Effects of Anodal tDCS Applied Over the Cerebellum Combined with Physical Therapy on Center of Gravity Sway in a Patient with Cerebellar Ataxia: A Single-Case Study.

Damage to the cerebellum results in dysfunctional standing postural control. Patients with cerebellar ataxia have a larger sway in the center of gravity (COG) while standing. Transcranial direct current stimulation (tDCS) has been applied in the rehabilitation of patients with central nervous system disorders; however, its effect on COG sway in patients with cerebellar ataxia remains unknown. We aimed to confirm the effects of anodal cerebellar tDCS (ctDCS) combined with physical therapy on COG sway in a patient with cerebellar ataxia using a retrospective ABA single-case study design. This study involved a patient with left cerebellar hemorrhage. Walking and postural balance rehabilitation were conducted in phase A. Anodal ctDCS was combined with the walking and postural balance rehabilitation in phase B. We measured COG sway in the open- and closed-eyes standing conditions daily throughout all the phases. In the open-eyes standing condition, there was no significant change in COG sway in phase B. Conversely, in the closed-eyes standing condition, the circumferential area, total sway path length, and anteroposterior sway path length decreased in phase B. No change was observed in the mediolateral sway path length. The combination of anodal ctDCS and physical therapy may decrease COG sway in patients with cerebellar ataxia in the closed-eyes standing condition, and its effect may be greater in the anteroposterior direction.

Effects of cerebellar transcranial direct current stimulation on the excitability of spinal motor neurons and vestibulospinal tract in healthy individuals.

Cerebellar transcranial direct current stimulation (ctDCS) modulates cerebellar cortical excitability in a polarity-dependent manner and affects inhibitory pathways from the cerebellum. The cerebellum modulates spinal reflex excitability via the vestibulospinal tract and other pathways projecting to the spinal motor neurons; however, the effects of ctDCS on the excitability of spinal motor neurons and vestibulospinal tract remain unclear. The experiment involved 13 healthy individuals. ctDCS (sham-ctDCS, anodal-ctDCS, and cathodal-ctDCS) was applied to the cerebellar vermis at 2 mA with an interval of at least 3 days between each condition. We measured the maximal M-wave (Mmax) and maximal H-reflex (Hmax) in the right soleus muscle to assess the excitability of spinal motor neurons. We applied galvanic vestibular stimulation (GVS) for 200 ms at 100 ms before tibial nerve stimulation to measure Hmax conditioned by GVS (GVS-Hmax) and calculated the change rate of Hmax by GVS as the excitability of vestibulospinal tract. We measured the Mmax, Hmax, and GVS-Hmax before, during, and after ctDCS in the sitting posture. No main effects of tDCS condition, main effects of time, or interaction effects were observed in Hmax/Mmax or the change rate of Hmax by GVS. It has been suggested that ctDCS does not affect the excitability of spinal motor neurons and vestibulospinal tract, as measured by neurophysiological methods, such as the H-reflex, in healthy individuals in a sitting posture. Effect of ctDCS on other descending pathways to spinal motor neurons, the neurological mechanism of tDCS and the cerebellar activity during the experiment may have contributed to these results. Therefore, we need to investigate the involvement of the cerebellum in Hmax/Mmax and the change rate of Hmax by GVS under different neuromodulation techniques and postural conditions.

I am not the cause of this pain: An experimental study of the cognitive processes underlying causal attribution in the unpredictable situation whether negative outcomes.

OBJECTIVES: Pain causal attribution is the attribution of pain causes to self or others, which may depend on one's choice of actions. The study aimed to examine how the cognitive processes of pain causal attribution as one aspect of the sense of agency change in healthy individuals based on free or forced choice, using a temporal binding (TB) experimental task. METHODS: Participants pressed keys (action) in a combined TB task, with one key having a high probability of delivering pain (with tone). In fact, only the bias between the free-choice and the forced choice conditions was manipulated. Participants estimated the time between their action and tone, with shorter intervals indicating internal attribution. RESULTS: Interval estimation was significantly longer in the forced-choice condition than in the free-choice condition when a pain stimulus was delivered. CONCLUSIONS: Explicit complaints of pain being caused by others may be represented in implicit cognitive processes.

A comprehensive multivariate analysis of the center of pressure during quiet standing in patients with Parkinson's disease.

BACKGROUND: We hypothesized that postural instability observed in individuals with Parkinson's disease (PD) can be classified as distinct subtypes based on comprehensive analyses of various evaluated parameters obtained from time-series of center of pressure (CoP) data during quiet standing. The aim of this study was to characterize the postural control patterns in PD patients by performing an exploratory factor analysis and subsequent cluster analysis using CoP time-series data during quiet standing. METHODS: 127 PD patients, 47 aged 65 years or older healthy older adults, and 71 healthy young adults participated in this study. Subjects maintain quiet standing for 30 s on a force platform and 23 variables were calculated from the measured CoP time-series data. Exploratory factor analysis and cluster analysis with a Gaussian mixture model using factors were performed on each variable to classify subgroups based on differences in characteristics of postural instability in PD. RESULTS: The factor analysis identified five factors (magnitude of sway, medio-lateral frequency, anterio-posterior frequency, component of high frequency, and closed-loop control). Based on the five extracted factors, six distinct subtypes were identified, which can be considered as subtypes of distinct manifestations of postural disorders in PD patients. Factor loading scores for the clinical classifications (younger, older, and PD severity) overlapped, but the cluster classification scores were clearly separated. CONCLUSIONS: The cluster categorization clearly identifies symptom-dependent differences in the characteristics of the CoP, suggesting that the detected clusters can be regarded as subtypes of distinct manifestations of postural disorders in patients with PD.

Trends in amount of use to upper limb function in patients with subacute stroke: a cross-sectional study using segmental regression analysis.

BACKGROUND: Hemiparesis affects approximately 33-80% of patients with stroke, and a quarter of these individuals experience difficulty with the voluntary use of their paretic upper limb for performing activities of daily living within five years of stroke onset. Therefore, assessing upper limb functionality and use after a stroke is crucial. The Fugl-Meyer Assessment (FMA) and the Motor Activity Log (MAL) are the two most widely used methods for assessing post-stroke paretic upper limb. While previous research has shown a strong correlation between the FMA of Upper Extremity (FMA-UE) and the MAL scores, to date, no study has investigated the differences in the characteristics and trends of upper extremity usage frequency in the FMA-UE. This study aimed to statistically categorize the FMA-UE scores using segmental regression analysis and identify disparities in the trends of paretic upper extremity utilization frequency in MAL. METHODS: Patients with first-episode subacute stroke were chosen for the cohort study. The primary assessments used were FMA-UE and MAL Amount of Use (MAL-A); age, gender, and time since onset served as secondary assessments. Segmental regression analysis was used, with FMA-UE as the independent variable and MAL-A as the dependent variable. R2 values were calculated using linear and polynomial regression on binary values, and the coefficients of determination were compared using segmental regression analysis. RESULTS: The study included 203 participants with a mean age of 70.1 ± 13.1 years; 113 were male and 90 female. The mean time since onset was 29.2 ± 14.8 days, the mean FMA-UE score was 43.6 ± 22.3 points, and the mean MAL-A score was 2.3 ± 2.0 points. The segmental regression analysis revealed that the inflection point for FMA-UE was 45.3 points, and the slope of the regression line underwent a transformation before and after the inflection point. CONCLUSIONS: This study indicates that the trend in the amount of use of paretic upper limb utilization changes around inflection point 45 in the FMA-UE. These findings could be useful for designing rehabilitation strategies to improve paretic upper limb utilization by increasing exercise duration in patients with subacute stroke.

Influence of vibrotactile random noise on the smoothness of the grasp movement in patients with chemotherapy-induced peripheral neuropathy.

Patients with chemotherapy-induced peripheral neuropathy (CIPN) often suffer from sensorimotor dysfunction of the distal portion of the extremities (e.g., loss of somatosensory sensation, numbness/tingling, difficulty typing on a keyboard, or difficulty buttoning/unbuttoning a shirt). The present study aimed to reveal the effects of subthreshold vibrotactile random noise stimulation on sensorimotor dysfunction in CIPN patients without exacerbating symptoms. Twenty-five patients with CIPN and 28 age-matched healthy adults participated in this study. To reveal the effects of subthreshold vibrotactile random noise stimulation on sensorimotor function, participants were asked to perform a tactile detection task and a grasp movement task during random noise stimulation delivered to the volar and dorsal wrist. We set three intensity conditions of the vibrotactile random noise: 0, 60, and 120% of the sensory threshold (Noise 0%, Noise 60%, and Noise 120% conditions). In the tactile detection task, a Semmes-Weinstein monofilament was applied to the volar surface of the tip of the index finger using standard testing measures. In the grasp movement task, the distance between the thumb and index finger was recorded while the participant attempted to grasp a target object, and the smoothness of the grasp movement was quantified by calculating normalized jerk in each experimental condition. The experimental data were compared using two-way repeated-measures analyses of variance with two factors: experimental condition (Noise 0, 60, 120%) × group (Healthy controls, CIPN patients). The tactile detection threshold and the smoothness of the grasp movement were only improved in the Noise 60% condition without exacerbating numbness/tingling in CIPN patients and healthy controls. The current study suggested that the development of treatment devices using stochastic resonance can improve sensorimotor function for CIPN patients.

Shared decision-making in physiotherapy: a cross-sectional study of patient involvement factors and issues in Japan.

BACKGROUND: Evidence-based medicine education has not focused on how clinicians involve patients in decision-making. Although shared decision-making (SDM) has been investigated to address this issue, there are insufficient data on SDM in physiotherapy. This study aimed to clarify the issues concerning patient involvement in Japan, and to examine whether SDM is related to perceptions of patient involvement in decision-making. METHODS: The study participants were recruited from among acute and sub-acute inpatients and community residents receiving physiotherapy outpatient care, day care, and/or home rehabilitation. The Control Preference Scale (CPS) was used to measure the patients' involvement in decision-making. The nine-item Shared Decision-Making Questionnaire (SDM-Q-9) was used to measure SDM. In analysis I, we calculated the weighted kappa coefficient to examine the congruence in the CPS between the patients' actual and preferred roles. In analysis II, we conducted a logistic regression analysis using two models to examine the factors of patient involvement. RESULTS: Analysis I included 277 patients. The patients' actual roles were as follows: most active (4.0%), active (10.8%), collaborative (24.6%), passive (35.0%), and most passive (25.6%). Their preferred roles were: most active (3.3%), active (18.4%), collaborative (39.4%), passive (24.5%), and most passive (14.4%). The congruence between actual and preferred roles by the kappa coefficient was 0.38. Analysis II included 218 patients. The factors for patient involvement were the clinical environment, the patient's preferred role, and the SDM-Q-9 score. CONCLUSIONS: The patients in Japan indicated a low level of decision-making involvement in physiotherapy. The patients wanted more active involvement than that required in the actual decision-making methods. The physiotherapist's practice of SDM was revealed as one of the factors related to perceptions of patient involvement in decision-making. Our results demonstrated the importance of using SDM for patient involvement in physiotherapy.

Task-specific fear influences abnormal trunk motor coordination in workers with chronic low back pain: a relative phase angle analysis of object-lifting.

BACKGROUND: Pain-related fear influences impaired trunk movement (e.g., limited movement of range and velocity), but it is unclear how fear relates to trunk motor coordination (e.g., a more "in-phase" upper-lower trunk motion pattern). We conducted the present study to: (1) identify the motor coordination pattern of the in-phase upper-lower lumbar movements during the lifting, and (2) determine how pain-related fear is related to the trunk coordination pattern in workers with chronic low back pain (CLBP). METHODS: We examined 31 male workers with CLBP (CLBP group) and 20 healthy controls with no history of CLBP (HC group). The movement task was lifting a box, the weight of which was 10, 30%, or 50% of the subject's body weight. We used a 3D motion capture system to calculate the mean absolute relative phase angle (MARP) angle as an index of coordination and the mean deviation phase (DP) as an index of variability. We used a numerical rating scale to assess the subjects' task-specific fear. RESULTS: The MARP angle during trunk extension movement in the 50% condition was significantly decreased in the CLBP group compared to the HCs; i.e., the upper lumbar movement was more in-phase with the lower lumbar movement. The hierarchical multiple regression analysis results demonstrated that a decreased MARP angle was associated with high task-specific fear. CONCLUSIONS: A more 'in-phase' upper-lower lumbar movement pattern was predicted by task-specific fear evoked when performing a work-related activity. Our findings suggest that an intervention for task-specific fear may be necessary to improve an individual's impaired trunk motor coordination.

Posture influences on vestibulospinal tract excitability.

The human vestibulospinal tract has important roles in postural control, but it has been unknown whether vestibulospinal tract excitability is influenced by the body's postures. We investigated whether postures influence the vestibulospinal tract excitability by a neurophysiological method, i.e., applying galvanic vestibular stimulation (GVS) 100 ms before tibial nerve stimulation evoking the soleus H-reflex. GVS is a percutaneous stimulation, and it has not been clarified how the cutaneous input from GVS influences the facilitation effect of cathodal GVS on the soleus H-reflex amplitude. In Experiment 1, we evaluated the effects of GVS on the soleus H-reflex amplitude of subjects in the prone, supine, and sitting positions in random order to clarify the differences in the GVS effects among these postures. In Experiment 2, to determine whether the effects of GVS in the supine and sitting positions are due solely to cutaneous input from GVS, we provided GVS and cutaneous stimulations as conditioning stimuli and compared the effects in both postures. Interaction effects between postures and stimulus conditions were observed in both experiments. The facilitation rate of the maximum H-reflex amplitude by GVS in the sitting position was significantly higher than those in the prone and supine positions (Experiment 1). The facilitation rate of GVS was significantly larger than the cutaneous stimulation only in the sitting position (Experiment 2). These results indicate that vestibulospinal tract excitability may be higher in the sitting position than in either lying position (prone and supine), due mainly to the increased need for postural control.

The Effects of Transcranial Direct Current Stimulation Combined with Aerobic Exercise on Pain Thresholds and Electroencephalography in Healthy Adults.

OBJECTIVES: We examined whether transcranial direct current stimulation (tDCS) combined with aerobic exercise (AE) modulated the pressure pain threshold (PPT) and peak alpha frequency (PAF) measured via resting electroencephalography. DESIGN: Single-blind experimental study with a cross-over design. SETTING: Neuro Rehabilitation Research Center, Kio University. SUBJECTS: Ten healthy controls participated in this study. METHODS: Three types of sessions--(i) tDCS, (ii) Sham tDCS/AE, and (iii) tDCS/AE--were tested in this investigation. Anodal stimulation (2 mA, 20 minutes) was applied over the left primary motor cortex. Each session was 20 minutes long. We used the PPT and short-form Profile of Mood States-Brief, as well as PAF measured via resting-electroencephalography, to investigate the effects of tDCS and AE. Heart rate and scores on the Borg scale were used to confirm exercise intensity. PAF was calculated in four regions of interest: frontal, central, parietal, and occipital areas. RESULTS: The change ratio of PPT increased during each session. The maximum change ratio of PPT were tDCS: 40.7%, Sham tDCS/AE: 51.5%, and tDCS/AE: 83.4%. change ratio of PPT was earlier and higher in the tDCS/AE trials compared with the other sessions. Negative mood was improved after session completion. Significant differences in PAF were found in the occipital area in the Sham tDCS/AE and tDCS/AE sessions. CONCLUSIONS: The combined tDCS and AE intervention induced significant changes in PPT in a single session, with a PAF that was earlier and higher than those produced during the Sham tDCS/AE and tDCS sessions.

Direct evidence of EEG coherence in alleviating phantom limb pain by virtual referred sensation: Case report.

Virtual reality (VR) systems have been integrated into rehabilitation techniques for phantom limb pain (PLP). In this case report, we used electroencephalography (EEG) to analyze corticocortical coherence between the bilateral sensorimotor cortices during vibrotactile stimulation in conjunction with VR rehabilitation in two PLP patients. As a result, we observed PLP alleviation and increased alpha wave coherence during VR rehabilitation when stimulation was delivered to the cheek and shoulder (referred sensation areas) of the affected side. Vibrotactile stimulation with VR rehabilitation may enhance the awareness and movement of the phantom hand.

Development of More Precise Measurement to Predict Pain 1 Month Postoperatively Based on Use of Acute Postoperative Pain Score in Patients With Distal Radial Fracture.

BACKGROUND: A method for modeling the acute pain trajectory using the simple linear fit of an individual's pain intensity scores after surgery was developed and affords more precise measurement than conventional pain assessment. However, the method has the disadvantage of using only the slope without considering the intercept. The purpose of this study was to verify our modification of the pain trajectory model including slope and intercept and to identify clusters. METHODS: The pain intensity was measured in 60 patients after surgery, and we calculated their pain trajectories. The pain trajectory normally resolves in intensity over a period of days, and the linear fit of an individual patient's pain intensity score defines the trajectory. In this simple linear model (x axis, days; y axis, pain intensity), each patient's trajectory has the slope and the intercept. A multiple regression analysis model known as structural equation modeling was used to predict postoperative pain at 30 days after surgery. Finally, we performed hierarchical cluster analysis using the pain trajectory. RESULTS: The slope and intercept model was the best fit among the models. Based on cluster analysis results, we created 4 pain trajectory groups (slope and intercept). CONCLUSION: Our results suggest that the pain trajectory using the slope and intercept is quite useful for predicting postoperative pain at 30 days after surgery. Additionally, patients were classified into 4 groups using the slope and intercept. By considering both the slope and intercept, clinicians may be able to detect the risk for prolonged pain earlier than other methods.

Experimental Pain Is Alleviated by Manual Traction Itself Rather than Subjective Bias in the Knee: A Signal Detection Analysis.

BACKGROUND: Manual traction is used for pain relief, but it is not clear whether the pain relief effect of manual traction is due to sensitivity or to subjective bias. The differences between manual traction and touch have also been unclear. OBJECTIVES: We used signal detection theory to investigate whether manual traction and touch were effective for pain relief, and we compared the pain relief effect between manual traction and touch. DESIGN: Repeated measures and single blinding. METHODS: Twenty healthy adult volunteers performed an intensity judgment task immediately before and after each intervention. The intervention was either manual traction or touch for 10 minutes. We measured the intensity judgment task's signal detection measures of hit rates, false alarm rates, sensitivity (d'), and response bias (C) in an Aδ fiber-mediated pain condition and C fiber-mediated pain condition. RESULTS: Manual traction did not provide a significant level of change, but its effect sizes differed. In our comparison of the effect sizes, manual traction tended to reduce the hit rate and altered the sensitivity value rather than the response bias in Aδ fiber-mediated pain. There was no significant difference in the amount of change in the hit rate between touch and manual traction regarding Aδ fiber-mediated pain and C fiber-mediated pain. CONCLUSIONS: In terms of effect sizes, manual traction was effective for the pain relief of the first pain by producing a change in pain sensitivity rather than by subjective bias. Manual traction reduced the first pain, whereas touch reduced the first pain and second pain.

Characteristics of Phantom Limb Pain Alleviated with Virtual Reality Rehabilitation.

OBJECTIVES: Neurorehabilitation techniques using virtual reality (VR) systems have recently become widespread as a rehabilitation method for restoring phantom limb movement and alleviating phantom limb pain (PLP). However, analgesic effects have varied between studies, possibly because of differences in the characteristics of PLP between patients (e.g., cramping, burning, shooting). We aimed to reveal the relationship between VR effects and PLP characteristics using an exploratory factor analysis. METHODS: PLP characteristics of 19 patients were measured using the Short-Form McGill Pain Questionnaire (SF-MPQ), and all PLP patients performed the VR rehabilitation protocol for 20 minutes. During VR rehabilitation, mirror-reversed computer graphic images of an intact arm (the virtual phantom limb) were presented to patients via a head-mounted display, inducing the perception of voluntary execution of movements of their phantom limb when intending bimanual movements. RESULTS: VR rehabilitation significantly restored movement representation (P < 0.0001) quantified using the bimanual coupling effect and significantly alleviated PLP intensity (P < 0.0001). The factor analysis revealed that PLP characteristics could be divided into two factors: "somatosensory-related pain characteristics" and "kinesthesia-related pain characteristics." PLP alleviation via VR rehabilitation was significantly correlated with "kinesthesia-related pain characteristics" (r = 0.47, P = 0.02) but not "somatosensory-related pain characteristics" (r = 0.22, P = 0.17). CONCLUSIONS: The current findings indicate that VR rehabilitation may be particularly effective for PLP associated with distorted phantom limb movement and body representations (e.g., clamping, gnawing), compared with typical neuropathic sensations (e.g., shooting, burning, dysesthesia).

Correction to: Kinesiophobia modulates lumbar movements in people with chronic low back pain: a kinematic analysis of lumbar bending and returning movement.

In the figure 2, "CLBP Low fear" located at the right end of Time of Phase 1 is wrong. The correct statement is "CLBP High fear". The complete correct figure 2 is given below.

Kinesiophobia modulates lumbar movements in people with chronic low back pain: a kinematic analysis of lumbar bending and returning movement.

PURPOSE: We aimed to kinematically analyze lumbar bending and returning movements and clarify the relationship between fear of movement and kinematic output. METHODS: We recruited 45 participants with CLBP (i.e., > 6 months) and 20 healthy control (HC) participants with no history of CLBP. We used the numerical rating pain scale (NRS), Tampa Scale for Kinesiophobia (TSK-11), and Pain Self-Efficacy Questionnaire (PSEQ-2) as qualitative outcome measurements. CLBP participants were divided into two subgroups (high- and low-fear groups) based on the median split of the total TSK-11 score. In the kinematic recording session, a starting-cue beep signaled participants to bend forward using the lumbar region of their spine and then return to an upright posture, and we used a flexible twin-axis electrogoniometer to record the lumbar movements. The time series of lumbar movements was divided into four phases according to lumbar movement velocity, and we calculated the length (sec) of each phase. RESULTS: Phase 1 (duration prior to cue-induced movement initiation) and phase 3 (switch in the direction of lumbar movement from forward to backward) were significantly longer in the CLBP high-fear group compared with those in the CLBP low-fear group and HC group (p < 0.05). The increased lengths of these two phases were positively correlated with not only pain intensity but also TSK-11 scores (p < 0.05). CONCLUSIONS: These results represent evidence of a particular lumbar movement pattern associated with kinesiophobia. These results might help to identify psychological factors that impact lumbar movement patterns in individuals with CLBP. These slides can be retrieved under Electronic Supplementary Material.

Kinematic evaluation for impairment of skilled hand function in chemotherapy-induced peripheral neuropathy.

INTRODUCTION: Chemotherapy-induced peripheral neuropathy (CIPN) usually affects both sensory and motor function of hands and feet, resulting in impaired skilled hand function (e.g., typing a keyboard). However, quantitative and objective evaluations for this condition have not been established. PURPOSE OF THE STUDY: We evaluated skilled hand function using a kinematic analysis and investigated relationships among hand kinematic function and the clinical sensory and motor features of CIPN. STUDY DESIGNS: Clinical measurement. METHODS: Twelve CIPN patients and 12 age-matched control participants were enrolled. We recorded their reach and grasp movements using a three-dimensional measurement system, and calculated the normalized jerk of these movements as quantitative indexes of skilled hand function. Additionally, we used the number of sequential hand grip-release cycles in 10 seconds as an evaluation of clinical motor function. RESULTS: Our kinematic analyses revealed significant difference in normalized jerk of grasp movement (CIPN: 3.7 ± 0.2, control: 3.4 ± 0.1; P = .005), but this was not the case for reach movement (CIPN: 2.5 ± 0.1, control: 2.5 ± 0.2; P = .43), indicating that the distal part of the forearm is particularly affected in CIPN. Such disturbed grasp movement was directly correlated with poor scores on the hand grip-release test and the sensory tests. DISCUSSION: We revealed deficit impaired hand function objectively and quantitatively in CIPN patients using a kinematic analysis. Further, the hand grip test could represent such kinematic abnormality and could be useful for evaluating skilled hand function of CIPN patients. CONCLUSIONS: Our kinematic and clinical measurements objectively and quantitatively evaluate skilled hand function in individuals with CIPN in clinical settings. LEVEL OF EVIDENCE: Cross-sectional observational study.

Modified feedback-control task for examining the relationship between sense of agency and motor control: a pilot study.

[Purpose] A sense of agency and feedback control may be related when the sensory feedback is attributed to the self; however, the relationship between sense of agency and movement disorders remains unclear. Although a feedback-control task might enable the examination of this relationship, it may be difficult for patients with movement disorders to complete this task. The present study modified the feedback-control task for future clinical research. [Participants and Methods] Twenty-four healthy adults participated in the study. The basic procedure followed that of a previous study in which participants traced a target line while receiving visual feedback of their actual or fake movement. The task was modified to reduce the width of the movement area, change the shape of the line from sinusoidal to horizontal, and reduce the number of trials from 45 to 15. [Results] When participants received the visual feedback of their actual movement, the movement error significantly decreased, whereas when participants received the fake movement that represented pre-recordings of their previous own movements, the movement error significantly increased. [Conclusion] The results partially agreed with those of the previous study. This modified task might help in examining the relationship between sense of agency and movement disorders in terms of motor control.

A "matched" sensory reference can guide goal-directed movements of the affected hand in central post-stroke sensory ataxia.

Patients with central post-stroke sensory ataxia (CPSA) suffer from not only somatosensory dysfunction but also the ataxic movement disorder of the affected limb. These sensory and motor impairments possibly interfere each other, but such interference is still unclear. We evaluated smoothness of grasp movements in CPSA patients using a kinematic analysis, and verified the effect of somatosensory reference from the intact hand on grasp movements. Eight CPSA patients were enrolled. We recorded their reach-and-pinch movements of both affected and intact hands toward the tip of the 3-cm-diameter vertical bar, using a three-dimensional measurement system. When executing these movements of one hand, the patients simultaneously pinched the same diameter bar as the goal tip (matched-reference condition: Matched-Ref) or the 5-cm-diameter thicker bar (mismatched-reference condition: Mismatched-Ref) by the other hand. The normalized jerk index (i.e., movement smoothness) of the affected hand was disturbed compared with the intact hand. The kinematic data of the finger opening and closing phases were also disturbed. These disturbances were partially improved with Matched-Ref but not Mismatched-Ref of the intact hand. We successfully evaluated the features of CPSA, indicating that the somatosensory reference method could be useful for rehabilitation in sensory ataxia.

Intentional gaze shift to neglected space: a compensatory strategy during recovery after unilateral spatial neglect.

Unilateral spatial neglect is a common neurological syndrome following predominantly right hemispheric stroke. While most patients lack insight into their neglect behaviour and do not initiate compensatory behaviours in the early recovery phase, some patients recognize it and start to pay attention towards the neglected space. We aimed to characterize visual attention capacity in patients with unilateral spatial neglect with specific focus on cortical processes underlying compensatory gaze shift towards the neglected space during the recovery process. Based on the Behavioural Inattention Test score and presence or absence of experience of neglect in their daily life from stroke onset to the enrolment date, participants were divided into USN+‰‰+ (do not compensate, n = 15), USN+ (compensate, n = 10), and right hemisphere damage groups (no neglect, n = 24). The patients participated in eye pursuit-based choice reaction tasks and were asked to pursue one of five horizontally located circular objects flashed on a computer display. The task consisted of 25 trials with 4-s intervals, and the order of highlighted objects was randomly determined. From the recorded eye tracking data, eye movement onset and gaze shift were calculated. To elucidate the cortical mechanism underlying behavioural results, electroencephalagram activities were recorded in three USN+‰‰+, 13 USN+ and eight patients with right hemisphere damage. We found that while lower Behavioural Inattention Test scoring patients (USN+‰‰+) showed gaze shift to non-neglected space, some higher scoring patients (USN+) showed clear leftward gaze shift at visual stimuli onset. Moreover, we found a significant correlation between Behavioural Inattention Test score and gaze shift extent in the unilateral spatial neglect group (r = -0.62, P < 0.01). Electroencephalography data clearly demonstrated that the extent of increase in theta power in the frontal cortex strongly correlated with the leftward gaze shift extent in the USN+‰‰+ and USN+ groups. Our results revealed a compensatory strategy (continuous attention to the neglected space) and its neural correlates in patients with unilateral spatial neglect. In conclusion, patients with unilateral spatial neglect who recognized their own neglect behaviour intentionally focused on the neglected space as a compensatory strategy to avoid careless oversight.