Testing silicone digit extensions as a way to suppress natural sensation to evaluate supplementary tactile feedback.

Dexterous use of the hands depends critically on sensory feedback, so it is generally agreed that functional supplementary feedback would greatly improve the use of hand prostheses. Much research still focuses on improving non-invasive feedback that could potentially become available to all prosthesis users. However, few studies on supplementary tactile feedback for hand prostheses demonstrated a functional benefit. We suggest that confounding factors impede accurate assessment of feedback, e.g., testing non-amputee participants that inevitably focus intently on learning EMG control, the EMG's susceptibility to noise and delays, and the limited dexterity of hand prostheses. In an attempt to assess the effect of feedback free from these constraints, we used silicone digit extensions to suppress natural tactile feedback from the fingertips and thus used the tactile feedback-deprived human hand as an approximation of an ideal feed-forward tool. Our non-amputee participants wore the extensions and performed a simple pick-and-lift task with known weight, followed by a more difficult pick-and-lift task with changing weight. They then repeated these tasks with one of three kinds of audio feedback. The tests were repeated over three days. We also conducted a similar experiment on a person with severe sensory neuropathy to test the feedback without the extensions. Furthermore, we used a questionnaire based on the NASA Task Load Index to gauge the subjective experience. Unexpectedly, we did not find any meaningful differences between the feedback groups, neither in the objective nor the subjective measurements. It is possible that the digit extensions did not fully suppress sensation, but since the participant with impaired sensation also did not improve with the supplementary feedback, we conclude that the feedback failed to provide relevant grasping information in our experiments. The study highlights the complex interaction between task, feedback variable, feedback delivery, and control, which seemingly rendered even rich, high-bandwidth acoustic feedback redundant, despite substantial sensory impairment.

Influence of the visuo-proprioceptive illusion of movement and motor imagery of the wrist on EEG cortical excitability among healthy participants.

INTRODUCTION: Motor Imagery (MI) is a powerful tool to stimulate sensorimotor brain areas and is currently used in motor rehabilitation after a stroke. The aim of our study was to evaluate whether an illusion of movement induced by visuo-proprioceptive immersion (VPI) including tendon vibration (TV) and Virtual moving hand (VR) combined with MI tasks could be more efficient than VPI alone or MI alone on cortical excitability assessed using Electroencephalography (EEG). METHODS: We recorded EEG signals in 20 healthy participants in 3 different conditions: MI tasks involving their non-dominant wrist (MI condition); VPI condition; and VPI with MI tasks (combined condition). Each condition lasted 3 minutes, and was repeated 3 times in randomized order. Our main judgment criterion was the Event-Related De-synchronization (ERD) threshold in sensori-motor areas in each condition in the brain motor area. RESULTS: The combined condition induced a greater change in the ERD percentage than the MI condition alone, but no significant difference was found between the combined and the VPI condition (p = 0.07) and between the VPI and MI condition (p = 0.20). CONCLUSION: This study demonstrated the interest of using a visuo-proprioceptive immersion with MI rather than MI alone in order to increase excitability in motor areas of the brain. Further studies could test this hypothesis among patients with stroke to provide new perspectives for motor rehabilitation in this population.

Acupuncture of fascia points to relieve hand spasm after stroke: a study protocol for a multicenter randomized controlled trial.

BACKGROUND: The loss of functional ability of patients after stroke is mostly caused by dysfunction of the upper limbs, especially the hands. Hand functional exercise is the premise of alleviating hand dysfunction, and the relief of hand spasm is the basis of timely and effective hand functional exercise. Previous clinical observation have shown that fascial-point needling can effectively alleviate hand spasm immediately after stroke, but further evidence from large-sample studies is needed. The overall objective of this trial is to further evaluate the clinical efficacy of fascial-point acupuncture on hand spasm after stroke. METHODS/DESIGN: This multicenter randomized controlled trial will compare the efficacy of fascial-point acupuncture versus sham acupuncture and routine rehabilitation therapy in stroke patients with hand spasm. Patients will be randomized to undergo either the fascial-point acupuncture, the sham acupuncture or the control (routine rehabilitation therapy). We will recruit 210 stroke inpatients who meet the trial criteria and observe the remission of hand spasm and improvement of limb function after 4 weeks of intervention. The first evaluation indices are the remission of hand spasm and the duration of spasm remission. The second evaluation indices are the hand function of the affected limbs and the activities of daily living. When the accumulative total number of cases included reaches 120, a mid-term analysis will be conducted to determine any evidence that experimental intervention does have an advantage. DISCUSSION: Our aim is to evaluate the efficacy of fascial-point acupuncture in relieving hand spasm after stroke. The results should provide more evidence for the clinical application of this therapy in the future. TRIAL REGISTRATION: Chinese Clinical Trial Registry (ChiCTR), ID: ChiCTR1900022379. Registered on 9 April 2019.

Ultrasound Guidance Enhances the Efficiency of Brachial Plexus Block and Ameliorates the Vascular Injury Compared with Nerve Stimulator Guidance in Hand Surgery Patients.

Background: Nerve stimulation guidance and ultrasound guidance are two major methods that have been widely accepted and applied in axillary brachial plexus block. However, the differences between the effects of these two types of guidance still need to be further elucidated for clinical usage. Materials and Methods: Overall, 208 patients undergoing elective upper limb surgeries and receiving axillary brachial plexus block were recruited in our study. The patients were randomly assigned to receive either ultrasound guidance (group U, n = 112) or nerve stimulation (group N, n = 96). Pinprick test was performed for assessing the sensory blockades. The pain was evaluated by visual analog scale (VAS). Reactive oxygen species (ROS) levels were measured by dichloro-dihydro-fluorescein diacetate staining and serum levels of nitric oxide (NO), nitric oxide synthases (NOS), tumor necrosis factor (TNF)-α, and monocyte chemoattractant protein 1 (MCP1) were evaluated by ELISA. Results: Ultrasound guidance significantly enhanced the quality of the sensory blockade and reduced the VAS scores when compared with the nerve stimulator guidance. In addition, the production of ROS, NO, NOS, TNF-α, and MCP-1 were significantly alleviated by ultrasound guidance. Conclusion: Ultrasound-guided brachial plexus block relieves pain during operation, provides higher success rates in the nerve block, causes less vascular damage and results in lower levels of inflammatory cytokines secretion when compared with neurostimulator-directed brachial plexus blockage.

Electrical stimulation-induced SSSEP as an objective index to evaluate the difference of tactile acuity between the left and right hand.

OBJECTIVE: The objective of this study is to propose an objective index to evaluate the difference of tactile acuity between the left and right hand based on steady-state somatosensory evoked potential (SSSEP). APPROACH: Two kinds of tactile sensations (vibration and pressure) with three levels of intensities (low/medium/high) were evoked on two finger areas of the left or right hand (thumb and index for healthy hands, thumb and index-projected areas for disabled hands) via transcutaneous electrical nerve stimulation (TENS). Three forearm amputees and 13 able-bodied subjects were recruited to discriminate the specific level and area of the applied stimulation. Electroencephalography was adopted to simultaneously record the somatosensory cortex response to TENS. We assessed the discrimination performance (discrimination accuracy rate (AR) and response time (RT)) to quantify the tactile acuity, while the evoked SSSEP was synchronously analyzed. Linear regression analyses were performed between the difference of SSSEP amplitudes and the difference of discrimination performance for the left and right hand stimulation. MAIN RESULTS: Frequency domain analysis revealed that SSSEP amplitude increased with the increase of the stimulation intensity. There were positive correlations between the difference of SSSEP amplitudes and the difference of ARs for the left and right hand stimulation in the sensations of vibration (R 2 = 0.6389 for able-bodied subjects, R 2 = 0.5328 for amputees) and pressure (R 2 = 0.6102 for able-bodied subjects, R 2 = 0.5452 for amputees), respectively. Significance The SSSEP amplitude could be used as an objective index to evaluate the difference of the tactile acuity between the left and right hand and has the potential to be applied in sensory rehabilitation for amputees or stroke patients.

What Role Does Positive Psychology Play in Understanding Pain Intensity and Disability Among Patients with Hand and Upper Extremity Conditions?

BACKGROUND: A large body of research shows that psychologic distress and ineffective coping strategies substantially contribute to more severe pain and increased physical limitations among patients with orthopaedic disorders. However, little is known about the relationship between positive psychology (constructs that enable individuals to thrive and adapt to challenges) and pain and physical limitations in this population. QUESTIONS/PURPOSES: (1) Which positive-psychology factors (satisfaction with life, gratitude, coping through humor, resilience, mindfulness, and optimism) are independently associated with fewer upper-extremity physical limitations after controlling for the other clinical and demographic variables? (2) Which positive-psychology factors are independently associated with pain intensity after controlling for relevant clinical and demographic variables? METHODS: In a cross-sectional study, we recruited patients presenting for a scheduled appointment with an orthopaedic surgeon at a hand and upper-extremity clinic of a major urban academic medical center. Of 125 approached patients, 119 (44% men; mean age, 50 ± 17 years) met screening criteria and agreed to participate. Patients completed a clinical and demographic questionnaire, the Numerical Rating Scale to assess pain intensity, the Patient-reported Outcomes Measurement Information System (PROMIS) Upper Extremity Physical Function computerized adaptive test to assess physical limitations, and six measures assessing positive-psychology constructs: The Satisfaction with Life Scale, the Gratitude Questionnaire, the Coping Humor Scale, the Brief Resilience Scale, the Cognitive and Affective Mindfulness Scale-Revised, and the Life Orientation Test-Revised. We first examined bivariate associations among physical limitations, pain intensity, and all positive-psychology factors as well as demographic and clinical variables. All variables that demonstrated associations with physical limitations or pain intensity at p < 0.05 were included in two-stage multivariable hierarchical regression models. RESULTS: After controlling for the potentially confounding effects of prior surgical treatment and duration since pain onset (step1; R total = 0.306; F[7,103] = 6.50), the positive-psychology variables together explained an additional 15% (R change = 0.145, F change [5, 103] = 4.297, p = 0.001) of the variance in physical limitations. Among the positive-psychology variables tested, mindfulness was the only one associated with fewer physical limitations (ß = 0.228, t = 2.293, p = 0.024, 4% variance explained). No confounding demographic or clinical variables were found for pain intensity in bivariate analyses. All positive-psychology variables together explained 23% of the variance in pain intensity (R = 0.23; F[5,106] = 6.38, p < 0.001). Among the positive-psychology variables, satisfaction with life was the sole factor independently associated with higher intensity (ß = -0.237, t = -2.16, p = 0.033, 3% variance explained). CONCLUSIONS: Positive-psychology variables explained 15% of the variance in physical limitations and for 23% of the variance in pain intensity among patients with heterogenous upper extremity disorders within a hand and upper extremity practice. Of all positive-psychology factors, mindfulness and satisfaction with life were most important for physical limitations and pain intensity, respectively. As positive-psychology factors are more easily modifiable through skills-based interventions than pain and physical limitations, results suggest implementation of such interventions to potentially improve outcomes in this population. Skills-based interventions targeting mindfulness and satisfaction with life may be of particular benefit. LEVEL OF EVIDENCE: Level II, prognostic study.

Reach and palmar grasp in tetraplegics with neuromuscular electrical stimulation / Alcance e preensão palmar em tetraplégicos com estimulação elétrica neuromuscular / Alcance y prensión palmar en tetrapléjicos con estimulación eléctrica neuromuscular

OBJECTIVE: To evaluate the movement strategies of quadriplegics, assisted by neuromuscular electrical stimulation, on reach and palmar grasp using objects of different weights. METHODS: It was a prospective clinical trial. Four chronic quadriplegics (C5-C6), with injuries of traumatic origin, were recruited and all of them had their reach and palmar grasp movement captured by four infrared cameras and six retro-reflective markers attached to the trunk and right arm, assisted or not by neuromuscular electrical stimulation to the triceps, extensor carpi radialis longus, extensor digitorum communis, flexor digitorum superficialis, opponens pollicis and lumbricals. It was measured by a Neurological and Functional Classification of Spinal Cord Injuries of the American Spinal Injury Association, Functional Independence Measure and kinematic variables. RESULTS: The patients were able to reach and execute palmar grasp in all cylinders using the stimulation sequences assisted by neuromuscular electrical stimulation. The quadriplegics produced lower peak velocity, a shorter time of movement and reduction in movement segmentation, when assisted by neuromuscular electrical stimulation. CONCLUSION: This study showed that reach and palmar grasp movement assisted by neuromuscular electrical stimulation was able to produce motor patterns more similar to healthy subjects. Level of evidence IV; Case series.

OBJETIVO: Avaliar as estratégias de movimento de quadriplégicos com o auxílio de estimulação elétrica neuromuscular sobre o alcance e a preensão palmar com objetos de diferentes pesos. MÉTODOS: Estudo clínico prospectivo. Quatro quadriplégicos crônicos (C5-C6) com lesões de origem traumática foram recrutados e todos tiveram o alcance e movimento de preensão palmar capturado por quatro câmeras infravermelho e seis marcadores retrorreflexivos fixados no tronco e braço direito, assistidos ou não por estimulação neuromuscular do tríceps, extensor radial longo do carpo, extensor dos dedos, flexor superficial dos dedos, oponente do polegar e músculos lumbricais. A medida foi feita com base na Classificação Neurológica e Funcional de Lesões Medulares da American Spinal Injury Association, na Medida de Independência Funcional e em variáveis cinemáticas. RESULTADOS: Os pacientes foram capazes de alcançar e realizar preensão palmar em todos os cilindros utilizando as sequências de estimulação auxiliadas por estimulação elétrica neuromuscular. Os quadriplégicos produziram menor velocidade de pico, menor tempo de movimento e redução na segmentação do movimento, quando foram auxiliados pela estimulação elétrica neuromuscular. CONCLUSÃO: Este estudo mostrou que o alcance e o movimento de preensão palmar assistidos por estimulação elétrica neuromuscular foi capaz de produzir padrões motores mais semelhantes aos dos indivíduos saudáveis. Nível de evidência IV; Série de casos.

OBJETIVO: Evaluar las estrategias de movimiento de cuadripléjicos, con el auxilio de estimulación eléctrica neuromuscular sobre el alcance y la prensión palmar con objetos de diferentes pesos. MÉTODOS: Estudio clínico prospectivo. Fueron reclutados cuatro cuadripléjicos crónicos (C5-C6) con lesiones de origen traumático y todos ellos tuvieron su alcance y movimiento de prensión palmar capturado por cuatro cámaras infrarrojas y seis marcadores retrorreflexivos fijados al tronco y al brazo derecho, asistidos o no por estimulación neuromuscular del tríceps, extensor radial largo del carpo, extensor de los dedos, flexor superficial de los dedos, oponente del pulgar y músculos lumbricales. La medición fue hecha con base en la Clasificación Neurológica y Funcional de Lesiones Medulares de la American Spinal Injury Association, en la Medida de Independencia Funcional y en variables cinemáticas. RESULTADOS: Los pacientes fueron capaces de alcanzar y realizar prensión palmar en todos los cilindros utilizando las secuencias de estimulación auxiliadas por estimulación eléctrica neuromuscular. Los cuadripléjicos produjeron menor velocidad de pico, menor tiempo de movimiento y reducción en la segmentación del movimiento, cuando fueron auxiliados por la estimulación eléctrica neuromuscular. CONCLUSIÓN: El presente estudio mostró que el alcance y el movimiento de prensión palmar asistidos por estimulación eléctrica neuromuscular fue capaz de producir patrones motores más similares a los individuos saludables. Nivel de evidencia IV; Serie de casos.

Right Hemisphere Contributions to Bilateral Force Control in Chronic Stroke: A Preliminary Report.

BACKGROUND: Bilateral motor control deficits poststroke may be lateralized by hemisphere damage. This preliminary study investigated bilateral force control between left and right hemisphere-damaged groups at baseline and after coupled bilateral movement training with neuromuscular stimulation. METHODS: Stroke participants (8 left hemisphere and 6 right hemisphere cerebrovascular accidents) performed a bilateral isometric force control task at 3 submaximal force levels (5%, 25%, and 50% of maximum voluntary contraction [MVC]) before and after training. Force accuracy, force variability, and interlimb force coordination were analyzed in 3-way mixed design ANOVAs (2 × 2 × 3; Group × Test Session × Force Level) with repeated measures on test session and force level. RESULTS: The findings indicated that force accuracy and variability at 50% of MVC in the right hemisphere-damaged group were more impaired than lower targeted force levels at baseline, and the impairment at the highest target level was improved after coupled bilateral movement training. However, these patterns were not observed in the left hemisphere-damaged group. CONCLUSIONS: Current findings support a proposition that the right hemisphere presumably contributes to controlling bilateral force production.

Evoked haptic sensations in the hand via non-invasive proximal nerve stimulation.

OBJECTIVE: Haptic perception of a prosthetic limb or hand is a crucial, but often unmet, need which impacts the utility of the prostheses. In this study, we seek to evaluate the feasibility of a non-invasive transcutaneous nerve stimulation method in generating haptic feedback in a transradial amputee subject as well as intact able-bodied subjects. APPROACH: An electrode grid was placed on the skin along the medial side of the upper arm beneath the short head of the biceps brachii, in proximity to the median and ulnar nerves. Varying stimulation patterns were delivered to different electrode pairs, in order to emulate different types of sensations (Single Tap, Press-and-Hold, Double Tap) at different regions of the hand. Subjects then reported the magnitude of sensation by pressing on a force transducer to transform the qualitative haptic perception into a quantitative measurement. MAIN RESULTS: Altering current stimulations through electrode pairs on the grid resulted in repeatable alterations in the percept regions of the hand. Most subjects reported spatial coverage of individual fingers or phalanges, which can resemble the whole hand through different pairs of stimulation electrodes. The different stimulation patterns were also differentiable by all subjects. The amputee subject also reported haptic sensations similar to the able-bodied subjects. SIGNIFICANCE: Our findings demonstrated the capabilities of our transcutaneous stimulation method. Subjects were able to perceive spatially distinct sensations with graded magnitudes that emulated tapping and holding sensation in their hands. The elicitation of haptic sensations in the phantom hand of an amputee is a significant step in the development of our stimulation method, and provides insight into the future adaptation and implementation of prostheses with non-invasive sensory feedback to the users.

Second-order spinal cord pathway contributes to cortical responses after long recoveries from dorsal column injury in squirrel monkeys.

Months after the occurrence of spinal cord dorsal column lesions (DCLs) at the cervical level, neural responses in the hand representation of somatosensory area 3b hand cortex recover, along with hand use. To examine whether the second-order spinal cord pathway contributes to this functional recovery, we injected cholera toxin subunit B (CTB) into the hand representation in the cuneate nucleus (Cu) to label the spinal cord neurons, and related results to cortical reactivation in four squirrel monkeys (Saimiri boliviensis) at least 7 months after DCL. In two monkeys with complete DCLs, few CTB-labeled neurons were present below the lesion, and few neurons in the affected hand region in area 3b responded to touch on the hand. In two other cases with large but incomplete DCLs, CTB-labeled neurons were abundant below the lesion, and the area 3b hand cortex responded well to tactile stimulation in a roughly somatotopic organization. The proportions of labeled neurons in the spinal cord hand region reflected the extent of cortical reactivation to the hand. Comparing monkeys with short and long recovery times suggests that the numbers of labeled neurons below the lesion increase with time following incomplete DCLs (<95%) but decrease with time after nearly complete DCLs (≥95%). Taken together, these results suggest that the second-order spinal cord pathway facilitates cortical reactivation, likely through the potentiation of persisting tactile inputs from the hand to the Cu over months of postlesion recovery.

Does transcutaneous nerve stimulation have effect on sympathetic skin response?

OBJECTIVE: This study examined the effects of transcutaneous electrical nerve stimulation (TENS) on the sympathetic nerve system by sympathetic skin response test. METHODS: Fifty-five healthy volunteers received either: (i) 30minutes TENS (25 participants) (ii) 30minutes sham TENS (30 participants) and SSR test was performed pre- and post-TENS. The mean values of latency and peak-to-peak amplitude of five consecutive SSRs were calculated. RESULTS: A significant amplitude difference was found between TENS and sham TENS group both in right and left hand (p=0.04, p=0.01, respectively). However there was no significant latancy difference between two groups (p>0.05 ). CONCLUSION: TENS has an inhibitory effect on elicited SNS responses when compared with sham TENS control group.

Brain-Computer Interfaces With Multi-Sensory Feedback for Stroke Rehabilitation: A Case Study.

Conventional therapies do not provide paralyzed patients with closed-loop sensorimotor integration for motor rehabilitation. This work presents the recoveriX system, a hardware and software platform that combines a motor imagery (MI)-based brain-computer interface (BCI), functional electrical stimulation (FES), and visual feedback technologies for a complete sensorimotor closed-loop therapy system for poststroke rehabilitation. The proposed system was tested on two chronic stroke patients in a clinical environment. The patients were instructed to imagine the movement of either the left or right hand in random order. During these two MI tasks, two types of feedback were provided: a bar extending to the left or right side of a monitor as visual feedback and passive hand opening stimulated from FES as proprioceptive feedback. Both types of feedback relied on the BCI classification result achieved using common spatial patterns and a linear discriminant analysis classifier. After 10 sessions of recoveriX training, one patient partially regained control of wrist extension in her paretic wrist and the other patient increased the range of middle finger movement by 1 cm. A controlled group study is planned with a new version of the recoveriX system, which will have several improvements.

Effects of somatosensory electrical stimulation on motor function and cortical oscillations.

BACKGROUND: Few patients recover full hand dexterity after an acquired brain injury such as stroke. Repetitive somatosensory electrical stimulation (SES) is a promising method to promote recovery of hand function. However, studies using SES have largely focused on gross motor function; it remains unclear if it can modulate distal hand functions such as finger individuation. OBJECTIVE: The specific goal of this study was to monitor the effects of SES on individuation as well as on cortical oscillations measured using EEG, with the additional goal of identifying neurophysiological biomarkers. METHODS: Eight participants with a history of acquired brain injury and distal upper limb motor impairments received a single two-hour session of SES using transcutaneous electrical nerve stimulation. Pre- and post-intervention assessments consisted of the Action Research Arm Test (ARAT), finger fractionation, pinch force, and the modified Ashworth scale (MAS), along with resting-state EEG monitoring. RESULTS: SES was associated with significant improvements in ARAT, MAS and finger fractionation. Moreover, SES was associated with a decrease in low frequency (0.9-4 Hz delta) ipsilesional parietomotor EEG power. Interestingly, changes in ipsilesional motor theta (4.8-7.9 Hz) and alpha (8.8-11.7 Hz) power were significantly correlated with finger fractionation improvements when using a multivariate model. CONCLUSIONS: We show the positive effects of SES on finger individuation and identify cortical oscillations that may be important electrophysiological biomarkers of individual responsiveness to SES. These biomarkers can be potential targets when customizing SES parameters to individuals with hand dexterity deficits. TRIAL REGISTRATION: NCT03176550; retrospectively registered.

The effectiveness of low-level laser therapy on pain, self-reported hand function, and grip strength compared to placebo or "sham" treatment for adults with carpal tunnel syndrome: A systematic review.

BACKGROUND: Carpal tunnel syndrome (CTS) is one of the most common peripheral neuropathies in the upper extremity. OBJECTIVE: The aim of this review was to systematically and critically appraise the available literature for the effectiveness of Low-Level Laser Therapy (LLLT) on pain, self-reported hand function, and grip strength compared to placebo treatment in adults with CTS. METHODOLOGY: Seven databases were searched from 2000 to March 2015 namely: Cinahl, Cochrane Library, EBSCOhost, PEDro, PubMed, Science Direct, and Scopus. Key search terms were: CTS, LLLT, and physiotherapy. Specific inclusion and exclusion criteria were applied. The methodological quality was appraised with the PEDro scale. Data were extracted and captured on an Excel spreadsheet. RESULTS: The nine included randomized control trials (RCTs) had an average score of 8.2/11 according to the PEDro scale. The heterogeneity of the LLLT regimes used made statistical pooling inappropriate for this review and results were described narratively. CONCLUSION: No strong evidence exists concerning the effects of LLLT on CTS in adults. Studies that used 780-860 nm Lasers and energy dosages of 9-11 J/cm2 or 10.8 J reported a more favorable outcome for pain, symptom severity, and functional ability as well as grip strength at the end of treatment and short-term follow up.

GLIMPSE: Google Glass interface for sensory feedback in myoelectric hand prostheses.

OBJECTIVE: Providing sensory feedback to the user of the prosthesis is an important challenge. The common approach is to use tactile stimulation, which is easy to implement but requires training and has limited information bandwidth. In this study, we propose an alternative approach based on augmented reality. APPROACH: We have developed the GLIMPSE, a Google Glass application which connects to the prosthesis via a Bluetooth interface and renders the prosthesis states (EMG signals, aperture, force and contact) using augmented reality (see-through display) and sound (bone conduction transducer). The interface was tested in healthy subjects that used the prosthesis with (FB group) and without (NFB group) feedback during a modified clothespins test that allowed us to vary the difficulty of the task. The outcome measures were the number of unsuccessful trials, the time to accomplish the task, and the subjective ratings of the relevance of the feedback. MAIN RESULTS: There was no difference in performance between FB and NFB groups in the case of a simple task (basic, same-color clothespins test), but the feedback significantly improved the performance in a more complex task (pins of different resistances). Importantly, the GLIMPSE feedback did not increase the time to accomplish the task. Therefore, the supplemental feedback might be useful in the tasks which are more demanding, and thereby less likely to benefit from learning and feedforward control. The subjects integrated the supplemental feedback with the intrinsic sources (vision and muscle proprioception), developing their own idiosyncratic strategies to accomplish the task. SIGNIFICANCE: The present study demonstrates a novel self-contained, ready-to-deploy, wearable feedback interface. The interface was successfully tested and was proven to be feasible and functionally beneficial. The GLIMPSE can be used as a practical solution but also as a general and flexible instrument to investigate closed-loop prosthesis control.

Detecting neuronal dysfunction of hand motor cortex in ALS: A MRSI study.

BACKGROUND: Although hand motor cortex (HMC) has been constantly used for identification of primary motor cortex in magnetic resonance spectroscopy (MRS) studies of amyotrophic lateral sclerosis (ALS), neurochemical profiles of HMC have never been assessed independently. As HMC has a constant location and the clinic-anatomic correlation between hand motor function and HMC has been established, we hypothesize that HMC may serve as a promising region of interest in diagnosing ALS. PATIENTS AND METHODS: Fourteen ALS patients and 14 age- and gender-matched healthy controls (HC) were recruited in this study. An optimized magnetic resonance spectroscopic imaging (MRSI) method was developed and for each subject bilateral HMC areas were scanned separately (two-dimensional multi-voxel MRSI, voxel size 0.56 cm3). N-acetyl aspartate (NAA)-creatine (Cr) ratio was measured from HMC and the adjacent postcentral gyrus. RESULTS: Compared with HC, NAA/Cr ratios from HMC and the postcentral gyrus were significantly reduced in ALS. However, in each group the difference of NAA/Cr ratios between HMC and the postcentral gyrus was not significant. Limb predominance of HMC was not found in either ALS or HC. In ALS, there was a significant difference in NAA/Cr ratio between the most affected HMC and the less affected HMC. A positive relationship between NAA/Cr ratio of HMC and the severity of hand strength (assessed by finger tapping speed) was demonstrated. CONCLUSION: Neuronal dysfunction of HMC can differentiate ALS patients from HC when represented as reduced NAA/Cr ratio. Postcentral gyrus could not serve as normal internal reference tissue in diagnosing ALS. Asymmetrical NAA/Cr ratios from bilateral HMC may serve as a promising diagnostic biomarker of ALS at the individual level.

fMRI characterisation of widespread brain networks relevant for behavioural variability in fine hand motor control with and without visual feedback.

A bilateral visuo-parietal-motor network is responsible for fine control of hand movements. However, the sub-regions which are devoted to maintenance of contraction stability and how these processes fluctuate with trial-quality of task execution and in the presence/absence of visual feedback remains unclear. We addressed this by integrating behavioural and fMRI measurements during right-hand isometric compression of a compliant rubber bulb, at 10% and 30% of maximum voluntary contraction, both with and without visual feedback of the applied force. We quantified single-trial behavioural performance during 1) the whole task period and 2) stable contraction maintenance, and regressed these metrics against the fMRI data to identify the brain activity most relevant to trial-by-trial fluctuations in performance during specific task phases. fMRI-behaviour correlations in a bilateral network of visual, premotor, primary motor, parietal and inferior frontal cortical regions emerged during performance of the entire feedback task, but only in premotor, parietal cortex and thalamus during the stable contraction period. The trials with the best task performance showed increased bilaterality and amplitude of fMRI responses. With feedback, stronger BOLD-behaviour coupling was found during 10% compared to 30% contractions. Only a small subset of regions in this network were weakly correlated with behaviour without feedback, despite wider network activated during this task than in the presence of feedback. These findings reflect a more focused network strongly coupled to behavioural fluctuations when providing visual feedback, whereas without it the task recruited widespread brain activity almost uncoupled from behavioural performance.

[Experience of the Continuous Real Time fMRI Biofeedback of the Primary Motor Cortex Using a 1.5 T MR Scanner].

The neurofeedback based on the motor areas fMRI signal may be a promising treatment for improving motor impairment in post-stroke conditions and Parkinson's disease. In the majority of the studies has been conducted using the 3 T MR machines, and the region of interest has been placed to the secondary motor areas. The current study attempted to perform an fMRI neurofeeback based on response of the right hand projection locus within primary motor cortex utilizing the 1.5 T MR scanner and using the optimal parameters for the named magnetic field strength. The subjects were 16 healthy participants who underwent a 30-minute imaging session comprised 1) individual func- tional localization of the region of interest (using the hand clinging task) and attempts to control its activity with 2) motor imagery and 3) any cognitive strategy chosen by participant. In both self-regulation conditions subjects activated G. precentralis, G. cinguli anterior, G. frontalis superior, G. parietalis inferior, and 6-th Brodman area. Activation maps for these two tasks didn't differ one from another significantly, and the involved area had only a few overlays with the region of interest map which signifies that training was unsucessful. The limitations of the study and factors influenc- ing the biofeedback efficacy negatively are discussed.