Assaf Y. Dvorkin

Virtual reality and cognitive rehabilitation: A review of current outcome research

BACKGROUND Recent advancement in the technology of virtual reality (VR) has allowed improved applications for cognitive rehabilitation. OBJECTIVES The aim of this review is to facilitate comparisons of therapeutic efficacy of different VR interventions. METHODS A systematic approach for the review of VR cognitive rehabilitation outcome research addressed the nature of each sample, treatment apparatus, experimental treatment protocol, control treatment protocol, statistical analysis and results. Using this approach, studies that provide valid evidence of efficacy of VR applications are summarized. Applications that have not yet undergone controlled outcome study but which have promise are introduced. RESULTS Seventeen studies conducted over the past eight years are reviewed. The few randomized controlled trials that have been completed show that some applications are effective in treating cognitive deficits in people with neurological diagnoses although further study is needed. CONCLUSION Innovations requiring further study include the use of enriched virtual environments that provide haptic sensory input in addition to visual and auditory inputs and the use of commercially available gaming systems to provide tele-rehabilitation services. Recommendations are offered to improve efficacy of rehabilitation, to improve scientific rigor of rehabilitation research and to broaden access to the evidence-based treatments that this research has identified.

Mapping the Neglected Space: Gradients of Detection Revealed by Virtual Reality

Background. Spatial neglect affects perception along different dimensions. However, there is limited availability of 3-dimensional (3D) methods that fully map out a patient’s volume of deficit, although this could guide clinical management. Objective. To test whether patients with neglect exhibit simple contralesional versus complex perceptual deficits and whether deficits are best described using Cartesian (rectangular) or polar coordinates. Methods. Seventeen right-hemisphere persons with stroke (8 with a history of neglect) and 9 healthy controls were exposed to a 3D virtual environment. Targets placed in a dense array appeared one at a time in various locations. Results. When tested using rectangular array of targets, subjects in the neglect group exhibited complex asymmetries across several dimensions in both reaction time and target detection rates. Paper-and-pencil tests only detected neglect in 4 of 8 of these patients. When tested using polar array of targets, 2 patients who initially appeared to perform poorly in both left and near space only showed a simple left-side asymmetry that depended almost entirely on the angle from the sagittal plane. A third patient exhibited left neglect irrespective of the arrangements of targets used. An idealized model with pure dependence on the polar angle demonstrated how such deficits could be misconstrued as near neglect if one uses a rectangular array. Conclusions. Such deficits may be poorly detected by paper-and-pencil tests and even by computerized tests that use regular screens. Assessments that incorporate 3D arrangements of targets enable precise mapping of deficient areas and detect subtle forms of neglect whose identification may be relevant to treatment strategies.

A “virtually minimal” visuo-haptic training of attention in severe traumatic brain injury

BackgroundAlthough common during the early stages of recovery from severe traumatic brain injury (TBI), attention deficits have been scarcely investigated. Encouraging evidence suggests beneficial effects of attention training in more chronic and higher functioning patients. Interactive technology may provide new opportunities for rehabilitation in inpatients who are earlier in their recovery.MethodsWe designed a “virtually minimal” approach using robot-rendered haptics in a virtual environment to train severely injured inpatients in the early stages of recovery to sustain attention to a visuo-motor task. 21 inpatients with severe TBI completed repetitive reaching toward targets that were both seen and felt. Patients were tested over two consecutive days, experiencing 3 conditions (no haptic feedback, a break-through force, and haptic nudge) in 12 successive, 4-minute blocks.ResultsThe interactive visuo-haptic environments were well-tolerated and engaging. Patients typically remained attentive to the task. However, patients exhibited attention loss both before (prolonged initiation) and during (pauses during motion) a movement. Compared to no haptic feedback, patients benefited from haptic nudge cues but not break-through forces. As training progressed, patients increased the number of targets acquired and spontaneously improved from one day to the next.ConclusionsInteractive visuo-haptic environments could be beneficial for attention training for severe TBI patients in the early stages of recovery and warrants further and more prolonged clinical testing.

Tolerance of a virtual reality intervention for attention remediation in persons with severe TBI

Objective: To evaluate the feasibility of applying virtual reality and robotics technology to improve attention in patients with severe traumatic brain injury (TBI) in the early stages of recovery. Methods: A sample of TBI patients (n = 18, aged 19–73) who were receiving acute inpatient rehabilitation completed three-dimensional cancellation exercises over two consecutive days in an interactive virtual environment that minimized distractions and that integrated both visual and haptic (tactile) stimuli. Observations of behaviour during the intervention and of the instructions needed to encourage compliance were recorded. Performance data were compiled to assess improvement across three different treatment conditions. Outcomes: Fifteen of the 18 patients demonstrated tolerance of the virtual environment by completing the entire treatment protocol. Within-subjects comparisons of target acquisition time during treatment showed that a treatment condition that included haptic cues produced improved performance compared to a condition in which such cues were not provided. Separating out participants who were in post-traumatic amnesia showed that this group also demonstrated improvement in performance across trials despite their memory impairment. Conclusions: It is proposed that attention exercises using virtual environments are well-tolerated and engaging and that they could be beneficial for inpatients with severe TBI.

Reaching within a dynamic virtual environment

BackgroundPlanning and execution of reaching requires a series of computational processes that involve localization of both the target and initial arm position, and the translation of this spatial information into appropriate motor commands that bring the hand to the target. We have investigated the effects of shifting the visual field on visuomotor control using a virtual visual environment in order to determine how changes in visuo-spatial relations alter motor planning during a reach.MethodsFive healthy subjects were seated in front of an immersive, stereo virtual scene while reaching for a visual target that remained stationary in space or unpredictably shifted to a second position (either to the right or left of the first target) with different inter-stimulus intervals. Motion of the scene either matched the motion of their head or was rotated counter clockwise at 130 deg/s in the roll plane.ResultsInitial results suggested that both the temporal and spatial aspects of reaching were affected by a rolling visual field. Subjects were able to amend ongoing motion to match target position regardless of scene motion, but the presence of visual field motion produced significantly longer pauses during the reach movement when the target was shifted in space. In addition, terminal arm posture exhibited a drift in the direction opposite to the roll motion.ConclusionThese findings suggest that roll motion of the visual field of view interfered with the ability to imultaneously process two consecutive stimuli. Observed changes in arm position following the termination of the reach suggest that subjects were compensating for a perceived change in their visual reference frame.

A virtual environment-based paradigm for improving attention in TBI

Attention deficits are one of the most profound problems facing the traumatic brain injured individual. The Traumatic Brain Injury (TBI) inpatient population in the rehabilitation unit is difficult to study with new technology because it is often very difficult to render and evaluate such interventions in the short time span when a patient is still in the hospital, even though that is precisely the time when clinical attentional therapy is considered most critical. We developed and performed a preliminary test of a haptic/graphic paradigm for improving attention and concentration in early stages of recovery in the TBI inpatient population. Six TBI patients and three healthy controls were exposed to a minimal distraction/minimal interaction environment while reaching for a visual target. Our initial results showed (1) the subjects tolerated the experience, (2) the number of targets acquired in successive one-minute intervals indicated a sustained attention for the task, and (3) haptic interaction in such an environment was well tolerated, engaging, and enjoyable -- often considered a game. These findings have provided the foundation for a larger, intensive, protracted study with repeated treatment.

Treatment challenges with profound behaviour disturbance after traumatic brain injury: A case report

Abstract Background: Severe behavioural disturbances exhibited during the earliest stages of recovery from severe traumatic brain injury often limit the ability to provide standard care. Studies that focus on treatment options for inpatients with such behaviours are scarce. There is limited guidance on how to approach therapy that will maximize the patient’s tolerance and participation and how to measure meaningful progress. Case report: This case study describes how the use of an innovative treatment approach to improve attention was beneficial in rehabilitation of a patient with severe traumatic brain injury whose profound behaviour disturbances substantially precluded participation in traditional therapies. The study shows how rehabilitation utilizing an interactive virtual reality-robotics environment that minimized distractions was associated with improved engagement in therapy, decreased disruptive behaviour during treatment and more sensitive measurement of progress. Conclusion: These results may be instructive in how technology can be used to modify therapy sessions to make them accessible to patients with profound behaviour disturbance and how meaningful progress can be measured even in the absence of gains in traditional metrics.

Assessment and monitoring of recovery of spatial neglect within a Virtual Environment

Spatial neglect has proven to be a significant factor limiting the success of the rehabilitation process following stroke. Current tests for neglect however have several substantial drawbacks, which often lead to a misdiagnosis of less severe cases. Further, while asymmetries of performance have been reported in the past along independent spatial dimensions, current tests are mostly limited to the horizontal dimension and do not reflect the reality of a three-dimensional world. We have previously demonstrated the feasibility of virtual reality tools for detailed assessments of attentional deficits [1]. We now provide further evidence for the sensitivity of our Virtual Environment for Spatial Neglect Assessment (VESNA) application for assessment of neglect as well as for monitoring recovery of patients. Seven stroke patients with neglect, nine stroke patients without neglect and nine age-matched healthy controls were tested on a target-detection task. Subjects were exposed to a three-dimensional virtual scene and were instructed to press a response button when they detected a target appearing within the scene. Percent of correct detection and reaction time to initiate a button press were calculated. Our results indicated significant differences between neglect patients and control subjects. All neglect patients exhibited asymmetries of performance, where their mean reaction time and detection accuracy systematically varied across space. This asymmetry was not a harsh transition but instead showed a gradual reduction of attention across the space. Importantly, while these results indicated an obvious spatial neglect for all seven neglect patients, their performance on the standard paper-and-pencil tests, administered at the day of testing, was less conclusive. A follow-up study with two of the neglect patients (10 months following the initial testing) revealed an obvious recovery pattern, showing a reduction of the spatial bias over time. By contrast, the paper-and-pencil tests showed no obvious change. Thus, we demonstrated that our paradigm provided a quantitative and more sensitive assessment and monitoring of recovery of neglect. This might provide clinicians with a more precise description of a patientpsilas deficit which will help direct training.

Visuo-haptic environment for remediating attention in severe traumatic brain injury

Attention deficits are a highly prevalent result of traumatic brain injury (TBI) that has a profound effect on an individuals functional abilities. However, studies that test the severely impaired inpatient population are scarce. 21 severe TBI inpatients completed 2-week intervention (either visuo-haptic environment training or standard attention training). Results indicate that patients who received the VR intervention may exhibit greater improvement in clinical attention scores compared to those in the control group. Performance during the VR intervention was retained from one day to the next, (even when patients were in post-traumatic amnesia). Visuo-haptic environments could be beneficial for this population.

Reaching Within a Dynamic Virtual Environment

Planning and execution of reaching movements requires a series of computational processes that involves the localization of both the target and initial arm position, and the translation of this spatial information into appropriate motor commands that will bring the hand to the target. Voluntary and/or involuntary changes in the spatial relationship between our hand and the space in which we plan to reach may occur at any time. In the current study we investigated the effects of shifting both the central and peripheral visual field on visuomotor control using a virtual visual environment. In two separate experiments, six seated healthy subjects were exposed to either stationary or roll motion of a 3D virtual scene while reaching for a visual target that remained stationary in space or unexpectedly shifted to a second position with different inter-stimulus intervals. Our initial results suggest that both temporal and spatial aspects of the reaching movement were affected by roll of the visual field. Whereas the results indicate that subjects were able to amend their ongoing motion to match the target position with both scene conditions, the presence of peripheral visual field motion produced significantly longer pauses during the reach movement when the target shifted in space. We conclude from this that motion in the peripheral field of view interfered with the ability to simultaneously process two consecutive stimuli. The terminal arm posture also exhibited a drift in the direction opposite to the roll motion suggesting that subjects were compensating for a perceived change in their visual reference frame