Learning and retention of movement sequences in Parkinson's disease

The effects of auditory cues and weighted pens on handwriting in individuals with Parkinson's disease

BACKGROUND

Micrographia, or small handwriting, is a common symptom of Parkinson's disease (PD). Weighted pens have previously been recommended to improve handwriting, but there is limited research supporting their effectiveness. Additionally, previous research has demonstrated that music as an auditory cue can reduce variability in fine motor movements, but its effect on handwriting in people with PD remains unknown.

PURPOSE

This study explored potential handwriting interventions for people with PD by evaluating the effectiveness of weighted pens and auditory cues on handwriting.

STUDY DESIGN

This was a pilot cohort study.

METHODS

Eight older adults with PD used a standard pen and a weighted pen to write continuous cursive "l"s on 1.5-cm-lined paper for a total of 10 seconds while listening to auditory cues in 4 conditions: control (silence), metronome, activating music, and relaxing music. Kinematic data were measured with sensors attached to the tip of each pen, and muscle activity was measured with electromyography sensors adhered to the extensor digitorum communis and first dorsal interosseous.

RESULTS

When writing with the standard pen, peak-to-peak time was reduced in the metronome (control = 0.807 ± 0.121 seconds, metronome = 0.701 ± 0.100 seconds, p = 0.024) and activating (control = 0.807 ± 0.121 seconds, activating = 0.691 ± 0.113 seconds, p = 0.009) conditions compared to the control condition. Furthermore, the weighted pen increased the variability of distance between letter peaks (standard = 0.187 ± 0.010, weighted = 0.482 ± 0.065, p = 0.033) and the variability of time needed to complete each letter (standard = 0.176 ± 0.010, weighted = 0.187 ± 0.016, p = 0.042) compared to the standard pen. Finally, area under the curve of the extensor digitorum communis was reduced in the metronome (metronome = 66.03 ± 25.74 mV, control = 88.98 ± 30.40 mV, p = 0.034) and activating music (activating = 66.49 ± 26.02 mV, control = 88.98 ± 30.40 mV, p = 0.012) conditions compared to control when writing with the standard pen.

CONCLUSIONS

These results suggest that weighted pens may not improve handwriting in novice users, but auditory cues appear beneficial. This can inform future directions in the research and clinical application of handwriting interventions for persons with PD.

Motor Memory Consolidation Deficits in Parkinson's Disease: A Systematic Review with Meta-Analysis

BACKGROUND

The ability to encode and consolidate motor memories is essential for persons with Parkinson's disease (PD), who usually experience a progressive loss of motor function. Deficits in memory encoding, usually expressed as poorer rates of skill improvement during motor practice, have been reported in these patients. Whether motor memory consolidation (i.e., motor skill retention) is also impaired is unknown.

OBJECTIVE

To determine whether motor memory consolidation is impaired in PD compared to neurologically intact individuals.

METHODS

We conducted a pre-registered systematic review (PROSPERO: CRD42020222433) following PRISMA guidelines that included 46 studies.

RESULTS

Meta-analyses revealed that persons with PD have deficits in retaining motor skills (SMD = -0.17; 95% CI = -0.32, -0.02; p = 0.0225). However, these deficits are task-specific, affecting sensory motor (SMD = -0.31; 95% CI -0.47, -0.15; p = 0.0002) and visuomotor adaptation (SMD = -1.55; 95% CI = -2.32, -0.79; p = 0.0001) tasks, but not sequential fine motor (SMD = 0.17; 95% CI = -0.05, 0.39; p = 0.1292) and gross motor tasks (SMD = 0.04; 95% CI = -0.25, 0.33; p = 0.7771). Importantly, deficits became non-significant when augmented feedback during practice was provided, and additional motor practice sessions reduced deficits in sensory motor tasks. Meta-regression analyses confirmed that deficits were independent of performance during encoding, as well as disease duration and severity.

CONCLUSION

Our results align with the neurodegenerative models of PD progression and motor learning frameworks and emphasize the importance of developing targeted interventions to enhance motor memory consolidation in PD.

What Can Altered Auditory Feedback Paradigms Tell Us About Vocal Motor Control in Individuals With Voice Disorders?

Purpose

The goal of this review article is to provide a summary of the progression of altered auditory feedback (AAF) as a method to understand the pathophysiology of voice disorders. This review article focuses on populations with voice disorders that have thus far been studied using AAF, including individuals with Parkinson's disease, cerebellar degeneration, hyperfunctional voice disorders, vocal fold paralysis, and laryngeal dystonia. Studies using AAF have found that individuals with Parkinson's disease, cerebellar degeneration, and laryngeal dystonia have hyperactive auditory feedback responses due to differing underlying causes. In persons with PD, the hyperactivity may be a compensatory mechanism for atypically weak feedforward motor control. In individuals with cerebellar degeneration and laryngeal dystonia, the reasons for hyperactivity remain unknown. Individuals with hyperfunctional voice disorders may have auditory-motor integration deficits, suggesting atypical updating of feedforward motor control.

Conclusions

These findings have the potential to provide critical insights to clinicians in selecting the most effective therapy techniques for individuals with voice disorders. Future collaboration between clinicians and researchers with the shared objective of improving AAF as an ecologically feasible and valid tool for clinical assessment may provide more personalized therapy targets for individuals with voice disorders.

Parkinson's disease: Alterations of motor plasticity and motor learning

This chapter reviews the alterations in motor learning and motor cortical plasticity in Parkinson's disease (PD), the most common movement disorder. Impairments in motor learning, which is a hallmark of basal ganglia disorders, influence the performance of motor learning-related behavioral tasks and have clinical implications for the management of disturbance in gait and posture, and for rehabilitative management of PD. Although plasticity is classically induced and assessed in sliced preparation in animal models, in this review we have concentrated on the results from non-invasive brain stimulation techniques such as transcranial magnetic stimulation (TMS), transcranial alternating current stimulation (tACS) and transcranial direct current stimulation (tDCS) in patients with PD, in addition to a few animal electrophysiologic studies. The chapter summarizes the results from different cortical and subcortical plasticity investigations. Plasticity induction protocols reveal deficient plasticity in PD and these plasticity measures are modulated by medications and deep brain stimulation. There is considerable variability in these measures that are related to inter-individual variations, different disease characteristics and methodological considerations. Nevertheless, these pathophysiologic studies expand our knowledge of cortical excitability, plasticity and the effects of different treatments in PD. These tools of modulating plasticity and motor learning improve our understanding of PD pathophysiology and help to develop new treatments for this disabling condition.

Feasibility and longitudinal effects of repeated participation in an annual, brief and intense exercise program in individuals with Parkinson's disease: A case report

BACKGROUND

Functional decline is expected over time in persons with Parkinson's disease (PD). Intense exercise (RPE ≥ 5-7/10), incorporating motor learning principles, may be beneficial. Purpose:The purpose of this case report is to describe the feasibility and longitudinal effects after individuals with PD participated in multiple, 3.5-day, intensive exercise programs called Movement Camp (Camp).

METHODS

Developed based on the principles of skill, capacity, and motivation, the Camp was offered four times (spring 2014-spring 2017) over the course of three years. Camp consisted of 3.5 days, with approximately 5.5 hours of exercise per day. The four participants on whom we are reporting were selected because they participated in three or more Camps, thus providing longitudinal data. Participants rotated through high-intensity, one-hour exercise stations targeting balance, endurance, gait, upper extremity function and three 30-minute group training sessions. Balance (Mini-BESTest), endurance (six-minute walk test), gait speed, and function (five times sit-to-stand) were examined.

RESULTS

Testing was completed prior to, post, and six weeks post intervention. Over three years, participants maintained or improved performance on most measures.

CONCLUSION

The outcomes of this case report suggest that brief, intensive exercise based on motor learning principles is feasible and may maintain or improve function in persons with PD over three years.

tDCS-Enhanced Consolidation of Writing Skills and Its Associations With Cortical Excitability in Parkinson Disease: A Pilot Study

Background. Learning processes of writing skills involve the re-engagement of previously established motor programs affected by Parkinson disease (PD). To counteract the known problems with consolidation in PD, transcranial direct current stimulation (tDCS) could be imperative to achieve a lasting regeneration of habitual motor skills. Objective. To examine tDCS-enhanced learning of writing and explore alterations in cortical excitability after stimulation in PD compared with healthy controls (HCs). Methods. Ten patients and 10 HCs received 2 training sessions combined with 20 minutes of 1-mA anodal tDCS or sham on the left primary motor cortex in a randomized crossover design. Writing skills on a tablet and paper were assessed at baseline, after training, and after 1 week of follow-up. Before and immediately after the intervention, cortical excitability and inhibition were measured during rest and activity. Results. Writing amplitude and velocity improved when practice was tDCS supplemented compared with sham in PD. Benefits were sustained at retention for trained and untrained tasks on the tablet as well as for writing on paper. No improvements were found for HCs. Reduced resting motor thresholds after tDCS indicated tDCS-enhanced cortical excitability. Additionally, increments in motor-evoked potential amplitudes correlated with improved writing in PD, whereas HCs showed the opposite pattern. Conclusion. Our results endorse the usefulness of tDCS-boosted learning in PD, at least when applied to improving writing capacity. Although further confirmatory studies are needed, these novel findings are striking because tDCS-mediated consolidation was found for learning a motor task directly affected by PD.

Repetitive Finger Movement and Dexterity Tasks in People With Parkinson’s Disease

BACKGROUND. Little is known regarding how repetitive finger movement performance, an assessment of bradykinesia (slowness of movement), is related to fine-motor dexterity tasks in people with Parkinson’s disease (PD).

OBJECTIVE. This pilot study examined the relationship between the performance of fine-motor dexterity tasks and repetitive finger movement in people with PD.

METHOD. Forty-six participants with PD completed an acoustically cued repetitive finger movement task (1–3 Hz). Movement amplitude, movement rate difference, and coefficient of variation were obtained for each tone rate. Participants also completed a buttoning and Purdue pegboard assembly task. Buttoning time and number of assemblies were recorded.

RESULTS. A significant association was found between movement rate difference and movement rate difference coefficient of variation and buttoning performance in which higher movement rate and higher variability were associated with slower buttoning times. No significant associations between any of the repetitive finger movement outcome measures and Purdue pegboard assembly performance were revealed.

CONCLUSION. Changes in movement amplitude and movement rate may influence fine-motor dexterity tasks differently. Thus, it is important to consider the quantitative assessment of both movement rate and movement amplitude because they may indicate differential clinical applications in the treatment of people with PD.

Motor Learning Deficits in Parkinson's Disease (PD) and Their Effect on Training Response in Gait and Balance: A Narrative Review

Parkinson's disease (PD) is a neurological disorder traditionally associated with degeneration of the dopaminergic neurons within the substantia nigra, which results in bradykinesia, rigidity, tremor, and postural instability and gait disability (PIGD). The disorder has also been implicated in degradation of motor learning. While individuals with PD are able to learn, certain aspects of learning, especially automatic responses to feedback, are faulty, resulting in a reliance on feedforward systems of movement learning and control. Because of this, patients with PD may require more training to achieve and retain motor learning and may require additional sensory information or motor guidance in order to facilitate this learning. Furthermore, they may be unable to maintain these gains in environments and situations in which conscious effort is divided (such as dual-tasking). These shortcomings in motor learning could play a large part in degenerative gait and balance symptoms often seen in the disease, as patients are unable to adapt to gradual sensory and motor degradation. Research has shown that physical and exercise therapy can help patients with PD to adapt new feedforward strategies to partially counteract these symptoms. In particular, balance, treadmill, resistance, and repeated perturbation training therapies have been shown to improve motor patterns in PD. However, much research is still needed to determine which of these therapies best alleviates which symptoms of PIGD, the needed dose and intensity of these therapies, and long-term retention effects. The benefits of such technologies as augmented feedback, motorized perturbations, virtual reality, and weight-bearing assistance are also of interest. This narrative review will evaluate the effect of PD on motor learning and the effect of motor learning deficits on response to physical therapy and training programs, focusing specifically on features related to PIGD. Potential methods to strengthen therapeutic effects will be discussed.

A randomized controlled study of whether setting specific goals improves the effectiveness of therapy in people with Parkinson's disease

OBJECTIVE:

To evaluate the effects of an intervention based on a specific set of goals on goal attainment, manual dexterity, hand grip strength and finger prehension force compared to a standardized approach in patients with Parkinson's disease.

DESIGN:

Randomized controlled trial.

SETTING:

Home-based.

PARTICIPANTS:

Fifty patients with a clinical diagnosis of Parkinson's disease acknowledging impaired manual ability were randomized into two groups.

INTERVENTIONS:

Patients in the experimental group ( n = 25) were included in an intervention focused on task components that involved goals proposed by participants. Patients in the control group ( n = 25) received a standard intervention focused on impairments in range of motion, grasp and manipulation. Home condition and duration (four weeks, twice a week) were similar in both groups.

MAIN OUTCOME MEASURES:

The primary outcome measure was goal achievement assessed with the Goal Attainment Scaling. Secondary outcomes were manual dexterity evaluated with the Purdue Pegboard Test and hand grip strength and finger prehension force assessed using a dynamometer.

RESULTS:

After four weeks, significant between-group improvement in goal attainment was observed in the experimental group (change 17.36 ± 7.48 vs. 4.03 ± 6.43, P < 0.001). Compared to the control group, the experimental group also showed a significant improvement ( P < 0.05) in manual dexterity (postintervention values in the most affected arm 10.55 ± 1.95 vs. 7.33 ± 3.63 pins, P < 0.001) and finger prehension force (postintervention values in the most affected arm 8.03 ± 1.93 vs. 6.31 ± 1.85 kg, P = 0.010).

CONCLUSIONS:

Targeting therapy toward specific goals leads to greater changes in arm function than a standardized approach in people with Parkinson's disease.

Reduced striatal dopamine release during motor skill acquisition in Parkinson's disease

Background

Striatal dopamine is functionally important for the acquisition of motor skills. However, it remains controversial as to whether intrinsic processing of motor learning is impaired in patients with Parkinson’s disease (PD), and if yes, whether the impairment is associated with altered striatal dopamine release. Additionally, most neuro-imaging studies of patients with PD have focused on motor sequence learning. In contrast, skill acquisition, specifically, the reconstruction of muscle control of isolated movements, has barely been studied.

Method

In this study, we used a repetitive skill training task to measure the peak acceleration of left thumb movement during a process to achieve fine tuning of motor skill. Using ¹¹C-raclopride (RAC) positron emission tomography, we investigated changes in striatal dopamine levels in two conditions of a skill acquisition task: initial skill training (Day 1) and acquired condition (Day 2) with eight patients with PD and age-matched healthy subjects (HS).

Result

In HS, the mean acceleration of each session improved through repeated training sessions on Day 1. However, in patients with PD, the training-associated increase was less than that for HS, and this suggests that repetitive skill training does not result in the effective improvement of motor performance. The regions of interest (ROI) analysis revealed that the RAC-binding potential (BP) was significantly reduced in the right putamen on Day 1 compared with Day 2 in HS. In patients with PD, BP within the right putamen was unchanged. Further, we found that patients with PD had increased dopamine levels within the right ventral striatum (VST) and right caudate (CAU) on Day 2, which was greater than that in HS. These results suggest the impaired activation of the putamen during skill acquisition in patients with PD and compensated hyperactivation of the VST and CAU for the reduced dopamine release within the dorsal putamen (DPU).

Conclusion

Our findings suggest that patients with PD had insufficiency in the process to improve motor skills. Different patterns of striatal dopamine release are relevant to the impairment of these motor functions in patients with PD, at the early stage of the disease.

Learning "How to Learn": Super Declarative Motor Learning Is Impaired in Parkinson's Disease

Learning new information is crucial in daily activities and occurs continuously during a subject's lifetime. Retention of learned material is required for later recall and reuse, although learning capacity is limited and interference between consecutively learned information may occur. Learning processes are impaired in Parkinson's disease (PD); however, little is known about the processes related to retention and interference. The aim of this study is to investigate the retention and anterograde interference using a declarative sequence learning task in drug-naive patients in the disease's early stages. Eleven patients with PD and eleven age-matched controls learned a visuomotor sequence, SEQ1, during Day1; the following day, retention of SEQ1 was assessed and, immediately after, a new sequence of comparable complexity, SEQ2, was learned. The comparison of the learning rates of SEQ1 on Day1 and SEQ2 on Day2 assessed the anterograde interference of SEQ1 on SEQ2. We found that SEQ1 performance improved in both patients and controls on Day2. Surprisingly, controls learned SEQ2 better than SEQ1, suggesting the absence of anterograde interference and the occurrence of learning optimization, a process that we defined as “learning how to learn.” Patients with PD lacked such improvement, suggesting defective performance optimization processes.

The many facets of motor learning and their relevance for Parkinson's disease

The final goal of motor learning, a complex process that includes both implicit and explicit (or declarative) components, is the optimization and automatization of motor skills. Motor learning involves different neural networks and neurotransmitters systems depending on the type of task and on the stage of learning. After the first phase of acquisition, a motor skill goes through consolidation (i.e., becoming resistant to interference) and retention, processes in which sleep and long-term potentiation seem to play important roles. The studies of motor learning in Parkinson's disease have yielded controversial results that likely stem from the use of different experimental paradigms. When a task's characteristics, instructions, context, learning phase and type of measures are taken into consideration, it is apparent that, in general, only learning that relies on attentional resources and cognitive strategies is affected by PD, in agreement with the finding of a fronto-striatal deficit in this disease. Levodopa administration does not seem to reverse the learning deficits in PD, while deep brain stimulation of either globus pallidus or subthalamic nucleus appears to be beneficial. Finally and most importantly, patients with PD often show a decrease in retention of newly learned skill, a problem that is present even in the early stages of the disease. A thorough dissection and understanding of the processes involved in motor learning is warranted to provide solid bases for effective medical, surgical and rehabilitative approaches in PD.

Relearning of Writing Skills in Parkinson's Disease After Intensive Amplitude Training

BACKGROUND

Micrographia occurs in approximately 60% of people with Parkinson's disease (PD). Although handwriting is an important task in daily life, it is not clear whether relearning and consolidation (ie the solid storage in motor memory) of this skill is possible in PD. The objective was to conduct for the first time a controlled study into the effects of intensive motor learning to improve micrographia in PD.

METHODS

In this placebo-controlled study, 38 right-handed people with PD were randomized into 2 groups, receiving 1 of 2 equally time-intensive training programs (30 min/day, 5 days/week for 6 weeks). The experimental group (n = 18) performed amplitude training focused at improving writing size. The placebo group (n = 20) received stretch and relaxation exercises. Participants' writing skills were assessed using a touch-sensitive writing tablet and a pen-and-paper test, pre- and posttraining, and after a 6-week retention period. The primary outcome was change in amplitude during several tests of consolidation: (1) transfer, using trained and untrained sequences performed with and without target zones; and (2) automatization, using single- and dual-task sequences.

RESULTS

The group receiving amplitude training significantly improved in amplitude and variability of amplitude on the transfer and automatization task. Effect sizes varied between 7% and 17%, and these benefits were maintained after the 6-week retention period. Moreover, there was transfer to daily life writing.

CONCLUSIONS

These results show automatization, transfer, and retention of increased writing size (diminished micrographia) after intensive amplitude training, indicating that consolidation of motor learning is possible in PD. © 2016 International Parkinson and Movement Disorder Society.

Basal ganglia and cortical networks for sequential ordering and rhythm of complex movements

Voluntary actions require the concurrent engagement and coordinated control of complex temporal (e.g., rhythm) and ordinal motor processes. Using high-resolution functional magnetic resonance imaging (fMRI) and multi-voxel pattern analysis (MVPA), we sought to determine the degree to which these complex motor processes are dissociable in basal ganglia and cortical networks. We employed three different finger-tapping tasks that differed in the demand on the sequential temporal rhythm or sequential ordering of submovements. Our results demonstrate that sequential rhythm and sequential order tasks were partially dissociable based on activation differences. The sequential rhythm task activated a widespread network centered around the supplementary motor area (SMA) and basal-ganglia regions including the dorsomedial putamen and caudate nucleus, while the sequential order task preferentially activated a fronto-parietal network. There was also extensive overlap between sequential rhythm and sequential order tasks, with both tasks commonly activating bilateral premotor, supplementary motor, and superior/inferior parietal cortical regions, as well as regions of the caudate/putamen of the basal ganglia and the ventro-lateral thalamus. Importantly, within the cortical regions that were active for both complex movements, MVPA could accurately classify different patterns of activation for the sequential rhythm and sequential order tasks. In the basal ganglia, however, overlapping activation for the sequential rhythm and sequential order tasks, which was found in classic motor circuits of the putamen and ventro-lateral thalamus, could not be accurately differentiated by MVPA. Overall, our results highlight the convergent architecture of the motor system, where complex motor information that is spatially distributed in the cortex converges into a more compact representation in the basal ganglia.

Retraining function in people with Parkinson's disease using the Microsoft kinect: game design and pilot testing

Background

Computer based gaming systems, such as the Microsoft Kinect (Kinect), can facilitate complex task practice, enhance sensory feedback and action observation in novel, relevant and motivating modes of exercise which can be difficult to achieve with standard physiotherapy for people with Parkinson’s disease (PD). However, there is a current need for safe, feasible and effective exercise games that are appropriate for PD rehabilitation. The aims of this study were to i) develop a computer game to rehabilitate dynamic postural control for people with PD using the Kinect; and ii) pilot test the game’s safety and feasibility in a group of people with PD.

Methods

A rehabilitation game aimed at training dynamic postural control was developed through an iterative process with input from a design workshop of people with PD. The game trains dynamic postural control through multi-directional reaching and stepping tasks, with increasing complexity across 12 levels of difficulty. Nine people with PD pilot tested the game for one session. Participant feedback to identify issues relating to safety and feasibility were collected using semi-structured interviews.

Results

Participants reported that they felt safe whilst playing the game. In addition, there were no adverse events whilst playing. In general, the participants stated that they enjoyed the game and seven of the nine participants said they could imagine themselves using the game at home, especially if they felt it would improve their balance. The Flow State Scale indicated participants were immersed in the gameplay and enjoyed the experience. However, some participants reported that they found it difficult to discriminate between different types and orientations of visual objects in the game and some also had difficulty with the stepping tasks, especially when performed at the same time as the reaching tasks.

Conclusion

Computer-based rehabilitation games using the Kinect are safe and feasible for people with PD although intervention trials are needed to test their safety, feasibility and efficacy in the home.

Effects of dopaminergic therapy on locomotor adaptation and adaptive learning in persons with Parkinson's disease

Persons with Parkinson's disease (PD) are characterized by multifactorial gait deficits, though the factors which influence the abilities of persons with PD to adapt and store new gait patterns are unclear. The purpose of this study was to investigate the effects of dopaminergic therapy on the abilities of persons with PD to adapt and store gait parameters during split-belt treadmill (SBT) walking. Ten participants with idiopathic PD who were being treated with stable doses of orally-administered dopaminergic therapy participated. All participants performed two randomized testing sessions on separate days: once while optimally-medicated (ON meds) and once after 12-h withdrawal from dopaminergic medication (OFF meds). During each session, locomotor adaptation was investigated as the participants walked on a SBT for 10 min while the belts moved at a 2:1 speed ratio. We assessed locomotor adaptive learning by quantifying: (1) aftereffects during de-adaptation (once the belts returned to tied speeds immediately following SBT walking) and (2) savings during re-adaptation (as the participants repeated the same SBT walking task after washout of aftereffects following the initial SBT task). The withholding of dopaminergic medication diminished step length aftereffects significantly during de-adaptation. However, both locomotor adaptation and savings were unaffected by levodopa. These findings suggest that dopaminergic pathways influence aftereffect storage but do not influence locomotor adaptation or savings within a single session of SBT walking. It appears important that persons with PD should be optimally-medicated if walking on the SBT as gait rehabilitation.

Locomotor adaptation and locomotor adaptive learning in Parkinson's disease and normal aging

OBJECTIVE

Locomotor adaptation enables safe, efficient navigation among changing environments. We investigated how healthy young (HYA) and older (HOA) adults and persons with Parkinson's disease (PD) adapt to walking on a split-belt treadmill, retain adapted gait parameters during re-adaptation, and store aftereffects to conventional treadmill walking.

METHODS

Thirteen PD, fifteen HYA, and fifteen HOA walked on a split-belt treadmill for ten minutes with one leg twice as fast as the other. Participants later re-adapted to the same conditions to assess retention of the split-belt gait pattern. After re-adaptation, we assessed aftereffects of this pattern during conventional treadmill walking.

RESULTS

Persons with PD exhibited step length asymmetry throughout many adaptation and adaptive learning conditions. Early adaptation was similar across groups, though HYA and HOA continued to adapt into late adaptation while PD did not. Despite pervasive step length asymmetry among conditions which were symmetric in HYA and HOA, persons with PD demonstrated significant step length aftereffects during conventional treadmill walking after split-belt walking.

CONCLUSIONS

Though they may exhibit a default asymmetry under various walking conditions, persons with PD can adapt and store new walking patterns.

SIGNIFICANCE

Locomotor adaptation therapy may be effective in ameliorating asymmetric gait deficits in persons with PD.

A cane improves postural recovery from an unpracticed slip during walking in people with Parkinson disease

BACKGROUND

Little is known about the effects of use of a cane on balance during perturbed gait or whether people with Parkinson disease (PD) benefit from using a cane.

OBJECTIVES

The purpose of this study was to evaluate the effects of cane use on postural recovery from a slip due to repeated surface perturbations in individuals with PD compared with age- and sex-matched individuals who were healthy.

DESIGN

This was a prospective study with 2 groups of participants.

METHODS

Fourteen individuals with PD (PD group) and 11 individuals without PD (control group) walked across a platform that translated 15 cm rightward at 30 cm/s during the single-limb support phase of the right foot. Data from 15 trials in 2 conditions (ie, with and without an instrumented cane in the right hand) were collected in random order. Outcome measures included lateral displacement of body center of mass (COM) due to the slip and compensatory step width and length after the perturbation.

RESULTS

Cane use improved postural recovery from the first untrained slip, characterized by smaller lateral COM displacement, in the PD group but not in the control group. The beneficial effect of cane use, however, occurred only during the first perturbation, and those individuals in the PD group who demonstrated the largest COM displacement without a cane benefited the most from use of a cane. Both PD and control groups gradually decreased lateral COM displacement across slip exposures, but a slower learning rate was evident in the PD group participants, who required 6, rather than 3, trials for adapting balance recovery.

LIMITATIONS

Future studies are needed to examine the long-term effects of repeated slip training in people with PD.

CONCLUSIONS

Use of a cane improved postural recovery from an unpracticed slip in individuals with PD. Balance in people with PD can be improved by training with repeated exposures to perturbations.

The influence of movement initiation deficits on the quantification of retention in Parkinson's disease

In patients with an impaired motor system, like Parkinson’s disease (PD), deficits in motor learning are expected and results of various studies seem to confirm these expectations. However, most studies in this regard are behaviorally based and quantify learning by performance changes between at least two points in time, e.g., baseline and retention. But, performance in a retention test is also dependent on other factors than learning. Especially in patients, the functional capacity of the control system might be altered unspecific to a certain task and learning episode. The aim of the study is to test whether characteristic temporal deficits exist in PD patients that affect retention performance. We tested the confounding effects of typical PD motor control deficits, here movement initiation deficits, on retention performance in the motor learning process. 12 PD patients and 16 healthy control participants practiced a virtual throwing task over 3 days with 24 h rest between sessions. Retention was tested comparing performance before rest with performance after rest. Movement initiation deficits were quantified by the timing of throwing release that should be affected by impairments in movement initiation. To scrutinize the influence of the initiation deficits on retention performance we gave participants a specific initiation intervention prior to practice on one of the three practice days. We found that only for the PD patients, post-rest performance as well as release timing was better with intervention as compared to without intervention. Their performance could be enhanced through a tuning of release initiation. Thus, we suggest that in PD patients, performance decline after rest that might be easily interpreted as learning deficits could rather result from disease-related deficiencies in motor control.

Motor Skill Learning, Retention, and Control Deficits in Parkinson's Disease

Parkinson's disease, which affects the basal ganglia, is known to lead to various impairments of motor control. Since the basal ganglia have also been shown to be involved in learning processes, motor learning has frequently been investigated in this group of patients. However, results are still inconsistent, mainly due to skill levels and time scales of testing. To bridge across the time scale problem, the present study examined de novo skill learning over a long series of practice sessions that comprised early and late learning stages as well as retention. 19 non-demented, medicated, mild to moderate patients with Parkinson's disease and 19 healthy age and gender matched participants practiced a novel throwing task over five days in a virtual environment where timing of release was a critical element. Six patients and seven control participants came to an additional long-term retention testing after seven to nine months. Changes in task performance were analyzed by a method that differentiates between three components of motor learning prominent in different stages of learning: Tolerance, Noise and Covariation. In addition, kinematic analysis related the influence of skill levels as affected by the specific motor control deficits in Parkinson patients to the process of learning. As a result, patients showed similar learning in early and late stages compared to the control subjects. Differences occurred in short-term retention tests; patients' performance constantly decreased after breaks arising from poorer release timing. However, patients were able to overcome the initial timing problems within the course of each practice session and could further improve their throwing performance. Thus, results demonstrate the intact ability to learn a novel motor skill in non-demented, medicated patients with Parkinson's disease and indicate confounding effects of motor control deficits on retention performance.

Effect of step training and rhythmic auditory stimulation on functional performance in Parkinson patients

BACKGROUND

Rhythmic auditory stimulation (RAS) can influence movement during straight line walking and direction transition in individuals with Parkinson disease (PD).

OBJECTIVE

The authors studied whether multidirectional step training with RAS would generalize to functional gait conditions used in daily activities and balance.

METHODS

In a matched-pairs design, 8 patients practiced externally paced (EP) stepping (RAS group), and 8 patients practiced internally paced (IP) stepping (no RAS group) for 6 weeks. Participants were evaluated on the first and last days of practice, and 1 week, 4 weeks, and 8 weeks after practice termination. Evaluations included a primary measurement--the Dynamic Gait Index (DGI)--and secondary measurements--the Unified Parkinson's Disease Rating Scale (UPDRS), Tinetti-gait and balance tests, Timed-Up-and-Go (TUG), and Freezing of Gait Questionnaire (FOGQ).

RESULTS

The RAS group significantly improved performance on the DGI and several secondary measures, and they maintained improvements for the DGI, Tinetti, FOGQ, and balance and gait items of the UPDRS above pretraining values at least 4 weeks after practice termination. The no RAS group revealed several improvements with training but could not maintain these improvements for as long as the other group.

CONCLUSIONS

Individuals with PD can generalize motor improvements achieved during multidirectional step training to contexts of functional gait and balance. Training with RAS is advantageous for enhancing functional gait improvements and the maintenance of functional gait and balance improvements over 8 weeks.

Basal ganglia-dependent processes in recalling learned visual-motor adaptations

Humans learn and remember motor skills to permit adaptation to a changing environment. During adaptation, the brain develops new sensory-motor relationships that become stored in an internal model (IM) that may be retained for extended periods. How the brain learns new IMs and transforms them into long-term memory remains incompletely understood since prior work has mostly focused on the learning process. A current model suggests that basal ganglia, cerebellum, and their neocortical targets actively participate in forming new IMs but that a cerebellar cortical network would mediate automatization. However, a recent study (Marinelli et al. 2009) reported that patients with Parkinson's disease (PD), who have basal ganglia dysfunction, had similar adaptation rates as controls but demonstrated no savings at recall tests (24 and 48 h). Here, we assessed whether a longer training session, a feature known to increase long-term retention of IM in healthy individuals, could allow PD patients to demonstrate savings. We recruited PD patients and age-matched healthy adults and used a visual-motor adaptation paradigm similar to the study by Marinelli et al. (2009), doubling the number of training trials and assessed recall after a short and a 24-h delay. We hypothesized that a longer training session would allow PD patients to develop an enhanced representation of the IM as demonstrated by savings at the recall tests. Our results showed that PD patients had similar adaptation rates as controls but did not demonstrate savings at both recall tests. We interpret these results as evidence that fronto-striatal networks have involvement in the early to late phase of motor memory formation, but not during initial learning.

Effectiveness of an inpatient multidisciplinary rehabilitation program for people with Parkinson disease

BACKGROUND AND PURPOSE

In the outpatient setting, it can be difficult to effectively manage the complex medical and rehabilitation needs of people with Parkinson disease (PD). A multidisciplinary approach in the inpatient rehabilitation environment may be a viable alternative. The purposes of this study were: (1) to investigate the effectiveness of an inpatient rehabilitation program for people with a primary diagnosis of PD, (2) to determine whether gains made were clinically meaningful, and (3) to identify predictors of rehabilitation outcome.

SUBJECTS

Sixty-eight subjects with a diagnosis of PD were admitted to an inpatient rehabilitation hospital with a multidisciplinary movement disorders program.

METHODS

Subjects participated in a rehabilitation program consisting of a combination of physical therapy, occupational therapy, and speech therapy for a total of 3 hours per day, 5 to 7 days per week, in addition to pharmacological adjustments based on data collected daily. A pretest-posttest design was implemented. The differences between admission and discharge scores on the Functional Independence Measure (FIM) (total, motor, and cognitive scores), Timed "Up & Go" Test, 2-Minute Walk Test, and Finger Tapping Test were analyzed.

RESULTS

An analysis of data obtained for the 68 subjects admitted with a diagnosis of PD revealed significant improvements across all outcome measures from admission to discharge. Subjects with PD whose medications were not adjusted during their admission (rehabilitation only) (n=10) showed significant improvements in FIM total, motor, and cognitive scores. Improvements exceeded the minimal clinically important difference in 71% of the subjects. Prior level of function at admission accounted for 20% of the variance in the FIM total change score.

DISCUSSION AND CONCLUSION

The results suggest that subjects with a diagnosis of PD as a primary condition benefited from an inpatient rehabilitation program designed to improve functional status.

Determining the Optimal Challenge Point for Motor Skill Learning in Adults With Moderately Severe Parkinson's Disease

Objective. To test the predictions of the Challenge Point Framework (CPF) for motor learning in individuals with Parkinson's disease (PD) by manipulating nominal task difficulty and conditions of practice. Methods. Twenty adults with PD and 20 nondisabled controls practiced 3 variations of a laboratory-based goal-directed arm movement over 2 days. A between-group (PD, nondisabled) 2-factor design compared 2 levels of nominal task difficulty (low, high) and 2 levels of practice condition (low, high demand). Learning was assessed with a no-feedback recall test 1 day after practice. Performance was quantified using a root mean square error difference between the goal and participant-generated movement. Results. All participants improved with practice. Under the low-demand practice condition, adults with PD demonstrated comparable learning to that of controls when nominal task difficulty was low but not high. In contrast, under the high-demand practice condition, adults with PD demonstrated preserved motor learning for both levels of task difficulty, but only if recall was tested under the same context as that used during practice. Conclusions. In general, the predictions of CPF were supported. Together, the level of nominal task difficulty and the inherent demand of the practice condition played a critical role in determining the optimal challenge point for motor learning in individuals with PD. More important, and in contrast to the predictions of CPF, a high-demand practice condition appeared to have a facilitative effect on motor learning. However, this benefit revealed the context specificity of motor learning in adults with PD.

Multiple-task walking training in people with mild to moderate Parkinson's disease: a pilot study

Objective: To determine whether multiple-task training of walking is feasible and worthwhile in people with mild to moderate Parkinson's disease.

Design: Baseline-controlled pilot study with three-week baseline, training and retention phases.

Setting: University research laboratory.

Subjects: Five people aged 61 ±8 years with mild to moderate Parkinson's disease (Hoehn and Yahr stages II—III).

Interventions: Multiple-task training was performed for 30 minutes once a week during the three-week training phase.

Main measures: Participants were tested and trained during the `on' phase

of medication. Feasibility of training was examined using 10 cm visual analogue scales to measure participant perception of mental fatigue, physical fatigue, difficulty, anxiety and confidence. Walking velocity, stride length and cadence under multiple-task conditions were measured.

Results: Participants reported low levels of mental fatigue, physical fatigue, difficulty and anxiety as well as high levels of confidence associated with multiple-task training. No adverse effects of training were reported. Multiple-task walking velocity increased by 0.09 ± 0.06 m/s (95% confidence interval (CI) 0.02 to 0.16) between the baseline and training phase and this increase was maintained in the retention phase.

Conclusion: Multiple-task training is feasible in people with mild to moderate Parkinson's disease. The data suggest sustained benefits on multiple-task walking velocity are possible. A randomized controlled trial of multiple-task training efficacy is warranted.