Deepesh Kumar

SmartEye: Developing a Novel Eye Tracking System for Quantitative Assessment of Oculomotor Abnormalities

Eye movements are a continuous and ubiquitous part of sensory perception. To properly generate highly accurate and co-ordinate ocular movements, a vast network of brain areas are engaged, from low-level visual processing to motor control of gaze orientation. This renders oculomotor system vulnerable to various neurological disorders with unique clinical patterns. Therefore, oculomotor examination can serve as an early and sensitive indicator for various neurological conditions. A simple-to-use, clinically valid system for objectively assessing the oculomotor function can thus bring a paradigm shift in diagnosis and treatment of brain disorders. In principal accordance, this paper presents a gaze assessment tool, called SmartEye, which is based on eye fixation, smooth pursuit, and blinking in response to both static and dynamic visual stimuli. The gaze related indices were evaluated in real-time by SmartEye and these were mapped to the reported pathological state in chronic ( > 3 months) patients with stroke. Our preliminary feasibility study with eight pairs of chronic ( > 3 months) stroke survivors and healthy individuals revealed that gaze related indices in response to both static and dynamic visual stimuli may serve as potential quantitative biomarkers for stroke assessment.

Engagement-sensitive interactive neuromuscular electrical therapy system for post-stroke balance rehabilitation - a concept study

Stroke is caused when an artery carrying blood from heart to an area in the brain bursts or a clot obstructs the blood flow thereby preventing delivery of oxygen and nutrients. About half of the stroke survivors are left with some degree of disability. Neuroplasticity is involved in post-stroke functional disturbances, but also in rehabilitation. Beneficial neuroplastic changes may be facilitated with neuromuscular electrical stimulation (NMES) where active cortical participation in rehabilitation procedures may be facilitated by driving NMES with electromyogram (EMG), electrooculogram (EOG), and electroencephalogram (EEG) derived biopotentials, that represent simultaneous volitional effort and task engagement. During the visuomotor standing balance task, we propose that gaze-interaction (e.g., fixation duration, pupil diameter, blink rate) with the visual stimuli can be a measure of task engagement which can be used to adapt task difficulty to facilitate post-stroke residual visuomotor function. Here, the elapsed time between the last visual fixation to the target and the initiation of the motor response, known as the quiet eye (QE) period, has emerged as a characteristic of higher levels of performance. In this article, we discuss this novel interactive therapy paradigm consisting of a low-cost static posturography system combined with engagement-sensitive volitionally driven NMES for post-stroke balance rehabilitation.

A Human-machine-interface Integrating Low-cost Sensors with a Neuromuscular Electrical Stimulation System for Post-stroke Balance Rehabilitation.

A stroke is caused when an artery carrying blood from heart to an area in the brain bursts or a clot obstructs the blood flow to brain thereby preventing delivery of oxygen and nutrients. About half of the stroke survivors are left with some degree of disability. Innovative methodologies for restorative neurorehabilitation are urgently required to reduce long-term disability. The ability of the nervous system to reorganize its structure, function and connections as a response to intrinsic or extrinsic stimuli is called neuroplasticity. Neuroplasticity is involved in post-stroke functional disturbances, but also in rehabilitation. Beneficial neuroplastic changes may be facilitated with non-invasive electrotherapy, such as neuromuscular electrical stimulation (NMES) and sensory electrical stimulation (SES). NMES involves coordinated electrical stimulation of motor nerves and muscles to activate them with continuous short pulses of electrical current while SES involves stimulation of sensory nerves with electrical current resulting in sensations that vary from barely perceivable to highly unpleasant. Here, active cortical participation in rehabilitation procedures may be facilitated by driving the non-invasive electrotherapy with biosignals (electromyogram (EMG), electroencephalogram (EEG), electrooculogram (EOG)) that represent simultaneous active perception and volitional effort. To achieve this in a resource-poor setting, e.g., in low- and middle-income countries, we present a low-cost human-machine-interface (HMI) by leveraging recent advances in off-the-shelf video game sensor technology. In this paper, we discuss the open-source software interface that integrates low-cost off-the-shelf sensors for visual-auditory biofeedback with non-invasive electrotherapy to assist postural control during balance rehabilitation. We demonstrate the proof-of-concept on healthy volunteers.

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.

Engagement sensitive visual stimulation

Stroke is one of leading cause of death and disability worldwide. Early detection during golden hour and treatment of individual neurological dysfunction in stroke using easy-to-access biomarkers based on a simple-to-use, cost-effective, clinically-valid screening tool can bring a paradigm shift in healthcare, both urban and rural. In our research we have designed a quantitative automatic home-based oculomotor assessment tool that can play an important complementary role in prognosis of neurological disorders like stroke for the neurologist. Once the patient has been screened for stroke, the next step is to design proper rehabilitation platform to alleviate the disability. In addition to the screening platform, in our research, we work in designing virtual reality based rehabilitation exercise platform that has the potential to deliver visual stimulation and in turn contribute to improving one’s performance.

Audio-visual stimulation in conjunction with functional electrical stimulation to address upper limb and lower limb movement disorder

Neurological disorders often manifest themselves in the form of movement deficit on the part of the patient. Conventional rehabilitation often used to address these deficits, though powerful are often monotonous in nature. Adequate audio-visual stimulation can prove to be motivational. In the research presented here we indicate the applicability of audio-visual stimulation to rehabilitation exercises to address at least some of the movement deficits for upper and lower limbs. Added to the audio-visual stimulation, we also use Functional Electrical Stimulation (FES). In our presented research we also show the applicability of FES in conjunction with audio-visual stimulation delivered through VR-based platform for grasping skills of patients with movement disorder.

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.