Source-Based EEG Neurofeedback for Sustained Motor Imagery of a Single Leg.

The aim of the study was to test the feasibility of visual-neurofeedback-guided motor imagery (MI) of the dominant leg, based on source analysis with real-time sLORETA derived from 44 EEG channels. Ten able-bodied participants took part in two sessions: session 1 sustained MI without feedback and session 2 sustained MI of a single leg with neurofeedback. MI was performed in 20 s on and 20 s off intervals to mimic functional magnetic resonance imaging. Neurofeedback in the form of a cortical slice presenting the motor cortex was provided from a frequency band with the strongest activity during real movements. The sLORETA processing delay was 250 ms. Session 1 resulted in bilateral/contralateral activity in the 8-15 Hz band dominantly over the prefrontal cortex while session 2 resulted in ipsi/bilateral activity over the primary motor cortex, covering similar areas as during motor execution. Different frequency bands and spatial distributions in sessions with and without neurofeedback may reflect different motor strategies, most notably a larger proprioception in session 1 and operant conditioning in session 2. Single-leg MI might be used in the early phases of rehabilitation of stroke patients. Simpler visual feedback and motor cueing rather than sustained MI might further increase the intensity of cortical activation.

Home-based rehabilitation using a soft robotic hand glove device leads to improvement in hand function in people with chronic spinal cord injury:a pilot study.

BACKGROUND: Loss of hand function following high level spinal cord injury (SCI) is perceived as a high priority area for rehabilitation. Following discharge, it is often impractical for the specialist care centre to provide ongoing therapy for people living with chronic SCI at home, which can lead to further deterioration of hand function and a direct impact on an individual's capability to perform essential activities of daily living (ADL). OBJECTIVE: This pilot study investigated the therapeutic effect of a self-administered home-based hand rehabilitation programme for people with cervical SCI using the soft extra muscle (SEM) Glove by Bioservo Technologies AB. METHODS: Fifteen participants with chronic cervical motor incomplete (AIS C and D) SCI were recruited and provided with the glove device to use at home to complete a set task and perform their usual ADL for a minimum of 4 h a day for 12 weeks. Assessment was made at Week 0 (Initial), 6, 12 and 18 (6-week follow-up). The primary outcome measure was the Toronto Rehabilitation Institute hand function test (TRI-HFT), with secondary outcome measures including pinch dynamometry and the modified Ashworth scale. RESULTS: The TRI-HFT demonstrated improvement in hand function at Week 6 of the therapy including improvement in object manipulation (58.3 ±3.2 to 66.9 ±1.8, p ≈ 0.01), and palmar grasp assessed as the length of the wooden bar that can be held using a pronated palmar grip (29.1 ±6.0 cm to 45.8 ±6.8 cm, p <0.01). A significant improvement in pinch strength, with reduced thumb muscle hypertonia was also detected. Improvements in function were present during the Week 12 assessment and also during the follow-up. CONCLUSIONS: Self-administered rehabilitation using the SEM Glove is effective for improving and retaining gross and fine hand motor function for people living with chronic spinal cord injury at home. Retention of improved hand function suggests that an intensive activity-based rehabilitation programme in specific individuals is sufficient to improve long-term neuromuscular activity. Future studies should characterise the neuromuscular mechanism of action and the minimal rehabilitation programme necessary with the assistive device to improve ADL tasks following chronic cervical SCI. TRIAL REGISTRATION NUMBER: Trial registration: ISRCTN, ISRCTN98677526, Registered 01/June/2017 - Retrospectively registered, http://www.isrctn.com/ISRCTN98677526.

A pressure monitoring approach for pressure ulcer prevention.

BACKGROUND: A pressure ulcer (PU) is a debilitating condition that disproportionately affects people with impaired mobility. PUs facilitate tissue damage due to prolonged unrelieved pressure, degrading quality of life with a considerable socio-economic impact. While rapid treatment is crucial, an effective prevention strategy may help avoid the development of PUs altogether. While pressure monitoring is currently used in PU prevention, available monitoring approaches are not formalised and do not appropriately account for accumulation and relief of the effect of an applied pressure over a prolonged duration. The aim of this study was to define an approach that incorporates the accumulation and relief of an applied load to enable continuous pressure monitoring. RESULTS: A tunable continuous pressure magnitude and duration monitoring approach that can account for accumulated damaging effect of an applied pressure and pressure relief over a prolonged period is proposed. Unlike classic pressure monitoring approaches, the presented method provides ongoing indication of the net impact of a load during and after loading. CONCLUSIONS: The tunable continuous pressure magnitude and duration monitoring approach proposed here may further development towards formalised pressure monitoring approaches that aim to provide information on the risk of PU formation in real-time.

Active proportional electromyogram controlled functional electrical stimulation system.

Neurophysiological theories and past studies suggest that intention driven functional electrical stimulation (FES) could be effective in motor neurorehabilitation. Proportional control of FES using voluntary EMG may be used for this purpose. Electrical artefact contamination of voluntary electromyogram (EMG) during FES application makes the technique difficult to implement. Previous attempts to date either poorly extract the voluntary EMG from the artefacts, require a special hardware or are unsuitable for online application. Here we show an implementation of an entirely software-based solution that resolves the current problems in real-time using an adaptive filtering technique with an optional comb filter to extract voluntary EMG from muscles under FES. We demonstrated that unlike the classic comb filter approach, the signal extracted with the present technique was coherent with its noise-free version. Active FES, the resulting EMG-FES system was validated in a typical use case among fifteen patients with tetraplegia. Results showed that FES intensity modulated by the Active FES system was proportional to intentional movement. The Active FES system may inspire further research in neurorehabilitation and assistive technology.

Is Implicit Motor Imagery a Reliable Strategy for a Brain-Computer Interface?

Explicit motor imagery (eMI) is a widely used brain-computer interface (BCI) paradigm, but not everybody can accomplish this task. Here, we propose a BCI based on implicit motor imagery (iMI). We compared classification accuracy between eMI and iMI of hands. Fifteen able-bodied people were asked to judge the laterality of hand images presented on a computer screen in a lateral or medial orientation. This judgment task is known to require mental rotation of a person's own hands, which in turn is thought to involve iMI. The subjects were also asked to perform eMI of the hands. Their electroencephalography was recorded. Linear classifiers were designed based on common spatial patterns. For discrimination between left hand and right hand, the classifier achieved maximum of 81 ± 8% accuracy for eMI and 83 ± 3% for iMI. These results show that iMI can be used to achieve similar classification accuracy as eMI. Additional classification was performed between iMI in medial and lateral orientations of a single hand; the classifier achieved 81 ± 7% for the left hand and 78 ± 7% for the right hand, which indicate distinctive spatial patterns of cortical activity for iMI of a single hand in different directions. These results suggest that a special BCI based on iMI may be constructed, for people who cannot perform explicit imagination, for rehabilitation of movement, or for treatment of bodily spatial neglect.

Rehabilitation of hand in subacute tetraplegic patients based on brain computer interface and functional electrical stimulation: a randomised pilot study.

OBJECTIVE: To compare neurological and functional outcomes between two groups of hospitalised patients with subacute tetraplegia. APPROACH: Seven patients received 20 sessions of brain computer interface (BCI) controlled functional electrical stimulation (FES) while five patients received the same number of sessions of passive FES for both hands. The neurological assessment measures were event related desynchronization (ERD) during movement attempt, Somatosensory evoked potential (SSEP) of the ulnar and median nerve; assessment of hand function involved the range of motion (ROM) of wrist and manual muscle test. MAIN RESULTS: Patients in both groups initially had intense ERD during movement attempt that was not restricted to the sensory-motor cortex. Following the treatment, ERD cortical activity restored towards the activity in able-bodied people in BCI-FES group only, remaining wide-spread in FES group. Likewise, SSEP returned in 3 patients in BCI-FES group, having no changes in FES group. The ROM of the wrist improved in both groups. Muscle strength significantly improved for both hands in BCI-FES group. For FES group, a significant improvement was noticed for right hand flexor muscles only. SIGNIFICANCE: Combined BCI-FES therapy results in better neurological recovery and better improvement of muscle strength than FES alone. For spinal cord injured patients, BCI-FES should be considered as a therapeutic tool rather than solely a long-term assistive device for the restoration of a lost function.

Influence of motor imagination on cortical activation during functional electrical stimulation.

OBJECTIVE: Motor imagination (MI) and functional electrical stimulation (FES) can activate the sensory-motor cortex through efferent and afferent pathways respectively. Motor imagination can be used as a control strategy to activate FES through a brain-computer interface as the part of a rehabilitation therapy. It is believed that precise timing between the onset of MI and FES is important for strengthening the cortico-spinal pathways but it is not known whether prolonged MI during FES influences cortical response. METHODS: Electroencephalogram was measured in ten able-bodied participants using MI strategy to control FES through a BCI system. Event related synchronisation/desynchronisation (ERS/ERD) over the sensory-motor cortex was analysed and compared in three paradigms: MI before FES, MI before and during FES and FES alone activated automatically. RESULTS: MI practiced both before and during FES produced strongest ERD. When MI only preceded FES it resulted in a weaker beta ERD during FES than when FES was activated automatically. Following termination of FES, beta ERD returns to the baseline level within 0.5s while alpha ERD took longer than 1s. CONCLUSIONS: When MI and FES are combined for rehabilitation purposes it is recommended that MI is practiced throughout FES activation period. SIGNIFICANCE: The study is relevant for neurorehabilitation of movement.

Similarities between explicit and implicit motor imagery in mental rotation of hands: an EEG study.

Chronometric and imaging studies have shown that motor imagery is used implicitly during mental rotation tasks in which subjects for example judge the laterality of human hand pictures at various orientations. Since explicit motor imagery is known to activate the sensorimotor areas of the cortex, mental rotation is expected to do similar if it involves a form of motor imagery. So far, functional magnetic resonance imaging and positron emission tomography have been used to study mental rotation and less attention has been paid to electroencephalogram (EEG) which offers a high time-frequency resolution. The time-frequency analysis is an established method for studying explicit motor imagery. Although hand mental rotation is claimed to involve motor imagery, the time-frequency characteristics of mental rotation have never been compared with those of explicit motor imagery. In this study, time-frequency responses of EEG recorded during explicit motor imagery and during a mental rotation task, inducing implicit motor imagery, were compared. Fifteen right-handed healthy volunteers performed motor imagery of hands in one condition and hand laterality judgement tasks in another while EEG of the whole head was recorded. The hand laterality judgement was the mental rotation task used to induce implicit motor imagery. The time-frequency analysis and sLORETA localisation of the EEG showed that the activities in the sensorimotor areas had similar spatial and time-frequency characteristics in explicit motor imagery and implicit motor imagery conditions. Furthermore this sensorimotor activity was different for the left and for the right hand in both explicit and implicit motor imagery. This result supports that motor imagery is used during mental rotation and that it can be detected and studied with EEG technology. This result should encourage the use of mental rotation of body parts in rehabilitation programmes in a similar manner as motor imagery.

Using a motor imagery questionnaire to estimate the performance of a Brain-Computer Interface based on object oriented motor imagery.

OBJECTIVES: The primary objective was to test whether motor imagery (MI) questionnaires can be used to detect BCI 'illiterate'. The second objective was to test how different MI paradigms, with and without the physical presence of the goal of an action, influence a BCI classifier. METHODS: Kinaesthetic (KI) and visual (VI) motor imagery questionnaires were administered to 30 healthy volunteers. Their EEG was recorded during a cue-based, simple imagery (SI) and goal oriented imagery (GOI). RESULTS: The strongest correlation (Pearson r(2)=0.53, p=1.6e-5) was found between KI and SI, followed by a moderate correlation between KI and GOI (r(2)=0.33, p=0.001) and a weak correlation between VI and SI (r(2)=0.21, p=0.022) and VI and GOI (r(2)=0.17, p=0.05). Classification accuracy was similar for SI (71.1 ± 7.8%) and GOI (70.5 ± 5.9%) though corresponding classification features differed in 70% participants. Compared to SI, GOI improved the classification accuracy in 'poor' imagers while reducing the classification accuracy in 'very good' imagers. CONCLUSION: The KI score could potentially be a useful tool to predict the performance of a MI based BCI. The physical presence of the object of an action facilitates motor imagination in 'poor' able-bodied imagers. SIGNIFICANCE: Although this study shows results on able-bodied people, its general conclusions should be transferable to BCI based on MI for assisted rehabilitation of the upper extremities in patients.