K. Ustinova

Role of cerebellum in learning postural tasks.

For a long time, the cerebellum has been known to be a structure related to posture and equilibrium control. According to the anatomic structure of inputs and internal structure of the cerebellum, its role in learning was theoretically reasoned and experimentally proved. The hypothesis of an inverse internal model based on feedback-error learning mechanism combines feedforward control by the cerebellum and feedback control by the cerebral motor cortex. The cerebellar cortex is suggested to acquire internal models of the body and objects in the external world. During learning of a new tool the motor cortex receives feedback from the realized movement while the cerebellum produces only feedforward command. To realize a desired movement without feedback of the realized movement, the cerebellum needs to form an inverse model of the hand/ arm system. This suggestion was supported by FMRi data. The role of cerebellum in learning new postural tasks mainly concerns reorganization of natural synergies. A learned postural pattern in dogs has been shown to be disturbed after lesions of the cerebral motor cortex or cerebellar nuclei. In humans, learning voluntary control of center of pressure position is greatly disturbed after cerebellar lesions. However, motor cortex and basal ganglia are also involved in the feedback learning postural tasks.

Development of a 3D immersive videogame to improve arm-postural coordination in patients with TBI.

BackgroundTraumatic brain injury (TBI) disrupts the central and executive mechanisms of arm(s) and postural (trunk and legs) coordination. To address these issues, we developed a 3D immersive videogame-- Octopus. The game was developed using the basic principles of videogame design and previous experience of using videogames for rehabilitation of patients with acquired brain injuries. Unlike many other custom-designed virtual environments, Octopus included an actual gaming component with a system of multiple rewards, making the game challenging, competitive, motivating and fun. Effect of a short-term practice with the Octopus game on arm-postural coordination in patients with TBI was tested.MethodsThe game was developed using WorldViz Vizard software, integrated with the Qualysis system for motion analysis. Avatars of the participants hands precisely reproducing the real-time kinematic patterns were synchronized with the simulated environment, presented in the first person 3D view on an 82-inch DLP screen. 13 individuals with mild-to-moderate manifestations of TBI participated in the study. While standing in front of the screen, the participants interacted with a computer-generated environment by popping bubbles blown by the Octopus. The bubbles followed a specific trajectory. Interception of the bubbles with the left or right hand avatar allowed flexible use of the postural segments for balance maintenance and arm transport. All participants practiced ten 90-s gaming trials during a single session, followed by a retention test. Arm-postural coordination was analysed using principal component analysis.ResultsAs a result of the short-term practice, the participants improved in game performance, arm movement time, and precision. Improvements were achieved mostly by adapting efficient arm-postural coordination strategies. Of the 13 participants, 10 showed an immediate increase in arm forward reach and single-leg stance time.ConclusionThese results support the feasibility of using the custom-made 3D game for retraining of arm-postural coordination disrupted as a result of TBI.

Impairment of Learning the Voluntary Control of Posture in Patients with Cortical Lesions of Different Locations: the Cortical Mechanisms of Pose Regulation

The process of learning to produce voluntary changes in the position of the center of pressures using biological feedback was studied by stabilography in patients with hemipareses due to cerebrovascular lesions in the zone supplied by the middle cerebral artery. There were significant impairments to learning in all groups of patients, who had lesions in different sites, demonstrating that cortical mechanisms are involved in learning to control posture voluntarily. These studies showed that patients with lesions in the right hemisphere had rather greater deficits in performing the task than those with lesions in the left hemisphere. There were significant differences in the initial deficit in performing the task on the first day of training depending on the side of the lesion. All groups of patients differed from healthy subjects in that significant learning occurred only at the initial stages of training (the first five days). Learning at the initial stage in patients with concomitant lesions of the parietal-temporal area and with combined lesions with motor, premotor, and parietal-temporal involvement was significantly worse and the level of task performance at the end of the initial stage was significantly worse than in patient with local lesions of the motor cortex. The level of learning was independent of the severity of the motor deficit (paresis, spasticity), but was associated with the severity of impairment of the proprioceptive sense and the severity of disruption to the upright posture (asymmetry in the distribution of support pressures, amplitude of variation in the position of the center of pressures). The learning process had positive effects on the severity of motor impairment and on the asymmetry of the distribution of support pressures in the standing posture. Reorganization of posture during bodily movements occurred mainly because of impairment to the developed “non-use” stereotype of the paralyzed lower limb.

Effect of viewing angle on arm reaching while standing in a virtual environment: Potential for virtual rehabilitation

Functional arm movements, such as reaching while standing, are planned and executed according to our perception of body position in space and are relative to environmental objects. The angle under which the environment is observed is one component used in creating this perception. This suggests that manipulation of viewing angle may modulate whole body movement to affect performance. We tested this by comparing its effect on reaching in a virtually generated environment. Eleven young healthy individuals performed forward and lateral reaches in the virtual environment, presented on a flat screen in third-person perspective. Participants saw a computer-generated model (avatar) of themselves standing in a courtyard facing a semi-circular hedge with flowers. The image was presented in five different viewing angles ranging from seeing the avatar from behind (0 degrees), to viewing from overhead (90 degrees). Participants attempted to touch the furthest flower possible without losing balance or stepping. Kinematic data were collected to analyze endpoint displacement, arm-postural coordination and center of mass (COM) displacement. Results showed that reach distance was greatest with angular perspectives of approximately 45-77.5 degrees , which are larger than those used in analogous real world situations. Larger reaches were characterized by increased involvement of leg and trunk body segments, altered inter-segmental coordination, and decreased inter-segmental movement time lag. Thus a viewing angle can be a critical visuomotor variable modulating motor coordination of the whole body and related functional performance. These results can be used in designing virtual reality games, in ergonomic design, teleoperation training, and in designing virtual rehabilitation programs that re-train functional movement in vulnerable individuals.

Effect of robotic locomotor training in an individual with Parkinson's disease: a case report

Purpose. The purpose was to test the effect of robot-assisted gait therapy with the Lokomat system in one representative individual with Parkinsons disease (PD). Methods. The patient was a 67-year-old female with more than an 8-year history of PD. The manifestations of the disease included depressive mood with lack of motivation, moderate bradykinesia, rigidity and resting tremor, both involving more the right side of the body, slow and shuffling gait with episodes of freezing and risk of falling. The patient underwent six sessions of robot-assisted gait training. The practice included treadmill walking at variable speed for 25–40 min with a partial body weight support and assistance from the Lokomat orthosis. Results. After the therapy, the patient increased the gait speed, stride length and foot clearance during over ground walking. She reduced the time required to complete a 180° turn and the latency of gait initiation. Improvements were observed in some items of the Unified Parkinsons Disease Rating Scale including motivation, bradykinesia, rigidity, freezing, leg agility, gait and posture. Conclusions. Although the results supported the feasibility of using robot-assisted gait therapy in the rehabilitation an individual with PD, further studies are needed to assess a potential advantage of the Lokomat system over conventional locomotor training for this population.

Cognitive ability predicts motor learning on a virtual reality game in patients with TBI

BACKGROUND Virtual reality games and simulations have been utilized successfully for motor rehabilitation of individuals with traumatic brain injury (TBI). Little is known, however, how TBI-related cognitive decline affects learning of motor tasks in virtual environments. OBJECTIVE To fill this gap, we examined learning within a virtual reality game involving various reaching motions in 14 patients with TBI and 15 healthy individuals with different cognitive abilities. METHODS All participants practiced ten 90-second gaming trials to assess various aspects of motor learning. Cognitive abilities were assessed with a battery of tests including measures of memory, executive functioning, and visuospatial ability. RESULTS Overall, participants with TBI showed both reduced performance and a slower learning rate in the virtual reality game compared to healthy individuals. Numerous correlations between overall performance and several of the cognitive ability domains were revealed for both the patient and control groups, with the best predictor being overall cognitive ability. CONCLUSIONS The results may provide a starting point for rehabilitation programs regarding which cognitive domains interact with motor learning.

Use of X-box Kinect Gaming Console for Rehabilitation of an Individual with Traumatic Brain Injury: A Case Report

The goal of the present experiment was to evaluate the feasibility of utilizing the Xbox Kinect gaming console for restoration of functional and motor abilities in a single representative patient with a history of traumatic brain injury (TBI). The patient was a 29 year old male with severe chronic functional and motor deficits secondary to brain injury that occurred 9 years prior to the study. The patient participated in ten sessions, three times a week for four consecutive weeks playing the Xbox Kinect games. These sessions consisted of playing five different games from Kinect Adventure series. The patient was evaluated with a battery of clinical tests before and after gaming practice. In addition to clinical assessments the patient’s movement performance was recorded with the Qualysis system for motion analysis. From kinematic data, the displacement and velocity of the trunk, dominant hand and foot were calculated and analyzed. After the gaming practice, the patient showed improvements in overall game performance, clinical outcomes, and movement performance characteristics throughout the various games. Results showed that the Xbox Kinect gaming console can be utilized with relative ease for recovery of severe functional, motor, and postural deficits even in a patient at chronic stage after TBI. Larger scale trials will the next viable step in validating the Xbox Kinect in its role of rehabilitation for TBI and other acquired brain injuries.

The effect of additional hand contact on postural stability perturbed by a moving environment

Additional hand contact of external objects has been shown to reduce postural instability caused by a deficiency of one or more senses. Little is known, however, if additional contact can help in an environment where the senses are available but conflicting. This question was investigated by analyzing the effect of different types of hand contact on postural stability perturbed by the moving visual scene. While standing for 1min on a rocker board in front of a screen, eight healthy young subjects observed a projection of a virtual ship rocking on water to simulate standing on the ships deck. In randomly assigned trials subjects were asked (a) to stand with arms at sides (with no contact); (b) to hold a standard cane parallel to the ground; (c) to lightly touch a rocker cane handle with their index finger; or (d) touch a standard quad cane handle with their index finger. Based on the kinematic data collected, the displacement of the center of mass (COM) and angular displacements in the hip and ankle joints were computed. Results showed that the moving visual scene perturbed body stability. However, additional contact with support of varying stability reduced the destabilizing effect. The results can be potentially used for practical purposes; when in an environment with visual perturbations simply holding an object in hand may help stabilize the body when at risk for a fall.

Virtual reality game-based therapy for treatment of postural and co-ordination abnormalities secondary to TBI: A pilot study

Abstract Primary objective: The study objective was to test the efficacy of game-based virtual reality (VR) therapy as a mean of correcting postural and co-ordination abnormalities in individuals with traumatic brain injury (TBI). Therapy was done with interactive customized VR games and scenarios, utilizing an Xbox Kinect sensor. Research design: The study was a pilot project using the structure of a phase II clinical trial. Methods and procedures: Fifteen participants with mild-to-moderate chronic TBI-related balance and motor co-ordination impairments participated in 15 sessions, each lasting ∼50–55 minutes, scheduled 2–3 times a week over 5–6 consecutive weeks. Participants were evaluated at baseline, immediately after the final session and in a 1-month follow-up with a battery of clinical tests (measuring postural stability, gait and co-ordination) and movement performance parameters. Movement parameters included arm–leg co-ordination, dynamic stability and arm precision, calculated from kinematic data recorded with Xbox Kinect sensor. Results: Following therapy, most participants improved their static and dynamic postural stability, gait and arm movements. These effects persisted over the retention interval. Conclusions: Results will be used to improve the VR program, with the goal of producing a cost-effective, accessible and easy to individualize therapeutic approach. The pilot data will be used for designing a larger scale clinical trial.

Postural stabilization by gripping a stick with different force levels

Hand contact with a stationary surface reduces postural sway in healthy individuals even when the level of force applied is mechanically insufficient. To make this phenomenon more applicable to a real-life situation, where a stationary support is not available, a mobile stick was used to measure and control grip force. The effect of a supra-postural task of stick gripping on stability was tested in 18 healthy individuals during quiet standing, standing in semi-tandem, and with eyes closed. Subjects stood either holding no haptic stick, or gripping with one of six force levels ranging from 1 to 9N and a self-selected force in the same range. The path length and velocity of the center of pressure (COP) were measured and compared within and between experimental conditions. Gripping the stick reduced the COP path length and velocity by up to 23% and 25%, respectively, and postural stability was increased at all force levels, including self-selected. The results confirmed the stabilizing effects of gripping an external portable object regardless of the amount of force applied. This knowledge may be useful for counseling people on prevention of stability loss in real life situations where balance is challenged.