Anirban Dutta

A Low-Cost Adaptive Balance Training Platform for Stroke Patients: A Usability Study

Stroke patients usually suffer from asymmetric posture due to hemi-paresis that can result in reduced postural controllability leading to a balance deficit. This deficit increases the risk of falls, which often makes them dependent on caregivers for community ambulation, thus deteriorating their quality of life. Conventional balance training involves rehabilitation exercises performed under physiotherapist’s supervision, where the scarcity of trained professionals as well as the cost of clinic-based rehabilitation programs can deter stroke survivors from undergoing regular balance training. Thus, researchers have been exploring technology-assisted solutions, e.g., home-based virtual reality (VR) setup. In this paper, we developed a VR-based balance training (VBaT) platform, where VR-augmented user-interface using Nintendo Wii balance boardwas tested in a laboratory setting for its feasibility. The VBaT offered tasks of varying difficulties to the participants that adapted to individual performance capability during balance training. We performed a preliminaryusability study with 7 stroke survivors (post-stroke period > 6 months). Preliminary results indicate the potential of theVBaT system to cause improvement in overall average task performance over the course of training while using the VBaT. Thus the VBaT system is proposed to be a step toward an effective balance training platform for people with balance disorder.

Virtual Reality-Based Center of Mass-Assisted Personalized Balance Training System

Poststroke hemiplegic patients often show altered weight distribution with balance disorders, increasing their risk of fall. Conventional balance training, though powerful, suffers from scarcity of trained therapists, frequent visits to clinics to get therapy, one-on-one therapy sessions, and monotony of repetitive exercise tasks. Thus, technology-assisted balance rehabilitation can be an alternative solution. Here, we chose virtual reality as a technology-based platform to develop motivating balance tasks. This platform was augmented with off-the-shelf available sensors such as Nintendo Wii balance board and Kinect to estimate one’s center of mass (CoM). The virtual reality-based CoM-assisted balance tasks (Virtual CoMBaT) was designed to be adaptive to one’s individualized weight-shifting capability quantified through CoM displacement. Participants were asked to interact with Virtual CoMBaT that offered tasks of varying challenge levels while adhering to ankle strategy for weight shifting. To facilitate the patients to use ankle strategy during weight-shifting, we designed a heel lift detection module. A usability study was carried out with 12 hemiplegic patients. Results indicate the potential of our system to contribute to improving one’s overall performance in balance-related tasks belonging to different difficulty levels.

Effects of anodal transcranial direct current stimulation over lower limb primary motor cortex on motor learning in healthy individuals

Transcranial direct current stimulation (tDCS) is a neuromodulatory technique which alters motor functions in healthy humans and in neurological patients. Most studies so far investigated the effects of tDCS on mechanisms underlying improvements in upper limb performance. To investigate the effect of anodal tDCS over the lower limb motor cortex (M1) on lower limb motor learning in healthy volunteers, we conducted a randomized, single‐blind and sham‐controlled study. Thirty‐three (25.81 ± 3.85, 14 female) volunteers were included, and received anodal or sham tDCS over the left M1 (M1‐tDCS); 0.0625 mA/cm2 anodal tDCS was applied for 15 min during performance of a visuo‐motor task (VMT) with the right leg. Motor learning was monitored for performance speed and accuracy based on electromyographic recordings. We also investigated the influence of electrode size and baseline responsivity to transcranial magnetic stimulation (TMS) on the stimulation effects. Relative to baseline measures, only M1‐tDCS applied with small electrodes and in volunteers with high baseline sensitivity to TMS significantly improved VMT performance. The computational analysis showed that the small anode was more specific to the targeted leg motor cortex volume when compared to the large anode. We conclude that anodal M1‐tDCS modulates VMT performance in healthy subjects. As these effects critically depend on sensitivity to TMS and electrode size, future studies should investigate the effects of intensified tDCS and/or model‐based different electrode positions in low‐sensitivity TMS individuals.

Neural interfacing non-invasive brain stimulation with NIRS-EEG joint imaging for closed-loop control of neuroenergetics in ischemic stroke

Stroke can be defined as a sudden onset of neurological deficits caused by a focal injury to the central nervous system from a vascular cause. In ischemic stroke (∼87% of all strokes) and transient ischemic attack (TIA), the blood vessel carrying blood to the brain is blocked causing deficit in the glucose supply - the main energy source. Here, neurovascular coupling (NVC) mechanism links neural activity with the corresponding blood flow that supplies glucose and oxygen for neuronal energy. Brain accounts for about 25% of total glucose consumption while being 2% of the total body weight. Therefore, a deficit in glucose supply can quickly change brains energy supply chain that can be transient (in TIA) or longer lasting (in stroke, vascular dementia). Here, implications of the failure of brains energy supply chain can be dysfunctional brain networks in cerebrovascular diseases. Using near-infrared spectroscopy (NIRS) in conjunction with electroencephalography (EEG), a non-invasive, real-time and point of care method to monitor the neuroenergetic status of the cortical gray matter is proposed. Furthermore, we propose that NIRS-EEG joint-imaging can be used to dose non-invasive brain stimulation (NIBS) - transcranial direct current stimulation (tDCS) and photobiomodulation - which may be able to provide therapeutic options for patients with energetic insufficiency by modulating the cortical neural activity and hemodynamics.

Development of a low-cost point of care device for near-infrared spectroscopy (NIRS) based online imaging during non-invasive electrical brain stimulation

All of us are exposed to optical (i.e., visible and near-infrared) radiation from the sun and other nsources throughout our lives. Assuming our eyes are shielded from excessive intensity, and our nskin is protected from the ultraviolet content of sunlight, we accept this exposure in the nknowledge that it is perfectly safe. Unlike x-rays, optical photons are insufficiently energetic to nproduce ionisation, and unless light is concentrated to such a high degree that it causes burning nto the skin, optical radiation offers no significant hazard. The diagnostic potential of optical nmethods has been widely known since Jobsis [1] first demonstrated that transmittance nmeasurements of near-infrared (NIR) radiation could be used to monitor the degree of noxygenation of certain metabolites. This led to the development and increasingly widespread use nof clinical near-infrared spectroscopy (NIRS), which offers a safe, non-invasive means of nmonitoring cerebral function at the bedside without the use of radioisotopes or other contrast nagents [2].

Post-stroke Engagement-sensitive Balance Rehabilitation Under An Adaptive Multi-level Electrotherapy: Clinical Hypothesis and Computational Framework

Stroke is caused due to burst or clot in an artery carrying blood from heart to an area in the brain. This prevents delivery of oxygen and nutrients to neurons thereby causing their death and leading to disability. Since about half of the stroke survivors are left with some degree of disability so innovative methodologies for restorative neurorehabilitation are urgently required to reduce long-term disability. Here, the ability of the nervous system to respond to stimuli by reorganizing its structure, function and connections may play an important role which is called neuroplastici- ty. Beneficial neuroplastic changes can be facilitated early in post-stroke rehabilitation using sensory and motor stimula- tion towards sensorimotor integration where electrical stimulation of the neural tissue may play an important role. Fur- thermore, active cortical participation may be required for such sensorimotor integration where volitional effort, detected with electromyogram- (EMG) and electroencephalogram- (EEG) derived biopotentials, may be assisted with non-invasive electrotherapy, such as neuromuscular electrical stimulation (NMES) and non-invasive brain stimulation (NIBS). In this article, we discuss this novel concept for an engagement-sensitive interactive system consisting of a low-cost static pos- turography system with adaptive response non-invasive electrotherapy technology for post-stroke balance rehabilitation that integrates a multi-level (central and peripheral nervous system) electrotherapy paradigm to assist volitional postural control.