Sarah B. Wallwork

Left/right neck rotation judgments are affected by age, gender, handedness and image rotation.

Understanding motor imagery of the hands and feet has led to promising new treatments for neurological and chronic pain disorders. We aimed to extend this line of research to the neck with a view to developing the definitive platform study upon which clinical and experimental studies can be based. In a cross-sectional experiment with a convenience sample, volunteers were shown 40 photographs of a model with their head turned to the left or right. Images were presented in random order and orientation. Participants judged the direction of neck rotation. They also completed a left/right hand judgment task. 1361 pain-free participants volunteered. Mean ± standard deviation response time (RT) for making left/right judgments of neck rotation was 1.621 ± 0.501 s. Median accuracy was 92.5%. RT was related to age, gender, and handedness (p < 0.001). That is, RT increased with age, was greater in females than in males and was greater in left-handers than in right-handers. Accuracy reduced with age (p < 0.001), but was unaffected by gender or handedness. Judgments were more accurate when images showed a neck rotated to the right than when they showed a neck rotated to the left (p < 0.001). The magnitude of image rotation affected both response time and accuracy (p < 0.001). In general, the performance parameters established for left/right limb judgments also apply for left/right neck rotation judgments. The current work establishes the definitive normative values against which clinical and experimental groups can be compared and reveals unpredicted effects of the direction neck rotation and the orientation of the image.

A New Kind of Spatial Inattention Associated With Chronic Limb Pain

Pathological limb pain patients show decreased attention to some stimuli on the painful limb and increased attention to others, a paradox that has dogged the field for over a decade. We hypothesized that pathological pain involves a spatial inattention confined to bodily representations. Patients showed inattention to the painful side for visual processing of body parts but not letters, tactile processing but not auditory, and body‐part bisection tasks but not line bisection tasks. We propose the new term “somatospatial inattention” to describe bodily‐specific spatial inattention associated with pathological limb pain. Ann Neurol 2016;79:701–704

Neural representations and the cortical body matrix: implications for sports medicine and future directions

Neural representations, or neurotags, refer to the idea that networks of brain cells, distributed across multiple brain areas, work in synergy to produce outputs. The brain can be considered then, a complex array of neurotags, each influencing and being influenced by each other. The output of some neurotags act on other systems, for example, movement, or on consciousness, for example, pain. This concept of neurotags has sparked a new body of research into pain and rehabilitation. We draw on this research and the concept of a cortical body matrix—a network of representations that subserves the regulation and protection of the body and the space around it—to suggest important implications for rehabilitation of sports injury and for sports performance. Protective behaviours associated with pain have been reinterpreted in light of these conceptual models. With a particular focus on rehabilitation of the injured athlete, this review presents the theoretical underpinnings of the cortical body matrix and its application within the sporting context. Therapeutic approaches based on these ideas are discussed and the efficacy of the most tested approaches is addressed. By integrating current thought in pain and cognitive neuroscience related to sports rehabilitation, recommendations for clinical practice and future research are suggested.

The blink reflex magnitude is continuously adjusted according to both current and predicted stimulus position with respect to the face

The magnitude of the hand-blink reflex (HBR), a subcortical defensive reflex elicited by the electrical stimulation of the median nerve, is increased when the stimulated hand is close to the face (‘far–near effect’). This enhancement occurs through a cortico-bulbar facilitation of the polysynaptic medullary pathways subserving the reflex. Here, in two experiments, we investigated the temporal characteristics of this facilitation, and its adjustment during voluntary movement of the stimulated hand. Given that individuals navigate in a fast changing environment, one would expect the cortico-bulbar modulation of this response to adjust rapidly, and as a function of the predicted spatial position of external threats. We observed two main results. First, the HBR modulation occurs without a temporal delay between when the hand has reached the stimulation position and when the stimulus happens (Experiments 1 and 2). Second, the voluntary movement of the hand interacts with the ‘far–near effect’: stimuli delivered when the hand is far from the face elicit an enhanced HBR if the hand is being moved towards the face, whereas stimuli delivered when the hand is near the face elicit an enhanced HBR regardless of the direction of the hand movement (Experiment 2). These results indicate that the top-down modulation of this subcortical defensive reflex occurs continuously, and takes into account both the current and the predicted position of potential threats with respect to the body. The continuous control of the excitability of subcortical reflex circuits ensures appropriate adjustment of defensive responses in a rapidly-changing sensory environment.

Are people who do yoga any better at a motor imagery task than those who do not

Background Yoga is a popular recreational activity in Western society and there is an abundance of literature suggesting that yoga may be beneficial for people with a chronic pain disorder. Despite consistently positive results in the literature, the mechanisms of effect are unclear. On the grounds that chronic pain is associated with disruptions of brain-grounded maps of the body, a possible mechanism of yoga is to refine these brain-grounded maps. A left/right body part judgement task is an established way of interrogating these brain-grounded maps of the body. Objective To determine if people who do regular yoga practice perform better at a left/right judgement task than people who do not. Methods Previously collected, cross-sectional data were used. Using a case–control design, participants who reported taking part in regular yoga were selected against age, gender, neck pain and arm pain-matched controls. Participants viewed 40 photographs of a model with their head turned to the left or right, and were asked to judge the direction of neck rotation. They then completed a left/right-hand judgement task. Results Of the 1737 participants, 86 of them reported regularly taking part in yoga. From the remaining participants, 86 matched controls were randomly selected from all matched controls. There was no difference between Groups (yoga and no yoga) for either response time (p=0.109) or accuracy (p=0.964). There was a difference between Tasks; people were faster (p<0.001) and more accurate (p=0.001) at making left/right neck rotation judgements than they were at making left/right-hand judgements, regardless of group. Conclusions People who do regular yoga perform no differently in a left/right judgement task than people who do not.

Dizzy people perform no worse at a motor imagery task requiring whole body mental rotation; a case-control comparison

We wanted to find out whether people who suffer from dizziness take longer than people who do not, to perform a motor imagery task that involves implicit whole body rotation. Our prediction was that people in the “dizzy” group would take longer at a left/right neck rotation judgment task but not a left/right hand judgment task, because actually performing the former, but not the latter, would exacerbate their dizziness. Secondly, we predicted that when dizzy participants responded to neck rotation images, responses would be greatest when images were in the upside down orientation; an orientation with greatest dizzy-provoking potential. To test this idea, we used a case-control comparison design. One hundred and eighteen participants who suffered from dizziness and 118 age, gender, arm pain, and neck pain-matched controls took part in the study. Participants undertook two motor imagery tasks; a left/right neck rotation judgment task and a left/right hand judgment task. The tasks were completed using the Recognise program; an online reaction time task program. Images of neck rotation were shown in four different orientations; 0°, 90°, 180°, and 270°. Participants were asked to respond to each “neck” image identifying it as either “right neck rotation” or a “left neck rotation,” or for hands, a right or a left hand. Results showed that participants in the “dizzy” group were slower than controls at both tasks (p = 0.015), but this was not related to task (p = 0.498). Similarly, “dizzy” participants were not proportionally worse at images of different orientations (p = 0.878). Our findings suggest impaired performance in dizzy people, an impairment that may be confined to motor imagery or may extend more generally.

Integrating Self-Localization, Proprioception, Pain, and Performance.

The ability to know where our own body and body parts are in space is often taken for granted, yet it is of fundamental importance for the majority of our everyday activities, let alone high performance activities such as dancing. This review focuses on the concept of self-localization, the monitoring of the space surrounding ones body, and the disruptions that occur in the presence of pain. A conceptual model is presented of the cortical body matrix with which to consider self-localization; also provided are its historical context, underlying assumptions, and current limitations. Issues described include the neurophysiological and behavioral background to the cortical body matrix model, its application to pain and performance, and the rapidly growing use of bodily illusions to investigate how it is that we know where we are, that we exist in a given location, and that we can interact with the space that surrounds us. Recent insights are drawn on from behavioral, clinical, neuroimaging, and physiological research. Spatial performance is discussed in people with and without pain and its relevance for prevention of injuries, the role of pain during performance, and pain education for dancers and their teachers.

Defensive reflexes in people with pain – a biomarker of the need to protect? A meta-analytical systematic review

Abstract Upregulation of defensive reflexes such as the nociceptive flexion reflex (NFR) has been attributed to sensitisation of peripheral and spinal nociceptors and is often considered biomarkers of pain. Experimental modulation of defensive reflexes raises the possibility that they might be better conceptualised as markers of descending cognitive control. Despite strongly held views on both sides and several narrative reviews, there has been no attempt to evaluate the evidence in a systematic manner. We undertook a meta-analytical systematic review of the extant English-language literature from inception. Thirty-six studies satisfied our a priori criteria. Seventeen were included in the meta-analysis. Reflexive threshold was lower in people with clinical pain than it was in pain-free controls, but reflex size, latency, and duration were unaffected. The pattern of difference was not consistent with sensitisation of nociceptive neurones, as these changes were not isolated to the affected body part but was more consistent with top-down cognitive control reflective of heightened protection of body tissue. The pattern of modulation is dependent on potentially complex evaluative mechanisms. We offer recommendations for future investigations and suggest that defensive reflex threshold may reflect a biomarker of a broader psychological construct related to bodily protection, rather than sensitisation of primary nociceptors, spinal nociceptors, or pain.

Rethinking blinking: No cognitive modulation of reflex eye protection in early onset blindness

Rethinking blinking: No cognitive modulation of reflex eye 1 protection in early onset blindness 2 3 4 SB Wallwork, RJ Bufacchi, GL Moseley, GD Iannetti 5 6 7 a Sansom Institute for Health Research, University of South Australia, Adelaide, 8 Australia. b Department of Neuroscience, Physiology and Pharmacology, and 9 c Centre for Mathematics and Physics in the Life Sciences and EXperimental Biology 10 (CoMPLEX), University College London, London, United Kingdom. 11 d Neuroscience Research Australia, Sydney, Australia 12 13

No Telescoping Effect with Dual Tendon Vibration.

The tendon vibration illusion has been extensively used to manipulate the perceived position of one’s own body part. However, findings from previous research do not seem conclusive sregarding the perceptual effect of the concurrent stimulation of both agonist and antagonist tendons over one joint. On the basis of recent data, it has been suggested that this paired stimulation generates an inconsistent signal about the limb position, which leads to a perceived shrinkage of the limb. However, this interesting effect has never been replicated. The aim of the present study was to clarify the effect of a simultaneous and equal vibration of the biceps and triceps tendons on the perceived location of the hand. Experiment 1 replicated and extended the previous findings. We compared a dual tendon stimulation condition with single tendon stimulation conditions and with a control condition (no vibration) on both ‘upward-downward’ and ‘towards-away from the elbow’ planes. Our results show a mislocalisation towards the elbow of the position of the vibrated arm during dual vibration, in line with previous results; however, this did not clarify whether the effect was due to arm representation contraction (i.e., a ‘telescoping’ effect). Therefore, in Experiment 2 we investigated explicitly and implicitly the perceived arm length during the same conditions. Our results clearly suggest that in all the vibration conditions there was a mislocalisation of the entire arm (including the elbow), but no evidence of a contraction of the perceived arm length.