A tool for measuring mental workload during prosthesis use: The Prosthesis Task Load Index (PROS-TLX).

When using a upper-limb prosthesis, mental, emotional, and physical effort is often experienced. These have been linked to high rates of device dissatisfaction and rejection. Therefore, understanding and quantifying the complex nature of workload experienced when using, or learning to use, a upper-limb prosthesis has practical and clinical importance for researchers and applied professionals. The aim of this paper was to design and validate a self-report measure of mental workload specific to prosthesis use (The Prosthesis Task Load Index; PROS-TLX) that encapsulates the array of mental, physical, and emotional demands often experienced by users of these devices. We first surveyed upper-limb prosthetic limb users who confirmed the importance of eight workload constructs taken from published literature and previous workload measures. These constructs were mental demands, physical demands, visual demands, conscious processing, frustration, situational stress, time pressure and device uncertainty. To validate the importance of these constructs during initial prosthesis learning, we then asked able-bodied participants to complete a coin-placement task using their anatomical hand and then using a myoelectric prosthesis simulator under low and high mental workload. As expected, using a prosthetic hand resulted in slower movements, more errors, and a greater tendency to visually fixate the hand (indexed using eye-tracking equipment). These changes in performance were accompanied by significant increases in PROS-TLX workload subscales. The scale was also found to have good convergent and divergent validity. Further work is required to validate whether the PROS-TLX can provide meaningful clinical insights to the workload experienced by clinical users of prosthetic devices.

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.

Neurophysiological markers discriminate different forms of motor imagery during action observation.

The dual-action simulation hypothesis proposes that both an observed and an imagined action can be represented simultaneously in the observer's brain. These two sensorimotor streams would either merge or compete depending on their relative suitability for action planning. To test this hypothesis, three forms of combined action observation and motor imagery (AO + MI) instructions were used in this repeated-measures experiment. Participants observed index finger abduction-adduction movements while imagining the same action (congruent AO + MI), little finger abduction-adduction (coordinative AO + MI), or a static hand (conflicting AO + MI). Single-pulse transcranial magnetic stimulation was applied to the left primary motor cortex. The amplitude of motor evoked potential responses were recorded from both the first dorsal interosseous (FDI) and abductor digiti minimi (ADM) muscles of the right-hand while eye movements were tracked. When controlling for the influence of relevant eye movements, corticospinal excitability was facilitated relative to control conditions in the concurrently observed and imagined muscles for both congruent and coordinative AO + MI conditions. Eye-movement metrics and social validation data from post-experiment interviews provided insight into the attentional and cognitive mechanisms underlying these effects. The findings provide empirical support for the dual-action simulation hypothesis, indicating for the first time that it is possible to co-represent observed and imagined actions simultaneously.

Observation of an action with a congruent contextual background facilitates corticospinal excitability: A combined TMS and eye-tracking experiment.

Action observation produces activity in similar regions of the brain to those involved in action execution and can offer an effective intervention for motor (re)learning, although optimal viewing conditions for such interventions remain to be established. In this experiment, single-pulse transcranial magnetic stimulation (TMS) and eye-tracking were used simultaneously to investigate the effect of manipulating background context on both corticospinal excitability and visual attention during action observation. Twenty-four participants observed four different videos: (i) a static hand holding a sponge (control condition); and an index finger-thumb pinch of a sponge against (ii) a plain black background; (iii) a background containing objects that were incongruent with the observed action; and (iv) a background containing objects that were congruent with the observed action. TMS was delivered to the hand representation of the left primary motor cortex, and motor evoked potentials were recorded from the first dorsal interosseous and abductor digiti minimi muscles of the right hand. Eye movements were recorded throughout the experiment. Results indicated that corticospinal excitability was facilitated during the congruent context condition compared to both the static hand and plain black background conditions. In addition, the number of fixations and percentage of time participants spent fixating on the background scene were significantly greater during the incongruent and congruent conditions compared to the static hand and plain black background conditions. These results indicate that the provision of additional visual information that is congruent with the observed movement contributes to a facilitation of corticospinal excitability by providing the observer with information regarding the goal and intention of the observed action. Providing congruent contextual information may enhance the efficacy of action observation interventions for motor (re)learning.

Screen Position Preference Offers a New Direction for Action Observation Research: Preliminary Findings Using TMS.

Action observation has been suggested to be an effective adjunct to physical practice in motor (re)learning settings. However, optimal viewing conditions for interventions are yet to be established. Single-pulse transcranial magnetic stimulation (TMS) was used to investigate the effect of two different screen positions and participants' screen position viewing preference on the amplitude of motor evoked potentials (MEPs) during observation of a ball pinch action. Twenty-four participants observed four blocked conditions that contained either a dynamic index finger-thumb ball pinch or a static hand holding a ball in a similar position on a horizontally or vertically positioned screen. TMS was delivered to the hand representation of the left primary motor cortex and MEPs were recorded from the first dorsal interosseous muscle of the right hand. Initial analysis of the normalized MEP amplitude data showed no significant differences between conditions. In a follow-up procedure, participants engaged in individual semi-structured interviews and completed a questionnaire designed to assess viewing affect and screen position viewing preference. The MEP data were subsequently split by screen position preference and re-analyzed using a 2 × 2 repeated measures ANOVA. Main effects indicated that participants who preferred the horizontal screen position (n = 16) demonstrated significantly greater MEP amplitudes during observation of the ball-pinch action compared to the static hand condition irrespective of screen position, and during the horizontal compared to the vertical screen position irrespective of video type. These results suggest that ensuring anatomical and perceptual congruency with the physical task, alongside consideration of participants' screen position viewing preferences, may be an important part of optimizing action observation interventions.

Directing visual attention during action observation modulates corticospinal excitability.

Transcranial magnetic stimulation (TMS) research has shown that corticospinal excitability is facilitated during the observation of human movement. However, the relationship between corticospinal excitability and participants' visual attention during action observation is rarely considered. Nineteen participants took part in four conditions: (i) a static hand condition, involving observation of a right hand holding a ball between the thumb and index finger; (ii) a free observation condition, involving observation of the ball being pinched between thumb and index finger; and (iii and iv) finger-focused and ball-focused conditions, involving observation of the same ball pinch action with instructions to focus visual attention on either the index finger or the ball. Single-pulse TMS was delivered to the left motor cortex and motor evoked potentials (MEPs) were recorded from the first dorsal interosseous (FDI) and abductor digiti minimi muscles of the right hand. Eye movements were recorded simultaneously throughout each condition. The ball-focused condition produced MEPs of significantly larger amplitude in the FDI muscle, compared to the free observation or static hand conditions. Furthermore, regression analysis indicated that the number of fixations on the ball was a significant predictor of MEP amplitude in the ball-focused condition. These results have important implications for the design and delivery of action observation interventions in motor (re)learning settings. Specifically, providing viewing instructions that direct participants to focus visual attention on task-relevant objects affected by the observed movement promotes activity in the motor system in a more optimal manner than free observation or no instructions.

Eye Gaze Markers Indicate Visual Attention to Threatening Images in Individuals with Chronic Back Pain.

Research into attentional biases and threatening, pain-related information has primarily been investigated using reaction time as the dependent variable. This study aimed to extend previous research to provide a more in depth investigation of chronic back pain and individuals' attention to emotional stimuli by recording eye movement behavior. Individuals with chronic back pain (n = 18) were recruited from a back rehabilitation program and age and sex matched against 17 non-symptomatic controls. Participants' eye movements were recorded whilst they completed a dot probe task, which included back pain specific threatening images and neutral images. There were no significant differences between chronic pain and control participants in attentional biases recorded using reaction time from the dot probe task. Chronic pain participants, however, demonstrated a significantly higher percentage of fixations, larger pupil diameter, a longer average fixation duration and faster first fixation to threatening compared to neutral images. They also had a significantly longer average fixation duration and larger pupil diameter to threatening images compared to control participants. The findings of this study suggest eye gaze metrics may provide a more sensitive measure of attentional biases in chronic pain populations. These findings may have important therapeutic implications for the patient and therapist.

Defensive High-Anxious Individuals Demonstrate Difference Responses to Pain Management to Those with Lower Levels of Defensiveness and Anxiety.

OBJECTIVES: Few studies have considered the effect of Weinberger et al.'s personality types on the management of pain. The aims of this study were to (1) identify whether the relationships between pain intensity, cognitive factors, and disability at 3 and 6 months postbaseline differ as a result of personality type; and (2) identify whether personality type affects the likelihood of achieving a minimal clinically important change in pain intensity or disability at 3 and 6 months. METHOD: Patients completed a set of validated questionnaires assessing personality type, cognitive factors, pain intensity, and disability at 3 and 6 months postbaseline. RESULTS: A greater proportion of defensive high-anxious individuals reported improvement for both pain (3 months = 25%; 6 months = 38%) and disability (3 months = 35%; 6 months = 50%) and showed stronger links between improvements in pain and disability and baseline psychological factors than nonextreme individuals. CONCLUSIONS: The high proportion of defensive high-anxious individuals highlights the need for psychologically based interventions to be delivered earlier in the care process. Stratifying the population, based on personality type, may allow for more targeted interventions, which could be more cost effective and reduce the number of patients remaining in the care system.

Personality Type Influences Attentional Bias in Individuals with Chronic Back Pain.

Attentional biases reflect an individual's selective attention to salient stimuli within their environment, for example an experience of back pain. Eysenck suggests that different personality types show different attentional biases to threatening information. This study is the first to test Eysenck's theory within a chronic back pain population by investigating the attentional biases of four different personality types using a back pain specific dot-probe paradigm. Participants were 70 volunteers (45 female) recruited from a back rehabilitation program at an NHS Trust. The four groups were selected on their trait anxiety and defensiveness scores: defensive high-anxious; high-anxious; repressor and non-extreme. Participants completed a dot probe task comprising 20 practice trials and 250 experimental trials. The experimental trials contained 100 threat-neutral pairs, 100 positive-neutral pairs and 50 neutral-neutral image pairings. The threat images were taken from the Photograph Series of Daily Activities (PHODA) and the neutral and positive images from the International Affective Picture System (IAPS) image bank. The results provided partial support for Eysenck's theory; defensive high-anxious individuals showed an attentional bias for threatening information compared to high-anxious individuals who demonstrated no bias. Repressors showed an avoidant bias to threatening images and an attentional bias to positive stimuli relative to neutral images. The clear difference in responses demonstrated by high-anxious individuals who vary in defensiveness highlight the need for separate investigation of these heterogeneous groups and help to explain the cognitive processes of defensive high-anxious individuals within a pain population. The demonstration of an attentional bias in this group to threatening information could explain why defensive high-anxious individuals are more likely to re-present for treatment.

A qualitative investigation of factors that matter to individuals in the pain management process.

OBJECTIVE: Chronic musculoskeletal pain is a complex condition to manage with widespread consequences including physical disability, psychosocial effects and increased use of healthcare. Previous research has found patients' experiences within health care can be influenced by factors such as expectations, therapist characteristics and treatment process. This study used patient interviews to identify the key factors that influence individuals' experiences in the management of chronic pain. DESIGN: Qualitative study using semi-structured interviews in either a home or hospital setting. METHODS: Semi-structured interviews were conducted on eight participants attending hospital-based pain management. Participants were asked about their experiences of pain management and living with a chronic pain condition. Interviews were transcribed and analysed thematically. RESULTS: Three main themes were identified; impact of their condition on daily life, clinical interactions and the pain management process. Understanding the condition was a key factor for the patients, in particular, explanation by the clinician. The temporality of their pain meant timing of appointments was critical. Patients reported factors such as family days and follow-up sessions would improve their treatment experience. CONCLUSIONS: This study highlighted important factors for healthcare professionals and patients in the management of chronic pain. Participants indicated a desire to understand their condition and learn strategies for self-management to allow them to cope better. As patients found benefit from being involved in the management process, discussions around the options for treatment may enhance management and rehabilitation. It is important we continue to research factors important to individuals with musculoskeletal pain to find an effective, evidence-based framework for understanding and managing this condition. Implications for rehabilitation This study highlights the importance to patients of being given information to help them understand their pain condition and to learn strategies for self-management to cope better. Where information was not provided and inadequate time allowed for questioning and discussion, patients tended to desire more frequent access to the care services. More effective communication may result in reduced demand and more efficient management. Patients suggested that ongoing peer support may offer an alternative to clinician-led services.

Influence of Defensiveness on Disability in a Chronic Musculoskeletal Pain Population.

OBJECTIVE: This study aimed to identify the following: (1) the proportion of the defensive high-anxious personality type in a chronic pain population; (2) whether personality type affects the relationships between cognitive factors and disability. METHOD: Sixty patients with chronic musculoskeletal pain, referred to a hospital for treatment, completed questionnaires assessing defensiveness, trait anxiety, pain intensity, disability, depression, catastrophizing, self-efficacy, and kinesiophobia. Personality type was assessed using the State-Trait Anxiety Inventory and the Marlowe-Crowne Social Desirability Scale. RESULTS: Within the defensive high-anxious group, lower levels of self-efficacy, and high levels of depression and catastrophizing most strongly predicted perceptions of disability. Interestingly, the cognitive variables failed to significantly predict disability for individuals lower in anxiety and defensiveness; however, pain intensity did have a greater effect, explaining 36% of the variance. CONCLUSIONS: The interaction between defensiveness and anxiety plays an important role in patients' perceptions of, and outcomes from, chronic pain. Differentiating the defensive high-anxious group revealed different patterns of relationship between a range of cognitive factors and disability. This highlights the necessity of assessing personality characteristics that include defensiveness in order to identify those individuals who may be more vulnerable to cognitive factors influencing their perceptions of disability. If personality type is identified as a predictor of poor adjustment, interventions could be customized to the unique needs of this group (eg. high defensive and anxious individuals).