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

The effect of blended learning on tacking technique improvement in preteen sailing

This study investigates the effects of two blended learning strategies on improving tacking technique in Optimist sailing among children aged 11-13. Specifically, it compares video feedback with online written instructions (BLIV) and online written instructions only (BLI). Thirty-one children aged 11-13 years old were randomly divided into three groups with different learning strategies: BLIV, BLI, and a control group (CONT). Each participant completed a pre-test (T0) and a post-test (T1) following a four-session learning unit. Evaluations focused on (i) tacking technique, rated by three sailing coaches, (ii) execution time measured using Kinovea software, and (iii) theoretical knowledge, assessed through a test involving error detection in a novice's video. Statistical analyses revealed that the BLIV group demonstrated significant improvements at T1 in technical performance (p < 0.001, Hedges' g = 2.71), execution time (p = 0.006, Hedges' g = 1.14), and theoretical knowledge (p < 0.001, Hedges' g = 1.98), outperforming the BLI and CONT groups in tacking performance. These findings underscore the effectiveness of the BLIV strategy in enhancing learning outcomes in environments with high levels of sensory distractions. By facilitating a deeper understanding of technique and error correction, this technology-enhanced instructional approach shows promise as a valuable tool for teaching complex motor skills in sports. The research findings suggest that BLIV demonstrates significant improvements in sailing skills, execution time, and theoretical understanding among young sailors compared to other methods. The study advocates for the integration of blended learning approaches that combine in-class activities with delayed video-based feedback delivered online to enhance skill acquisition young sailors.

Motor learning is modulated by dopamine availability in the sensorimotor putamen

Successful motor skill acquisition requires the dynamic interaction of multiple brain regions, with the striatum playing a critical role in this network. Animal studies suggest that dopaminergic mechanisms are involved in the regulation of motor learning-associated striatal plasticity. In humans, however, the contribution of nigrostriatal dopaminergic transmission to motor learning remains elusive beyond its well-characterized role in initiation and fluent execution of movements. In this prospective observational study, we investigated motor sequence learning in individuals who had undergone 123I-N-ω-fluoropropyl-2β-carbomethoxy-3β-(4-iodophenyl)nortropane single-photon emission computed tomography for the differential diagnosis of Parkinson's disease (n = 41) and age-matched healthy controls (n = 20). We found that striatal dopamine transporter depletion exhibited distinct spatial patterns that were associated with impairments in motor sequence learning and the manifestation of Parkinsonian motor symptoms, respectively. Specifically, significant associations between striatal dopamine transporter depletion and impairments in motor sequence learning were confined to posterior putaminal regions, whereas significant associations of striatal dopamine transporter depletion with Parkinsonian motor symptom severity showed a widespread spatial pattern across the entire striatal volume with an anterior maximum. Normative functional connectivity analysis revealed that both behavioural domains shared largely overlapping connectivity patterns with the basal ganglia and supplementary motor area. However, apart from connectivity with more posterior parts of the supplementary motor area, significant functional connectivity with primary motor cortical areas was only present for striatal dopamine transporter availability-related modulation of online motor learning. Our findings indicate that striatal dopaminergic signalling plays a specific role in motor sequence learning beyond its influence on mere motor execution, implicating learning-related sensorimotor striatum recruitment and cortico-striatal plasticity as dopamine-dependent mechanisms.

Changes of upper-limb kinematics during practice of a redundant motor task in patients with Parkinson's disease

The ability to learn novel motor skills is essential for patients with Parkinson's disease (PD) to regain activities of daily living. However, the underlying mechanisms of motor learning in PD remain unclear. To identify motor features that are distinctively manifested in PD during motor learning, we quantified a rich set of variables reflecting various aspects of the learning process in a virtual throwing task. While the performance outcome improved similarly over 3 days of practice for both PD patients and age-matched controls, further analysis revealed distinct learning processes between the two groups. PD patients initially performed with a slow release velocity and gradually increased it as practice progressed, whereas the control group began with an unnecessarily rapid release velocity, which they later stabilized at a lower value. Performance characteristics related to the timing of ball release and the inter-release interval did not show significant group differences, although they were modulated across practice in both groups. After one week, both groups retained the performance outcomes and underlying kinematics developed over practice. This study underscores the importance of analyzing the multi-faceted learning process to characterize motor skill learning in PD. The findings may provide insights into PD pathophysiology and inform rehabilitation strategies.

Slow but flexible or fast but rigid? Discrete and continuous processes compared

A tradeoff exists when dealing with complex tasks composed of multiple steps. High-level cognitive processes can find the best sequence of actions to achieve a goal in uncertain environments, but they are slow and require significant computational demand. In contrast, lower-level processing allows reacting to environmental stimuli rapidly, but with limited capacity to determine optimal actions or to replan when expectations are not met. Through reiteration of the same task, biological organisms find the optimal tradeoff: from action primitives, composite trajectories gradually emerge by creating task-specific neural structures. The two frameworks of active inference - a recent brain paradigm that views action and perception as subject to the same free energy minimization imperative - well capture high-level and low-level processes of human behavior, but how task specialization occurs in these terms is still unclear. In this study, we compare two strategies on a dynamic pick-and-place task: a hybrid (discrete-continuous) model with planning capabilities and a continuous-only model with fixed transitions. Both models rely on a hierarchical (intrinsic and extrinsic) structure, well suited for defining reaching and grasping movements, respectively. Our results show that continuous-only models perform better and with minimal resource expenditure but at the cost of less flexibility. Finally, we propose how discrete actions might lead to continuous attractors and compare the two frameworks with different motor learning phases, laying the foundations for further studies on bio-inspired task adaptation.

Sleep improves accuracy, but not speed, of generalized motor learning in young and older adults and in individuals with Parkinson's disease

An essential aspect of motor learning is generalizing procedural knowledge to facilitate skill acquisition across diverse conditions. Here, we examined the development of generalized motor learning during initial practice-dependent learning, and how distinct components of learning are consolidated over longer timescales during wakefulness or sleep. In the first experiment, a group of young healthy volunteers engaged in a novel motor sequence task over 36 h in a two-arm experimental design (either morning-evening-morning, or evening-morning-evening) aimed at controlling for circadian confounders. The findings unveiled an immediate, rapid generalization of sequential learning, accompanied by an additional long-timescale performance gain. Sleep modulated accuracy, but not speed, above and beyond equivalent wake intervals. To further elucidate the role of sleep across ages and under neurodegenerative disorders, a second experiment utilized the same task in a group of early-stage, drug-naïve individuals with Parkinson's disease and in healthy individuals of comparable age. Participants with Parkinson's disease exhibited comparable performance to their healthy age-matched group with the exception of reduced performance in recalling motor sequences, revealing a disease-related cognitive shortfall. In line with the results found in young subjects, both groups exhibited improved accuracy, but not speed, following a night of sleep. This result emphasizes the role of sleep in skill acquisition and provides a potential framework for deeper investigation of the intricate relationship between sleep, aging, Parkinson's disease, and motor learning.

Reduced inhibitory synaptic transmission onto striatopallidal neurons may underlie aging-related motor skill deficits

Human beings are living longer than ever before and aging is accompanied by an increased incidence of motor deficits, including those associated with the neurodegenerative conditions, Parkinson's disease (PD) and Huntington's disease (HD). However, the biological correlates underlying this epidemiological finding, especially the functional basis at the synapse level, have been elusive. This study reveals that motor skill performance examined via rotarod, beam walking and pole tests is impaired in aged mice. This study, via electrophysiology recordings, further identifies an aging-related reduction in the efficacy of inhibitory synaptic transmission onto dorsolateral striatum (DLS) indirect-pathway medium spiny neurons (iMSNs), i.e., a disinhibition effect on DLS iMSNs. In addition, pharmacologically enhancing the activity of DLS iMSNs by infusing an adenosine A2A receptor (A2AR) agonist, which presumably mimics the disinhibition effect, impairs motor skill performance in young mice, simulating the behavior in aged naïve mice. Conversely, pharmacologically suppressing the activity of DLS iMSNs by infusing an A2AR antagonist, in order to offset the disinhibition effect, restores motor skill performance in aged mice, mimicking the behavior in young naïve mice. In conclusion, this study identifies a functional inhibitory synaptic plasticity in DLS iMSNs that likely contributes to the aging-related motor skill deficits, which would potentially serve as a striatal synaptic basis underlying age being a prominent risk factor for neurodegenerative motor deficits.

Brain and muscles magnetic stimulation in a drug-free case of Parkinson's disease: Motor improvements concomitant to neuroplasticty

Noninvasive stimulation of the nervous system is of growing interest in Parkinson's disease (PD) to slow-down motor decline and decrease medication and its side-effects. Repetitive transcranial magnetic stimulation (rTMS) used in PD to modulate the excitability of the primary motor cortex (M1) provided controversial results, in part because of interactions with medication. This warrants to administer rTMS in drug-free patients. Repetitive peripheral magnetic stimulation (rPMS of muscles) has not yet been tested in PD. Its influence on M1 plasticity (as tested by TMS, transcranial magnetic stimulation) and sensorimotor disorders in other health conditions makes it worth be explored in PD. Thus, rTMS and rPMS were tested in a drug-free woman (52 years old, PD-diagnosed 10 years ago) in four different rTMS + rPMS combinations (one week apart): sham-sham, real-real, real-sham, sham-real. rTMS was applied over M1 contralateral to the most impaired bodyside, and rPMS on muscles of the legs, trunk, and arms, bilaterally. M1 plasticity (TMS measures) and motor symptoms and function (clinical outcomes) were measured at different timepoints. The real-real session induced the largest motor improvements, with possible summation of effects between sessions, and maintenance at follow-up (80 days later). This was paralleled by changes of M1 facilitation and inhibition. This sheds a new light on the link between TMS measures of M1 plasticity and motor changes in PD and informs on the remaining potential for neuroplasticity and functional improvement after 10 years of PD with no antiparkinsonian drug. De novo patients with PD (drug-free) should be motivated to participate in future randomized clinical trials to further test the slow-down or delay of motor decline under noninvasive neurostimulation regimens, whatever the stage of the disease.

In-Patient Multimodal Intensive Neurorehabilitation and Care Improve Motor and Non-Motor Functions in the Moderately Advanced Stages of Parkinson's Disease: A Retrospective Study in a U.S. Facility

(1) Background: Previous studies, mostly performed in European centers, have shown that in-patient multimodal intensive rehabilitation treatments lasting for two to four weeks can improve both motor and non-motor symptoms of Parkinson's disease (PD) with long-lasting effects. Here, we ascertain the effects of a similar in-patient program in a U.S. center with a retrospective study in a cohort of 153 patients in the moderately advanced stage of PD. (2) Methods: We compared indices of motor and non-motor functions before and immediately after such treatment and investigated the possible differences between men and women. We used the available records of the Beck Depression Inventory, PDQ39, PD Sleep Scale, Timed Up and Go, Vocal Volume, Voice Handicap, and total UPDRS scores. (3) Results: We found that at the end of treatment, which lasted an average of 14 days, all outcome measures significantly improved independently of sex. (4) Conclusions: These results confirm the previous findings with a similar in-patient approach in European centers. They further suggest that this in-patient treatment is a care model that is feasible in U.S. centers and can provide a more immediate benefit to the motor function and quality of life of patients with moderately advanced PD.

Influence of Verbal Instruction on Gait Training in Parkinson Disease: A Randomized Controlled Trial

OBJECTIVE

Verbal instruction is one of the most commonly used methods that therapists use to correct walking pattern for people with Parkinson disease. This study aimed to compare the long-term training effects of two different verbal instructions that either asked the participants to "take big steps" or "strike the ground with the heel" on walking ability in individuals with Parkinson disease.

DESIGN

Forty-five participants with Parkinson disease were randomized into the big-step or heel strike group. The participants underwent 12 sessions of treadmill and overground gait training. Throughout the interventions, the big-step group received an instruction to "take big steps," while the heel strike group received an instruction to "strike the ground with your heel." The primary outcome was gait performance, including velocity, stride length, cadence, and heel strike angle. The participants were assessed before, immediately after, and 1 mo after training.

RESULTS

Both groups showed significant improvements in gait performance after training. The heel strike group showed continuous improvements in velocity and stride length during the follow-up period; however, the big-step group showed slightly decreased performance.

CONCLUSIONS

A verbal instruction emphasizing heel strike can facilitate long-term retention of walking performance in people with Parkinson disease.

Wearable biofeedback device to assess gait features and improve gait pattern in people with parkinson's disease: a case series

INTRODUCTION

People with Parkinson's Disease (PD) show abnormal gait patterns compromising their independence and quality of life. Among all gait alterations due to PD, reduced step length, increased cadence, and decreased ground-reaction force during the loading response and push-off phases are the most common. Wearable biofeedback technologies offer the possibility to provide correlated single or multi-modal stimuli associated with specific gait events or gait performance, hence promoting subjects' awareness of their gait disturbances. Moreover, the portability and applicability in clinical and home settings for gait rehabilitation increase the efficiency in the management of PD. The Wearable Vibrotactile Bidirectional Interface (BI) is a biofeedback device designed to extract gait features in real-time and deliver a customized vibrotactile stimulus at the waist of PD subjects synchronously with specific gait phases. The aims of this study were to measure the effect of the BI on gait parameters usually compromised by the typical bradykinetic gait and to assess its usability and safety in clinical practice.

METHODS

In this case series, seven subjects (age: 70.4 ± 8.1 years; H&Y: 2.7 ± 0.3) used the BI and performed a test on a 10-meter walkway (10mWT) and a two-minute walk test (2MWT) as pre-training (Pre-trn) and post-training (Post-trn) assessments. Gait tests were executed in random order with (Bf) and without (No-Bf) the activation of the biofeedback stimulus. All subjects performed three training sessions of 40 min to familiarize themselves with the BI during walking activities. A descriptive analysis of gait parameters (i.e., gait speed, step length, cadence, walking distance, double-support phase) was carried out. The 2-sided Wilcoxon sign-test was used to assess differences between Bf and No-Bf assessments (p < 0.05).

RESULTS

After training subjects improved gait speed (Pre-trn_No-Bf: 0.72(0.59,0.72) m/sec; Post-trn_Bf: 0.95(0.69,0.98) m/sec; p = 0.043) and step length (Pre-trn_No-Bf: 0.87(0.81,0.96) meters; Post-trn_Bf: 1.05(0.96,1.14) meters; p = 0.023) using the biofeedback during the 10mWT. Similarly, subjects' walking distance improved (Pre-trn_No-Bf: 97.5 (80.3,110.8) meters; Post-trn_Bf: 118.5(99.3,129.3) meters; p = 0.028) and the duration of the double-support phase decreased (Pre-trn_No-Bf: 29.7(26.8,31.7) %; Post-trn_Bf: 27.2(24.6,28.7) %; p = 0.018) during the 2MWT. An immediate effect of the BI was detected in cadence (Pre-trn_No-Bf: 108(103.8,116.7) step/min; Pre-trn_Bf: 101.4(96.3,111.4) step/min; p = 0.028) at Pre-trn, and in walking distance at Post-trn (Post-trn_No-Bf: 112.5(97.5,124.5) meters; Post-trn_Bf: 118.5(99.3,129.3) meters; p = 0.043). SUS scores were 77.5 in five subjects and 80.3 in two subjects. In terms of safety, all subjects completed the protocol without any adverse events.

CONCLUSION

The BI seems to be usable and safe for PD users. Temporal gait parameters have been measured during clinical walking tests providing detailed outcomes. A short period of training with the BI suggests improvements in the gait patterns of people with PD. This research serves as preliminary support for future integration of the BI as an instrument for clinical assessment and rehabilitation in people with PD, both in hospital and remote environments.

TRIAL REGISTRATION

The study protocol was registered (DGDMF.VI/P/I.5.i.m.2/2019/1297) and approved by the General Directorate of Medical Devices and Pharmaceutical Service of the Italian Ministry of Health and by the ethics committee of the Lombardy region (Milan, Italy).

Visual feedback improves propulsive force generation during treadmill walking in people with Parkinson disease

Persons with Parkinson's disease experience gait alterations, such as reduced step length. Gait dysfunction is a significant research priority as the current treatments targeting gait impairment are limited. This study aimed to investigate the effects of visual biofeedback on propulsive force during treadmill walking in persons with Parkinson's. Sixteen ambulatory persons with Parkinson's participated in the study. They received real-time biofeedback of anterior ground reaction force during treadmill walking at a constant speed. Peak propulsive force values were measured and normalized to body weight. Spatiotemporal parameters were also assessed, including stride length and double support percent. Persons with Parkinson's significantly increased peak propulsive force during biofeedback compared to baseline (p <.0001, Cohen's dz = 1.69). Variability in peak anterior ground reaction force decreased across repeated trials (p <.0001, dz = 1.51). While spatiotemporal parameters did not show significant changes individually, stride length and double support percent improved marginally during biofeedback trials. Persons with Parkinson's can increase propulsive force with visual biofeedback, suggesting the presence of a propulsive reserve. Though stride length did not significantly change, clinically meaningful improvements were observed. Targeting push-off force through visual biofeedback may offer a potential rehabilitation technique to enhance gait performance in Persons with Parkinson's. Future studies could explore the long-term efficacy of this intervention and investigate additional strategies to improve gait in Parkinson's disease.

High-intensity acute exercise impacts motor learning in healthy older adults

Healthy aging is associated with changes in motor sequence learning, with some studies indicating decline in motor skill learning in older age. Acute cardiorespiratory exercise has emerged as a potential intervention to improve motor learning, however research in healthy older adults is limited. The current study investigated the impact of high-intensity interval exercise (HIIT) on a subsequent sequential motor learning task. Twenty-four older adults (aged 55-75 years) completed either 20-minutes of cycling, or an equivalent period of active rest before practicing a sequential force grip task. Skill learning was assessed during acquisition and at a 6-hour retention test. In contrast to expectation, exercise was associated with reduced accuracy during skill acquisition compared to rest, particularly for the oldest participants. However, improvements in motor skill were retained in the exercise condition, while a reduction in skill was observed following rest. Our findings indicate that high-intensity exercise conducted immediately prior to learning a novel motor skill may have a negative impact on motor performance during learning in older adults. We also demonstrated that exercise may facilitate early offline consolidation of a motor skill within this population, which has implications for motor rehabilitation.

Striatal dopamine neurotransmission is altered in age- and region-specific manner in a Parkinson's disease transgenic mouse

Dopamine (DA) plays a critical role in striatal motor control. The drop in DA level within the dorsal striatum is directly associated with the appearance of motor symptoms in Parkinson's disease (PD). The progression of the disease and inherent disruption of the DA neurotransmission has been closely related to accumulation of the synaptic protein α-synuclein. However, it is still unclear how α-synuclein affects dopaminergic terminals in different areas of dorsal striatum. Here we demonstrate that the overexpression of human α-synuclein (h-α-syn) interferes with the striatal DA neurotransmission in an age-dependent manner, preferentially in the dorsolateral striatum (DLS) of PDGF-h-α-syn mice. While 3-month-old mice showed an increase at the onset of h-α-syn accumulation in the DLS, 12-month-old mice revealed a decrease in electrically-evoked DA release. The enhanced DA release in 3-month-old mice coincided with better performance in a behavioural task. Notably, DA amplitude alterations were also accompanied by a delay in the DA clearance independently from the animal age. Structurally, dopamine transporter (DAT) was found to be redistributed in larger DAT-positive clumps only in the DLS of 3- and 12-month-old mice. Together, our data provide new insight into the vulnerability of DLS and suggest DAT-related dysfunctionalities from the very early stages of h-α-syn accumulation.

Neural correlates of fine motor grasping skills: Longitudinal insights into motor cortex activation using fNIRS

BACKGROUND

Motor learning is essential for performing specific tasks and progresses through distinct stages, including the rapid learning phase (initial skill acquisition), the consolidation phase (skill refinement), and the stable performance phase (skill mastery and maintenance). Understanding the cortical activation dynamics during these stages can guide targeted rehabilitation interventions.

METHODS

In this longitudinal randomized controlled trial, functional near-infrared spectroscopy was used to explore the temporal dynamics of cortical activation in hand-related motor learning. Thirty-one healthy right-handed individuals were randomly assigned to perform either easy or intricate motor tasks with their non-dominant hand over 10 days. We conducted 10 monitoring sessions to track cortical activation in the right hemisphere (according to lateralization principles, the primary hemisphere for motor control) and evaluated motor proficiency concurrently.

RESULTS

The study delineated three stages of nondominant hand motor learning: rapid learning (days 1 and 2), consolidation (days 3-7), and stable performance (days 8-10). There was a power-law enhancement of motor skills correlated with learning progression. Sustained activation was observed in the supplementary motor area (SMA) and parietal lobe (PL), whereas activation in the right primary motor cortex (M1R) and dorsolateral prefrontal cortex (PFCR) decreased. These cortical activation patterns exhibited a high correlation with the augmentation of motor proficiency.

CONCLUSIONS

The findings suggest that early rehabilitation interventions, such as transcranial magnetic stimulation and transcranial direct current stimulation (tDCS), could be optimally directed at M1 and PFC in the initial stages. In contrast, SMA and PL can be targeted throughout the motor learning process. This research illuminates the path for developing tailored motor rehabilitation interventions based on specific stages of motor learning.

NEW AND NOTEWORTHY

In an innovative approach, our study uniquely combines a longitudinal design with the robustness of generalized estimating equations (GEEs). With the synergy of functional near-infrared spectroscopy (fNIRS) and the Minnesota Manual Dexterity Test (MMDT) paradigm, we precisely trace the evolution of neural resources during complex, real-world fine-motor task learning. Centering on right-handed participants using their nondominant hand magnifies the intricacies of right hemisphere spatial motor processing. We unravel the brain's dynamic response throughout motor learning stages and its potent link to motor skill enhancement. Significantly, our data point toward the early-phase rehabilitation potential of TMS and transcranial direct current stimulation on the M1 and PFC regions. Concurrently, SMA and PL appear poised to benefit from ongoing interventions during the entire learning curve. Our findings carve a path for refined motor rehabilitation strategies, underscoring the importance of timely noninvasive brain stimulation treatments.

Specialized Allied Health Care for Parkinson's Disease: State of the Art and Future Directions

People with Parkinson's disease (PD) experience a range of progressive motor and non-motor symptoms, that negatively affect their daily functioning, social participation and quality of life. Allied health therapies have emerged as an effective treatment approach-complementary to pharmacological and neurosurgical treatments-which reduces the impact of PD in daily life. In this article, we propose criteria for what constitutes specialized allied health care for PD, and we review allied health research in PD in terms of meeting these criteria and its outcomes for monodisciplinary approaches as well as multi- or interdisciplinary allied health interventions. We focus on the three most studied allied health disciplines in PD: physical therapy, occupational therapy and speech-language therapy. Overall, the available evidence underscores the importance and potential benefits of specialized allied health care for people with PD. Our proposed criteria and recommendations for future research might help in further delineating specialized allied health care.

Neural correlates of weight-shift training in older adults: a randomized controlled study

Mediolateral weight-shifting is an important aspect of postural control. As it is currently unknown whether a short training session of mediolateral weight-shifting in a virtual reality (VR) environment can improve weight-shifting, we investigated this question and also probed the impact of practice on brain activity. Forty healthy older adults were randomly allocated to a training (EXP, n = 20, age = 70.80 (65-77), 9 females) or a control group (CTR, n = 20, age = 71.65 (65-82), 10 females). The EXP performed a 25-min weight-shift training in a VR-game, whereas the CTR rested for the same period. Weight-shifting speed in both single- (ST) and dual-task (DT) conditions was determined before, directly after, and 24 h after intervention. Functional Near-Infrared Spectroscopy (fNIRS) assessed the oxygenated hemoglobin (HbO2) levels in five cortical regions of interest. Weight-shifting in both ST and DT conditions improved in EXP but not in CTR, and these gains were retained after 24 h. Effects transferred to wider limits of stability post-training in EXP versus CTR. HbO2 levels in the left supplementary motor area were significantly increased directly after training in EXP during ST (change < SEM), and in the left somatosensory cortex during DT (change > SEM). We interpret these changes in the motor coordination and sensorimotor integration areas of the cortex as possibly learning-related.

Action observation and motor imagery improve motor imagery abilities in patients with Parkinson's disease - A functional MRI study

INTRODUCTION

Motor imagery (MI) skills can be affected in Parkinson's disease (PD). We aimed at assessing MI and brain functional changes after action observation and MI training (AOT-MI) associated with gait/balance exercises in PD patients with postural instability and gait disorders (PD-PIGD).

METHODS

Twenty-five PD-PIGD patients were randomized into two groups: DUAL-TASK + AOT-MI group performed 6-week gait/balance training combined with AOT-MI; DUAL-TASK group performed the same exercises without AOT-MI. Before and after training, MI was assessed using Kinesthetic-and-Visual-Imagery Questionnaire (KVIQ) and a MI functional MRI (fMRI) task. During fMRI, subjects were asked to watch first-person perspective videos representing gait/balance tasks and mentally simulate their execution. At baseline patients were compared with 23 healthy controls.

RESULTS

PD groups did not differ in the MI scores. Both patient groups increased kinesthetic KVIQ score after training, while only DUAL-TASK + AOT-MI group improved visual and total KVIQ scores. At baseline, both PD groups showed reduced fMRI activity of sensorimotor, temporal and cerebellar areas relative to controls. After training, DUAL-TASK + AOT-MI patients increased activity of anterior cingulate, fronto-temporal and motor cerebellar areas, and reduced the recruitment of cognitive cerebellar regions. DUAL-TASK group showed increased recruitment of occipito-temporal areas and reduced activity of cerebellum crus-I. DUAL-TASK + AOT-MI relative to DUAL-TASK group had increased activity of cerebellum VIII-IX. In DUAL-TASK + AOT-MI group, KVIQ improvement correlated with increased activity of cerebellum IX and anterior cingulate, and with reduced activity of crus-I.

CONCLUSIONS

AOT-MI improves MI abilities in PD-PIGD patients, promoting the functional plasticity of brain areas involved in MI processes and gait/balance control.

Goal-directed and habitual control: from circuits and functions to exercise-induced neuroplasticity targets for the treatment of Parkinson's disease

Parkinson's disease (PD) is a neurodegenerative disease characterized by motor and cognitive impairments. The progressive depletion of dopamine (DA) is the pathological basis of dysfunctional goal-directed and habitual control circuits in the basal ganglia. Exercise-induced neuroplasticity could delay disease progression by improving motor and cognitive performance in patients with PD. This paper reviews the research progress on the motor-cognitive basal ganglia circuit and summarizes the current hypotheses for explaining exercise intervention on rehabilitation in PD. Studies on exercise mediated mechanisms will contribute to the understanding of networks that regulate goal-directed and habitual behaviors and deficits in PD, facilitating the development of strategies for treatment of PD.

Effect of transcranial direct current stimulation on learning in older adults with and without Parkinson's disease: A systematic review with meta-analysis

Older adults with and without Parkinson's disease show impaired retention after training of motor or cognitive skills. This systematic review with meta-analysis aims to investigate whether adding transcranial direct current stimulation (tDCS) to motor or cognitive training versus placebo boosts motor sequence and working memory training. The effects of interest were estimated between three time points, i.e. pre-training, post-training and follow-up. This review was conducted according to the PRISMA guidelines (PROSPERO: CRD42022348885). Electronic databases were searched from conception to March 2023. Following initial screening, 24 studies were eligible for inclusion in the qualitative synthesis and 20 could be included in the meta-analysis, of which 5 studies concerned motor sequence learning (total n = 186) and 15 working memory training (total n = 650). Results were pooled using an inverse variance random effects meta-analysis. The findings showed no statistically significant additional effects of tDCS over placebo on motor sequence learning outcomes. However, there was a strong trend showing that tDCS boosted working memory training, although methodological limitations and some heterogeneity were also apparent. In conclusion, the present findings do not support wide implementation of tDCS as an add-on to motor sequence training at the moment, but the promising results on cognitive training warrant further investigations.

Comparative efficacy of 24 exercise types on postural instability in adults with Parkinson's disease: a systematic review and network meta-analysis

OBJECTIVE

To compare, rank and evaluate the 24 exercise types that improve postural instability in patients with Parkinson's disease (PD).

METHODS

We searched the data in PubMed, MEDLINE, Embase, PsycINFO, Cochrane library, and Web of Science from their inception date to January 23, 2023. Randomized controlled trials (RCTs) that aimed at determining the effectiveness of physical activity interventions on postural instability in adults with PD. This review focused on different balance outcome categories: (a) balance test batteries (BBS); (b) static steady-state balance (sSSB); (c) dynamic steady-state balance (dSSB); (d) proactive balance (PB); (e) reactive balance (RB).

RESULTS

Among 10,474 records, 199 studies (patients = 9523) were eligible for qualitative synthesis. The random-effects NMA model revealed that the following exercise training modalities had the highest p score of being best when compared with control group: body-weight support treadmill training (BWS_TT) for BBS (p score = 0.97; pooled standardised mean difference (95% CI): 1.56 (0.72 to 2.39)) and dSSB (1.00; 1.53 (1.07 to 2.00)), aquatic exercise (AQE) for sSSB (0.85; 0.94 (0.33 to 1.54)), Pilates for PB (0.95; 1.42 (0.59 to 2.26)). Balance and gait training with the external cue or attention (BGT_ECA) and robotic assisted gait balance (RA_GT) had similar superior effects in improving RB. The confidence in evidence was often low according to Confidence in Network Meta-Analysis.

CONCLUSIONS

There is low quality evidence that BWS_TT, AQE, Pilates, BGT_ECA and RA_GT are possibly the most effective treatments, pending outcome of interest, for adults with PD.

Nomen est omen: Serial reaction time task is not a motor but a visuomotor learning task

The serial reaction time task is a widely used task in behavioural and cognitive neuroscience to assess human and animal learning. Many publications refer to this task as a 'motor learning task', but it is also a perceptual learning task. We emphasize here that the incorrect use of the term 'motor learning' misleads researchers and medical doctors by emphasizing the motor cortex's exclusive role. It has the potential to lead to the misinterpretation of neuroscientific, neuroimaging and clinical studies. The domino effect has the potential to generate more flawed hypotheses and theories.

Assessing the impact of a knowledge translation intervention on physical therapists' self-efficacy and implementation of motor learning practice

BACKGROUND

The application of motor learning (ML) principles and research in physical therapy can optimize patient outcomes. However, the translation of the accumulated knowledge in ML to clinical practice is limited. Knowledge translation interventions, which are designed to promote changes in clinical behaviors, have the potential to address this implementation gap. We developed, implemented, and evaluated a knowledge translation intervention for ML implementation that focuses on building clinical capacity among physical therapists for the systematic application of ML knowledge in clinical practice.

METHODS

A total of 111 physical therapists underwent the intervention, which consisted of the following: (1) an interactive didactic 20-hour course; (2) an illustrated conceptual model of ML elements; and (3) a structured clinical-thinking form. Participants completed the Physical Therapists' Perceptions of Motor Learning (PTP-ML) questionnaire pre and post intervention. The PTP-ML was used to assess ML-related self-efficacy and implementation. Participants also provided post-intervention feedback. A sub-sample (n = 25) provided follow-up feedback more than a year after the completion of the intervention. Pre-post and post-follow-up changes in the PTP-ML scores were calculated. The information gathered from the open-ended items of the post-intervention feedback was analyzed to identify emerging themes.

RESULTS

Comparing pre- and post-intervention scores, significant changes were found in the total questionnaire scores, self-efficacy subscale scores, reported implementation subscale scores (P < .0001), and general perceptions and work environment subscale score (P < .005). The mean changes in the total questionnaire and self-efficacy scores also significantly exceeded the Reliable Change Index. In the follow-up sample, these changes were maintained. Participants felt that the intervention helped them organize their knowledge in a structured manner and consciously link their practice elements to concepts in ML. Discussion of clinical cases was reported to be the most valuable educational method, and the illustrated conceptual model of ML elements was the least valued. Respondents also suggested support activities to maintain and enhance the learning experience, including on-site mentorship and hands-on experience.

CONCLUSIONS

Findings support the positive effect of an educational tool, most prominently on physical therapists' ML self-efficacy. The addition of practical modeling or ongoing educational support may enhance intervention effects.

Implicit Motor Sequence Learning in People with Mild to Moderate Parkinson's Disease: Behavior and Related Brain Function

BACKGROUND

Deficits in motor learning could be an important explanation for the balance and gait impairments characteristic of people with Parkinson's disease (PD). Empirical studies often report that so-called implicit motor sequence learning is impaired in people with PD, but the results are inconclusive. Altered brain activity during implicit motor sequence learning has also been reported for people with PD in comparison to healthy individuals.

OBJECTIVE

To investigate implicit motor sequence learning and associated neural correlates in individuals with mild to moderate PD.

METHODS

Fifty-seven participants with PD and 34 healthy participants, all ≥60 years of age, performed the serial reaction time task (SRTT) during the acquisition of functional magnetic resonance imaging (fMRI) data. We analyzed the SRTT as a measure of implicit motor sequence learning in two complementary ways. We analyzed the task-induced fMRI data within regions of interest (ROIs) as well as functional connectivity between ROIs.

RESULTS

We found a significant group difference in SRTT performance indicating that the participants with PD had a somewhat lower level of implicit motor sequence learning than the healthy participants. Exploratory analyses suggested that impairments in implicit motor sequence learning for people with PD might be due to a lower learning rate. We did not find any significant group differences in the fMRI data.

CONCLUSION

Our exploratory finding of a lower implicit motor learning rate in PD could have important implications for how people with PD should practice new motor tasks and physical exercise. Future studies need to confirm this finding with hypothesis-driven analyses.

Altered Neurovascular Coupling for Multidisciplinary Intensive Rehabilitation in Parkinson's Disease

Effective rehabilitation in Parkinson's disease (PD) is related to brain reorganization with restoration of cortico-subcortical networks and compensation of frontoparietal networks; however, further neural rehabilitation evidence from a multidimensional perspective is needed. To investigate how multidisciplinary intensive rehabilitation treatment affects neurovascular coupling, 31 PD patients (20 female) before and after treatment and 30 healthy controls (17 female) underwent blood oxygenation level-dependent functional magnetic resonance imaging and arterial spin labeling scans. Cerebral blood flow (CBF) was used to measure perfusion, and fractional amplitude of low-frequency fluctuation (fALFF) was used to measure neural activity. The global CBF-fALFF correlation and regional CBF/fALFF ratio were calculated as neurovascular coupling. Dynamic causal modeling (DCM) was used to evaluate treatment-related alterations in the strength and directionality of information flow. Treatment reduced CBF-fALFF correlations. The altered CBF/fALFF exhibited increases in the left angular gyrus and the right inferior parietal gyrus and decreases in the bilateral thalamus and the right superior frontal gyrus. The CBF/fALFF alteration in right superior frontal gyrus showed correlations with motor improvement. Further, DCM indicated increases in connectivity from the superior frontal gyrus and decreases from the thalamus to the inferior parietal gyrus. The benefits of rehabilitation were reflected in the dual mechanism, with restoration of executive control occurring in the initial phase of motor learning and compensation of information integration occurring in the latter phase. These findings may yield multimodal insights into the role of rehabilitation in disease modification and identify the dorsolateral superior frontal gyrus as a potential target for noninvasive neuromodulation in PD.SIGNIFICANCE STATEMENT Although rehabilitation has been proposed as a promising supplemental treatment for PD as it results in brain reorganization, restoring cortico-subcortical networks and eliciting compensatory activation of frontoparietal networks, further multimodal evidence of the neural mechanisms underlying rehabilitation is needed. We measured the ratio of perfusion and neural activity derived from arterial spin labeling and blood oxygenation level-dependent fMRI data and found that benefits of rehabilitation seem to be related to the dual mechanism, restoring executive control in the initial phase of motor learning and compensating for information integration in the latter phase. We also identified the dorsolateral superior frontal gyrus as a potential target for noninvasive neuromodulation in PD patients.

Beyond physiology: Acute effects of side-alternating whole-body vibration on well-being, flexibility, balance, and cognition using a light and portable platform A randomized controlled trial

A good body-balance helps to prevent slips, trips and falls. New body-balance interventions must be explored, because effective methods to implement daily training are sparse. The purpose of the current study was to investigate acute effects of side-alternating whole-body vibration (SS-WBV) training on musculoskeletal well-being, flexibility, body balance, and cognition. In this randomized controlled trial, participants were randomly allocated into a verum (8.5 Hz, SS-WBV, N = 28) or sham (6 Hz, SS-WBV, N = 27) condition. The training consisted of three SS-WBV series that lasted one-minute each with two one-minute breaks in between. During the SS-WBV series, participants stood in the middle of the platform with slightly bent knees. During the breaks in between, participants could loosen up. Flexibility (modified fingertip-to-floor method), balance (modified Star Excursion Balance Test), and cognitive interference (Stroop Color Word Test) were tested before and after the exercise. Also, musculoskeletal well-being, muscle relaxation, sense of flexibility, sense of balance, and surefootedness were assessed in a questionnaire before and after the exercise. Musculoskeletal well-being was significantly increased only after verum. Also, muscle relaxation was significantly higher only after verum. The Flexibility-Test showed significant improvement after both conditions. Accordingly, sense of flexibility was significantly increased after both conditions. The Balance-Test showed significant improvement after verum, and after sham. Accordingly, increased sense of balance was significant after both conditions. However, surefootedness was significantly higher only after verum. The Stroop-Test showed significant improvement only after verum. The current study shows that one SS-WBV training session increases musculoskeletal well-being, flexibility, body balance and cognition. The abundance of improvements on a light and portable platform has great influence on the practicability of training in daily life, aiming to prevent slip trips and falls at work.

Split-Belt Treadmill Training to Improve Gait Adaptation in Parkinson's Disease

BACKGROUND

Gait deficits in people with Parkinson's disease (PD) are triggered by circumstances requiring gait adaptation. The effects of gait adaptation training on a split-belt treadmill (SBT) are unknown in PD.

OBJECTIVE

We investigated the effects of repeated SBT versus tied-belt treadmill (TBT) training on retention and automaticity of gait adaptation and its transfer to over-ground walking and turning.

METHODS

We recruited 52 individuals with PD, of whom 22 were freezers, in a multi-center randomized single-blind controlled study. Training consisted of 4 weeks of supervised treadmill training delivered three times per week. Tests were conducted pre- and post-training and at 4-weeks follow-up. Turning (primary outcome) and gait were assessed over-ground and during a gait adaptation protocol on the treadmill. All tasks were performed with and without a cognitive task.

RESULTS

We found that SBT-training improved gait adaptation with moderate to large effects sizes (P < 0.02) compared to TBT, effects that were sustained at follow-up and during dual tasking. However, better gait adaptation did not transfer to over-ground turning speed. In both SBT- and TBT-arms, over-ground walking and Movement Disorder Society-Unified Parkinson's Disease Rating Scale III (MDS-UPDRS-III scores were improved, the latter of which reached clinically meaningful effects in the SBT-group only. No impact was found on freezing of gait.

CONCLUSION

People with PD are able to learn and retain the ability to overcome asymmetric gait-speed perturbations on a treadmill remarkably well, but seem unable to generalize these skills to asymmetric gait off-treadmill. Future study is warranted into gait adaptation training to boost the transfer of complex walking skills. © 2022 The Authors. Movement Disorders published by Wiley Periodicals LLC on behalf of International Parkinson and Movement Disorder Society.

Influences of Aerobic Exercise on Motor Sequence Learning and Corticomotor Excitability in People With Parkinson's Disease

BACKGROUND

People with Parkinson's disease (PD) are known to have motor learning difficulties. Although numerous studies have demonstrated that a single bout of aerobic exercise (AEX) can facilitate motor learning in non-disabled adults, the same beneficial effect in PD is unknown. Furthermore, associated neuroplastic changes have not been investigated.

OBJECTIVES

This study aimed to determine whether a single bout of aerobic exercise (AEX) can facilitate motor sequence learning in people with PD and to investigate the associated neurophysiological changes.

METHODS

Thirty individuals with PD were recruited and randomized into the exercise group (PD + AEX) and non-exercise group (PD - AEX). At the first visit, corticomotor excitability was assessed using transcranial magnetic stimulation (TMS). All participants then performed a serial reaction time task (SRTT) followed by 20 minutes of moderately-high intensity aerobic exercise (AEX) for the PD + AEX group or rest for the PD - AEX group. The SRTT and TMS were reevaluated at 3 time points: immediately after aerobic exercise (AEX) or rest, on the second day after practice (D2), and a week after practice (D7).

RESULTS

Both groups showed improvement throughout practice. At retention, the PD + AEX group showed improved SRTT performance on D7 compared to D2 (P = .001), while the PD - AEX group showed no change in performance. TMS results showed that the PD + AEX group had significantly higher corticomotor excitability than the PD - AEX group on D7.

CONCLUSION

A single session of aerobic exercise (AEX) could enhance motor sequence learning and induce neuroplastic changes. Clinicians can consider providing aerobic exercise (AEX) after motor task training for people with PD.

CLINICAL REGISTRATION

NCT04189887 (ClinicalTrials.gov).

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.

[New approaches in exercise therapy for Parkinson's disease]

BACKGROUND

Exercise therapy is an important component in the treatment of motor symptoms in people with Parkinson's disease (PD). In this context, goal-based task-specific training has shown to be particularly effective compared to nonspecific approaches.

OBJECTIVE

In this article two novel exercise interventions for targeted improvement of motor function in PD are presented: 1) task-specific training with perturbations and 2) combined task-specific and cardiovascular training.

MATERIAL AND METHODS

Summary and discussion of the current evidence for both therapeutic approaches.

RESULTS

First randomized controlled trials show that perturbation training is an effective task-specific training to improve gait and balance function and potentially reduce falls. Experimental findings on combined cardiovascular exercise and task-specific training suggest that processes of neuroplasticity are enhanced, thereby improving therapy outcomes. However, the quality of evidence for both therapeutic approaches is currently low.

CONCLUSION

The presented exercise approaches show promising results in first randomized controlled studies and have the potential to improve treatment outcomes in PD. Further high-quality clinical studies are needed to ensure an effective transfer into practice.

Movement-related beta ERD and ERS abnormalities in neuropsychiatric disorders

Movement-related oscillations in the beta range (from 13 to 30 Hz) have been observed over sensorimotor areas with power decrease (i.e., event-related desynchronization, ERD) during motor planning and execution followed by an increase (i.e., event-related synchronization, ERS) after the movement's end. These phenomena occur during active, passive, imaged, and observed movements. Several electrophysiology studies have used beta ERD and ERS as functional indices of sensorimotor integrity, primarily in diseases affecting the motor system. Recent literature also highlights other characteristics of beta ERD and ERS, implying their role in processes not strictly related to motor function. Here we review studies about movement-related ERD and ERS in diseases characterized by motor dysfunction, including Parkinson's disease, dystonia, stroke, amyotrophic lateral sclerosis, cerebral palsy, and multiple sclerosis. We also review changes of beta ERD and ERS reported in physiological aging, Alzheimer's disease, and schizophrenia, three conditions without overt motor symptoms. The review of these works shows that ERD and ERS abnormalities are present across the spectrum of the examined pathologies as well as development and aging. They further suggest that cognition and movement are tightly related processes that may share common mechanisms regulated by beta modulation. Future studies with a multimodal approach are warranted to understand not only the specific topographical dynamics of movement-related beta modulation but also the general meaning of beta frequency changes occurring in relation to movement and cognitive processes at large. Such an approach will provide the foundation to devise and implement novel therapeutic approaches to neuropsychiatric disorders.

Implicit sensorimotor adaptation is preserved in Parkinson's disease

Our ability to enact successful goal-directed actions involves multiple learning processes. Among these processes, implicit motor adaptation ensures that the sensorimotor system remains finely tuned in response to changes in the body and environment. Whether Parkinson's disease impacts implicit motor adaptation remains a contentious area of research: whereas multiple reports show impaired performance in this population, many others show intact performance. While there is a range of methodological differences across studies, one critical issue is that performance in many of the studies may reflect a combination of implicit adaptation and strategic re-aiming. Here, we revisited this controversy using a visuomotor task designed to isolate implicit adaptation. In two experiments, we found that adaptation in response to a wide range of visual perturbations was similar in Parkinson's disease and matched control participants. Moreover, in a meta-analysis of previously published and unpublished work, we found that the mean effect size contrasting Parkinson's disease and controls across 16 experiments involving over 200 participants was not significant. Together, these analyses indicate that implicit adaptation is preserved in Parkinson's disease, offering a fresh perspective on the role of the basal ganglia in sensorimotor learning.

Split-Belt Adaptation and Savings in People With Parkinson Disease

BACKGROUND AND PURPOSE

Upper extremity studies suggest that implicit adaptation is less impaired than explicit learning in persons with Parkinson disease (PD). Little work has explored implicit locomotor adaptation and savings in this population, yet implicit locomotor learning is critical for everyday function. This cross-sectional study examined adaptation and savings in individuals with PD during split-belt treadmill walking.

METHODS

Fourteen participants completed the following treadmill protocol: Baseline (6 minutes belts tied), Adaptation (10 minutes split), Washout (10 minutes tied), and Readaptation (10 minutes split). Step length and step symmetry index (SSI) were calculated to determine magnitude and rate of adaptation and savings. Rate was calculated as strides to reach SSI plateau during Adaptation and Readaptation.

RESULTS

During Early Adaptation and Early Readaptation, SSI was perturbed from Baseline ( P < 0.001 and P = 0.002, respectively). Less perturbation in Early Readaptation ( P < 0.001) demonstrated savings. In Late Adaptation and Late Readaptation, participants returned to Baseline symmetry ( P = 0.026 and P = 0.022, respectively, with adjusted level of significance = 0.007). Adaptation was also seen in reverse asymmetry observed in Early Washout ( P = 0.003 vs Baseline). Readaptation rate was faster than in Adaptation ( P = 0.015), demonstrating savings.

DISCUSSION AND CONCLUSIONS

Individuals with PD showed locomotor adaptation in an implicit sensorimotor adaptation task. They also demonstrated savings, with less perturbation and faster adaptation during the second split-belt exposure. However, performance was variable; some individuals showed minimal adaptation. Variations in learning, savings, and clinical presentation highlight the need to further explore characteristics of individuals with PD most likely to benefit from adaptation-based locomotor training.Video Abstract available for more insights from the authors (see the Video, Supplemental Digital Content 1, available at: http://links.lww.com/JNPT/A395 ).

Clinical applications of exercise in Parkinson's disease: what we need to know?

INTRODUCTION

Exploring the potential of exercise in the rehabilitation process of patients with Parkinson's (PD) may be an interesting treatment perspective. Exercise-induced responses derived from neurotrophic elements appear to ameliorate the decline in neurodegeneration. Despite this understanding, the literature needs to be updated.

AREAS COVERED

Our review focuses on: a) the key mechanisms of exercise on PD, highlighting mainly the responses related to neuroplasticity; b) the effects induced by different traditional types of exercise, also highlighting the effects of complementary therapies related to movement; c) the volume of exercise required to support efficient results are explored in the context of PD. Additionally, the proposition of new clinical application strategies in the context of PD will also be determined.

EXPERT OPINION

It is suggested that different intensities of aerobic exercise be explored for the treatment of PD. The results associated with high intensity seem promising for performance, physiological and clinical parameters, such as BDNF production and cognition. On the other hand, the diversification of tasks and repetition of motor gestures appear as consistent arguments to exercise prescription. Finally, for future investigations, the neuromodulation strategy in association with aerobic exercise appears as a potential inducer of benefits on gait and cognitive function.

A meta-analytical review of transcranial direct current stimulation parameters on upper limb motor learning in healthy older adults and people with Parkinson's disease

Current literature lacks consolidated evidence for the impact of stimulation parameters on the effects of transcranial direct current stimulation (tDCS) in enhancing upper limb motor learning. Hence, we aim to synthesise available methodologies and results to guide future research on the usage of tDCS on upper limb motor learning, specifically in older adults and Parkinson's disease (PD). Thirty-two studies (Healthy older adults, N = 526, M = 67.25, SD = 4.30 years; PD, N = 216, M = 66.62, SD = 6.25 years) were included in the meta-analysis. All included studies consisted of active and sham protocols. Random effect meta-analyses were conducted for (i) subjects (healthy older adults and PD); (ii) intensity (1.0, 1.5, 2 mA); (iii) electrode montage (unilateral anodal, bilateral anodal, unilateral cathodal); (iv) stimulation site (cerebellum, frontal, motor, premotor, SMA, somatosensory); (v) protocol (online, offline). Significant tDCS effect on motor learning was reported for both populations, intensity 1.0 and 2.0 mA, unilateral anodal and cathodal stimulation, stimulation site of the motor and premotor cortex, and both online and offline protocols. Regression showed no significant relationship between tDCS effects and density. The efficacy of tDCS is also not affected by the number of sessions. However, studies that reported only single session tDCS found significant negative association between duration with motor learning outcomes. Our findings suggest that different stimulation parameters enhanced upper limb motor learning in older adults and PD. Future research should combine tDCS with neuroimaging techniques to help with optimisation of the stimulation parameters, considering the type of task and population.

Targeting thalamic circuits rescues motor and mood deficits in PD mice

Although bradykinesia, tremor and rigidity are the hallmark motor defects in patients with Parkinson's disease (PD), patients also experience motor learning impairments and non-motor symptoms such as depression1. The neural circuit basis for these different symptoms of PD are not well understood. Although current treatments are effective for locomotion deficits in PD2,3, therapeutic strategies targeting motor learning deficits and non-motor symptoms are lacking4-6. Here we found that distinct parafascicular (PF) thalamic subpopulations project to caudate putamen (CPu), subthalamic nucleus (STN) and nucleus accumbens (NAc). Whereas PF→CPu and PF→STN circuits are critical for locomotion and motor learning, respectively, inhibition of the PF→NAc circuit induced a depression-like state. Whereas chemogenetically manipulating CPu-projecting PF neurons led to a long-term restoration of locomotion, optogenetic long-term potentiation (LTP) at PF→STN synapses restored motor learning behaviour in an acute mouse model of PD. Furthermore, activation of NAc-projecting PF neurons rescued depression-like phenotypes. Further, we identified nicotinic acetylcholine receptors capable of modulating PF circuits to rescue different PD phenotypes. Thus, targeting PF thalamic circuits may be an effective strategy for treating motor and non-motor deficits in PD.

Central nervous system effects of 5-HT7 receptors: a potential target for neurodegenerative diseases

5-HT₇ receptors (5-HT₇R) are the most recently identified among the family of serotonin receptors. Their role in health and disease, particularly as mediators of, and druggable targets for, neurodegenerative diseases, is incompletely understood. Unlike other serotonin receptors, for which abundant preclinical and clinical data evaluating their effect on neurodegenerative conditions exist, the available information on the role of the 5-HT₇R receptor is limited. In this review, we describe the signaling pathways and cellular mechanisms implicated in the activation of the 5-HT₇R; also, we analyze different mechanisms of neurodegeneration and the potential therapeutic implications of pharmacological interventions for 5-HT₇R signaling.

Associations between resting-state functional connectivity changes and prolonged benefits of writing training in Parkinson's disease

BACKGROUND

Our earlier work showed that automaticity and retention of writing skills improved with intensive writing training in Parkinson's disease (PD). However, whether this training changed the resting-state networks in the brain and how these changes underlie retention of motor learning is currently unknown.

OBJECTIVE

To examine changes in resting-state functional connectivity (rs-FC) and their relation to behavioral changes immediately after writing training and at 6 week follow-up.

METHODS

Twenty-five PD patients underwent resting-state fMRI (ON medication) before and after 6 weeks writing training. Motor learning was evaluated with a dual task paradigm pre- and post-training and at follow-up. Next, pre-post within-network changes in rs-FC were identified by an independent component analysis. Significant clusters were used as seeds in ROI-to-ROI analyses and rs-FC changes were correlated with changes in behavioral performance over time.

RESULTS

Similar to our larger cohort findings, writing accuracy in single and dual task conditions improved post-training and this was maintained at follow-up. Connectivity within the dorsal attentional network (DAN) increased pre-post training, particularly with the right superior and middle temporal gyrus (rS/MTG). This cluster also proved more strongly connected to parietal and frontal areas and to cerebellar regions. Behavioral improvements from pre- to post-training and follow-up correlated with increased rs-FC between rS/MTG and the cerebellum.

CONCLUSIONS

Training-driven improvements in dual task writing led to functional reorganization within the DAN and increased connectivity with cerebellar areas. These changes were associated with the retention of writing gains and could signify task-specific neural changes or an inability to segregate neural networks.

Dopaminergic modulation of primary motor cortex: From cellular and synaptic mechanisms underlying motor learning to cognitive symptoms in Parkinson's disease

The primary motor cortex (M1) is crucial for movement execution, especially dexterous ones, but also for cognitive functions like motor learning. The acquisition of motor skills to execute dexterous movements requires dopamine-dependent and -independent plasticity mechanisms within M1. In addition to the basal ganglia, M1 is disturbed in Parkinson's disease (PD). However, little is known about how the lack of dopamine (DA), characteristic of PD, directly or indirectly impacts M1 circuitry. Here we review data from studies of PD patients and the substantial research in non-human primate and rodent models of DA depletion. These models enable us to understand the importance of DA in M1 physiology at the behavioral, network, cellular, and synaptic levels. We first summarize M1 functions and neuronal populations in mammals. We then look at the origin of M1 DA and the cellular location of its receptors and explore the impact of DA loss on M1 physiology, motor, and executive functions. Finally, we discuss how PD treatments impact M1 functions.

Single session transcranial direct current stimulation to the primary motor cortex fails to enhance early motor sequence learning in Parkinson's disease

INTRODUCTION

Explicit motor sequence learning is impaired in Parkinson's disease (PD). Transcranial direct current stimulation (tDCS) applied over the motor cortex in healthy can improve explicit motor learning, but comparative effects in PD are unknown. This exploratory study aims to examine the effect of single session tDCS on explicit motor sequence learning in PD.

METHODS

Thirty-three people with mild to moderate PD learnt a short and long finger tapping sequence with their right hand. Participants received either anodal, cathodal, or sham tDCS applied over the left primary motor cortex during task practice. Single- and dual-task finger tapping performance was assessed before and after task practice and functional near-infrared spectroscopy used to measure task related changes of oxygenated haemoglobin.

RESULTS

Finger tapping performance of short and long sequences under single-task conditions significantly improved following practice (p = 0.010 and p < 0.001, respectively). A condition-by-time interaction trend was observed for the long finger tapping sequence (p = 0.069) driven by improved performance in the cathodal (p = 0.001) and sham (p < 0.001) tDCS conditions, but not anodal tDCS (p = 0.198). The primary and premotor cortex and supplementary motor area were active in all tasks. No interaction or main effects were observed for task related changes of oxygenated haemoglobin.

CONCLUSIONS

PD patients retain the capacity to learn an explicit sequence of movements. Motor cortex tDCS does not improve explicit motor learning in PD and anodal tDCS may even suppress the rate of learning.

Reward and plasticity: Implications for neurorehabilitation

Neuroplasticity follows nervous system injury in the presence or absence of rehabilitative treatments. Rehabilitative interventions can be used to modulate adaptive neuroplasticity, reducing motor impairment and improving activities of daily living in patients with brain lesions. Learning principles guide some rehabilitative interventions. While basic science research has shown that reward combined with training enhances learning, this principle has been only recently explored in the context of neurorehabilitation. Commonly used reinforcers may be more or less rewarding depending on the individual or the context in which the task is performed. Studies in healthy humans showed that both reward and punishment can enhance within-session motor performance; but reward, and not punishment, improves consolidation and retention of motor skills. On the other hand, neurorehabilitative training after brain lesions involves complex tasks (e.g., walking and activities of daily living). The contribution of reward to neurorehabilitation is incompletely understood. Here, we discuss recent research on the role of reward in neurorehabilitation and the needed directions of future research.

Rehabilitation in movement disorders: From basic mechanisms to clinical strategies

Movement disorders encompass a variety of conditions affecting the nervous system at multiple levels. The pathologic processes underlying movement disorders alter the normal neural functions and could lead to aberrant neuroplastic changes and to clinical phenomenology that is not expressed only through mere motor symptoms. Given this complexity, the responsiveness to pharmacologic and surgical therapies is often disappointing. Growing evidence supports the efficacy of neurorehabilitation for the treatment of movement disorders. Specific form of training involving both goal-based practice and aerobic training could drive and modulate neuroplasticity in order to restore the circuitries dysfunctions and to achieve behavioral gains. This chapter provides an overview of the alterations expressed in some movement disorders in terms of clinical signs and symptoms and plasticity, and suggests which ones and why tailored rehabilitation strategies should be adopted for the management of the different movement 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.

Noninvasive neuromodulation in Parkinson's disease: Neuroplasticity implication and therapeutic perspectives

Noninvasive brain stimulation techniques can be used to study in vivo the changes of cortical activity and plasticity in subjects with Parkinson's disease (PD). Also, an increasing number of studies have suggested a potential therapeutic effect of these techniques. High-frequency repetitive transcranial magnetic stimulation (rTMS) and anodal transcranial direct current stimulation (tDCS) represent the most used stimulation paradigms to treat motor and nonmotor symptoms of PD. Both techniques can enhance cortical activity, compensating for its reduction related to subcortical dysfunction in PD. However, the use of suboptimal stimulation parameters can lead to therapeutic failure. Clinical studies are warranted to clarify in PD the additional effects of these stimulation techniques on pharmacologic and neurorehabilitation treatments.

Effectiveness of 7-chloro-4-(phenylselanyl) quinoline in improving learning, short-term memory, and anxiety-like behaviors in a mimetic model of Parkinson's disease in Drosophila melanogaster

The potential of 4-PSQ on psychomotor and non-motor behaviors of PD, such as spontaneous locomotor activity, learning, memory, and anxiety.

Use of Real-time Multimodal Sensory Feedback Home Program Improved Backward Stride and Retention for People with Parkinson Disease: a Pilot Study

•

Multimodal sensory feedback with home exercises increased backward stride for PwPD.

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Retention of gains occurred 6 weeks after exercise ended for participants using MMSF.

•

The MMSF home program improvements were likely due to integration of proprioception.

•

Outcomes were highly rated by MMSF participants on a Perceived Outcome Scale.

Introduction

Parkinson disease (PD) impairs sensory integration, contributes to motor dysfunction, loss of gait automaticity, and increased fall risk. Employing multimodal sensory feedback (MMSF) has the potential to improve proprioceptive integration and gait safety while reducing exercise burden especially for backward gait.

Methods

This single-blinded, randomized controlled pilot study used a home program with or without real-time visual, proprioceptive, and auditory feedback with stepping exercises which progressed in speed and distance. Both groups completed a six-week intervention followed by 6 weeks without exercise to assess long-term retention. Six additional weeks of exercises were completed to assess recovery of potential losses after the washout session.

Eleven people with PD exercised with real-time MMSF and 7 exercised without MMSF. Outcome measures included backward stride length, velocity, cadence, and double support time. The Dual Timed Up and Go measured automaticity. Self-perceived improvements in gait, activities of daily living, participation, and quality of life were registered by a questionnaire.

Results

Analysis was by repeated measures ANOVA. Using MMSF significantly improved backward stride length at 12 and 18 weeks, p = .007, η² = 0.239. Both groups improved in all outcome measures after the initial 6-week exercise program, supporting efficacy of stepping exercises. The MMSF + ex group's significant improvements after a 6-week washout supported automaticity development. Questionnaire items received higher agreement percentages from MMSF + ex participants.

Conclusion

Using real-time MMSF in a home program for pwPD provided significant and lasting improvements in backward stride, and potentially decreased fall risk and exercise burden compared to the same program without MMSF.

Identifying knowledge important to teach about the nervous system in the context of secondary biology and science education-A Delphi study

Teaching about the nervous system has become a challenging task in secondary biology and science education because of the fast development in the field of neuroscience. A major challenge is to determine what content to teach. Curricula goals are often too general to guide instruction, and information about the nervous system has become overwhelming and diverse with ubiquitous relevance in society. In addition, several misconceptions and myths are circulating in educational communities causing world-wide confusion as to what content is correct. To help teachers, textbook authors, and curricula developers in this challenging landscape of knowledge, the aim of the present study is to identify the expert view on what knowledge is important for understanding the nervous system in the context of secondary biology and science education. To accomplish this, we have conducted a thematic content analysis of textbooks followed by a Delphi study of 15 experts in diverse but relevant fields. The results demonstrate six curriculum themes including gross anatomy and function, cell types and functional units, the nerve signal, connections between neurons, when nerve signals travel through networks of neurons, and plasticity in the nervous system, as well as 26 content principles organized in a coherent curriculum progression from general content to more specific content. Whereas some of the principles clarify and elaborate on traditional school biology knowledge, others add new knowledge to the curriculum. Importantly, the new framework for teaching about the nervous system presented here, meets the needs of society, as expressed by recent international policy frameworks of OECD and WHO, and it addresses common misconceptions about the brain. The study suggests an update of the biology and science curriculum.

Repeated Gait Perturbation Training in Parkinson's Disease and Healthy Older Adults: A Systematic Review and Meta-Analysis

Background: Gait impairments are common in healthy older adults (HOA) and people with Parkinson's disease (PwPD), especially when adaptations to the environment are required. Traditional rehabilitation programs do not typically address these adaptive gait demands in contrast to repeated gait perturbation training (RGPT). RGPT is a novel reactive form of gait training with potential for both short and long-term consolidation in HOA and PwPD. The aim of this systematic review with meta-analysis is to determine whether RGPT is more effective than non-RGPT gait training in improving gait and balance in HOA and PwPD in the short and longer term. Methods: This review was conducted according to the PRISMA-guidelines and pre-registered in the PROSPERO database (CRD42020183273). Included studies tested the effects of any form of repeated perturbations during gait in HOA and PwPD on gait speed, step or stride length. Studies using balance scales or sway measures as outcomes were included in a secondary analysis. Effects of randomized controlled trials (RCT) on RGPT were pooled using a meta-analysis of final measures. Results: Of the 4421 studies, eight studies were deemed eligible for review, of which six could be included in the meta-analysis, totaling 209 participants (159 PwPD and 50 HOA). The studies were all of moderate quality. The meta-analysis revealed no significant effects of RGPT over non-RGPT training on gait performance (SMD = 0.16; 95% CI = -0.18, 0.49; Z = 0.92; P = 0.36). Yet, in some individual studies, favorable effects on gait speed, step length and stride length were observed immediately after the intervention as well as after a retention period. Gait variability and asymmetry, signifying more direct outcomes of gait adaptation, also indicated favorable RGPT effects in some individual studies. Conclusion: Despite some promising results, the pooled effects of RGPT on gait and balance were not significantly greater as compared to non-RGPT gait training in PwPD and HOA. However, these findings could have been driven by low statistical power. Therefore, the present review points to the imperative to conduct sufficiently powered RCT's to verify the true effects of RGPT on gait and balance in HOA and PwPD. Systematic Review Registration: https://www.crd.york.ac.uk/prospero/display_record.php? Identifier: CRD42020183273.

I can't count, but I can beat you playing cards: a case report on autoimmune encephalitis

Background

Autoimmune encephalitis (AE) is a rare inflammatory disorder characterized by important psychiatric and neurologic symptoms. The literature documents high rates of neuropsychological dysfunction in N-methyl D-aspartate-receptor (NMDAr) encephalitis but papers don’t consider specifically calculation disturbances between the long-term deficits, although deficits in executive control and episodic memory were less likely to resolve.

Case report

Here we present a severe case of NMDAr encephalitis in a young patient without a relevant past medical history. Upon first examination he presented psycho-motor slowdown, speech disorders, severe cognitive deficits in all areas: concentration, attention, memory, language, dual task functions, increased latency in responses, severe dyscalculia. Upon first evaluation, the young patient underwent a battery of neuropsychological tests and he showed a dysexecutive syndrome with performances significantly low for age and education. Our patient hence underwent 1 month of intensive cognitive rehabilitation. After the rehabilitation treatment, he presented an amelioration in all domains except calculations.

Conclusions

In our patient the calculation disorder has proved to be the most relevant problem and the most difficult to treat. Clinicians should consider a careful approach to determine the prognosis of this syndrome because of the wide range of deficits, the need of prolonged treatment and the rate of long-term sequelae.