The complex interplay between perception, cognition, and action: a commentary on Bach et al. 2022.

Bach (Psychological Research 2022, https://doi.org/10.1007/s00426-022-01773-w ) offer a re-conceptualisation of motor imagery, influenced by older ideas of ideomotor action and formulated in terms of action effects rather than motor output. We share the view of an essential role of action effect in action planning and motor imagery processes, but we challenge the claim that motor imagery is non-motoric in nature. In the present article, we critically review some of Bach et al.'s proposed ideas and pose questions of whether effect and motor processes are functionally separable, and if not, what mechanisms underlie motor imagery and what terminology best captures its function.

Observation and imitation of object-directed hand movements in Parkinson's disease.

Action observation and imitation may facilitate movement in Parkinson's disease (PD). People with PD have been found to imitate intransitive actions similarly to neurologically healthy older adults, but their imitation of object-directed hand movements has not previously been investigated using kinematic measures. The present study examined observation and imitation of object-directed hand movements in 18 participants with PD and 21 neurologically healthy age-matched control participants. Participants observed and immediately imitated sequences showing a human hand reaching for and transferring an object between horizontal positions. Both groups significantly modulated their finger movements, showing higher vertical amplitude when imitating elevated compared to direct trajectories. In addition, movements were lower in vertical amplitude and higher in velocity when imitating the reaching segment than the transfer segment. Eye-tracking revealed that controls made smaller saccades when observing predictable than unpredictable elevated movements, but no effects of predictability on eye movements were found for the PD group. This study provides quantitative evidence that people with mild to moderate PD can imitate object-directed hand movement kinematics, although their prediction of such movements may be reduced. These findings suggest that interventions targeting object-directed actions may capitalize on the ability of people with PD to imitate kinematic parameters of a demonstrated movement.

The role of primary motor cortex in manual inhibition of return: A transcranial magnetic stimulation study.

Inhibition of return (IOR) is a behavioural phenomenon characterised by longer response times (RTs) to stimuli presented at previously cued versus uncued locations. The neural mechanisms underlying IOR effects are not fully understood. Previous neurophysiological studies have identified a role of frontoparietal areas including posterior parietal cortex (PPC) in the generation of IOR, but the contribution of primary motor cortex (M1) has not been directly tested. The present study investigated the effects of single-pulse transcranial magnetic stimulation (TMS) over M1 on manual IOR in a key-press task where peripheral (left or right) targets followed a cue at the same or opposite location at different SOAs (100/300/600/1000 ms). In Experiment 1, TMS was applied over right M1 on a randomized 50% of trials. In Experiment 2, active or sham stimulation was provided in separate blocks. In the absence of TMS (non-TMS trials in Experiment 1 and sham trials in Experiment 2), evidence of IOR was observed in RTs at longer SOAs. In both experiments, IOR effects differed between TMS and non-TMS/sham conditions, but the effects of TMS were greater and statistically significant in Experiment 1 where TMS and non-TMS trials were randomly interspersed. The magnitude of motor-evoked potentials was not altered by the cue-target relationship in either experiment. These findings do not support a key role of M1 in the mechanisms of IOR but suggest the need for further research to elucidate the role of the motor system in manual IOR effects.

Motor imagery vividness and symptom severity in Parkinson's disease.

Motor imagery (MI), the mental simulation of movement in the absence of overt motor output, has demonstrated potential as a technique to support rehabilitation of movement in neurological conditions such as Parkinson's disease (PD). Existing evidence suggests that MI is largely preserved in PD, but previous studies have typically examined global measures of MI and have not considered the potential impact of individual differences in symptom presentation on MI. The present study investigated the influence of severity of overall motor symptoms, bradykinesia and tremor on MI vividness scores in 44 individuals with mild to moderate idiopathic PD. Linear mixed effects modelling revealed that imagery modality and the severity of left side bradykinesia significantly influenced MI vividness ratings. Consistent with previous findings, participants rated visual motor imagery (VMI) to be more vivid than kinesthetic motor imagery (KMI). Greater severity of left side bradykinesia (but not right side bradykinesia) predicted increased vividness of KMI, while tremor severity and overall motor symptom severity did not predict vividness of MI. The specificity of the effect of bradykinesia to the left side may reflect greater premorbid vividness for the dominant (right) side or increased attention to more effortful movements on the left side of the body resulting in more vivid motor imagery.

Moving online: Experiences and potential benefits of digital dance for older adults and people with Parkinson's disease.

BACKGROUND: Dance provides a range of beneficial effects for older adults including individuals with age-related neurological conditions such as Parkinson's disease (PD). The COVID-19 pandemic accelerated the development of at-home dance programs delivered digitally through live and pre-recorded media, but little is known about how participants may engage with and benefit from these resources. OBJECTIVE: This study explored experiences and potential benefits of digital dance participation among healthy older adults and people with PD. METHODS: An online survey consisting of fixed-choice and open questions was designed in collaboration with dance program providers and distributed between June and November 2020. RESULTS: Healthy older adults (N = 149) and people with PD (N = 178) participating in at-home dance programs reported frequent engagement and a range of benefits. People with PD reported greater levels of motor (e.g., ease of movement, balance) than non-motor (e.g., energy, confidence) outcomes, while healthy older adults reported similar numbers of motor and non-motor outcomes. Positive outcomes were associated with the use of movement imagery during dance in both groups, while singing was associated with benefits in people with PD and vocalising was associated with benefits in older adults. At-home dance resources were found to offer convenience and flexibility, but participants missed the interaction, support, and routine provided by in-person classes. The majority expressed a preference to continue with both digital and in-person participation in the future. Qualitative analysis of participants' comments further revealed that digital participation could help to maintain connection and well-being, as well as identifying further considerations for improving accessibility and facilitating digital engagement. CONCLUSIONS: At-home dance appears to be accessible, engaging, and potentially beneficial for older adults and people with PD, although barriers to participation should be addressed. Digital resources will be increasingly important to enable cost-effective, large-scale provision of home-based therapeutic activities.

Mental rotation of hands and objects in ageing and Parkinson's disease: differentiating motor imagery and visuospatial ability.

Motor imagery supports motor learning and performance and has the potential to be a useful strategy for neurorehabilitation. However, motor imagery ability may be impacted by ageing and neurodegeneration, which could limit its therapeutic effectiveness. Motor imagery can be assessed implicitly using a hand laterality task (HLT), whereby laterality judgements are slower for stimuli corresponding to physically more difficult postures, as indicated by a "biomechanical constraint" effect. Performance is also found to differ between back and palm views of the hand, which may differentially recruit visual and sensorimotor processes. Older adults and individuals with Parkinson's disease (PD) have shown altered performance on the HLT; however, the effects of both ageing and PD on laterality judgements for the different hand views (back and palm) have not been directly examined. The present study compared healthy younger, healthy older, and PD groups on the HLT, an object-based mental rotation task, and an explicit motor imagery measure. The older and PD groups were slower than the younger group on the HLT, particularly when judging laterality from the back view, and exhibited increased biomechanical constraint effects for the palm. While response times were generally similar between older and PD groups, the PD group showed reduced accuracy for the back view. Letter rotation was slower and less accurate only in the PD group, while explicit motor imagery ratings did not differ significantly between groups. These results suggest that motor imagery may be slowed but relatively preserved in both typical ageing and neurodegeneration, while a PD-specific impairment in visuospatial processing may influence task performance. The findings have implications for the use of motor imagery in rehabilitation protocols.

More Than Movement: Exploring Motor Simulation, Creativity, and Function in Co-developed Dance for Parkinson's.

Dance is an enjoyable, non-therapy-focused activity that may provide a range of benefits for people with Parkinson's. The internal simulation of movement through observation, imitation, and imagery, is intrinsic to dance and may contribute to functional improvements for people with Parkinson's. This study explored the feasibility and potential benefits of a dance program designed by a collaborative team of dance artists, researchers, physiotherapists, and people living with Parkinson's. The program incorporated motor simulation through observation, imitation and imagery of movement, supported by creative themes, expression, and music. A 6-week pilot trial of the program was conducted with 10 people with Parkinson's. A focus group following the trial (N = 8) provided insights into the use of imagery, observation and imitation within dance, and the link between creativity and functional outcomes, as well as indicating multidimensional benefits of dance as reported in previous studies. Exploratory outcome measures also suggested potential effects on motor simulation, functional dexterity, and quality of life. The present study demonstrates the feasibility of a co-developed dance program for Parkinson's and indicates how creative elements of dance may support functional outcomes. Future research should examine the role of motor simulation processes in dance for Parkinson's, including the potential to develop transferable cognitive-motor skills. This study also highlights the value of collaborative partnerships in designing dance for health programs, which may optimise beneficial effects by using creative approaches to incorporate evidence-based elements, with guidance from individuals with lived experience to ensure the relevance to their goals.

Feelings first? Sex differences in affective and cognitive processes in emotion recognition.

The recognition of emotional expressions is important for social understanding and interaction, but findings on the relationship between emotion recognition, empathy, and theory of mind, as well as sex differences in these relationships, have been inconsistent. This may reflect the relative involvement of affective and cognitive processes at different stages of emotion recognition and in different experimental paradigms. In this study, images of faces were morphed from neutral to full expression of five basic emotions (anger, disgust, fear, happiness, and sadness), which participants were asked to identify as quickly and accurately as possible. Accuracy and response times from healthy males (n = 46) and females (n = 43) were analysed in relation to self-reported empathy (Empathy Quotient; EQ) and mentalising/theory of mind (Reading the Mind in the Eyes Test). Females were faster and more accurate than males in recognising dynamic emotions. Linear mixed-effects modelling showed that response times were inversely related to the emotional empathy subscale of the EQ, but this was accounted for by a female advantage on both measures. Accuracy was unrelated to EQ scores but was predicted independently by sex and Eyes Test scores. These findings suggest that rapid processing of dynamic emotional expressions is strongly influenced by sex, which may reflect the greater involvement of affective processes at earlier stages of emotion recognition.

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

BACKGROUND: Parkinson's disease (PD) causes difficulties with hand movements, which few studies have addressed therapeutically. Training with action observation (AO) and motor imagery (MI) improves performance in healthy individuals, particularly when the techniques are applied simultaneously (AO + MI). Both AO and MI have shown promising effects in people with PD, but previous studies have only used these separately. OBJECTIVE: This article describes the development and pilot testing of an intervention combining AO + MI and physical practice to improve functional manual actions in people with PD. METHODS: The home-based intervention, delivered using a tablet computer app, was iteratively designed by an interdisciplinary team, including people with PD, and further developed through focus groups and initial field testing. Preliminary data on feasibility were obtained via a six-week pilot randomised controlled trial (ISRCTN 11184024) of 10 participants with mild to moderate PD (6 intervention; 4 treatment as usual). Usage and adherence data were recorded during training, and semistructured interviews were conducted with participants. Exploratory outcome measures included dexterity and timed action performance. RESULTS: Usage and qualitative data provided preliminary evidence of acceptability and usability. Exploratory outcomes also suggested that subjective and objective performance of manual actions should be tested in a larger trial. The importance of personalisation, choice, and motivation was highlighted, as well as the need to facilitate engagement in motor imagery. CONCLUSIONS: The results indicate that a larger RCT is warranted, and the findings also have broader relevance for the feasibility and development of AO + MI interventions for PD and other conditions.

Dance at Home for People With Parkinson's During COVID-19 and Beyond: Participation, Perceptions, and Prospects.

Emerging evidence shows that dance can provide both physical and non-physical benefits for people living with Parkinson's disease (PD). The suspension of in-person dance classes during the COVID-19 pandemic necessitated a transition to remote provision via live and recorded digital media. An online survey explored accessibility of and engagement with home-based dance programs, as well as potential benefits and processes involved in participation. The survey was co-developed by researchers and dance program providers, with input from people with PD and physiotherapists. Responses were collected from 276 individuals, including 178 current users of home-based programs, the majority of whom were participating at least once per week. Among respondents not currently using digital resources, lack of knowledge and motivation were the primary barriers. Most participants (94.9%) reported that home based practise provided some benefits, including physical (e.g., balance, posture) and non-physical (e.g., mood, confidence) improvements. Participants valued the convenience and flexibility of digital participation, but noted limitations including reductions in social interaction, support from instructors and peers, and motivation. There was a strong preference (70.8%) for continuing with home-based practise alongside in-person classes in the future. The results indicate that at-home dance is accessible and usable for people with PD, and that some of the previously-reported benefits of dance may be replicated in this context. Digital dance programs will likely remain a key element of future provision for people with PD, and the present findings will inform further development of resources and research into mechanisms and outcomes of home-based dance participation.

Action observation and imitation in Parkinson's disease: The influence of biological and non-biological stimuli.

Action observation and imitation have been found to influence movement in people with Parkinson's disease (PD), but simple visual stimuli can also guide their movement. To investigate whether action observation may provide a more effective stimulus than other visual cues, the present study examined the effects of observing human pointing movements and simple visual stimuli on hand kinematics and eye movements in people with mild to moderate PD and age-matched controls. In Experiment 1, participants observed videos of movement sequences between horizontal positions, depicted by a simple cue with or without a moving human hand, then imitated the sequence either without further visual input (consecutive task) or while watching the video again (concurrent task). Modulation of movement duration, in accordance with changes in the observed stimulus, increased when the simple cue was accompanied by the hand and in the concurrent task, whereas modulation of horizontal amplitude was greater with the simple cue alone and in the consecutive task. Experiment 2 compared imitation of kinematically-matched dynamic biological (human hand) and non-biological (shape) stimuli, which moved with a high or low vertical trajectory. Both groups exhibited greater modulation for the hand than the shape, and differences in eye movements suggested closer tracking of the hand. Despite producing slower and smaller movements overall, the PD group showed a similar pattern of imitation to controls across tasks and conditions. The findings demonstrate that observing human action influences aspects of movement such as duration or trajectory more strongly than non-biological stimuli, particularly during concurrent imitation.

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

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

Measuring emotion recognition by people with Parkinson's disease using eye-tracking with dynamic facial expressions.

BACKGROUND: Motion is an important cue to emotion recognition, and it has been suggested that we recognize emotions via internal simulation of others' expressions. There is a reduction of facial expression in Parkinson's disease (PD), which may influence the ability to use motion to recognise emotions in others. However, the majority of previous work in PD has used only static expressions. Moreover, few studies have used eye-tracking to explore emotion processing in PD. NEW METHOD: We measured accuracy and eye movements in people with PD and healthy controls when identifying emotions from both static and dynamic facial expressions. RESULTS: The groups did not differ overall in emotion recognition accuracy, but motion significantly increased recognition only in the control group. Participants made fewer and longer fixations when viewing dynamic expressions, and interest area analysis revealed increased gaze to the mouth region and decreased gaze to the eyes for dynamic stimuli, although the latter was specific to the control group. COMPARISON WITH EXISTING METHODS: Ours is the first study to directly compare recognition of static and dynamic emotional expressions in PD using eye-tracking, revealing subtle differences between groups that may otherwise be undetected. CONCLUSIONS: It is feasible and informative to use eye-tracking with dynamic expressions to investigate emotion recognition in PD. Our findings suggest that people with PD may differ from healthy older adults in how they utilise motion during facial emotion recognition. Nonetheless, gaze patterns indicate some effects of motion on emotional processing, highlighting the need for further investigation in this area.

Action observation produces motor resonance in Parkinson's disease.

Observation of movement activates the observer's own motor system, influencing the performance of actions and facilitating social interaction. This motor resonance is demonstrated behaviourally through visuomotor priming, whereby response latencies are influenced by the compatibility between an intended action and an observed (task-irrelevant) action. The impact of movement disorders such as Parkinson's disease (PD) on motor resonance is unclear, as previous studies of visuomotor priming have not separated imitative compatibility (specific to human movement) from general stimulus-response compatibility effects. We examined visuomotor priming in 23 participants with mild-to-moderate PD and 24 healthy older adults, using a task that pitted imitative compatibility against general stimulus-response compatibility. Participants made a key press after observing a task-irrelevant moving human finger or rectangle that was either compatible or incompatible with their response. Imitative compatibility effects, rather than general stimulus-response compatibility effects, were found specifically for the human finger. Moreover, imitative compatibility effects did not differ between groups, indicating intact motor resonance in the PD group. These findings constitute the first unambiguous demonstration of imitative priming in both PD and healthy ageing, and have implications for therapeutic techniques to facilitate action, as well as the understanding of social cognition in PD.

Patients' Views on a Combined Action Observation and Motor Imagery Intervention for Parkinson's Disease.

Background. Action observation and motor imagery activate neural structures involved in action execution, thereby facilitating movement and learning. Although some benefits of action observation and motor imagery have been reported in Parkinson's disease (PD), methods have been based on stroke rehabilitation and may be less suitable for PD. Moreover, previous studies have focused on either observation or imagery, yet combining these enhances effects in healthy participants. The present study explores the feasibility of a PD-specific home-based intervention combining observation, imagery, and imitation of meaningful everyday actions. Methods. A focus group was conducted with six people with mild to moderate PD and two companions, exploring topics relating to the utility and feasibility of a home-based observation and imagery intervention. Results. Five themes were identified. Participants reported their experiences of exercise and use of action observation and motor imagery in everyday activities, and the need for strategies to improve movement was expressed. Motivational factors including feedback, challenge, and social support were identified as key issues. The importance of offering a broad range of actions and flexible training was also highlighted. Conclusions. A home-based intervention utilising action observation and motor imagery would be useful and feasible in mild to moderate PD.

Conductive Education as a Method of Stroke Rehabilitation: A Single Blinded Randomised Controlled Feasibility Study.

Background. Conductive Education for stroke survivors has shown promise but randomised evidence is unavailable. This study assessed the feasibility of a definitive randomised controlled trial to evaluate efficacy. Methods. Adult stroke survivors were recruited through local community notices. Those completing the baseline assessment were randomised using an online program and group allocation was independent. Intervention group participants received 10 weekly 1.5-hour sessions of Conductive Education at the National Institute of Conductive Education in Birmingham, UK. The control group participants attended two group meetings. The study evaluated the feasibility of recruitment procedures, delivery of the intervention, retention of participants, and appropriateness of outcome measures and data collection methods. Independent assessments included the Barthel Index, the Stroke Impact Scale, the Timed Up and Go test, and the Hospital Anxiety and Depression Scale. Results. Eighty-two patients were enrolled; 77 completed the baseline assessment (46 men, mean age 62.1 yrs.) and were randomised. 70 commenced the intervention (n = 37) or an equivalent waiting period (n = 33). 32/37 completed the 10-week training and 32/33 the waiting period. There were no missing items from completed questionnaires and no adverse events. Discussion. Recruitment, intervention, and assessment methods worked well. Transport issues for intervention and assessment appointments require review. Conclusion. A definitive trial is feasible. This trial is registered with ISRCTN84064492.

Enhancing voluntary imitation through attention and motor imagery.

Action observation activates brain areas involved in performing the same action and has been shown to increase motor learning, with potential implications for neurorehabilitation. Recent work indicates that the effects of action observation on movement can be increased by motor imagery or by directing attention to observed actions. In voluntary imitation, activation of the motor system during action observation is already increased. We therefore explored whether imitation could be further enhanced by imagery or attention. Healthy participants observed and then immediately imitated videos of human hand movement sequences, while movement kinematics were recorded. Two blocks of trials were completed, and after the first block participants were instructed to imagine performing the observed movement (Imagery group, N = 18) or attend closely to the characteristics of the movement (Attention group, N = 15), or received no further instructions (Control group, N = 17). Kinematics of the imitated movements were modulated by instructions, with both Imagery and Attention groups being closer in duration, peak velocity and amplitude to the observed model compared with controls. These findings show that both attention and motor imagery can increase the accuracy of imitation and have implications for motor learning and rehabilitation. Future work is required to understand the mechanisms by which these two strategies influence imitation accuracy.

Language and spatial reorientation: evidence from severe aphasia.

Investigating spatial cognition in individuals with acquired language impairments can inform our understanding of how components of language are involved in spatial representation. Using the reorientation paradigm of Hermer-Vazquez, Spelke, and Katsnelson (1999), we examined spatial cue integration (landmark-geometry conjunctions) in individuals with severe agrammatic or global aphasia and in a group of healthy older adults. Participants with aphasia performed similarly to healthy controls in the reorientation task, demonstrating the ability to integrate landmark and geometric cues, even during a concurrent verbal task designed to block access to any residual lexical resources. These results extend previous findings with healthy adults by suggesting that neither syntax nor lexicon is essential for spatial cue representation in a mature cognitive system, and provide further evidence that language deficits in aphasia can be independent from other domains of reasoning.