Unimanual actions can interfere with or facilitate similar actions performed with the opposite hand, especially when in close temporal proximity. Across three sequential button-press experiments, we tested how effector homology – anatomical similarity between fingers – and temporal delays between actions shape these effects. Specifically, we examined whether a priming action altered the reaction time (RT) of a subsequent action. Compared with baseline unimanual RTs, we indexed slowing of the second action’s RT as interference, and quickening as facilitation. Priming with homologous actions (e.g., index finger-index finger) produced interference (RTs slower than baseline) for temporal delays ≤ 200 ms and facilitation (RTs faster than baseline) at temporal delays ≥ 400 ms. Priming with non-homologous actions (e.g., little finger-index finger) also produced interference at short temporal delays, but never resulted in facilitation. Critically, these patterns emerged whether the priming actions were performed with the opposite or the same hand, indicating that interference and facilitation do not depend on interhemispheric dynamics. Our results reveal a previously undocumented phenomenon whereby homologous actions separated by longer delays result in behavioural facilitation, challenging models that explain the interaction between parallel actions solely by competitive interhemispheric dynamics or central bottleneck processes. We propose that facilitation and interference flexibly coexist, and are shaped by effector homology and action timing. These findings extend current models of bimanual coordination and highlight new opportunities for enhancing motor performance and neurorehabilitation.

BACKGROUND:The aim of the study was to investigate the impact of aging on visual attention across four computer-based tasks. METHODS:A cross-sectional observational approach was utilised in this study. A battery of four computer-based tasks, with previously demonstrated sensitivity in detecting spatial bias, were employed to assess visual-attention between young and older adults. The duration of each task was approximately 5 min. Performance measures across all tasks included response time (ms) and accuracy (%) data. RESULTS:125 participants, 51 younger (aged between 18 and 30) and 74 older adults (aged between 65 and 90) took part. Older adults had significantly slower response times compared to younger adults across all tasks, but accuracy was largely comparable. However, in the feature visual search task, older adults demonstrated superior accuracy, especially on the right side of space. More generally, results highlight the presence of a more pronounced leftward bias in the younger group, indicative of the previously described pseudo-neglect phenomenon. Increasing task demands, for example, by adding a dynamic component or introducing more complex or a larger number of distractors, had a greater impact on older adults' performance. CONCLUSION:The study provides valuable insights regarding the effect of age on visual attention and demonstrates the high sensitivity and feasibility of using simple computer-based assessments to identify these in unimpaired populations. Data presented here provide a basis for future studies using the same tasks with clinical populations.

Background/Objectives: To investigate the impact of a routine botulinum toxin type A (BoNT-A) injection in combination with outpatient therapy on the daily activities of stroke survivors with upper extremity spasticity and to facilitate patient-centred assessment focusing on individual needs during daily life. Methods: Design: Observational study across one treatment cycle (3 months). SETTING:Spasticity outpatient clinic of a neurorehabilitation hospital in Germany. PARTICIPANTS:Adult stroke survivors (n = 27) with upper extremity spasticity receiving routine BoNT-A treatment. INTERVENTIONS:Participants received one BoNT-A injection and outpatient therapies as part of their routine management. Augmented assessment was conducted directly before the injection (T0), and at 4 to 6 weeks (Tmax1) and 12 to 14 weeks (T2) following the injection. MAIN OUTCOME MEASURES:The Canadian Occupational Performance Measure (COPM), Goal Attainment Scaling (GAS), and Arm Activity Measure (ArmA). SECONDARY OUTCOME MEASURES:The Resistance to Passive Movement Scale (REPAS), Motricity Index (MI), SF-12v2 Health Survey (SF-12v2), Global Clinical Impression (GCI), and importance of and satisfaction with the BoNT-A treatment. Results: Performance of individually selected daily activities and satisfaction with their performance (COPM), passive care tasks (ArmA, part A), and resistance to passive movement (REPAS) significantly improved from T0 to Tmax1. Improvements largely remained at T2. Individual goals were all set at the activities and participation levels of the International Classification of Functioning, Disability and Health. These improved for 75% of participants and were fully attained by 33.3% at Tmax1. Responder analysis indicated that COPM and ArmA improvements were clinically significant for up to 50% of participants. Active upper extremity use (ArmA, part B), health-related quality of life (SF-12v2), and upper extremity strength (MI) remained unchanged. Conclusions: Our results indicate that BoNT-A in combination with routine outpatient therapy positively influenced the individually valued daily activities of stroke survivors. COPM, GAS, and ArmA are suitable for facilitating a patient-centred and daily life-oriented spasticity management post-stroke.

Mirror therapy has become an effective and recommended intervention for a range of conditions affecting the upper limb (e.g. hemiparesis following stroke). However, little is known about how mirror feedback affects the control of bimanual movements (as performed during mirror therapy). In this study, in preparation for future clinical investigations, we examined the kinematics of bimanual circle drawing in unimpaired participants both with (Experiment 1) and without (Experiment 2) a visual template to guide movement. In both experiments, 15 unimpaired right-handed participants performed self-paced continuous bimanual circle-drawing movements with a mirror/symmetrical coordination pattern. For the mirror condition, vision was directed towards the mirror in order to monitor the reflected limb. In the no mirror condition, the direction of vision was unchanged, but the mirror was replaced with an opaque screen. Movements of both hands were recorded using motion capture apparatus. In both experiments, the most striking feature of movements was that the hand behind the mirror drifted spatially during the course of individual trials. Participants appeared to be largely unaware of this marked positional change of their unseen hand, which was most pronounced when a template to guide movement was visible (Experiment 1). Temporal asynchrony between the limbs was also affected by mirror feedback in both experiments; in the mirror condition, illusory vision of the unseen hand led to a relative phase lead for that limb. Our data highlight the remarkable impact that the introduction of a simple mirror can have on bimanual coordination. Modulation of spatial and temporal features is consistent with the mirror inducing a rapid and powerful visual illusion, the latter appearing to override proprioceptive signals.

Patients recovering from hemiparetic stroke have been shown to benefit from mirror therapy in terms of improving their motor function. The clinical improvement in motor function may differ depending on the mirror therapy protocol used. Previous studies have shown that four parameters are influential: the size of the mirror (large and small), manipulation of objects (with or without), the complexity of action (simple and complex), and movement execution (unilateral and bilateral). We examined the impact of these parameters on the subjective quality (believability) of the mirror illusion in unimpaired participants. Forty healthy participants completed 16 different combinations of the four parameters during mirror visual feedback. Participants rated each trial for its level of believability on a 10-point Likert scale. A repeated measures ANOVA was used to examine the data. The large mirror consistently elicited higher ratings than the small mirror. And while bimanual movements generally elicited higher ratings than unimanual movements, ratings for bimanual movements were significantly reduced when participants made complex movements with objects. We attributed these results to the congruency of multisensory information. Conditions that elicit congruency between illusory information and other sensory inputs appear to maximise believability over the illusory hand. The findings of this study reveal the parameters maximising illusion believability in unimpaired participants and have implications for optimal mirror therapy conditions in patients’ groups. ### Competing Interest Statement The authors have declared no competing interest. ### Funding Statement The author(s) received no specific funding for this work. ### Author Declarations I confirm all relevant ethical guidelines have been followed, and any necessary IRB and/or ethics committee approvals have been obtained. Yes The details of the IRB/oversight body that provided approval or exemption for the research described are given below: The study was approved by the University of Birmingham's Science, Technology, Engineering and Mathematics Ethical Review Committee (ERN_15–1573). I confirm that all necessary patient/participant consent has been obtained and the appropriate institutional forms have been archived, and that any patient/participant/sample identifiers included were not known to anyone (e.g., hospital staff, patients or participants themselves) outside the research group so cannot be used to identify individuals. Yes I understand that all clinical trials and any other prospective interventional studies must be registered with an ICMJE-approved registry, such as ClinicalTrials.gov. I confirm that any such study reported in the manuscript has been registered and the trial registration ID is provided (note: if posting a prospective study registered retrospectively, please provide a statement in the trial ID field explaining why the study was not registered in advance). Yes I have followed all appropriate research reporting guidelines, such as any relevant EQUATOR Network research reporting checklist(s) and other pertinent material, if applicable. Yes Due to the sensitive nature of the data, information created during and/or analysed during the current study is available from the corresponding author (Jin Min Kim/j.m.kim@bham.ac.uk) on reasonable request to bona fide researchers.

Background To date, no gold standard exists for the assessment of unilateral spatial neglect (USN), a common post-stroke cognitive impairment, with limited sensitivity provided by currently used clinical assessments. Extensive research has shown that computer-based (CB) assessment can be more sensitive, but these have not been adopted by stroke services yet. Objective We conducted a systematic review providing an overview of existing CB tests for USN to identify knowledge gaps and positive/negative aspects of different methods. This review also investigated the benefits and barriers of introducing CB assessment tasks to clinical settings and explored practical implications for optimizing future designs. Methodology We included studies that investigated the efficacy of CB neglect assessment tasks compared to conventional methods in detecting USN for adults with brain damage. Study identification was conducted through electronic database searches (e.g., Scopus), using keywords and standardized terms combinations, without date limitation (last search: 08/06/2022). Literature review and study selection were based on prespecified inclusion criteria. The quality of studies was assessed with the quality assessment of diagnostic accuracy studies tool (Quadas-2). Data synthesis included a narrative synthesis, a table summarizing the evidence, and vote counting analysis based on a direction of effect plot. Results A total of 28 studies met the eligibility criteria and were included in the review. According to our results, 13/28 studies explored CB versions of conventional tasks, 11/28 involved visual search tasks, and 5/28 other types of tasks. The vote counting analysis revealed that 17/28 studies found CB tasks had either equal or higher sensitivity than conventional methods and positive correlation with conventional methods (15/28 studies). Finally, 20/28 studies showed CB tasks effectively detected patients with USN within different patient groups and control groups (17/28). Conclusions The findings of this review provide practical implications for the implementation of CB assessment in the future, offering important information to enhance a variety of methodological issues. The study adds to our understanding of using CB tasks for USN assessment, exploring their efficacy and benefits compared to conventional methods, and considers their adoption in clinical environments.

Although synchrony between the limbs is an often-cited feature of bimanual coordination, recent studies have also highlighted the small asynchronies that can occur. The visuo-motor demands of any bimanual task are considered central to the emergence of asynchrony, but the relationship between the two remains largely unexplored. This study aimed to address this issue. Hand and eye movements were measured in 19 participants, while they made either unimanual or bimanual reach-to-point (aiming) movements to targets presented on a touchscreen. Bimanual movements were either congruent (same-sized targets) or incongruent (different-sized targets). Resulting hand data showed many of the typical patterns of movement previously reported. While temporal coupling between the limbs remained largely evident for bimanual movements, small between-limb asynchronies were apparent and demonstrated clear associations with the competing precision requirements of the targets and related visual attention. Participants mainly directed their gaze towards the more difficult target with corresponding reaching movements demonstrating greater precision than for the easier target. Additionally, there was a reliable tendency for the hand reaching towards the more difficult target to lead. Importantly, it was the competing visuo-motor demands of individual movements rather than overall difficulty that resulted in greater between-limb asynchrony; accordingly, where both targets were small (i.e., the most difficult condition), asynchrony was significantly less pronounced than for incongruent bimanual conditions. The results show how the visuo-motor system balances its apparent drive for synchrony in coordinating bimanual movements with the competing demands that characterise the constituent unimanual movements.

Objective People exhibiting post-stroke lateropulsion actively push their body across the midline to the more affected side and/or resist weight shift toward the less affected side. Despite its prevalence and associated negative rehabilitation outcomes, no clinical practice guidelines exist for the rehabilitation of post-stroke lateropulsion. We aimed to develop consensus-based clinical practice recommendations for managing post-stroke lateropulsion using an international expert panel. Design This Delphi panel process conformed with Guidance on Conducting and Reporting Delphi Studies recommendations. Participants Panel members had demonstrated clinical and/or scientific background in the rehabilitation of people with post-stroke lateropulsion. Main Measures The process consisted of four electronic survey rounds. Round One consisted of 13 open questions. Subsequent rounds ascertained levels of agreement with statements derived from Round One. Consensus was defined a priori as ≥75% agreement (agree or strongly agree), or ≥70% agreement after excluding ‘unsure’ responses. Results Twenty participants completed all four rounds. Consensus was achieved regarding a total of 119 recommendations for rehabilitation approaches and considerations for rehabilitation delivery, positioning, managing fear of falling and fatigue, optimal therapy dose, and discharge planning. Statements for which ‘some agreement’ (50%–74% agreement) was achieved and those for which recommendations remain to be clarified were recorded. Conclusions These recommendations build on existing evidence to guide the selection of interventions for post-stroke lateropulsion. Future research is required to elaborate specific rehabilitation strategies, consider the impact of additional cognitive and perceptual impairments, describe positioning options, and detail optimal therapy dose for people with lateropulsion.

Objectives Even though individuals who have DCD may have difficulties learning a motor skill, few studies have investigated the mechanisms involved. Understanding these mechanisms and whether individuals with DCD show selective deficits would be of theoretical and practical interest. This study examined implicit motor sequence learning in adults with and without DCD using a serial response time (SRT) task. Methods Eleven participants with DCD (according to the DSM-5 criteria) and 18 participants without DCD matched for age, gender and handedness completed a version of the serial response time (SRT) task. Following this, a free generation task (FGT) assessed explicit sequence knowledge. Results Both groups were able to complete the SRT task and showed comparable accuracy. A Condition x Block interaction for response time (RT) data during the learning phase was explained by a failure of the DCD group to improve their performance, while the control group showed the typical learning effect of gradually faster RTs. Responses on the FGT revealed that the DCD group also acquired significantly less sequence knowledge than the control group during the task. Controlling for the development of sequence knowledge across the two groups still revealed an implicit learning deficit in the DCD group. Conclusions Adults with DCD failed to demonstrate the typical signs of implicit (procedural) learning on an established and influential sequence learning task. In addition, difficulties in acquiring task-related knowledge may point towards multiple difficulties in learning motor skills.

Introduction Hand dexterity is the ability to execute the skilful movements using the hand and fingers. It is commonly impaired poststroke resulting in a profound deterioration in the quality of life for patients with stroke. Transcranial direct current stimulation (tDCS) is a form of non-invasive brain stimulation, which has gained a popularity as an adjunct therapy in recovering motor dysfunction poststroke. Promising results have been gained from applying tDCS in combination with motor rehabilitation, however, the outcome of tDCS on the upper limb motor function poststroke has been varied. Different results are potentially related to the discrepancy of the area of brain stimulation. Therefore, we aim to enhance the application of tDCS to improve its effectiveness in recovering hand dexterity through testing our hypothesis that stimulating the primary motor cortex could improve fine dexterity more than gross dexterity. Methods and analysis This protocol has been reported according to Preferred Reporting Items for Systematic Review and Meta-Analyses Protocols guidelines. CENTRAL, MEDLINE, EMBASE, SCOPUS, Web of Science and CINAHL databases will be searched with no restriction in language and publication date. The selected studies will be randomised controlled trial investigating the effect of tDCS alone or in combination with motor rehabilitation in improving hand dexterity of patients with stroke with upper limb hemiparesis. The outcomes of interest are fine and gross hand dexterity measures. Two independent reviewers will assess the eligibility of the study, extract data and appraise the methodological quality. The data will be pooled in a meta-analysis if applicable or interpreted narratively. Grading of Recommendations, Assessment, Development and Evaluation approach will be used to assess the overall quality of evidence for the fine and gross dexterity measures. Ethics and dissemination Ethical approval is not required for this study. The dissemination plan is to publish the results in a peer-review journal and presenting results in a conference. PROSPERO registration number CRD42021262186.

Post-stroke lateropulsion is prevalent. The global inconsistency in terminology used to describe the condition presents obstacles in accurately comparing research results, reaching consensus on use of measurement tools, agreeing upon a consistent approach to rehabilitation, and translating research to clinical practice. Commencing in 2021, 20 international experts undertook a Delphi Process that aimed to compile clinical practice recommendations for the rehabilitation of lateropulsion. As a part of the process, the panel agreed to aim to reach consensus regarding terminology used to describe the condition. Improved understanding of the condition could lead to improved management, which will enhance patient outcomes after stroke and increase efficiency of healthcare resource utilisation. While consensus was not reached, the panel achieved some agreement that 'lateropulsion' is the preferred term to describe the phenomenon of 'active pushing of the body across the midline toward the more affected side, and / or actively resisting weight shift toward the less affected side'. This group recommends that 'lateropulsion' is used in future research and in clinical practice.

BACKGROUND Although the reliability of pain drawings (PDs) has been confirmed in people with chronic pain, there is a lack of evidence about the validity of the PD, that is, does the PD accurately represent the pain experience of the patient? OBJECTIVES We investigate whether people with chronic neck pain (CNP) can recognize their own PD to support the validity of the PD in reporting the experience of pain. Moreover, we examined the association between their ability to recognize their own PD with their levels of pain intensity and disability and extent of psychosocial and somatic features. STUDY DESIGN Experimental. SETTING University Laboratory. METHODS Individuals with CNP completed their PD on a digital body chart, which was then automatically modified with specific dimensions using a novel software, providing an objective range of distortion and eliminating errors, which could potentially occur in manually controlled visual-subjective based methods. Following a 10-minute break listening to music, a series of 20 PDs were presented to each patient in a random order, with only 2 being their original PD. For each PD, the patients rated its likeliness to their own original PD on a scale from 0 to 100, with 100 representing "this is my pain." RESULTS Overall, the patients rated their original PD with a median score of 92% similarity, followed by 91.8% and 89.5% similarity when presented with a PD scaled down to 75% and scaled up by 150% of the original size, respectively; these scores were not significantly different to the ratings given for their original PD. The PD with horizontal translation by 40 pixels (8%) and vertical translation by 70 pixels (12.8%) were rated as the most dissimilar to their original PD; these scores were significantly different to their original PD scores. The Spearman correlation coefficient revealed a significant negative association between their ability to recognize their original PD and their Modified Somatic Perceptions Questionnaire scores. LIMITATIONS The patients in the study presented with relatively mild CNP, and the results may not be generalized to those with more severe symptoms. CONCLUSIONS People with CNP are generally able to identify their own PD but that their ability to recognize their original PD is negatively correlated with the extent of somatic awareness. KEY WORDS Chronic pain, perception, pain drawings, somatic awareness.

BACKGROUND:The cerebellum and primary motor cortex (M1) are crucial to coordinated and accurate movements of the upper limbs. There is also appreciable evidence that these two structures exert somewhat divergent influences upon proximal versus distal upper limb control. Here, we aimed to differentially regulate the contribution of the cerebellum and M1 to proximal and distal effectors during motor adaptation, with transcranial direct current stimulation (tDCS). For this, we employed tasks that promote similar motor demands, but isolate whole arm from hand/finger movements, in order to functionally segregate the hierarchy of upper limb control.METHODS:Both young and older adults took part in a visuomotor rotation task; where they adapted to a 60° visuomotor rotation using either a hand-held joystick (requiring finger/hand movements) or a 2D robotic manipulandum (requiring whole-arm reaching movements), while M1, cerebellar or sham tDCS was applied.RESULTS:We found that cerebellar stimulation improved adaptation performance when arm movements were required to complete the task, while in contrast stimulation of M1 enhanced adaptation during hand and finger movements only. This double-dissociation was replicated in an independent group of older adults, demonstrating that the behaviour remains intact in ageing.CONCLUSIONS:These results suggest that stimulation of distinct motor areas can selectively improve motor adaptation in the proximal and distal upper limb. This also highlights new ways in which tDCS might be best applied to achieve reliable rehabilitation of upper limb motor deficits.

PURPOSE Working body schema (WBS) of the limbs may be indirectly assessed using left/right limb judgement (LRLJ) task performance. This study aimed to investigate if: 1) Total Knee Replacement (TKR) patients perform LRLJ tasks with reference to their WBS; 2) patients have a disrupted WBS following a TKR for the replaced knee compared to the contralateral knee; and 3) lower limb-based LRLJ task performance changes following post-surgical rehabilitation using change in upper limb-based LRLJ task performance as a control. METHODS In a convenience sample (n= 18, age 69 ± 7 yrs, 12F 6M) of TKR patients < 1 month post-surgery, WBS was assessed using LRLJ task performance for the upper (pictures of the hand) and lower limb (pictures of the foot) before and after rehabilitation. Accuracy and response time (RT) were analysed using a series of 2 × 2 × 2 ANOVAs. RESULTS LRLJ task performance for images corresponding with the operated and non-operated side were comparable for accuracy (p= 0.83) and RT (p= 0.28). Accuracy for hand images was comparable from baseline to post-rehabilitation (p= 0.54) whereas accuracy for feet images increased significantly (p= 0.03). Responses for awkward posture images were significantly slower than for more natural posture images (p= 0.001). CONCLUSIONS LRLJ task performance data reflected the typical biomechanical constraints indicative of implicit motor imagery being performed by patients. There was no evidence of a disrupted LRLJ task performance for the replaced knee compared to the contralateral knee. Following post-surgical rehabilitation, patients' lower limb LRLJ task performance improved whilst upper limb LRLJ task performance remained unchanged. These findings are the first to show that WBS improves with rehabilitation following TKR, and this may explain some of the clinical improvements observed. Undertaking LRLJ tasks could theoretically be a useful adjunct to current post-TKR rehabilitation.

The original article [1] contained a minor error in the following sentence in the Discussion.

Background: Left/right judgment tasks (LRJTs) are used in the management of chronic pain. This use is predicated on their ability to elicit the simulation of movements (i.e. motor imagery), including those where the execution of the same movements induces pain. While established for limb-based LRJTs, the ability of trunk-based LRJTs to elicit motor imagery of trunk movements has not been demonstrated. Objective: To establish whether data from a trunk-based LRJT are indicative of motor imagery being elicited for the specific lateralised trunk postures presented. Design: Cross-sectional repeated measures (within-subject experiment). Methods: Twenty-nine unimpaired and pain-free participants completed a trunk-based LRJT typical of those used in practice. Accordingly, left/right judgements were made to images depicting a human figure with its trunk rotated or side-flexed to the left or right. The extent (amplitude) of this movement was manipulated (small, medium, large). The whole figure was also oriented to different degrees (0 degrees, 45 degrees, 90 degrees, 135 degrees, 180 degrees) and along different axes (sagittal, axial, coronal). Results: Accuracy was higher and response times (RTs) faster (p < 0.001 for both) when lateralised trunk movements depicted had a larger amplitude, contrary to predictions if motor imagery was elicited. Differences in accuracy and RTs depending on the orientation of the whole figure were consistent with previous studies. Discussion: Data were not consistent with motor imagery of lateralised trunk movements being elicited by the trunk-based LRJT. The study presented here questions the value of trunk-based LRJTs in clinical practice.

BACKGROUND:Chronic upper limb motor impairment is a common outcome of stroke. Therapeutic training can reduce motor impairment. Recently, a growing interest in evaluating motor training provided by robotic assistive devices has emerged. Robot-assisted therapy is attractive because it provides a means of increasing practice intensity without increasing the workload of physical therapists. However, movements practised through robotic assistive devices are commonly pre-defined and fixed across individuals. More optimal training may result from individualizing the selection of the trained movements based on the individual's impairment profile. This requires quantitative assessment of the degree of the motor impairment prior to training, in relevant movement tasks. However, standard clinical measures for profiling motor impairment after stroke are often subjective and lack precision. We have developed a novel robot-mediated method for systematic and fine-grained mapping (or profiling) of individual performance across a wide range of planar arm reaching movements. Here we describe and demonstrate this mapping method and its utilization for individualized training. We also present a novel principle for the individualized selection of training movements based on the performance maps.METHODS AND RESULTS:To demonstrate the utility of our method we present examples of 2D performance maps produced from the kinetic and kinematics data of two individuals with stroke-related upper limb hemiparesis. The maps outline distinct regions of high motor impairment. The procedure of map-based selection of training movements and the change in motor performance following training is demonstrated for one participant.CONCLUSIONS:The performance mapping method is feasible to produce (online or offline). The 2D maps are easy to interpret and to be utilized for selecting individual performance-based training. Different performance maps can be easily compared within and between individuals, which potentially has diagnostic utility.