) size, were used to evaluate potential AR-FOV-size effects on the gait-modifying effects of AR cues as well as on the head orientation required for interacting with them.

Results

Participants modified their gait speed, step length, and crossing step length significantly to changes in both real-world and AR cues, with step lengths also being statistically equivalent to those imposed. Due to technical issues, step-height modulation could not be analyzed. AR-FOV size had no significant effect on gait modifications, although small differences in head orientation were observed when interacting with nearby objects between AR headsets.

Conclusion

People with PD can modify their gait to AR cues as effectively as to real-world cues with state-of-the-art AR headsets, for which AR-FOV size is no longer a limiting factor. Future studies are warranted to explore the merit of a library of cue modalities and individually-tailored AR cueing for facilitating gait in real-world environments.

Enhancing Perceptual-Motor Skills in Sports: The Role of Ecological Sounds

Starting approximately from the beginning of the new millennium, a series of studies highlighted that auditory information deriving from biological motion can significantly influence the behavioral, cognitive and neurophysiological processes involved in the perception and execution of complex movements. In particular, it was observed that an appropriate use of sounds deriving from one's own movement promotes improvements in the movement execution itself. Two main approaches can be used, namely the sonification one or the ecological sound one; the former is based on the conversion of physiological and/or physical movement data into sound, while the latter is based on the use of auditory recordings of movement sounds as models. In the present article, some of the main applications of both approaches-especially the latter-to the domains of sport and motor rehabilitation are reviewed, with the aim of addressing two questions: Is it possible to consider rhythm as a Gestalt of human movement? If so, is it possible to build up cognitive strategies to improve/standardize movement performance from this Gestalt? As with most topics in science, a definitive answer is not possible, yet the evidence leads us to lean toward a positive answer to both questions.

Holographic Hintways: A systems feasibility and usability study of augmented reality cueing for gait adaptation

BACKGROUND

Through providing on-demand visual and auditory cues while walking,augmented reality (AR) can theoretically cue spatiotemporal gait adaptations in, populations such as those with Parkinson's disease. However, given the novelty of the, technology, the type and extent of gait adaptations in response to such a cueing, system are unknown. Before such systems can be incorporated into rehabilitation, approaches, it is important to understand how people interact with the technology.

RESEARCH QUESTIONS

What are the effects of visual and auditory cues delivered, through AR on spatiotemporal walking patterns and variability in a healthy, young, population? Is there a relationship between system usability and gait variability?

, METHODS

Twenty healthy, young participants walked in four different cueing conditions using an AR headset: No Cues (NC) (i.e., natural gait), Auditory (A), Visual (V), and Auditory + Visual (AV). Inertial measurement units recorded spatiotemporal gait data at 200 Hz, a System Usability Survey was administered afterward, and linear regression models were developed to examine whether gait variability is predictive of system usability.

RESULTS

All cueing conditions exhibited a significantly slower cadence compared to, NC trials. Cadence variability was significantly higher for A trials compared to V and, NC. V trials exhibited significantly decreased stride lengths compared to NC. Increased, reported system usability was significantly correlated with decreased stance phase, time variability across A trials.

SIGNIFICANCE

Our findings support that holographic spatial-visual and auditory cues, are promising to evoke spatiotemporal gait adaptations. Results also support the, notion that the type of system and cue delivery design may impact gait outcomes.,Before an AR cueing system can be applied to a specific population in future, interventions, a more holistic approach towards finding the relationship between this, technology and its users is needed.

Paradoxical kinesia may no longer be a paradox waiting for 100 years to be unraveled

Parkinson's disease (PD) is a progressive neurodegenerative disorder mainly characterized by bradykinesia and akinesia. Interestingly, these motor disabilities can depend on the patient emotional state. Disabled PD patients remain able to produce normal motor responses in the context of urgent or externally driven situations or even when exposed to appetitive cues such as music. To describe this phenomenon Souques coined the term "paradoxical kinesia" a century ago. Since then, the mechanisms underlying paradoxical kinesia are still unknown due to a paucity of valid animal models that replicate this phenomenon. To overcome this limitation, we established two animal models of paradoxical kinesia. Using these models, we investigated the neural mechanisms of paradoxical kinesia, with the results pointing to the inferior colliculus (IC) as a key structure. Intracollicular electrical deep brain stimulation, glutamatergic and GABAergic mechanisms may be involved in the elaboration of paradoxical kinesia. Since paradoxical kinesia might work by activation of some alternative pathway bypassing basal ganglia, we suggest the IC as a candidate to be part of this pathway.

One cue does not fit all: a systematic review with meta-analysis of the effectiveness of cueing on freezing of gait in Parkinson's disease

The difficulty in assessing FOG and the variety of existing cues, hamper to determine which cueing modality should be applied and which FOG-related aspect should be targeted to reach personalized treatments for FOG. This systematic review aimed to highlight: i) whether cues could reduce FOG and improve FOG-related gait parameters, ii) which cues are the most effective, iii) whether medication state (ON-OFF) affects cues-related results. Thirty-three repeated measure design studies assessing cueing effectiveness were included and subdivided according to gait tasks (gait initiation, walking, turning) and to the medication state. Main results reveal that: preparatory phase of gait initiation benefit from visual and auditory cues; spatio-temporal parameters (e.g., step and stride length) and are improved by visual cues during walking; turning time and step time variability are reduced by applying auditory and visual cues. Some findings on the potential benefits of cueing on FOG and FOG gait-related parameters were found. Questions remain about which are the best behavioral strategies according to FOG features and PD clinical characteristics.

The Effect of Human Settlement Pedestrian Environment on Gait of Older People: An Umbrella Review

Older people are limited by the pedestrian environment in human settlements and are prone to travel difficulties, falls, and stumbles. Furthermore, we still lack systematic knowledge of the pedestrian environment affecting the gait of older people. The purpose of this review is to synthesize current evidence of effective human settlement pedestrian environments interfering with gait in older people. The systematic effects of the human settlement pedestrian environment on gait in older people are discussed. Databases such as Web of Science, Medline (via PubMed), Scopus, and Embase were searched for relevant studies up to June 2022. The literature was screened to extract relevant evidence from the included literature, assess the quality of the evidence, and analyze the systematic effects of the pedestrian environment on gait in older people. From the 4297 studies identified in the initial search, 11 systematic reviews or meta-analysis studies were screened, from which 18 environmental factors and 60 gait changes were extracted. After removing duplicate elements and merging synonymous features, a total of 53 relationships between environmental factors and gait change in older people were extracted: the main human settlement pedestrian environmental factors affecting gait change in older people in existing studies were indoor and outdoor stairs/steps, uneven and irregular ground, obstacles, walking path turns, vibration interventions, mechanical perturbation during gait, and auditory sound cues. Under the influence of these factors, older people may experience changes in the degree of cautiousness and conservatism of gait and stability, and their body posture performance and control, and muscle activation may also be affected. Factors such as ground texture or material, mechanical perturbations during gait, and vibration interventions stimulate older people's understanding and perception of their environment, but there is controversy over the results of specific gait parameters. The results support that human settlements' pedestrian environment affects the gait changes of older people in a positive or negative way. This review may likely contribute evidence-based information to aid communication among practitioners in public health, healthcare, and environmental construction. The above findings are expected to provide useful preference for associated interdisciplinary researchers to understand the interactions among pedestrian environments, human behavior, and physiological characteristics.

Does Cueing Need Attention? A Pilot Study in People with Parkinson's Disease

We previously showed that both open-loop (beat of a metronome) and closed-loop (phase-dependent tactile feedback) cueing may be similarly effective in reducing Freezing of Gait (FoG), assessed with a quantitative FoG Index, while turning in place in the laboratory in a group of people with Parkinson's disease (PD). Despite the similar changes on the FoG Index, it is not known whether both cueing responses require attentional control, which would explain FoG Index improvement. The mechanisms underlying cueing responses are poorly understood. Here, we tested the hypothesis that the salience network would predict responsiveness (i.e., FoG Index improvement) to open-loop and closed-loop cueing in people with and without FoG of PD, as salience network contributes to tasks requiring attention to external stimuli in healthy adults. Thirteen people with PD with high-quality imaging data were analyzed to characterize relationships between resting-state MRI functional connectivity and responses to cues. The interaction of the salience network and retrosplenial-temporal networks was the best predictor of responsiveness to open-loop cueing, presenting the largest effect size (d = 1.16). The interaction between the salience network and subcortical as well as cingulo-parietal and subcortical networks were the strongest predictors of responsiveness to closed-loop cueing, presenting the largest effect sizes (d = 1.06 and d = 0.84, respectively). Salience network activity was a common predictor of responsiveness to both cueing, which suggests that auditory and proprioceptive stimuli during turning may require some level of cognitive and insular activity, anchored within the salience network, which explain FoG Index improvements in people with PD.

How to orchestrate a soccer team: Generalized synchronization promoted by rhythmic acoustic stimuli

Interpersonal coordination requires precise actions concerted in space and time in a self-organized manner. We found, using soccer teams as a testing ground, that a common timeframe provided by adequate acoustic stimuli improves the interplay between teammates. We provide quantitative evidence that the connectivity between teammates and the scoring rate of male soccer teams improve significantly when playing under the influence of an appropriate acoustic environment. Unexpectedly, female teams do not show any improvement under the same experimental conditions. We show by follow-up experiments that the acoustic rhythm modulates the attention level of the participants with a pronounced tempo preference and a marked gender difference in the preferred tempo. These results lead to a consistent explanation in terms of the dynamical system theory, nonlinear resonances, and dynamic attention theory, which may illuminate generic mechanisms of the brain dynamics and may have an impact on the design of novel training strategies in team sports.

Weighting for the Beat: Using a Dance Cue to Facilitate Turning in People with Parkinson's Disease and Freezing of Gait

Freezing of gait (FOG) can severely compromise daily functioning in people with Parkinson's disease. Inability to initiate a step from FOG is likely underpinned, at least in part, by a deficient preparatory weight-shift. Conscious attempts to weight-shift in preparation to step can improve success of initiating forward steps following FOG. However, FOG often occurs during turning, where weight-shifting is more complex and risk of falling is higher. We explored the effectiveness of a dance-based ('cha-cha') weight-shifting strategy to re-initiate stepping following FOG during turning. Results suggest that this simple movement strategy can enhance turning steps following FOG, without compromising safety.

Effects of Rhythmic Auditory Stimulation on Gait and Motor Function in Parkinson's Disease: A Systematic Review and Meta-Analysis of Clinical Randomized Controlled Studies

Objective

This study aimed to summarize the effectiveness of rhythmic auditory stimulation (RAS) for the treatment of gait and motor function in Parkinson's disease (PD) through a systematic review and meta-analysis.

Methods

All studies were retrieved from eight databases. The effects of RAS on PD were determined using the following indicators: gait parameters including step length, stride width, step cadence, velocity, stride length; motor function including 6 min walk test (6MWT) and timed up-and-go test (TUGT); the Unified Parkinson's Disease Rating Scale (UPDRS); and the Berg Balance Scale (BBS). The risk map of bias of the quality of the studies and the meta-analysis results of the indicators was prepared with RevMan 5.2 software.

Results

Twenty-one studies were included in the systematic review, and 14 studies were included in the meta-analysis. In the meta-analysis, the results of gait parameters, namely, velocity, step length, and stride length, were statistically significant (P < 0.05), whereas the results of cadence and stride width were not statistically significant (P ≧ 0.05). The results of 6MWT and TUGT for motor function as well as UPDRS-II, UPDRS-III, and BBS were statistically significant (P < 0.05).

Conclusions

RAS could improve gait parameters, walking function, balance function, and daily living activities of individuals with PD. The application of RAS in conventional rehabilitation approaches can enhance motor performance in PD. Future studies should use a large sample size and a rigorous design to obtain strong conclusions about the advantages of RAS for the treatment of gait and motor function in PD.

Sonification of Golf Putting Gesture Reduces Swing Movement Variability in Novices

Purpose: To study whether novices can use sonification to enhance golf putting performance and swing movements. Method: Forty participants first performed a series of 2 m and 4 m putts, where swing velocities associated with successful trials were used to calculate their mean velocity profile (MVP). Participants were then divided into four groups with different auditory conditions: static pink noise unrelated to movement, auditory guidance based on personalized MVP, and two sonification strategies that mapped the real-time error between observed and MVP swings to modulate either the stereo display or roughness of the auditory guidance signal. Participants then performed a series of 2 m and 4 m putts with the auditory condition designated to their group. Results: In general our results showed significant correlations between swing movement variability and putting performance for all sonification groups. More specifically, in comparison to the group exposed to static pink noise, participants who were presented auditory guidance significantly reduced the deviation from their average swing movement. In addition, participants exposed to error-based sonification with stereo display modulation significantly lowered their variability in timing swing movements. These results provide further evidence of the benefits of sonification for novices performing complex motor skill tasks. Conclusions: More importantly, our findings suggest participants were able to better use online error-based sonification rather than auditory guidance to reduce variability in the execution and timing of their movements.

Action Imagery and Observation in Neurorehabilitation for Parkinson's Disease (ACTION-PD): Development of a User-Informed Home Training Intervention to Improve Functional Hand Movements

Background

Parkinson's disease (PD) causes difficulties with hand movements, which few studies have addressed therapeutically. Training with action observation (AO) and motor imagery (MI) improves performance in healthy individuals, particularly when the techniques are applied simultaneously (AO + MI). Both AO and MI have shown promising effects in people with PD, but previous studies have only used these separately.

Objective

This article describes the development and pilot testing of an intervention combining AO + MI and physical practice to improve functional manual actions in people with PD.

Methods

The home-based intervention, delivered using a tablet computer app, was iteratively designed by an interdisciplinary team, including people with PD, and further developed through focus groups and initial field testing. Preliminary data on feasibility were obtained via a six-week pilot randomised controlled trial (ISRCTN 11184024) of 10 participants with mild to moderate PD (6 intervention; 4 treatment as usual). Usage and adherence data were recorded during training, and semistructured interviews were conducted with participants. Exploratory outcome measures included dexterity and timed action performance.

Results

Usage and qualitative data provided preliminary evidence of acceptability and usability. Exploratory outcomes also suggested that subjective and objective performance of manual actions should be tested in a larger trial. The importance of personalisation, choice, and motivation was highlighted, as well as the need to facilitate engagement in motor imagery.

Conclusions

The results indicate that a larger RCT is warranted, and the findings also have broader relevance for the feasibility and development of AO + MI interventions for PD and other conditions.

Ankle Push-Off Based Mathematical Model for Freezing of Gait in Parkinson's Disease

Freezing is an involuntary stopping of gait observed in late-stage Parkinson's disease (PD) patients. This is a highly debilitating symptom lacking a clear understanding of its causes. Walking in these patients is also associated with high variability, making both prediction of freezing and its understanding difficult. A neuromechanical model describes the motion of the mechanical (motor) aspects of the body under the action of neuromuscular forcing. In this work, a simplified neuromechanical model of gait is used to infer the causes for both the observed variability and freezing in PD. The mathematical model consists of the stance leg (during walking) modeled as a simple inverted pendulum acted upon by the ankle-push off forces from the trailing leg and pathological forces by the plantar-flexors of the stance leg. We model the effect on walking of the swing leg in the biped model and provide a rationale for using an inverted pendulum model. Freezing and irregular walking is demonstrated in the biped model as well as the inverted pendulum model. The inverted pendulum model is further studied semi-analytically to show the presence of horseshoe and chaos. While the plantar flexors of the swing leg push the center of mass (CoM) forward, the plantar flexors of the stance leg generate an opposing torque. Our study reveals that these opposing forces generated by the plantar flexors can induce freezing. Other gait abnormalities nearer to freezing such as a reduction in step length, and irregular walking patterns can also be explained by the model.

An Initial Investigation of the Responsiveness of Temporal Gait Asymmetry to Rhythmic Auditory Stimulation and the Relationship to Rhythm Ability Following Stroke

Temporal gait asymmetry (TGA) is a persistent post-stroke gait deficit. Compared to conventional gait training techniques, rhythmic auditory stimulation (RAS; i.e., walking to a metronome) has demonstrated positive effects on post-stroke TGA. Responsiveness of TGA to RAS may be related to several factors including motor impairment, time post-stroke, and individual rhythm abilities. The purpose of this study was to investigate the relationship between rhythm abilities and responsiveness of TGA when walking to RAS. Assessed using behavioral tests of beat perception and production, participants with post-stroke TGA (measured as single limb support time ratio) were categorized according to rhythm ability (as strong or weak beat perceivers/producers). We assessed change in TGA between walking without cues (baseline) and walking while synchronizing footsteps with metronome cues. Most individuals with stroke were able to maintain or improve TGA with a single session of RAS. Within-group analyses revealed a difference between strong and weak rhythm ability groups. Strong beat perceivers and producers showed significant reduction (improvement) in TGA with the metronome. Those with weak ability did not and exhibited high variability in the TGA response to metronome. Moreover, individuals who worsened in TGA when walking to metronome had poorer beat production scores than those who did not change in TGA. However, no interaction between TGA improvement when walking to metronome and rhythm perception or production ability was found. While responsiveness of TGA to RAS did not significantly differ based on strength of rhythm abilities, these preliminary findings highlight rhythm ability as a potential consideration when treating post-stroke individuals with rhythm-based treatments.

'Recoupling' the attentional and motor control of preparatory postural adjustments to overcome freezing of gait in Parkinson's

Objectives

This study examined if people with Parkinson’s and freezing of gait pathology (FoG) could be trained to increase preparatory weight-shift amplitude, and facilitate step initiation during FoG.

Methods

Thirty-five people with Parkinson’s and FoG attempted to initiate forward walking from a stationary position caused by a freeze (n = 17, FoG-F) or voluntarily stop (n = 18, FoG-NF) in a Baseline condition and two conditions where an increased weight-shift amplitude was trained via: (i) explicit verbal instruction, and (ii) implicit movement analogies.

Results

At Baseline, weight-shift amplitudes were smaller during: (i) unsuccessful, compared to successful step initiations (FoG-F group), and (ii) successful step initiations in the FoG-F group compared to FoG-NF. Both Verbal and Analogy training resulted in significant increases in weight-shift amplitude in both groups, and a corresponding pronounced reduction in unsuccessful attempts to initiate stepping (FoG-F group).

Conclusions

Hypometric preparatory weight-shifting is associated with failure to initiate forward stepping in people with Parkinson’s and FoG. However, impaired weight-shift characteristics are modifiable through conscious strategies. This current study provides a novel and critical evaluation of preparatory weight-shift amplitudes during FoG events. The intervention described represents an attractive ‘rescue’ strategy and should be further scrutinised regarding limitations posed by physical and cognitive deficits.

Feasibility of Music-Assisted Treadmill Training in Parkinson's Disease Patients With and Without Deep Brain Stimulation: Insights From an Ongoing Pilot Randomized Controlled Trial

Background: Music-assisted treadmill training (MATT) is a new therapeutic approach for Parkinson's disease (PD) patients, combining treadmill training with rhythmic auditory cueing and visual feedback. PD studies have shown larger positive effects on motor outcomes than usual treadmill training. However, effects on cognition, in contrast, are less clear. Existing studies provided intensive training protocols and included only stable medicated patients. Thus, a pilot randomized controlled trial was designed to analyze the feasibility of a shorter training protocol as well as preliminary effects on cognition, motor function, and patient-centered outcomes in a rehabilitation setting where PD patients with and without deep brain stimulation (DBS) undergo adaptation of medication and DBS settings. Here, we present the results from the feasibility analysis of the still ongoing trial.

Methods: Non-demented PD patients with and without DBS were recruited during their inpatient rehabilitation and randomized to an experimental group (EG; 20 min MATT) or an active control group (CG; 20 min bike ergometer training). The trainings took place for 8 consecutive days and were added to the usual rehabilitation. Feasibility was assessed with the following parameters: patients' study protocol acceptance, study protocol transferability into clinical routine, training-induced adverse events, and patients' training perception.

Results: Thirty-two patients (EG: n = 15; CG: n = 17; 72% DBS) were included. The study protocol was well-accepted (inclusion rate: 84%). It was transferable into clinical routines; dropout rates of 40% (EG) and 18% (CG) were observed. However, an in-depth analysis of the dropout cohort did not reveal intervention-related dropout reasons. The MATT and the standard ergometer training showed no adverse events and were positively perceived by PD patients with and without DBS.

Conclusion: MATT was shown to be a feasible, safe, and enjoyable treatment option in PD patients with and without DBS. Furthermore, the dropout cohort analysis revealed some exciting first insights into possible dropout reasons that go beyond the form of intervention. Therefore, research would benefit from a common practice of dropout analyses, as this would enhance our understanding of patients' therapy adherence and expectations.

Mental Singing Reduces Gait Variability More Than Music Listening for Healthy Older Adults and People With Parkinson Disease

BACKGROUND AND PURPOSE

Previously, we showed that internal cues (such as singing) produce similar motor benefits as external cues (such as listening to music) for people with Parkinson disease (PD). This study takes that research further by exploring how singing-either aloud or mentally-at different tempos can ameliorate gait, and it offers insight into how internal cueing techniques may enhance motor performance for older adults and people with PD.

METHODS

Sixty participants aged 50 years and older (30 female) were recruited; 30 had PD and 30 were healthy age-matched controls. Participants completed walking trials involving internal and external cueing techniques at 90%, 100%, and 110% of preferred cadence. The effects of different cue types and rates were assessed in a repeated-measures cross-sectional study by comparing gait characteristics (velocity, cadence, stride length) and variabilities (coefficients of variation of stride length, stride time, single support time).

RESULTS

All participants modified their cadence and stride length during cued conditions, resulting in changes in gait velocity closely reflecting expected changes based upon cue rate. External cues resulted in increased gait variability, whereas internal cues decreased gait variability relative to uncued walking. Variability decreases were more substantial during mental singing at tempos at or above preferred cadence.

DISCUSSION AND CONCLUSIONS

Matching movement to one's own voice improves gait characteristics while reducing gait variability for older adults and people with PD. Optimizing the use of internal cues to facilitate movement is an important step toward more effectively meeting the needs of people with gait disorders related to aging or neurological disease.Video Abstract available for more insights from authors (see Video, Supplemental Digital Content 1, available at: http://links.lww.com/JNPT/A286).

Dance and Parkinson's: A review and exploration of the role of cognitive representations of action

Parkinson's disease (PD) is a neurodegenerative condition that causes both sensorimotor and non-motor impairments, and there is a clear need for non-medical approaches to improve quality of life. Dance is an increasingly popular activity among people with PD, which demonstrates potential therapeutic benefits. However, findings to date have been inconsistent, and little is known about the mechanisms underlying benefits of dance in PD. In this review, we provide an overview of research into dance for people with PD. The majority of quantitative evidence is in the sensorimotor domain, but cognitive, psychological and social effects have also been reported. We consider the role of cognitive representations of action within dance through observation, imitation and imagery, which may contribute to both sensorimotor and non-motor outcomes for people with PD. Moreover, we discuss how these processes may be enhanced through dance to provide further benefits in everyday life. Finally, we propose avenues for future research to increase understanding of action representation in dance for PD, which has the potential to inform practice and maximize benefits.

A Technological Review of Wearable Cueing Devices Addressing Freezing of Gait in Parkinson's Disease

Freezing of gait is one of the most debilitating symptoms of Parkinson’s disease and is an important contributor to falls, leading to it being a major cause of hospitalization and nursing home admissions. When the management of freezing episodes cannot be achieved through medication or surgery, non-pharmacological methods such as cueing have received attention in recent years. Novel cueing systems were developed over the last decade and have been evaluated predominantly in laboratory settings. However, to provide benefit to people with Parkinson’s and improve their quality of life, these systems must have the potential to be used at home as a self-administer intervention. This paper aims to provide a technological review of the literature related to wearable cueing systems and it focuses on current auditory, visual and somatosensory cueing systems, which may provide a suitable intervention for use in home-based environments. The paper describes the technical operation and effectiveness of the different cueing systems in overcoming freezing of gait. The “What Works Clearinghouse (WWC)” tool was used to assess the quality of each study described. The paper findings should prove instructive for further researchers looking to enhance the effectiveness of future cueing systems.

A Review on the Relationship Between Sound and Movement in Sports and Rehabilitation

The role of auditory information on perceptual-motor processes has gained increased interest in sports and psychology research in recent years. Numerous neurobiological and behavioral studies have demonstrated the close interaction between auditory and motor areas of the brain, and the importance of auditory information for movement execution, control, and learning. In applied research, artificially produced acoustic information and real-time auditory information have been implemented in sports and rehabilitation to improve motor performance in athletes, healthy individuals, and patients affected by neurological or movement disorders. However, this research is scattered both across time and scientific disciplines. The aim of this paper is to provide an overview about the interaction between movement and sound and review the current literature regarding the effect of natural movement sounds, movement sonification, and rhythmic auditory information in sports and motor rehabilitation. The focus here is threefold: firstly, we provide an overview of empirical studies using natural movement sounds and movement sonification in sports. Secondly, we review recent clinical and applied studies using rhythmic auditory information and sonification in rehabilitation, addressing in particular studies on Parkinson's disease and stroke. Thirdly, we summarize current evidence regarding the cognitive mechanisms and neural correlates underlying the processing of auditory information during movement execution and its mental representation. The current state of knowledge here reviewed provides evidence of the feasibility and effectiveness of the application of auditory information to improve movement execution, control, and (re)learning in sports and motor rehabilitation. Findings also corroborate the critical role of auditory information in auditory-motor coupling during motor (re)learning and performance, suggesting that this area of clinical and applied research has a large potential that is yet to be fully explored.

The Limitations of Being a Copycat: Learning Golf Putting Through Auditory and Visual Guidance

The goal of this study was to investigate whether sensory cues carrying the kinematic template of expert performance (produced by mapping movement to a sound or visual cue) displayed prior to and during movement execution can enhance motor learning of a new skill (golf putting) in a group of novices. We conducted a motor learning study on a sample of 30 participants who were divided into three groups: a control, an auditory guide and visual guide group. The learning phase comprised of two sessions per week over a period of 4 weeks, giving rise to eight sessions. In each session participants made 20 shots to three different putting distances. All participants had their measurements taken at separate sessions without any guidance: baseline, transfer (different distances) and retention 2 weeks later. Results revealed a subtle improvement in goal attainment and a decrease in kinematic variability in the sensory groups (auditory and visual) compared to the control group. The comparable changes in performance between the visual and auditory guide groups, particularly during training, supports the idea that temporal patterns relevant to motor control can be perceived similarly through either visual or auditory modalities. This opens up the use of auditory displays to inform motor learning in tasks or situations where visual attention is otherwise constrained or unsuitable. Further research into the most useful template actions to display to learners may thus still support effective auditory guidance in motor learning.

Music Therapy and Dance as Gait Rehabilitation in Patients With Parkinson Disease: A Review of Evidence

AIM

This review aims to demonstrate the efficiency of music and dance for gait improvement and symptom alleviation in Parkinson disease.

METHODOLOGY

Studies that analyzed sound stimuli and dance in gait improvement in Parkinson disease were searched through PubMed, Scopus, Doaj, MEDLINE, and ScienceDirect databases from November 2017 to April 2018 and repeated in September 2018.

RESULTS AND DISCUSSION

Forty-five studies met the inclusion criteria to synthesize the findings on dance and music performance as a treatment for classical symptoms of Parkinson disease. Five reviews and 40 experimental papers have shown that rhythmic stimulation and dance provide the motor, cognitive, and quality of life benefits for participants with Parkinson disease. Thus, sound stimuli and dance offer satisfactory effects for gait, improving cognitive abilities such as motor control and adjustment and spatial memory. In addition, these new treatment modalities stimulate the elderly population to practice physical exercise, generating well-being and helping self-esteem.

CONCLUSION

Dance and music therapy interventions are noninvasive, simple treatment options, which promote gait and cognition.

Gait festination in parkinsonism: introduction of two phenotypes

Gait festination is one of the most characteristic gait disturbances in patients with Parkinson’s disease or atypical parkinsonism. Although festination is common and disabling, it has received little attention in the literature, and different definitions exist. Here, we argue that there are actually two phenotypes of festination. The first phenotype entails a primary locomotion disturbance, due to the so-called sequence effect: a progressive shortening of step length, accompanied by a compensatory increase in cadence. This phenotype strongly relates to freezing of gait with alternating trembling of the leg. The second phenotype results from a postural control problem (forward leaning of the trunk) combined with a balance control deficit (inappropriately small balance-correcting steps). In this viewpoint, we elaborate on the possible pathophysiological substrate of these two phenotypes of festination and discuss their management in daily clinical practice.

Effect of Rhythmic Auditory Cueing on Aging Gait: A Systematic Review and Meta-Analysis

Rhythmic auditory cueing has been widely used in gait rehabilitation over the past decade. The entrainment effect has been suggested to introduce neurophysiological changes, alleviate auditory-motor coupling and reduce cognitive-motor interferences. However, a consensus as to its influence over aging gait is still warranted. A systematic review and meta-analysis was carried out to analyze the effects of rhythmic auditory cueing on spatiotemporal gait parameters among healthy young and elderly participants. This systematic identification of published literature was performed according to PRISMA guidelines, from inception until May 2017, on online databases: Web of science, PEDro, EBSCO, MEDLINE, Cochrane, EMBASE, and PROQUEST. Studies were critically appraised using PEDro scale. Of 2789 records, 34 studies, involving 854 (499 young/355 elderly) participants met our inclusion criteria. The meta-analysis revealed enhancements in spatiotemporal parameters of gait i.e. gait velocity (Hedge's g: 0.85), stride length (0.61), and cadence (1.1), amongst both age groups. This review, for the first time, evaluates the effects of auditory entrainment on aging gait and discusses its implications under higher and lower information processing constraints. Clinical implications are discussed with respect to applications of auditory entrainment in rehabilitation settings.

Virtual Footprints Can Improve Walking Performance in People With Parkinson's Disease

In Parkinson's disease (PD) self-directed movement, such as walking, is often found to be impaired while goal directed movement, such as catching a ball, stays relatively unaltered. This dichotomy is most clearly observed when sensory cueing techniques are used to deliver patterns of sound and/or light which in turn act as an external guide that improves gait performance. In this study we developed visual cues that could be presented in an immersive, interactive virtual reality (VR) environment. By controlling how the visual cues (black footprints) were presented, we created different forms of spatial and temporal information. By presenting the black footprints at a pre-specified distance apart we could recreate different step lengths (spatial cues) and by controlling when the black footprints changed color to red, we could convey information about the timing of the foot placement (temporal cues). A group of healthy controls (HC; N = 10) and a group of idiopathic PD patients (PD, N = 12) were asked to walk using visual cues that were tailored to their own gait performance [two spatial conditions (115% [N] and 130% [L] of an individual's baseline step length) and three different temporal conditions (spatial only condition [NT], 100 and 125% baseline step cadence)]. Both groups were found to be able to match their gait performance (step length and step cadence) to the information presented in all the visual cue conditions apart from the 125% step cadence conditions. In all conditions the PD group showed reduced levels of gait variability (p < 0.05) while the HC group did not decrease. For step velocity there was a significant increase in the temporal conditions, the spatial conditions and of the interaction between the two for both groups of participants (p < 0.05). The coefficient of variation of step length, cadence, and velocity were all significantly reduced for the PD group compared to the HC group. In conclusion, our results show how virtual footsteps presented in an immersive, interactive VR environment can significantly improve gait performance in participants with Parkinson's disease.

Effects of Real-Time (Sonification) and Rhythmic Auditory Stimuli on Recovering Arm Function Post Stroke: A Systematic Review and Meta-Analysis

Background: External auditory stimuli have been widely used for recovering arm function post-stroke. Rhythmic and real-time auditory stimuli have been reported to enhance motor recovery by facilitating perceptuomotor representation, cross-modal processing, and neural plasticity. However, a consensus as to their influence for recovering arm function post-stroke is still warranted because of high variability noted in research methods. Objective: A systematic review and meta-analysis was carried out to analyze the effects of rhythmic and real-time auditory stimuli on arm recovery post stroke. Method: Systematic identification of published literature was performed according to PRISMA guidelines, from inception until December 2017, on online databases: Web of science, PEDro, EBSCO, MEDLINE, Cochrane, EMBASE, and PROQUEST. Studies were critically appraised using PEDro scale. Results: Of 1,889 records, 23 studies which involved 585 (226 females/359 males) patients met our inclusion criteria. The meta-analysis revealed beneficial effects of training with both types of auditory inputs for Fugl-Meyer assessment (Hedge's g: 0.79), Stroke impact scale (0.95), elbow range of motion (0.37), and reduction in wolf motor function time test (-0.55). Upon further comparison, a beneficial effect of real-time auditory feedback was found over rhythmic auditory cueing for Fugl-meyer assessment (1.3 as compared to 0.6). Moreover, the findings suggest a training dosage of 30 min to 1 h for at least 3-5 sessions per week with either of the auditory stimuli. Conclusion: This review suggests the application of external auditory stimuli for recovering arm functioning post-stroke.

Effects of Rhythmic Auditory Cueing in Gait Rehabilitation for Multiple Sclerosis: A Mini Systematic Review and Meta-Analysis

Rhythmic auditory cueing has been shown to enhance gait performance in several movement disorders. The "entrainment effect" generated by the stimulations can enhance auditory motor coupling and instigate plasticity. However, a consensus as to its influence over gait training among patients with multiple sclerosis is still warranted. A systematic review and meta-analysis was carried out to analyze the effects of rhythmic auditory cueing in studies gait performance in patients with multiple sclerosis. This systematic identification of published literature was performed according to PRISMA guidelines, from inception until Dec 2017, on online databases: Web of science, PEDro, EBSCO, MEDLINE, Cochrane, EMBASE, and PROQUEST. Studies were critically appraised using PEDro scale. Of 602 records, five studies (PEDro score: 5.7 ± 1.3) involving 188 participants (144 females/40 males) met our inclusion criteria. The meta-analysis revealed enhancements in spatiotemporal parameters of gait i.e., velocity (Hedge's g: 0.67), stride length (0.70), and cadence (1.0), and reduction in timed 25 feet walking test (-0.17). Underlying neurophysiological mechanisms, and clinical implications are discussed. This present review bridges the gaps in literature by suggesting application of rhythmic auditory cueing in conventional rehabilitation approaches to enhance gait performance in the multiple sclerosis community.

The Use of Footstep Sounds as Rhythmic Auditory Stimulation for Gait Rehabilitation in Parkinson's Disease: A Randomized Controlled Trial

Background

The use of rhythmic auditory stimulation (RAS) has been proven useful in the management of gait disturbances associated with Parkinson’s disease (PD). Typically, the RAS consists of metronome or music-based sounds (artificial RAS), while ecological footstep sounds (ecological RAS) have never been used for rehabilitation programs.

Objective

The aim of this study was to compare the effects of a rehabilitation program integrated either with ecological or with artificial RAS.

Methods

An observer-blind, randomized controlled trial was conducted to investigate the effects of 5 weeks of supervised rehabilitation integrated with RAS. Thirty-eight individuals affected by PD were randomly assigned to one of the two conditions (ecological vs. artificial RAS); thirty-two of them (age 68.2 ± 10.5, Hoehn and Yahr 1.5–3) concluded all phases of the study. Spatio-temporal parameters of gait and clinical variables were assessed before the rehabilitation period, at its end, and after a 3-month follow-up.

Results

Thirty-two participants were analyzed. The results revealed that both groups improved in the majority of biomechanical and clinical measures, independently of the type of sound. Moreover, exploratory analyses for separate groups were conducted, revealing improvements on spatio-temporal parameters only in the ecological RAS group.

Conclusion

Overall, our results suggest that ecological RAS is equally effective compared to artificial RAS. Future studies should further investigate the role of ecological RAS, on the basis of information revealed by our exploratory analyses. Theoretical, methodological, and practical issues concerning the implementation of ecological sounds in the rehabilitation of PD patients are discussed.

Clinical Trial Registration

www.ClinicalTrials.gov, identifier NCT03228888.

Effect of rhythmic auditory cueing on parkinsonian gait: A systematic review and meta-analysis

The use of rhythmic auditory cueing to enhance gait performance in parkinsonian patients' is an emerging area of interest. Different theories and underlying neurophysiological mechanisms have been suggested for ascertaining the enhancement in motor performance. However, a consensus as to its effects based on characteristics of effective stimuli, and training dosage is still not reached. A systematic review and meta-analysis was carried out to analyze the effects of different auditory feedbacks on gait and postural performance in patients affected by Parkinson's disease. Systematic identification of published literature was performed adhering to PRISMA guidelines, from inception until May 2017, on online databases; Web of science, PEDro, EBSCO, MEDLINE, Cochrane, EMBASE and PROQUEST. Of 4204 records, 50 studies, involving 1892 participants met our inclusion criteria. The analysis revealed an overall positive effect on gait velocity, stride length, and a negative effect on cadence with application of auditory cueing. Neurophysiological mechanisms, training dosage, effects of higher information processing constraints, and use of cueing as an adjunct with medications are thoroughly discussed. This present review bridges the gaps in literature by suggesting application of rhythmic auditory cueing in conventional rehabilitation approaches to enhance motor performance and quality of life in the parkinsonian community.

Effect of rhythmic auditory cueing on gait in cerebral palsy: a systematic review and meta-analysis

Auditory entrainment can influence gait performance in movement disorders. The entrainment can incite neurophysiological and musculoskeletal changes to enhance motor execution. However, a consensus as to its effects based on gait in people with cerebral palsy is still warranted. A systematic review and meta-analysis were carried out to analyze the effects of rhythmic auditory cueing on spatiotemporal and kinematic parameters of gait in people with cerebral palsy. Systematic identification of published literature was performed adhering to Preferred Reporting Items for Systematic Reviews and Meta-Analyses and American Academy for Cerebral Palsy and Developmental Medicine guidelines, from inception until July 2017, on online databases: Web of Science, PEDro, EBSCO, Medline, Cochrane, Embase and ProQuest. Kinematic and spatiotemporal gait parameters were evaluated in a meta-analysis across studies. Of 547 records, nine studies involving 227 participants (108 children/119 adults) met our inclusion criteria. The qualitative review suggested beneficial effects of rhythmic auditory cueing on gait performance among all included studies. The meta-analysis revealed beneficial effects of rhythmic auditory cueing on gait dynamic index (Hedge's g=0.9), gait velocity (1.1), cadence (0.3), and stride length (0.5). This review for the first time suggests a converging evidence toward application of rhythmic auditory cueing to enhance gait performance and stability in people with cerebral palsy. This article details underlying neurophysiological mechanisms and use of cueing as an efficient home-based intervention. It bridges gaps in the literature, and suggests translational approaches on how rhythmic auditory cueing can be incorporated in rehabilitation approaches to enhance gait performance in people with cerebral palsy.

Comparison of three physical therapy interventions with an emphasis on the gait of individuals with Parkinson’s disease

Abstract Introduction: Gait impairments are one of the earliest signs reported by patients with Parkinson’s disease (PD) and cause an increased number of falls and decreased quality of life among these patients. Objective: To compare the effectiveness of three physical therapy interventions using Rhythmic Cues (RC), Swiss Ball (SB) and Dual Task (DT), with an emphasis on gait treatment (step and stride length, duration and velocity), in individuals with PD. Methods: Quasi-randomized clinical trial addressing a sample composed of 45 individuals assigned to three groups. The individuals were assessed before and after the intervention protocol using the following: Modified Hoehn and Yahr Scale (HY), Unified Parkinson’s Disease Rating Scale (UPDRS), Footprint analysis, Video Gait analysis, and Timed Up and Go Test (TUG). The groups were homogeneous concerning age, HY and UPDRS. Statistical analysis was performed using SPSS, version 20.0. Results: Statistically significant differences were found in all the variables analyzed in the RC and SB groups when compared in the pre- and post-intervention. With the exception of the TUG variable, the DT group presented statistically significant differences in all the remaining variables. Conclusion: The three interventions were effective for the outcomes under study, but the SB group presented the greatest magnitude of change (effect size), while the RC group presented the greatest improvement in the temporal gait variables (duration and velocity) and TUG.

Prolonged Walking with a Wearable System Providing Intelligent Auditory Input in People with Parkinson's Disease

Rhythmic auditory cueing is a well-accepted tool for gait rehabilitation in Parkinson's disease (PD), which can now be applied in a performance-adapted fashion due to technological advance. This study investigated the immediate differences on gait during a prolonged, 30 min, walk with performance-adapted (intelligent) auditory cueing and verbal feedback provided by a wearable sensor-based system as alternatives for traditional cueing. Additionally, potential effects on self-perceived fatigue were assessed. Twenty-eight people with PD and 13 age-matched healthy elderly (HE) performed four 30 min walks with a wearable cue and feedback system. In randomized order, participants received: (1) continuous auditory cueing; (2) intelligent cueing (10 metronome beats triggered by a deviating walking rhythm); (3) intelligent feedback (verbal instructions triggered by a deviating walking rhythm); and (4) no external input. Fatigue was self-scored at rest and after walking during each session. The results showed that while HE were able to maintain cadence for 30 min during all conditions, cadence in PD significantly declined without input. With continuous cueing and intelligent feedback people with PD were able to maintain cadence (p = 0.04), although they were more physically fatigued than HE. Furthermore, cadence deviated significantly more in people with PD than in HE without input and particularly with intelligent feedback (both: p = 0.04). In PD, continuous and intelligent cueing induced significantly less deviations of cadence (p = 0.006). Altogether, this suggests that intelligent cueing is a suitable alternative for the continuous mode during prolonged walking in PD, as it induced similar effects on gait without generating levels of fatigue beyond that of HE.

Effects of Physical Rehabilitation Integrated with Rhythmic Auditory Stimulation on Spatio-Temporal and Kinematic Parameters of Gait in Parkinson's Disease

Movement rehabilitation by means of physical therapy represents an essential tool in the management of gait disturbances induced by Parkinson’s disease (PD). In this context, the use of rhythmic auditory stimulation (RAS) has been proven useful in improving several spatio-temporal parameters, but concerning its effect on gait patterns, scarce information is available from a kinematic viewpoint. In this study, we used three-dimensional gait analysis based on optoelectronic stereophotogrammetry to investigate the effects of 5 weeks of supervised rehabilitation, which included gait training integrated with RAS on 26 individuals affected by PD (age 70.4 ± 11.1, Hoehn and Yahr 1–3). Gait kinematics was assessed before and at the end of the rehabilitation period and after a 3-month follow-up, using concise measures (Gait Profile Score and Gait Variable Score, GPS and GVS, respectively), which are able to describe the deviation from a physiologic gait pattern. The results confirm the effectiveness of gait training assisted by RAS in increasing speed and stride length, in regularizing cadence and correctly reweighting swing/stance phase duration. Moreover, an overall improvement of gait quality was observed, as demonstrated by the significant reduction of the GPS value, which was created mainly through significant decreases in the GVS score associated with the hip flexion–extension movement. Future research should focus on investigating kinematic details to better understand the mechanisms underlying gait disturbances in people with PD and the effects of RAS, with the aim of finding new or improving current rehabilitative treatments.

Movement Sonification: Effects on Motor Learning beyond Rhythmic Adjustments

Motor learning is based on motor perception and emergent perceptual-motor representations. A lot of behavioral research is related to single perceptual modalities but during last two decades the contribution of multimodal perception on motor behavior was discovered more and more. A growing number of studies indicates an enhanced impact of multimodal stimuli on motor perception, motor control and motor learning in terms of better precision and higher reliability of the related actions. Behavioral research is supported by neurophysiological data, revealing that multisensory integration supports motor control and learning. But the overwhelming part of both research lines is dedicated to basic research. Besides research in the domains of music, dance and motor rehabilitation, there is almost no evidence for enhanced effectiveness of multisensory information on learning of gross motor skills. To reduce this gap, movement sonification is used here in applied research on motor learning in sports. Based on the current knowledge on the multimodal organization of the perceptual system, we generate additional real-time movement information being suitable for integration with perceptual feedback streams of visual and proprioceptive modality. With ongoing training, synchronously processed auditory information should be initially integrated into the emerging internal models, enhancing the efficacy of motor learning. This is achieved by a direct mapping of kinematic and dynamic motion parameters to electronic sounds, resulting in continuous auditory and convergent audiovisual or audio-proprioceptive stimulus arrays. In sharp contrast to other approaches using acoustic information as error-feedback in motor learning settings, we try to generate additional movement information suitable for acceleration and enhancement of adequate sensorimotor representations and processible below the level of consciousness. In the experimental setting, participants were asked to learn a closed motor skill (technique acquisition of indoor rowing). One group was treated with visual information and two groups with audiovisual information (sonification vs. natural sounds). For all three groups learning became evident and remained stable. Participants treated with additional movement sonification showed better performance compared to both other groups. Results indicate that movement sonification enhances motor learning of a complex gross motor skill-even exceeding usually expected acoustic rhythmic effects on motor learning.

Seeing Circles and Drawing Ellipses: When Sound Biases Reproduction of Visual Motion

The perception and production of biological movements is characterized by the 1/3 power law, a relation linking the curvature and the velocity of an intended action. In particular, motions are perceived and reproduced distorted when their kinematics deviate from this biological law. Whereas most studies dealing with this perceptual-motor relation focused on visual or kinaesthetic modalities in a unimodal context, in this paper we show that auditory dynamics strikingly biases visuomotor processes. Biologically consistent or inconsistent circular visual motions were used in combination with circular or elliptical auditory motions. Auditory motions were synthesized friction sounds mimicking those produced by the friction of the pen on a paper when someone is drawing. Sounds were presented diotically and the auditory motion velocity was evoked through the friction sound timbre variations without any spatial cues. Remarkably, when subjects were asked to reproduce circular visual motion while listening to sounds that evoked elliptical kinematics without seeing their hand, they drew elliptical shapes. Moreover, distortion induced by inconsistent elliptical kinematics in both visual and auditory modalities added up linearly. These results bring to light the substantial role of auditory dynamics in the visuo-motor coupling in a multisensory context.

Parkinson's Is Time on Your Side? Evidence for Difficulties with Sensorimotor Synchronization

There is lack of consistent evidence as to how well PD patients are able to accurately time their movements across space with an external acoustic signal. For years, research based on the finger-tapping paradigm, the most popular paradigm for exploring the brain's ability to time movement, has provided strong evidence that patients are not able to accurately reproduce an isochronous interval [i.e., Ref. (1)]. This was undermined by Spencer and Ivry (2) who suggested a specific deficit in temporal control linked to emergent, rhythmical movement not event-based actions, which primarily involve the cerebellum. In this study, we investigated motor timing of seven idiopathic PD participants in event-based sensorimotor synchronization task. Participants were asked to move their finger horizontally between two predefined target zones to synchronize with the occurrence of two sound events at two time intervals (1.5 and 2.5 s). The width of the targets and the distance between them were manipulated to investigate impact of accuracy demands and movement amplitude on timing performance. The results showed that participants with PD demonstrated specific difficulties when trying to accurately synchronize their movements to a beat. The extent to which their ability to synchronize movement was compromised was found to be related to the severity of PD, but independent of the spatial constraints of the task.

Validation of a Footwear-Based Gait Analysis System With Action-Related Feedback

Quantitative gait analysis enables clinicians to evaluate patient mobility and to diagnose neuromuscular disorders. The clinical application of gait analysis is currently limited by the high operating costs of gait laboratories. The use of instrumented footwear that performs out of the lab measurements on subjects' walking patterns is a promising way to overcome this limitation. Besides serving as assessment tools, such devices can also act as retraining tools that help regulate a patient's gait with acoustic or vibrotactile stimuli.

(Dis-)Harmony in movement: effects of musical dissonance on movement timing and form

While the origins of consonance and dissonance in terms of acoustics, psychoacoustics and physiology have been debated for centuries, their plausible effects on movement synchronization have largely been ignored. The present study aimed to address this by investigating whether, and if so how, consonant/dissonant pitch intervals affect the spatiotemporal properties of regular reciprocal aiming movements. We compared movements synchronized either to consonant or to dissonant sounds and showed that they were differentially influenced by the degree of consonance of the sound presented. Interestingly, the difference was present after the sound stimulus was removed. In this case, the performance measured after consonant sound exposure was found to be more stable and accurate, with a higher percentage of information/movement coupling (tau coupling) and a higher degree of movement circularity when compared to performance measured after the exposure to dissonant sounds. We infer that the neural resonance representing consonant tones leads to finer perception/action coupling which in turn may help explain the prevailing preference for these types of tones.

Putting reins on the brain. How the body and environment use it

Radical embodied cognitive neuroscience (RECN) will probably rely on dynamical systems theory (DST) and complex systems theory for methods and formalism. Yet, there have been plenty of non-radical neurodynamicists out there for quite some time. How much of their work fits with radical embodied cognitive science, what do they need RECN for, and what are the inconsistencies between RECN and established neurodynamics that would have to be resolved? This paper is both theoretical hypothesis and review. First, it provides a brief overview of the typical, purely structural considerations why the central nervous systems (CNS) should be treated as a nonlinear dynamical system and what this entails. The reader will learn about the circular causality enclosing brain and behavior and different attempts to formalize this circularity. Then, three different attempts at linking dynamics and theory of brain function are described in more detail and criticized. A fourth method based on ecological psychology could fix some of the issues that the others encounter. It is argued that studying self-organization of the brain without taking its ecological embedding into account is insufficient. Finally, based on existing theoretical work we propose two roles that the CNS has to be fulfilling in order to allow an animal to behave adequately in its niche. In its first role the CNS has to be enslaved easily by patterns of behavior that guide the animal through its environment. In the second role the brain has to flexibly switch among patterns, what can be called the metastable circuit breaker. The relevance of this idea is supported using certain motor symptoms of Parkinson's disease (PD). These symptoms can be explained as consequent to an excessive stability of the (metastable) circuit breaker.

Detection of freezing of gait in Parkinson disease: preliminary results

Freezing of gait (FOG) is a common symptom in Parkinsonism, which affects the gait pattern and is associated to a fall risk. Automatized FOG episode detection would allow systematic assessment of patient state and objective evaluation of the clinical effects of treatments. Techniques have been proposed in the literature to identify FOG episodes based on the frequency properties of inertial sensor signals. Our objective here is to adapt and extend these FOG detectors in order to include other associated gait pattern changes, like festination. The proposed approach is based on a single wireless inertial sensor placed on the patient's lower limbs. The preliminary experimental results show that existing frequency-based freezing detectors are not sufficient to detect all FOG and festination episodes and that the observation of some gait parameters such as stride length and cadence are valuable inputs to anticipate the occurrence of upcoming FOG events.