Elena Slobounov

Differential rate of recovery in athletes after first and second concussion episodes.

OBJECTIVE Clinical observations suggest that a history of previous concussions may cause a slower recovery of neurological function after recurrent concussion episodes. However, direct examination of this notion has not been provided. This report investigates the differential rate of restoring the visual-kinesthetic integration in collegiate athletes experiencing single versus recurrent concussion episodes. METHODS One hundred sixty collegiate athletes were tested preseason using multimodal research methodology. Of these, 38 experienced mild traumatic brain injury (MTBI) and were tested on Days 10, 15, and 30 after injury. Nine of these MTBI patients experienced a second MTBI within 1 year after the first brain injury and were retested. The postconcussion symptoms checklist, neuropsychological evaluations, and postural responses to visual field motion were recorded using a virtual reality environment. RESULTS All patients were asymptomatic at Day 10 of testing and were cleared for sport participation based on clinical symptoms resolution. Balance deficits, as evident by incoherence with visual field motion postural responses, were present at least 30 days after injury (P < 0.001). Most importantly, the rate of balance symptoms restoration was significantly reduced after a recurrent, second concussion (P < 0.001) compared with those after the first concussion. CONCLUSION The findings of this study confirm our previous research indicating the presence of long-term residual visual-motor disintegration in concussed individuals with normal neuropsychological measures. Most importantly, athletes with a history of previous concussion demonstrate significantly slower rates of recovery of neurological functions after the second episode of MTBI.

Alteration of Postural Responses to Visual Field Motion in Mild Traumatic Brain Injury

OBJECTIVE Balance deficits in individuals experiencing mild traumatic brain injury have been documented in numerous recent studies. However, long-lasting balance deficits and specific mechanisms causing these deficits have not been systematically examined. This article aimed to present empirical evidence showing destabilizing effects of visual field motion in concussed individuals up to 30 days postinjury. METHODS Sixty student athletes participated in the pilot (n = 12) and major experiments (n = 48) before injury. Eight of these 48 subjects who experienced mild traumatic brain injury in athletic events were tested again on Days 3, 10, and 30 after the incident. Postural responses to visual field motion were recorded using a virtual reality environment in conjunction with balance (AMTI force plate) and motion tracking (Flock of Birds) technologies. RESULTS The area of the center of pressure during upright stance did not change from Day 3 to 30 postinjury with respect to pre-injury status (P > .05). However, balance deficits induced by visual field motion were present up to 30 days postinjury. Destabilizing effect of visual field motion was observed via significant increase of the center of pressure data (P < .05) and reduced coherence value. CONCLUSION Our data suggest the presence of residual sensory integration dysfunction in concussed individuals at least 30 days postinjury and may indicate a lower threshold for brain reinjury.

Application of Virtual Reality Graphics in Assessment of Concussion

Abnormal balance in individuals suffering from traumatic brain injury (TBI) has been documented in numerous recent studies. However, specific mechanisms causing balance deficits have not been systematically examined. This paper demonstrated the destabilizing effect of visual field motion, induced by virtual reality graphics in concussed individuals but not in normal controls. Fifty five student-athletes at risk for concussion participated in this study prior to injury and 10 of these subjects who suffered MTBI were tested again on day 3, day 10, and day 30 after the incident. Postural responses to visual field motion were recorded using a virtual reality (VR) environment in conjunction with balance (AMTI force plate) and motion tracking (Flock of Birds) technologies. Two experimental conditions were introduced where subjects passively viewed VR scenes or actively manipulated the visual field motion. Long-lasting destabilizing effects of visual field motion were revealed, although subjects were asymptomatic when standard balance tests were introduced. The findings demonstrate that advanced VR technology may detect residual symptoms of concussion at least 30 days post-injury.

Modulation of cortical activity in 2D versus 3D virtual reality environments: An EEG study

There is a growing empirical evidence that virtual reality (VR) is valuable for education, training, entertaining and medical rehabilitation due to its capacity to represent real-life events and situations. However, the neural mechanisms underlying behavioral confounds in VR environments are still poorly understood. In two experiments, we examined the effect of fully immersive 3D stereoscopic presentations and less immersive 2D VR environments on brain functions and behavioral outcomes. In Experiment 1 we examined behavioral and neural underpinnings of spatial navigation tasks using electroencephalography (EEG). In Experiment 2, we examined EEG correlates of postural stability and balance. Our major findings showed that fully immersive 3D VR induced a higher subjective sense of presence along with enhanced success rate of spatial navigation compared to 2D. In Experiment 1 power of frontal midline EEG (FM-theta) was significantly higher during the encoding phase of route presentation in the 3D VR. In Experiment 2, the 3D VR resulted in greater postural instability and modulation of EEG patterns as a function of 3D versus 2D environments. The findings support the inference that the fully immersive 3D enriched-environment requires allocation of more brain and sensory resources for cognitive/motor control during both tasks than 2D presentations. This is further evidence that 3D VR tasks using EEG may be a promising approach for performance enhancement and potential applications in clinical/rehabilitation settings.

The VR-Desktop: An Accessible Approach to VR Environments in Teaching and Research

The VR-Desktop initiative is an effort to bring key benefits of projection-based virtual reality into the mainstream of teaching and research at the Pennsylvania State University, through the deployment of comparatively low cost and easy to use virtual reality and integrated multimedia display systems within a variety of contexts. Recent experiences with design and implementation of single- and multi-screen VR systems for teaching and research are described. The systems discussed employ low cost and readily available hardware components, familiar desktop computing environments, and open-source VR development toolkits. The approach is modular and easily adaptable to various applications in research or instruction.