Mental motor imagery indexes pain: the hand laterality task

Impact of chronic low back pain on implicit motor imagery assessed by a new laterality judgment task

It is clear that implicit motor imagery (IMI) is impaired by chronic pain in peripheral regions (hand, feet), but unclear in axial regions (neck, shoulder, back). Previous IMI tasks displayed small-amplitude movements of axial regions, which limits person-centered IMI processes mobilization. This study aimed to assess the impact of chronic low back pain (CLBP) on IMI processes with a new task displaying large-amplitude whole-body movements mobilizing the lumbar spine. Twenty patients with CLBP and twenty age-matched controls performed a laterality judgment task on four distinct whole-body movements (trunk flexion, trunk rotation, capoeira, kickboxing). Participants viewed images from four different body viewpoints (back, left, right and front), randomly presented. Mixed ANOVAs were used to compare judgment accuracy and response times between groups and conditions. In participants with CLBP, response times were longer than in controls. The response times of participants with CLBP were also associated with DN4 scores, a self-reported questionnaire assessing neuropathic pain. We validated the use of a person-centered IMI because, for all participants, the accuracy decreased and the response times increased for images presented in the front viewpoint, i.e. when a 180° turn in IMI was required, compared to other viewpoints. The laterality judgment task proposed here confirmed that CLBP impacts IMI processes, and that the nature of pain (neuropathic or mechanical) needs to be considered because it seems to modulate IMI processes. PERSPECTIVES: A laterality judgment task with large-amplitude lumbar movements is key to show that CLBP alters processing speed of sensorimotor information originating from the painful region. This task could become an objective tool, transferable in clinical settings, for assessing the impact and the progression of CLBP on motor control processes.

The effectiveness of graded motor imagery and its components on phantom limb pain in amputated patients: A systematic review

BACKGROUND

Phantom limb pain (PLP) can be defined as pain in a missing part of the limb. It is reported in 50%-80% of people with amputation.

OBJECTIVES

To provide an overview of the effectiveness of graded motor imagery (GMI) and the techniques which form it on PLP in amputees.

STUDY DESIGN

Systematic review.

METHODS

Two authors independently selected relevant studies, screened the articles for methodological validity and risk of bias, and extracted the data. Inclusion criteria used were clinical studies, written in English or Spanish, using GMI, laterality recognition, motor imagery, mirror therapy, or a combination of some of them as an intervention in amputated patients, and one of the outcomes was PLP, and it was assessed using a validated scale. The databases used were PubMed, Scopus, Web of Science, CINAHL, and PEDro.

RESULTS

Fifteen studies were included in the review. After the intervention, all the groups in which the GMI or one of the techniques that comprise it was used showed decrease in PLP.

CONCLUSION

The 3 GMI techniques showed effectiveness in decreasing PLP in amputees, although it should be noted that the application of the GMI showed better results.

Can they touch? A novel mental motor imagery task for the assessment of back pain

Introduction

As motor imagery is informed by the anticipated sensory consequences of action, including pain, we reasoned that motor imagery could provide a useful indicator of chronic back pain. We tested the hypothesis that mental motor imagery regarding body movements can provide a reliable assessment of low back pain.

Methods

Eighty-five subjects with back pain and forty-five age-matched controls were shown two names of body parts and asked to indicate if they could imagine moving so that the named body parts touched. Three types of imagined movements were interrogated: movements of arms, movements of legs and movements requiring flexion and/or rotation of the low back.

Results

Accuracy and reaction times were measured. Subjects with back pain were less likely to indicate that they could touch body parts than age-matched controls. The effect was observed only for those movements that required movement of the low back or legs, suggesting that the effect was not attributable to task difficulty or non-specific effects. There was an effect of pain severity. Compared to subjects with mild pain, subjects with severe pain were significantly less likely to indicate that they could move so that named body parts touched. There was a correlation between pain ratings and impaired performance for stimuli that involved the lower but not upper body.

Discussion

As the Can They Touch task is quick, easy to administer and does not require an explicit judgment of pain severity, it may provide useful information to supplement the assessment of subjects with chronic pain.

Body image disturbance, interoceptive sensibility and the body schema across female adulthood: a pre-registered study

Introduction

Body image disturbance (BID) typically involves explicit negative attitudes toward one's shape and weight and is associated with altered interoceptive sensibility (the subjective perception of internal bodily states). This association is a known risk factor for the development and maintenance of eating disorders. However, while research has centred on younger women with eating disorders, diverse facets of BID appear in women without eating disorders across adulthood. Research shows that in the general population, young women (ages 18-25) with high BID exhibit disturbances in the body schema: an implicit sensorimotor representation of the body in space which includes mental simulation of a movement such as motor imagery. Given that body image is subject to age-related influences, it is important to investigate how age-related variation in BID can influence the body schema beyond young adulthood alone. Here, we examine the relationship between BID, interoceptive sensibility and the body schema across female adulthood.

Methods

Cross-sectional data was collected online from 1,214 women across four age groups: Young adults (18-24), Adults (25-39), Middle-aged adults (40-59), and Older aged adults (60-75). BID was indexed by questionnaires measuring body objectification, state, and trait body dissatisfaction. Interoceptive sensibility (IS) was measured using the MAIA-2 questionnaire. The body schema was evaluated through the Own Body Transformation task: a mental rotation task which assesses the capacity to make an embodied mental transformation.

Results

Analyses revealed that while body objectification and trait body dissatisfaction decreased from young to older adulthood, state body dissatisfaction showed a marked increase. A negative relationship between IS and BID across all age groups was also evidenced. Finally, age, BID and orientation of the presented body were significant predictors of the time taken to make an embodied transformation.

Discussion

These findings highlight the consistent relationship of BID and IS across age groups beyond young adulthood and demonstrate the varying importance of different aspects of BID as individuals age. We also evidence for the first time that disruptions in body image have the potential to impact implicit sensorimotor representations of the body even in women without eating disorders across female adulthood.

Does mental rotation emulate motor processes? An electrophysiological study of objects and body parts

Several arguments suggest that motor planning may share embodied neural mechanisms with mental rotation (MR). However, it is not well established whether this overlap occurs regardless of the type of stimulus that is manipulated, in particular manipulable or non-manipulable objects and body parts. We here used high-density electroencephalography (EEG) to examine the cognitive similarity between MR of objects that do not afford specific hand actions (chairs) and bodily stimuli (hands). Participants had identical response options for both types of stimuli, and they gave responses orally in order to prevent possible interference with motor imagery. MR of hands and chairs generated very similar behavioral responses, time-courses and neural sources of evoked-response potentials (ERPs). ERP segmentation analysis revealed distinct time windows during which differential effects of stimulus type and angular disparity were observed. An early period (90-160 ms) differentiated only between stimulus types, and was associated with occipito-temporal activity. A later period (290-330 ms) revealed strong effects of angular disparity, associated with electrical sources in the right angular gyrus and primary motor/somatosensory cortex. These data suggest that spatial transformation processes and motor planning are recruited simultaneously, supporting the involvement of motor emulation processes in MR.

Distorted body schema after mastectomy with immediate breast reconstruction: a 4-month follow up study

Background

After breast cancer, some patients report residual pain-related upper limb disability without physical impairment. Although pain and altered proprioception are known to affect the working body schema (WBS), there is little available evidence investigating the WBS of breast cancer survivors (BrCS). WBS-body representations in the brain-affect the "neuromatrix" that modulates pain sensitivity and the threshold for threatening stimuli. The aim of this study was to investigate whether WBS was disrupted after mastectomy with immediate breast reconstruction (IBR) for breast cancer and whether pain and proprioceptive changes affected WBS.

Methods

Thirty-five BrCS participated in the 4-month follow-up study. They were observed at 1 and 4 months postoperatively. The main outcome measures were the left right judgement test (LRJT) results, absolute angle error, pectoralis minor length index (PMI), pain, and Quick-Disabilities of the Arm, Shoulder, and Hand (Q-DASH) score. They were measured at each observation, and parametric tests were performed to identify the nature of WBS.

Results

Both the reaction time and accuracy of the hand LRJT were poorer than those of the foot and back LRJT (p < 0.001). The hand LRJT reaction time and accuracy were unchanged over the total follow-up period (p = 0.77 and p = 0.47, respectively). There was a weak correlation between the LRJT reaction time and PMI (r = -0.26, p = 0.07), pain severity (r = 0.37, p = 0.02), and Q-DASH score (r = 0.37, p = 0.02). There was also a weak correlation between LRJT accuracy and Q-DASH score (r = -0.31, p = 0.04). The LRJT accuracy of BrCS who underwent surgery on their dominant side was higher than that of BrCS who underwent surgery on their non-dominant side (p = 0.002). Regression analysis found a weak but significant relationship between the early hand LRJT results and late pain severity (adjusted R² = 0.179, p = 0.007). A similar relationship was found between early hand LRJT results and Q-DASH score (adjusted R² = 0.099, p = 0.039).

Conclusion

To the best of our knowledge, this is the first study providing the nature of WBS after mastectomy with IBR. In this population, it is necessary to postoperatively preserve WBS integrity for pain and upper limb disability.

Effectiveness of graded motor imagery protocol in phantom limb pain in amputed patient: Protocol of a randomized clinical trial

OBJECTIVE

The aim of this study is to analyse the effectiveness of the Graded Motor Imagery (GraMI) protocol in phantom limb pain in amputee patients.

MATERIALS AND METHODS

A randomised clinical trial will be conducted, with two parallel groups and simple blinding, and a phenomenological study with semi-structured interviews. People over the age of 18, with amputation of one limb, with a minimum score of 3 on the visual analogue scale of pain, who are pharmacologically stable and have been discharged from hospital, will be recruited. An initial assessment, a post-intervention assessment (9 weeks) and a follow-up assessment (12 weeks post-intervention) will be performed, in which pain, quality of life, functionality and psychological aspects will be assessed. The aim of the qualitative study is to find out about the experience of living with phantom limb pain and to identify the satisfaction with the intervention. A descriptive, univariate and bivariate quantitative statistical analysis will be performed using the SPSS program, with a 95% confidence level and a statistical significance level of p < 0.05. The qualitative analysis will be carried out using the Atlas.ti 8.0 program, where the different interviews will be analysed, coded and categorised.

DISCUSSION

The GraMI protocol allows the patient to work on motor learning through brain reorganisation, analytical movements, sensory stimulation, and functional activities. In addition, it can help to standardise the use of graded motor imagery in future studies and in clinical practice with this patient profile.

TRIAL REGISTRATION

NCT05083611.

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.

Hand laterality recognition in distal radius and/or ulna fracture

INTRODUCTION

Hand laterality, an important ability to determine the orientation of a limb is common to get affected after short term immobilization. Distal radius and/or ulna fracture is a commonly encountered fracture resulting from upper-limb trauma. Conservative treatment using closed reduction and plaster cast application to immobilize the joint remains choice of treatment over surgery in the treatment of these fractures. There is a paucity of literature reporting impairment in hand laterality after long term immobilization as commonly performed in patients with distal radius and/or ulna fractures. Understanding effect of immobilization on hand laterality in distal-end radius/ulna fractures warranted present investigation.

PURPOSE

To evaluate hand laterality based on the accuracy and response time for hand determination after plaster cast removal in distal radius and/or ulna fracture.

STUDY DESIGN

Prospective cross sectional study.

METHODOLOGY

Subjects (n = 60, age range = 40-59 years, females (n) = 28 and males (n) = 32) were shown 24 real-hand images with various degrees of angular rotation and instructed to identify the hand as left and/or right. Accuracy (% correctly identified) and Response time (milliseconds to identify left or right hand in the image) of motor imagery during hand laterality task were recorded. Pain intensity before and after the hand laterality task were noted using Visual Analogue Scale. Repeated measures of ANOVA and t tests were used to analyze the accuracy and response times among two groups.

RESULTS

The experimental group showed significantly (P < .05) lower accuracy and longer response time as compared to the control group. No significant difference in the accuracy and response time were noted in the immobilization of the dominant and the non-dominant hand within the experimental group (P > .05). Also, there was no change in pain pre- to post-hand laterality task.

CONCLUSION

Findings of this study could aid in enhancing the understanding of post-immobilization effect on hand laterality and open new arenas for assessment and rehabilitation of distal-end radius and/or ulna fractures where immobilization is the principal treatment.

The sensorimotor theory of pathological pain revisited

Harris (1999) proposed that pain can arise in the absence of tissue damage because changes in the cortical representation of the painful body part lead to incongruences between motor intention and sensory feedback. This idea, subsequently termed the sensorimotor theory of pain, has formed the basis for novel treatments for pathological pain. Here we review the evidence that people with pathological pain have changes to processes contributing to sensorimotor function: motor function, sensory feedback, cognitive representations of the body and its surrounding space, multisensory processing, and sensorimotor integration. Changes to sensorimotor processing are most evident in the form of motor deficits, sensory changes, and body representations distortions, and for Complex Regional Pain Syndrome (CRPS), fibromyalgia, and low back pain. Many sensorimotor changes are related to cortical processing, pain, and other clinical characteristics. However, there is very limited evidence that changes in sensorimotor processing actually lead to pain. We therefore propose that the theory is more appropriate for understanding why pain persists rather than how it arises.

Bodily Illusions and Motor Imagery in Fibromyalgia

Fibromyalgia (FM) is characterised by chronic, continuous, widespread pain, often associated with a sense of fatigue, non-restorative sleep and physical exhaustion. Due to the nature of this condition and the absence of other neurological issues potentially able to induce disorders in body representations per se, it represents a perfect model since it provides an opportunity to study the relationship between pain and the bodily self. Corporeal illusions were investigated in 60 participants with or without a diagnosis of FM by means of an ad hoc devised interview. In addition, motor imagery was investigated and illusions relating to body part movements and changes in body size, feelings of alienness, and sensations of body parts not belonging to one's own body (disownership and somatoparaphrenic-like sensations) were found. Crucially, these symptoms do not correlate with any of the clinical measures of pain or functional deficits. The results showed that motor imagery was also impaired, and the severity of the deficits found correlated with the functional impairment of the participant. This indicates that disorders in body representations and motor imagery are part of the clinical expression of FM. However, while motor imagery seems to be linked to reduced autonomy and functional deficits, bodily illusions are independent and potentially represent a concurrent symptom.

EXPRESS: Does physical weight alter the mental representation of the body? Evidence from motor imagery in obesity

OBJECTIVE

Obesity is a clinical condition that impacts severely the physical body. However, evidence related to the mental representation of the body in action is scarce. The few available studies only focus on avoiding obstacles, rather than participants imagining their own body.

METHOD

To advance knowledge in this field, we assessed the performance of twenty-two individuals with obesity compared to thirty individuals with a healthy weight in two tasks that implied different motor (more implicit vs. more explicit) imagery strategies. Two tasks were also administered to control for visual imagery skills, to rule out confounding factors. Moreover, we measured body uneasiness, through a standard questionnaire, as body image negativity could impact on other body representation components.

RESULTS

Our findings do not show differences in the motor imagery tasks between individuals with obesity and individuals with healthy weight. On the other hand, some differences emerge in visual imagery skills. Crucially, individuals with obesity did report a higher level of body uneasiness.

CONCLUSIONS

Despite a negative body image and visual imagery differences, obesity per se does not impact on the representation of the body in action. Importantly, this result is independent from the level of awareness required to access the mental representation of the body.

OUP accepted manuscript

Neuralgic amyotrophy is a common peripheral nerve disorder caused by autoimmune inflammation of the brachial plexus, clinically characterized by acute pain and weakness of the shoulder muscles, followed by motor impairment. Despite recovery of the peripheral nerves, patients often have residual motor dysfunction of the upper extremity, leading to persistent pain related to altered biomechanics of the shoulder region. Building on clinical signs that suggest a role for cerebral mechanisms in these residual complaints, here we show and characterize cerebral alterations following neuralgic amyotrophy. Neuralgic amyotrophy patients often develop alternative motor strategies, which suggests that (mal)adaptations may occur in somatomotor and/or visuomotor brain areas. Here, we tested where changes in cerebral sensorimotor representations occur in neuralgic amyotrophy, while controlling for altered motor execution due to peripheral neuropathy. We additionally explore the relation between potential cerebral alterations in neuralgic amyotrophy and clinical symptoms. During functional MRI scanning, 39 neuralgic amyotrophy patients with persistent, lateralized symptoms in the right upper extremity and 23 matched healthy participants solved a hand laterality judgement task that can activate sensorimotor representations of the upper extremity, across somatomotor and visuomotor brain areas. Behavioural and cerebral responses confirmed the involvement of embodied, sensorimotor processes across groups. Compared with healthy participants, neuralgic amyotrophy patients were slower in hand laterality judgement and had decreased cerebral activity specific to their affected limb in two higher-order visual brain regions: the right extrastriate cortex and the parieto-occipital sulcus. Exploratory analyses revealed that across patients, extrastriate activity specific to the affected limb decreased as persistent pain increased, and affected limb-related parieto-occipital activity decreased as imagery performance of the affected limb became slower. These findings suggest that maladaptive cerebral plasticity in visuomotor areas involved in sensorimotor integration plays a role in residual motor dysfunction and subsequent persistent pain in neuralgic amyotrophy. Rehabilitation interventions that apply visuomotor strategies to improve sensorimotor integration may help to treat neuralgic amyotrophy patients.

Body representation among adults with phantom limb pain: Results from a foot identification task

BACKGROUND

Impaired body representation (i.e. disrupted body awareness or perception) may be a critical, but understudied, factor underlying phantom limb pain (PLP). This cross-sectional study investigated whether adults with lower-limb loss (LLL) and PLP demonstrate impaired body representation as compared to Pain-Free peers with and without LLL.

METHODS

Participants (n = 41 adults with PLP, n = 27 Pain-Free peers with LLL, n = 39 Controls with intact limbs) completed an online foot identification task. Participants judged whether randomized images depicted left or right feet (i.e. left-right discrimination) as quickly as possible without limb movement. Using two Generalized Estimating Equations, effects of group, image characteristics (i.e. side, foot type, view, angle) and trial block (i.e. 1-4) were evaluated, with task response time and accuracy as dependent variables (a ≤ 0.050).

RESULTS

Adults with PLP demonstrated slower and less accurate performance as compared to Controls with intact limbs (p = 0.018) but performed similarly to Pain-Free peers with LLL (p = 0.394). Significant three-way interactions of group, view and angle indicated between-group differences were greatest for dorsal-view images, but smaller and angle-dependent for plantar-view images. While all groups demonstrated significant response time improvements across blocks, improvements were greatest among adults with PLP, who also reported significant reductions in pain intensity.

CONCLUSIONS

Adults with PLP demonstrate body representation impairments as compared to Controls with intact limbs. Body representation impairments, however, may not be unique to PLP, given similar performance between adults with and without PLP following LLL.

SIGNIFICANCE

Following lower-limb loss, adults with phantom limb pain (PLP) demonstrate impaired body representation as compared to Controls with intact limbs, evidenced by slower response times and reduced accuracy when completing a task requiring mental rotation. Importantly, 80% of participants with pre-task PLP reported reduced pain intensity during the task, providing compelling evidence for future investigations into whether imagery-based, mind-body interventions have positive effects on PLP.

From Action to Cognition: Neural Reuse, Network Theory and the Emergence of Higher Cognitive Functions

The aim of this article is to discuss the logic and assumptions behind the concept of neural reuse, to explore its biological advantages and to discuss the implications for the cognition of a brain that reuses existing circuits and resources. We first address the requirements that must be fulfilled for neural reuse to be a biologically plausible mechanism. Neural reuse theories generally take a developmental approach and model the brain as a dynamic system composed of highly flexible neural networks. They often argue against domain-specificity and for a distributed, embodied representation of knowledge, which sets them apart from modular theories of mental processes. We provide an example of reuse by proposing how a phylogenetically more modern mental capacity (mental rotation) may appear through the reuse and recombination of existing resources from an older capacity (motor planning). We conclude by putting arguments into context regarding functional modularity, embodied representation, and the current ontology of mental processes.

Development and Validation of a Graded Motor Imagery Intervention for Phantom Limb Pain in Patients with Amputations (GraMI Protocol): A Delphi Study

BACKGROUND

Phantom limb pain can be defined as discomfort or pain in a missing part of the limb. The aims of this study were to develop and validate, through a Delphi methodology, a graded motor imagery protocol in order to reduce phantom limb pain.

METHOD

Physiotherapists and/or occupational therapists with experience in research and a minimum clinical experience of five years in the field of neurorehabilitation and/or pain were recruited by part of a group of experts to assess the intervention. The study was conducted through an online questionnaire, where experts assessed each aspect of the intervention through a Likert scale. As many rounds as necessary were carried out until consensus was reached among experts.

RESULTS

A total of two rounds were required to fully validate the intervention. During the second round, the relative interquartile range of all aspects to be assessed was less than 15%, thus showing a consensus among experts and with good concordance (Kappa index of 0.76).

CONCLUSION

Experts validated a graded motor imagery intervention of phantom limb pain in patients with amputations (GraMi protocol). This intervention can help to homogenize the use of graded motor imagery in future studies and in clinical practice.

Cognitive Training Improves Disconnected Limbs' Mental Representation and Peripersonal Space after Spinal Cord Injury

Paraplegia following spinal cord injury (SCI) affects the mental representation and peripersonal space of the paralysed body parts (i.e., lower limbs). Physical rehabilitation programs can improve these aspects, but the benefits are mostly partial and short-lasting. These limits could be due to the absence of trainings focused on SCI-induced cognitive deficits combined with traditional physical rehabilitation. To test this hypothesis, we assessed in 15 SCI-individuals the effects of adding cognitive recovery protocols (motor imagery–MI) to standard physical rehabilitation programs (Motor + MI training) on mental body representations and space representations, with respect to physical rehabilitation alone (control training). Each training comprised at least eight sessions administered over two weeks. The status of participants’ mental body representation and peripersonal space was assessed at three time points: before the training (T0), after the training (T1), and in a follow-up assessment one month later (T2). The Motor + MI training induced short-term recovery of peripersonal space that however did not persist at T2. Body representation showed a slower neuroplastic recovery at T2, without differences between Motor and the Motor + MI. These results show that body and space representations are plastic after lesions, and open new rehabilitation perspectives.

Is implicit motor imagery altered in people with shoulder pain? The shoulder left/right judgement task

BACKGROUND

Implicit motor imagery performance is altered in a variety of chronic pain conditions, but it is not known whether this is the case in shoulder pain.

OBJECTIVES

The aim of this study was to assess implicit motor imagery performance, using a valid and reliable shoulder left/right judgement task in people with shoulder pain.

DESIGN

Cross-sectional observational study.

METHODS

Participants with (n = 369) and without (n = 747) shoulder pain completed the shoulder left/right judgement task (LRJT). Response times (RT), accuracy were determined. Age, gender, hand dominance, current pain intensity, Shoulder Pain and Disability Index (SPADI) and pain duration recorded. Planned analysis included ANOVAs for current pain, RT and accuracy.

RESULTS

Gender and hand dominance distribution were similar between groups (p > 0.5). The shoulder pain participants were older, mean age (SD); 47(14)years, than the control group; 41(14)years, p < 0.01. Participants with shoulder pain were slower, mean RT(SD); 1809(746)ms than the controls; 1701(749)ms; p = 0.02, but no different in accuracy, mean % (SD); 93.2(8.5)% to controls; 94.1(9.4)%; p = 0.13. The differences in RT were resolved when age was entered as a covariate (p = 0.83). Regression of the data from the shoulder pain group only found that current pain was positively related to RT (B = 43.97) and negatively to accuracy (B = -0.70).

CONCLUSIONS

Participants with shoulder pain do not demonstrate poorer implicit motor imagery performance than people who are pain-free. However, more intense shoulder pain is associated with poorer implicit motor imagery performance. We recommend further research utilising the LRJT in well-defined clinically homogenous groups, with verified pain severity, functional disability, and chronicity.

Imagined paralysis alters somatosensory evoked-potentials

Recent studies employing body illusions have shown that multisensory conflict can alter body representations and modulate low-level sensory processing. One defining feature of these body illusions is that they are sensory driven and thus passive on behalf of the participant. Thus, it remained to establish whether explicit alteration of own-body representations modulates low-level sensory processing. We investigated whether tibial nerve somatosensory-evoked potentials were modulated when participants imagined paralysis of their legs and arms. Imagined paralysis of the legs decreased P40 amplitude, but not imagined paralysis of the arms. These results show modulation of early somatosensory processing via explicit, top-down alteration to the internal representation of the body. Interestingly, P40 suppression positively correlated with bodily awareness scores whereas it negatively correlated with body dissociation scores. This suggests that the ability to actively alter own-body representation and its corresponding sensory processing depends upon dispositions to attend to and focus on bodily sensations.

Altered sensorimotor representations after recovery from peripheral nerve damage in neuralgic amyotrophy

Neuralgic amyotrophy is a common peripheral nerve disorder caused by acute autoimmune inflammation of the brachial plexus. Subsequent weakness of the stabilizing shoulder muscles leads to compensatory strategies and abnormal motor control of the shoulder. Despite recovery of peripheral nerves and muscle strength over time, motor dysfunction often persists. Suboptimal motor recovery has been linked to maladaptive changes in the central motor system in several nervous system disorders. We therefore hypothesized that neuralgic amyotrophy patients with persistent motor dysfunction may have altered cerebral sensorimotor representations of the affected upper limb. To test this hypothesis, 21 neuralgic amyotrophy patients (mean age 45 ± 12 years, 5 female) with persistent lateralized symptoms in the right upper limb and 20 age- and sex-matched healthy controls, all right-handed, performed a hand laterality judgement task in a cross-sectional comparison. Previous evidence has shown that to solve this task, subjects rely on sensorimotor representations of their own upper limb, using a first-person imagery perspective without actual motor execution. This enabled us to investigate altered central sensorimotor representations while controlling for altered motor output and altered somatosensory afference. We found that neuralgic amyotrophy patients were specifically less accurate for laterality judgments of their affected right limb, as compared to healthy controls. There were no significant group differences in reaction times. Both groups used a first-person imagery perspective, as evidenced by changes in reaction times as a function of participants' own arm posture. We conclude that cerebral sensorimotor representations of the affected upper limb are altered in neuralgic amyotrophy patients. This suggests that maladaptive central neuroplasticity may occur in response to peripheral nerve damage, thereby contributing to motor dysfunction. Therapies focused on altering cerebral sensorimotor representations may help to treat peripheral nerve disorders such as neuralgic amyotrophy.

Long-term disuse of the hand affects motor imagery ability in patients with complete brachial plexus palsy

The purpose of this study was to examine motor imagery ability in patients with peripheral nerve disorder using the hand mental rotation task. Five patients with left total avulsion brachial plexus palsy (BPP) and 16 healthy age-matched adults participated in this study. The mean±SD time from the injury was 103.6±49.7 months. Participants performed a hand mental rotation task as the motor imagery task; outcome measures included the reaction time from cognizing hand stimuli to the judgment of hand laterality (right or left) and the error rate. Patients also completed the Hand 20 questionnaire to assess the use of their affected limb. Log-transformed reaction times of the affected limb in patients with BPP were significantly higher than those of the unaffected limb and the left-sided limb of the healthy participants. Log-transformed reaction times of the unaffected limb in patients were significantly higher than those of the right-sided limb in healthy participants. Log-transformed error rate did not differ between patients and healthy participants. According to the results of the Hand 20 questionnaire, patients with BPP hardly used their affected limb because of severe sensory-motor dysfunction. Motor imagery ability of the affected and unaffected limbs in patients with complete BPP may be decreased owing to long-term disuse. These findings suggest that long-term disuse in those with severe peripheral nerve disorders could affect motor imagery ability of both the affected and unaffected limbs.

Thumbs up: Imagined hand movements counteract the adverse effects of post-surgical hand immobilization. Clinical, behavioral, and fMRI longitudinal observations

Motor imagery (M.I.) training has been widely used to enhance motor behavior. To characterize the neural foundations of its rehabilitative effects in a pathological population we studied twenty-two patients with rhizarthrosis, a chronic degenerative articular disease in which thumb-to-fingers opposition becomes difficult due to increasing pain while the brain is typically intact. Before and after surgery, patients underwent behavioral tests to measure pain and motor performance and fMRI measurements of brain motor activity.

After surgery, the affected hand was immobilized, and patients were enrolled in a M.I. training. The sample was split in those who had a high compliance with the program of scheduled exercises (T+, average compliance: 84%) and those with low compliance (T−, average compliance: 20%; cut-off point: 55%). We found that more intense M.I. training counteracts the adverse effects of immobilization reducing pain and expediting motor recovery. fMRI data from the post-surgery session showed that T+ patients had decreased brain activation in the premotor cortex and the supplementary motor area (SMA); meanwhile, for the same movements, the T− patients exhibited a reversed pattern. Furthermore, in the post-surgery fMRI session, pain intensity was correlated with activity in the ipsilateral precentral gyrus and, notably, in the insular cortex, a node of the pain matrix.

These findings indicate that the motor simulations of M.I. have a facilitative effect on recovery by cortical plasticity mechanisms and optimization of motor control, thereby establishing the rationale for incorporating the systematic use of M.I. into standard rehabilitation for the management of post-immobilization syndromes characteristic of hand surgery.

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Motor imagery training counteracts the effects of post-surgical hand immobilization.

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It also reduces pain and expedites motor recovery after immobilization.

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These effects were accompanied by significant fMRI signs of brain plasticity.

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The clinical-fMRI evidence advocates for the use of motor imagery in rehabilitation.

Reliability and validity of a mobile tablet for assessing left/right judgements

BACKGROUND

Left/right judgement (LRJ) of body parts is commonly used to assess the ability to perform implicit motor imagery and the integrity of brain-grounded maps of the body. Clinically, LRJ are often undertaken using a mobile tablet, but the concurrent validity and reliability of this approach has not yet been established.

OBJECTIVES

To evaluate the concurrent validity and test-retest reliability of a mobile tablet for assessing LRJ.

METHOD

Participants completed LRJ for 50 hand images (Experiment 1), and 40 back, foot, or neck images (Experiment 2) using a mobile tablet and desktop computer in random order. Participants in Experiment 2 performed a repeat test the following day to assess test-retest reliability. Accuracy and response time (RT) were recorded.

RESULTS

Twenty participants aged 55.3 (±6.7) years in Experiment 1, and 37 participants aged 38.2 (±12.3) years in Experiment 2, were recruited. Concurrent validity of the mobile tablet was good to excellent for hand judgements (ICC_3,1 = 0.836 for RT; ICC = 0.909 for accuracy), and was good for back, foot, and neck judgements (ICC = 0.781 for accuracy; ICC = 0.880 for RT). Test-retest reliability of the mobile tablet was good to excellent (ICC = 0.824 for accuracy; ICC = 0.903 for RT).

CONCLUSIONS

The mobile tablet demonstrated good to excellent concurrent validity with the desktop computer in two separate samples. The mobile tablet also demonstrated good to excellent test-retest reliability. The mobile tablet for LRJ is a valid alternative to the original desktop version.

Left/right limb judgement task performance following total knee replacement

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.

Effect of acute experimental hand pain on left-right discrimination response latency for hand recognition

Background: Recent work has indicated that acute experimental pain affects left-right discrimination latency. This phenomenon highlights an effect of pain on the cortex that may have significant clinical importance in the form of pain state assessment. However, to date only limited study has further qualified this effect. A more thorough understanding of the magnitude and characteristics of this phenomenon is needed to determine its potential clinical utility. Objective: This study aimed to closely replicate previous studies investigating response latency changes for left-right discrimination judgements as a result of acute experimental pain. Methods: Twenty-two right-handed participants (n = 11 female, n = 11 male) free from pain, analgesia use, pain-related conditions, upper limb trauma/conditions, visual impairment, and dyslexia took part in this study. Participants completed a hand left-right discrimination judgement task before, during, and after an experimental pain stimulus was delivered to each hand separately. Experimental pain was achieved using an intramuscular injection of hypertonic (5%) saline into the thenar eminence of the left and right hands. Mean response times for the left-right discrimination task were determined and compared for pain location (right, left), pain condition (before, during, after), and image laterality (right, left). Pain intensity was rated at 20 s intervals during each left-right discrimination task. Results: A main effect of pain condition (p = 0.028) confirmed that pain intensity was significantly higher in the "during pain" condition compared to the "before pain" and "after pain" conditions. A main effect of image laterality (p = 0.002) further showed that response latency for right-hand pain was significantly shorter compared to left-hand pain. No significant interaction between the factors pain location and image laterality (p = 0.086) was found. For right-hand pain, response latencies for the unaffected hand were, however, descriptively greater compared to the affected hand, and this was not the case for left-hand pain. Furthermore, no main effect of pain stimulus or of pain location on response times was found (p = 1.00 and p = 0.202, respectively). Conclusion: Our results were not consistent with previous hand left-right discrimination response latency results and may cast doubt on the attentional bias hypothesis that is currently considered to underpin response latency changes during acute experimental hand pain. Individual responses to pain, subsets of participants, and differing mental rotation strategies during the left-right discrimination task may have influenced the results.

Laterality judgment performance between people with chronic pain and pain-free individuals. A systematic review and meta-analysis

Background: Treatment of chronic pain is challenging and there is often failure of recovery, with the need to look at different approaches in its management. Central mechanisms may contribute to chronicity (i.e. disturbance in body schema). Laterality judgment is dependent on body schema and can determine affected central mechanisms. Objective: This review aimed to determine whether there are laterality judgment differences between chronic pain and pain-free individuals. Methods: A search was done of various databases, using combinations of keywords, and reference lists of full-text articles. Articles were considered from inception until February 2018. Eighteen studies were included. Methodological quality was assessed by two reviewers using the JBI Critical Appraisal Checklist. Studies were analyzed broadly then divided into subgroups. A meta-analysis or narrative review was done. Results: There was high heterogeneity for broad outcome measures, complex regional pain syndrome (CRPS1), and upper limb pain. Analysis for accuracy in lower limb conditions showed a medium significant effect size (0.59) and significant 95%CI (0.11-1.07). Low back and cervical pain results could not be pooled into meta-analysis (due to different methods of reporting). Conclusions: Laterality judgment impairment was shown in CPRS1, upper limb pain, hand and wrist pain, carpal-tunnel syndrome, facial pain, knee osteoarthritis, and leg pain. No conclusions could be drawn in low back pain, due to the low-quality evidence and differing results. There was no impairment in whiplash-associated disorders and nonspecific cervical pain showed conflicting evidence.

Left Right Judgement Task and Sensory, Motor, and Cognitive Assessment in Participants with Wrist/Hand Pain

The Left Right Judgement Task (LRJT) involves determining if an image of the body part is of the left or right side. The LRJT has been utilized as part of rehabilitation treatment programs for persons with pain associated with musculoskeletal injuries and conditions. Although studies often attribute changes and improvement in LRJT performance to an altered body schema, imaging studies suggest that the LRJT implicates other cortical regions. We hypothesized that cognitive factors would be related to LRJT performance of hands and feet and that sensory, motor, and pain related factors would be related to LRJT in the affected hand of participants with wrist/hand pain. In an observational cross-sectional study, sixty-one participants with wrist/hand pain participated in a study assessing motor imagery ability, cognitive (Stroop test), sensory (Two-Point Orientation Discrimination, pressure pain thresholds), motor (grip strength, Purdue Pegboard Test), and pain related measures (West Haven Yale Multidimensional Pain Inventory) as well as disability (Disability of the Arm, Shoulder and Hand). Multiple linear regression found Stroop test time and motor imagery ability to be related to LRJT performance. Tactile acuity, motor performance, participation in general activities, and the taking of pain medications were predictors of LRJT accuracy in the affected hand. Participants who took pain medications performed poorly in both LRJT accuracy (p=0.001) and reaction time of the affected hand (p=0.009). These participants had poorer cognitive (p=0.013) and motor function (p=0.002), and higher pain severity scores (p=0.010). The results suggest that the LRJT is a complex mental task that involves cognitive, sensory, motor, and behavioural processes. Differences between persons with and without pain and improvement in LRJT performance may be attributed to any of these factors and should be considered in rehabilitation research and practice utilizing this task.

Implicit Mental Motor Imagery Task Demonstrates a Distortion of the Body Schema in Patients With Eating Disorders

OBJECTIVES

A rich body of literature has established the role of body image distortion and dissatisfaction in the development and maintenance of eating disorders. However, many of the currently used techniques require explicit comparison of the person's body to an external stimulus. As the body schema is a largely unconscious construct, explicit comparison tasks may reflect a proxy, rather than the body schema itself.

METHODS

Here we use an implicit mental motor imagery (MMI) task to interrogate the body schema in healthy control participants (N=40) and participants at a residential eating disorder treatment center (N=42). By comparing the time it takes to imagine making a movement along a part of the body to the time it takes to actually make the same movement, we were able to assess participants' mental image of their body (i.e., body schema).

RESULTS

We found that participants with eating disorders, but not healthy controls, exhibited distortions of the body schema such that they believed their abdomen, buttocks, and thighs to be larger than they really are. Additionally, the MMI task used here provided information above and beyond traditional self-report measures (i.e., Body Shape Questionnaire). Together the MMI task and traditional measures provide the most information.

CONCLUSIONS

Findings using the novel MMI task are in line with the literature; participants with eating disorders consider themselves to be larger than they truly are. Taken together, results of this study suggest that MMI tasks provide complementary information to traditional self-report measures. (JINS, 2018, 24, 715-723).

Difference in Response to a Motor Imagery Task: A Comparison between Individuals with and without Painful Temporomandibular Disorders

The aim of the study was to investigate the difference in response to a motor imagery task between individuals with and without painful temporomandibular disorders (TMDs). The participants were 24 adults with and without TMD (TMD and control group, resp.). A set of photographic images of the profile view of a person's head and neck and a hand and a foot were presented in a random order. The set consisted of six different orientations with rotations of each image at 0, 60, 120, 180, 240, and 300 degrees and included left and right representations. The participants were required to view the image and make a decision as to whether it was a left or a right side presented, that is, mental rotation (MR) task. Data were collected on 48 tasks (including left and right) at each orientation for each body part. Reaction times (RTs) for correct answers and accuracy in making the left or right judgements were recorded. The RT was slower in the TMD group than in the control group. The RT for the profile image was slower than those for the hand and foot images. For images that were 180 degrees, the RT was slower and the accuracy was lower than those for five of the other image orientations. The judgements made about the 180-degree rotated image were more inaccurate compared to images of all other orientations among all types of stimuli.

Laterality recognition of images, motor performance, and aspects related to pain in participants with and without wrist/hand disorders: An observational cross-sectional study

OBJECTIVE

Musculoskeletal disorders are associated with altered sensory, proprioceptive and cognitive processes. Sensory processes affect the internal cortical representation of the body in space, the body schema, which in turn influences motor control. The purpose of this study was to determine if participants with wrist/hand disorders had impaired performance on a task associated with the body schema, the Left/Right Judgement Task (LRJT) and secondly how LRJT performance, motor performance, disability, pain and related aspects are associated.

METHODS

Fifteen healthy control participants and 15 participants with hand/wrist pain were asked to determine the laterality of images of hands. Measures of motor performance (Purdue Pegboard test), self-reported disability (Australian Canadian Hand Index), and pain related aspects (pain intensity, symptom duration, pain interference and affective distress) were recorded.

RESULTS

Participants with wrist/hand pain scored lower on all segments of the Purdue Pegboard test. There were differences in LRJT performance between groups for both Accuracy (p = 0.03) and Reaction Time (RT) (p < 0.01). There was no correlation between RT and Accuracy with pain intensity, pain duration, and disability. Both motor performance (r = 0.58-0.64) and LRJT performance Accuracy (r = 0.59) and RT (r = -0.56) were correlated with affective distress. A significant correlation was observed between RT and motor performance in healthy control participants (r = -0.56, p = 0.03) but not in participants with wrist/hand pain (r = -0.26, p = 0.44).

CONCLUSIONS

LRJT and motor performance was correlated with affective distress in participants with wrist/hand pain suggestive of complex interactions between cognitive-affective processes and sensorimotor integration.

The reliability of card-based and tablet-based left/right judgment measurements

BACKGROUND

Left/right judgment (LRJ) measurement is a potential way to identify dysfunction in cortical body maps, and to measure improvement related to corresponding treatments. Few studies have explored the reliability of various methods for LRJ measurement.

OBJECTIVES

To determine measurement reliability of LRJ utilizing two methods: card-based (CB) and tablet-based (TB). Establish minimal detectable difference (MDD) for accuracy and reaction time for both assessments.

METHODS

Testing was done over two different days. Session 1 consisted of testing LRJ utilizing CB assessment with photos of left and right hands over two trial periods. The TB format was also tested over two trial periods. Session 2 tested with the CB assessment for two trial periods. 40 images were used in the basic upright position for both CB and TB formats.

RESULTS

Fifty participants (N = 50; female = 35) with an average age of 24.3 (range 19-35) were studied. ICC (2,k) for reaction time for both methods were >0.84. The MDD for reaction time was between 0.19 and 0.49 s for various test points for both methods. Combined left and right accuracy ICC (2,k) for both methods were >0.51, with MDD between 5 and 14%.

CONCLUSIONS

This study examined the reliability and MDD for the LRJ measurement for card and tablet-based assessments. Generally, LRJ reaction time had good reliability, while accuracy had moderate reliability and varied between testing methods.

Test Procedures to Assess Somatosensory Abnormalities in Individuals with Peripheral Joint Pain: A Systematic Review of Psychometric Properties

BACKGROUND

Test procedures that were developed to assess somatosensory abnormalities should possess optimal psychometric properties (PMPs) to be used in clinical practice. The aim of this systematic review was to evaluate the literature to assess the level of evidence for PMPs of test procedures investigated in individuals with peripheral joint pain (PJP).

METHODS

A comprehensive electronic literature search was conducted in 7 databases from inception to March 2016. The Quality Appraisal for Reliability Studies (QAREL) checklist and the Consensus-based Standards for the Selection of Health Status Measurement Instruments (COSMIN) tool were used to assess risk for bias of the included studies. Level of evidence was evaluated based on the methodological quality and the quality of the measurement properties.

RESULTS

Forty-one studies related to PJP were included. The majority of included studies were considered to be of insufficient methodological quality, and the level of evidence for PMPs varied across different test procedures. The level of evidence for PMPs varied across different test procedures in different types of PJP. Hand-held pressure algometry is the only test procedure that showed moderate positive evidence of intrarater reliability, agreement, and responsiveness, simultaneously, when it was investigated in patients with chronic knee osteoarthritis.

CONCLUSIONS

This systematic review identified that the level of evidence for PMPs varied across different testing procedures to assess somatosensory abnormalities for different PJP populations. Further research with standardized protocols is recommended to further investigate the predictive ability and responsiveness of reported test procedures in order to warrant their extended utility in clinical practice.

Sensorimotor performance and function in people with osteoarthritis of the hand: A case-control comparison

OBJECTIVES

To determine whether hand left/right judgements, tactile acuity, and body perception are impaired in people with hand OA. To examine the relationships between left right judgements, tactile acuity and hand pain. To explore the relationships between sensorimotor measures (left/right judgements and tactile acuity) and measures of hand function in people with hand OA.

METHODS

Twenty patients with symptomatic hand OA and 19 healthy pain-free controls undertook a hand left/right judgment task, a control left/right judgement task, two-point discrimination (TPD) threshold testing (assessing tactile acuity), a neglect-like symptoms questionnaire (assessing body perception) and several established measures of hand function.

RESULTS

Neglect-like symptoms were experienced more frequently in the hand OA group (P < 0.05). People with hand OA were slower (P < 0.05) and less accurate (P < 0.05) in the hand left/right judgement task when compared to healthy controls, with no significant difference in the control task. Significant associations were found between hand left/right judgement reaction time and pain intensity (P < 0.05) and accuracy and pain intensity (P < 0.05). TPD was not different between groups, and no correlation was found between TPD and left/right judgement performance. No association was found between left/right judgement performance and measures of hand function (all P > 0.05). However, TPD (tactile acuity) was related to several measures of hand function (all P < 0.05).

CONCLUSION

People with hand OA had more frequent neglect-like symptoms and were slower and less accurate compared to healthy controls at hand left/right judgments, which was indicative of disrupted working body schema. Future studies may wish to examine whether interventions targeting sensorimotor dysfunction are effective at reducing pain and improving hand function and dexterity in people with hand OA.

Different patterns in mental rotation of facial expressions in complex regional pain syndrome patients

Although facial pain expressions are considered to be the most visible pain behaviors, it is known that the association between pain intensity and facial pain expression is weak for chronic pain. The authors hypothesized that the facial pain expressiveness was altered in chronic pain and investigated it with a mental rotation task using various facial expression, which seems to be associated with actual facial movements. As a task stimulus, 4 types of facial expression stimuli consisted of upper (tightening of eye and furrowed brows) and lower (raising upper lip) pain-specific facial expressions, and upper (eyeball deviation) and lower (tongue protrusion) facial movements not using facial muscles were used. Participants were asked to judge whether a stimulus presented at various rotation angles was left- or right-sided. The authors tested 40 patients with complex regional pain syndrome (CRPS) (12 women, age range 21-60) and 35 healthy controls (15 women, age range 26-64). In an analysis of reaction time (RT) using a linear mixed model, patients were slower to react to all types of stimuli (P = .001) and a significant interaction between group (patient or control) and type of facial expression was observed (P = .01). In the post hoc analysis only patients showed longer RTs to raising upper lip than other types of facial expressions. This reflects a deficit in mental rotation tasks especially for lower facial region pain expressions in CRPS, which may be related to the psychosocial aspects of pain. However, comprehensive intra- and interpersonal influences should be further investigated.

The development of a shoulder specific left/right judgement task: Validity & reliability

BACKGROUND

Disruption of cortically-held working body schema has been associated with a variety of pain conditions. A motor imagery technique - the left right judgement task (LRJT) - has been used as an indirect assessment of the integrity of the working body schema. To date there is no LRJT specifically designed to investigate the body schema of persons with shoulder pain.

OBJECTIVES

To develop a shoulder specific LRJT and assess its validity and reliability.

DESIGN

Cross-sectional repeated measures.

METHODS

Shoulder images were developed representing the shoulder in a variety of postures of graded complexity/awkwardness and degree of rotation. These images were digitally mirrored to represent both left and right shoulders. Participants viewed the images on a computer and determined whether images were of a left or right shoulder.

RESULTS

1413 participants were recruited worldwide and performed the shoulder LRJT (laterality judgement). Mean response time (SD) for the task was 1738(741) ms. Mean accuracy (SD) was 93.5(9.2)%. Chronbach's Alpha for shoulder image response times was 0.95. Participants were fastest responding to images of simple postures and slowest to images corresponding to the more awkward postures (mean difference 520 ms, 95%CI 469-570 ms). Participants were fastest responding to the least rotated images and slowest responding to inverted images, (mean difference 981 ms, 95%CI 919-1043 ms).

CONCLUSIONS

The shoulder specific LRJT proved to be highly reliable. Response times increased with complexity and rotation of images, implying a motor imagery strategy was used to complete the task, validating the task as a measure of shoulder joint implicit motor imagery. Abnormal performance cut-offs for age were reported. This result will enable further research examining the relationship between shoulder pain and body schema.

Differential neural encoding of sensorimotor and visual body representations

Sensorimotor processing specifically impacts mental body representations. In particular, deteriorated somatosensory input (as after complete spinal cord injury) increases the relative weight of visual aspects of body parts’ representations, leading to aberrancies in how images of body parts are mentally manipulated (e.g. mental rotation). This suggests that a sensorimotor or visual reference frame, respectively, can be relatively dominant in local (hands) versus global (full-body) bodily representations. On this basis, we hypothesized that the recruitment of a specific reference frame could be reflected in the activation of sensorimotor versus visual brain networks. To this aim, we directly compared the brain activity associated with mental rotation of hands versus full-bodies. Mental rotation of hands recruited more strongly the supplementary motor area, premotor cortex, and secondary somatosensory cortex. Conversely, mental rotation of full-bodies determined stronger activity in temporo-occipital regions, including the functionally-localized extrastriate body area. These results support that (1) sensorimotor and visual frames of reference are used to represent the body, (2) two distinct brain networks encode local or global bodily representations, and (3) the extrastriate body area is a multimodal region involved in body processing both at the perceptual and representational level.

The effects of graded motor imagery and its components on phantom limb pain and disability in upper and lower limb amputees: a systematic review protocol

BACKGROUND

Phantom limb pain (PLP) is characterized by the anatomical shifting of neighbouring somatosensory and motor areas into a deafferented cortical area of the brain contralateral to the amputated limb. It has been shown that maladaptive neuroplasticity is positively correlated to the perception of PLP in amputees. Recent studies support the use of graded motor imagery (GMI) and its component to alleviate the severity of PLP and disability. However, there is insufficient collective empirical evidence exploring the effectiveness of these treatment modalities in amputees with PLP. This systematic review will therefore explore the effects of GMI and its individual components on PLP and disability in upper and lower limb amputees.

METHODS

We will utilize a customized search strategy to search PubMed, Cochrane Central register of Controlled Trials, MEDLINE, Embase, PsycINFO, PEDro, Scopus, CINAHL, LILACS, DARE, Africa-Wide Information and Web of Science. We will also look at clinicaltrials.gov ( http://www.clinicaltrials.gov/ ), Pactr.gov ( http://www.pactr.org/ ) and EU Clinical trials register ( https://www.clinicaltrialsregister.eu/ ) for ongoing research. Two independent reviewers will screen articles for methodological validity. Thereafter, data from included studies will be extracted by two independent reviewers through a customized pre-set data extraction sheet. Studies with a comparable intervention and outcome measure will be pooled for meta-analysis. Studies with high heterogeneity will be analysed through random effects model. A narrative data analysis will be considered where there is insufficient data to perform a meta-analysis.

DISCUSSION

Several studies investigating the effectiveness of GMI and its different components on PLP have drawn contrasting conclusions regarding the efficacy and applicability of GMI in clinical practice. This systematic review will therefore gather and critically appraise all relevant data, to generate a substantial conclusion and recommendations for clinical practice and research on this subject.

SYSTEMATIC REVIEW REGISTRATION

PROSPERO CRD42016036471.