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PubMed2002

Comparison of virtual and real electric powered wheelchair driving using a position sensing joystick and an isometric joystick.

There are limited interface options for electric powered wheelchairs, which results in the inability of some individuals to drive independently. In addition, the development of new interface technologies will necessitate the development of alternative training methods. This study compares a conventional position sensing joystick to a novel isometric joystick during a driving task in a virtual environment and a real environment. The results revealed that there were few differences in task completion time and root-mean-square error (RMSE) between the two types of joysticks. There were significant correlations between the RMSE in the virtual environment and the real environment for both types of joysticks. The data indicate that performance in the virtual environment was representative of driving ability in the real environment, and the isometric joystick performed comparably to the position sensing joystick.

Algorithms↗

PubMed1996

Presence of mind: a reaction to Thomas Sheridan's "Further musings on the psychophysics of presence."

An operator's sense of remote presence during teleoperation or use of virtual environment interfaces is analyzed as to what characteristics it should have to qualify it as an explanatory scientific construct. But the implicit goal of designing virtual environment interfaces to maximize presence is itself questioned in a second section in which examples of human-machine interfaces beneficially designed to avoid a strong sense of egocentric presence are cited. In conclusion, it is argued that the design of a teleoperation or virtual environment system should generally focus on the efficient communication of causal interaction. In this view the sense of presence, that is of actually being at the simulated or remote workplace, is an epiphenomena of secondary importance for design.

Computer Graphics↗

PubMed2004

Virtual reality and physical rehabilitation: a new toy or a new research and rehabilitation tool?

Virtual reality (VR) technology is rapidly becoming a popular application for physical rehabilitation and motor control research. But questions remain about whether this technology really extends our ability to influence the nervous system or whether moving within a virtual environment just motivates the individual to perform. I served as guest editor of this month's issue of the Journal of NeuroEngineering and Rehabilitation (JNER) for a group of papers on augmented and virtual reality in rehabilitation. These papers demonstrate a variety of approaches taken for applying VR technology to physical rehabilitation. The papers by Kenyon et al. and Sparto et al. address critical questions about how this technology can be applied to physical rehabilitation and research. The papers by Sveistrup and Viau et al. explore whether action within a virtual environment is equivalent to motor performance within the physical environment. Finally, papers by Riva et al. and Weiss et al. discuss the important characteristics of a virtual environment that will be most effective for obtaining changes in the motor system.

Journal Article↗

PubMed1998

VR interaction techniques for medical imaging applications.

Methods of virtual reality (VR) offer new ways of human-computer interaction. Medicine is predestined to benefit from this new technology in many ways. Virtual environments can support physicians in their work, alleviate communication between specialists from different fields or be established in educational and training applications. For the field of visualization and analysis of three-dimensional anatomical images (e.g. CT or MRI scans), an application is introduced which expedites recognition of spatial coherencies and the exploration and manipulation of the 3D data. To avoid long periods of learning and accustoming and to facilitate work in such an environment, a powerful human-oriented interface is required allowing interactions similar to the real world and utilization of our natural experiences. This paper shows the use of eye tracking parameters for a level-of-detail algorithm and the integration of a glove-based hand gesture recognition into the virtual environment as an essential component of the human-machine interface. Furthermore, virtual bronchoscopy and virtual angioscopy are presented as examples for the use of the virtual environment.

Diagnosis, Computer-Assisted↗

PubMed2006

The development and evaluation of the use of a virtual learning environment (Blackboard 5) to support the learning of pre-qualifying nursing students undertaking a human anatomy and physiology module.

Students commence nurse education with varying levels of understanding of human anatomy and physiology due to a wide range of previous exposure to the topic. All students, however, are required to attain a broad knowledge of this topic prior to qualification. This paper describes the use of a Virtual Learning Environment (VLE), Blackboard 5, and the associated development of appropriate resources aimed at supporting nursing students undertaking a human anatomy and physiology module at Higher Education Level 1. The VLE was used as part of a blended learning approach. The results suggested that the majority of students utilised the VLE throughout the academic year. Opportunities for independent and self-directed learning were available in that students chose when and where to learn. Students generally commented favourably on ease of use and type of resources available. Frequency of use of the VLE, however, did not correlate strongly with the final examination mark achieved. Overall the VLE and the associated available resources appeared useful in supporting student learning and has been adopted for use in subsequent years.

Anatomy↗

PubMed1997

The perception of spatial layout in real and virtual worlds.

As human-machine interfaces grow more immersive and graphically-oriented, virtual environment systems become more prominent as the medium for human-machine communication. Often, virtual environments (VE) are built to provide exact metrical representations of existing or proposed physical spaces. However, it is not known how individuals develop representational models of these spaces in which they are immersed and how those models may be distorted with respect to both the virtual and real-world equivalents. To evaluate the process of model development, the present experiment examined participant's ability to reproduce a complex spatial layout of objects having experienced them previously under different viewing conditions. The layout consisted of nine common objects arranged on a flat plane. These objects could be viewed in a free binocular virtual condition, a free binocular real-world condition, and in a static monocular view of the real world. The first two allowed active exploration of the environment while the latter condition allowed the participant only a passive opportunity to observe from a single viewpoint. Viewing conditions were a between-subject variable with 10 participants randomly assigned to each condition. Performance was assessed using mapping accuracy and triadic comparisons of relative inter-object distances. Mapping results showed a significant effect of viewing condition where, interestingly, the static monocular condition was superior to both the active virtual and real binocular conditions. Results for the triadic comparisons showed a significant interaction for gender by viewing condition in which males were more accurate than females. These results suggest that the situation model resulting from interaction with a virtual environment was indistinguishable from interaction with real objects at least within the constraints of the present procedure.

Adult↗

PubMed2001

Representation of sound source direction in the superior colliculus of the guinea pig in a virtual auditory environment.

The deep layers of the superior colliculus (SC) receive visual, auditory, and somatosensory input. A major function of the SC is the control of orientation movements of the eye, head, and pinna. While a topographical map for sound source direction remains elusive in primary auditory structures of mammals, such a map for azimuthal sound source directions has been reported in the deep layers of the SC. Moreover, a gradient of elevation tuning has been also seen in the SC of ferrets and cats. Here we demonstrate that a virtual auditory environment can be used to reveal azimuthal and elevational topography for auditory spatial receptive fields in neurons in the SC of guinea pigs. Individual, head-related transfer functions (HRTF) were measured in ten guinea pigs for 122 directions in the upper hemispheric field and convolved with white noise. Many neurons (39%) in the deep layers showed robust responses to these virtual sounds, and the majority of these neurons had small spatial receptive fields that were restricted to the contralateral hemifield. Best directions varied from 0 degree to 135 degree azimuth along the contralateral side and from --10 degree to 60 degree elevation. Like previous studies using free-field stimulation, a gradient of best azimuth direction was found along the rostral-caudal axis, with rear directions represented caudally and front directions rostrally. The topographical organization for best elevations had not been studied previously in the guinea pig. We found that it roughly followed the mediolateral axis, with preference for high elevations represented medially and low elevations laterally. A similar organization using free-field stimulation has been reported in the ferret.

Acoustic Stimulation↗

PubMed1999

Virtual reality exposure therapy for PTSD Vietnam Veterans: a case study.

Virtual reality (VR) integrates real-time computer graphics, body tracking devices, visual displays, and other sensory input devices to immerse a participant in a computer-generated virtual environment that changes in a natural way with head and body motion. VR exposure (VRE) is proposed as an alternative to typical imaginal exposure treatment for Vietnam combat veterans with posttraumatic stress disorder (PTSD). This report presents the results of the first Vietnam combat veteran with PTSD to have been treated with VRE. The patient was exposed to two virtual environments, a virtual Huey helicopter flying over a virtual Vietnam and a clearing surrounded by jungle. The patient experienced a 34% decrease on clinician-rated PTSD and a 45% decrease on self-rated PTSD. Treatment gains were maintained at 6-month follow-up.

Humans↗

PubMed2001

Localization of implanted EEG electrodes in a virtual-reality environment.

In the planning of epilepsy surgery procedures, intracranial electrodes are implanted in a significant fraction of the patients. Accurate localization of the individual electrode contacts with respect to the brain cortex is imperative. Because the manual tracking of an EEG electrode in a CT scan in a slice-by-slice fashion is cumbersome and subjective, the goal of this study was to develop an easier and more accurate way to localize implanted EEG electrodes. In this paper, we present our solution in the form of a virtual-reality environment with interactive tools to assist the clinician with EEG localization. With the help of a high-quality and fast volume renderer, a view is created of the inside of the patient's skull to obtain an overview of the electrodes in relation to the cortical structures. Depth, grid, and reed electrodes are characterized semi-interactively using different methods. For depth electrodes, the contacts (which are not visible in the CT scan) are derived by measuring off the theoretical distance between the contact and the end of the electrode from the central axis produced by a three-dimensional (3D) line tracker. For grid electrodes, the contacts are visible in a CT, so the 3D view is merely used to find the contacts and to resolve the overlap of grids with other grids, tail wires, or bone ridges. For reed electrodes, the contacts, which are again not visible in this case, are calculated from a line model fitted to the positions of lead markers. After letting the user place artificial spheres on the lead markers and wire, a B-spline is fitted to the spheres' centers to estimate the positions of the contacts. The approach was evaluated by applying it to CT scans of seven patients. It appeared that the method is generally applicable (even crossing electrodes or electrodes with gaps were correctly characterized), and that the display via 3D views and slices is so good that manual placement of spheres performed as well as semi-automatic placement. From computer experiments, it appeared that the final localization error in the position of EEG contacts could be estimated to lie in the order of the dimensions of one voxel.

Brain Mapping↗

PubMed2006

Head-mounted displays for clinical virtual reality applications: pitfalls in understanding user behavior while using technology.

The use of virtual environments with head-mounted displays (HMDs) offers unique assets to the evaluation and therapy of clinical populations. However, research examining the effects of this technology on clinical populations is sparse. Understanding how wearers interact with the HMD is vital. Discomfort leads to altered use of the HMD that could confound performance measures; the very measures which might be used as tools for clinical decision making. The current study is a post-hoc analysis of the relationship between HMD use and HMD comfort. The analysis was conducted to examine contributing factors for a high incidence of simulator sickness observed in an HMD-based driving simulator. Pearson correlation analysis was used to evaluate objective and subjective measures of HMD performance and self-reported user comfort ratings. The results indicated weak correlations between these variables, indicating the complexity of quantifying user discomfort and HMD performance. Comparison of two case studies detailing user behavior in the virtual environment demonstrates that selected variables may not capture how individuals use the HMD. The validity and usefulness of the HMD-based virtual environments must be understood to fully reap the benefits of virtual reality (VR) in rehabilitation medicine.

Adult↗

PubMed2001

Virtual reality exposure therapy for Vietnam veterans with posttraumatic stress disorder.

BACKGROUND: Virtual reality (VR) integrates real-time computer graphics, body-tracking devices, visual displays, and other sensory input devices to immerse a participant in a computer-generated virtual environment that changes in a natural way with head and body motion. VR exposure (VRE) is proposed as an alternative to typical imaginal exposure treatment for Vietnam combat veterans with posttraumatic stress disorder (PTSD). METHOD: This report presents the results of an open clinical trial using VRE to treat Vietnam combat veterans who have DSM-IV PTSD. In 8 to 16 sessions, 10 male patients were exposed to 2 virtual environments: a virtual Huey helicopter flying over a virtual Vietnam and a clearing surrounded by jungle. RESULTS: Clinician-rated PTSD symptoms as measured by the Clinician Administered PTSD Scale, the primary outcome measure, at 6-month follow-up indicated an overall statistically significant reduction from baseline (p = .0021) in symptoms associated with specific reported traumatic experiences. All 8 participants interviewed at the 6-month follow-up reported reductions in PTSD symptoms ranging from 15% to 67%. Significant decreases were seen in all 3 symptom clusters (p < .02). Patient self-reported intrusion symptoms as measured by the Impact of Event Scale were significantly lower (p < .05) at 3 months than at baseline but not at 6 months, although there was a clear trend toward fewer intrusive thoughts and somewhat less avoidance. CONCLUSION: Virtual reality exposure therapy holds promise for treating PTSD in Vietnam veterans.

Follow-Up Studies↗

PubMed2001

Focus, locus, and sensus: the three dimensions of virtual experience.

A model of virtual/physical experience is presented, which provides a three dimensional conceptual space for virtual and augmented reality (VR and AR) comprising the dimensions of focus, locus, and sensus. Focus is most closely related to what is generally termed presence in the VR literature. When in a virtual environment, presence is typically shared between the VR and the physical world. "Breaks in presence" are actually shifts of presence away from the VR and toward the external environment. But we can also have "breaks in presence" when attention moves toward absence--when an observer is not attending to stimuli present in the virtual environment, nor to stimuli present in the surrounding physical environment--when the observer is present in neither the virtual nor the physical world. We thus have two dimensions of presence: focus of attention (between presence and absence) and the locus of attention (the virtual vs. the physical world). A third dimension is the sensus of attention--the level of arousal determining whether the observer is highly conscious or relatively unconscious while interacting with the environment. After expanding on each of these three dimensions of experience in relation to VR, we present a couple of educational examples as illustrations, and also relate our model to a suggested spectrum of evaluation methods for virtual environments.

Communication↗

PubMed2003

The augmented-feedback rehabilitation technique facilitates the arm motor recovery in patients after a recent stroke.

Previous studies have shown that the motor training in a virtual-environment with the augmented feedback promotes motor learning in normal subjects and in long-term post-stroke patients. We evaluated whether this approach could be useful also for treating patients with arm motor deficits due to a recent stroke. Twenty-four patients were included in the study within 3 months from an ischemic stroke in the territory of the middle cerebral artery. Twelve subjects received virtual-environment-training (VET) therapy for the arm, and twelve patients received an equal amount of a conventional rehabilitation therapy focused to the upper limb. Before and after therapy, the autonomy of daily living activities were assessed with the Functional Independence Measure and the degree of motor impairment was measured with the Fugl-Meyer scale for the upper extremity. For both groups the therapy lasted from 5 to 7 weeks, 1 hour daily for five days a week. The VET therapy group showed 20,2% and 12,4% improvements in the Fugl-Meyer and the Functional Independence Measure scale mean scores respectively. In a comparable way, the conventional therapy determined significant, but smaller scores improvements: 11,3% and 9,1%, respectively. These data indicate that the recovery of arm motor function in patients after a recent stroke is promoted by an augmented feedback strategy applied through a virtual-environment.

Arm↗

PubMed2004

Considerations for the future development of virtual technology as a rehabilitation tool.

BACKGROUND: Virtual environments (VE) are a powerful tool for various forms of rehabilitation. Coupling VE with high-speed networking [Tele-Immersion] that approaches speeds of 100 Gb/sec can greatly expand its influence in rehabilitation. Accordingly, these new networks will permit various peripherals attached to computers on this network to be connected and to act as fast as if connected to a local PC. This innovation may soon allow the development of previously unheard of networked rehabilitation systems. Rapid advances in this technology need to be coupled with an understanding of how human behavior is affected when immersed in the VE. METHODS: This paper will discuss various forms of VE that are currently available for rehabilitation. The characteristic of these new networks and examine how such networks might be used for extending the rehabilitation clinic to remote areas will be explained. In addition, we will present data from an immersive dynamic virtual environment united with motion of a posture platform to record biomechanical and physiological responses to combined visual, vestibular, and proprioceptive inputs. A 6 degree-of-freedom force plate provides measurements of moments exerted on the base of support. Kinematic data from the head, trunk, and lower limb was collected using 3-D video motion analysis. RESULTS: Our data suggest that when there is a confluence of meaningful inputs, neither vision, vestibular, or proprioceptive inputs are suppressed in healthy adults; the postural response is modulated by all existing sensory signals in a non-additive fashion. Individual perception of the sensory structure appears to be a significant component of the response to these protocols and underlies much of the observed response variability. CONCLUSION: The ability to provide new technology for rehabilitation services is emerging as an important option for clinicians and patients. The use of data mining software would help analyze the incoming data to provide both the patient and the therapist with evaluation of the current treatment and modifications needed for future therapies. Quantification of individual perceptual styles in the VE will support development of individualized treatment programs. The virtual environment can be a valuable tool for therapeutic interventions that require adaptation to complex, multimodal environments.

Journal Article↗

PubMed2003

Avatars in clinical psychology: a framework for the clinical use of virtual humans.

Early applications of virtual reality (VR) technology in psychological assessment, treatment, and research have yielded promising results. In particular, an increasing number of studies analyze the unique features of the experience made by patients during their exposure to virtual environments. However, the majority of these studies explore how patients navigate in the virtual spaces and interact with virtual objects. Only a few of them investigate the features of inhabited virtual environments, where real people and autonomous virtual humans are able to interact and to cooperate. In particular, there is a lack of discussion of the role that such autonomous virtual humans could have in VR-aided psychotherapy. The main goal of this paper is to identify a framework for future research in this area. Three levels of analysis are identified. The purpose of the first two levels is the identification of the key "physical" features (e.g., appearance, structure) and "internal" characteristics (e.g., behavior, degree of autonomy, perceptual capabilities) needed by an effective simulation. The third level is concerned with the evaluation of the interaction characteristics required for a successful relationship between the patient and the virtual human.

Behavior Therapy↗

PubMedDate not supplied

Oral implant treatment planning in a virtual reality environment.

A system for three-dimensional oral implant treatment planning is presented. Virtual reality technologies are used in order to improve the human image interpretation and planning performance. The methods described are based on computer tomography (CT) data of the mandible and of the maxilla. A novel approach to volume rendering and voxel based modelling of implants is introduced which allows interactive three-dimensional manipulation of the anatomic model and real-time manipulation of virtual implants. A spline-based reconstruction method is described to assess the implant site in a clinically oriented view with regard to bone structures and angulation. Two parameters are deduced which represent the bone properties at the surface of implants. While an implant is navigated with six degrees of freedom, these parameters are acoustically rendered which is a novel approach to exploration of spatial bone properties in a CT data set.

Computer Simulation↗

PubMed2000

Velocity constancy in a virtual reality environment.

During everyday life the brain is continuously integrating multiple perceptual cues in order to allow us to make decisions and to guide our actions. In this study we have used a simulated (virtual reality--VR) visual environment to investigate how cues to speed judgments are integrated. There are two sources that could be used to provide signals for velocity constancy: temporal-frequency or distance cues. However, evidence from most psychophysical studies favours temporal-frequency cues. Here we report that two depth cues that provide a relative object--object distance--disparity and motion parallax--can provide a significant input to velocity-constancy judgments, particularly when combined. This result indicates that the second mechanism can also play a significant role in generating velocity constancy. Furthermore, we show that cognitive factors, such as familiar size, can influence the perception of object speed. The results suggest that both low-level cues to spatiotemporal structure and depth, and high-level cues, such as object familiarity, are integrated by the brain during velocity estimation in real-world viewing.

Cues↗

PubMed2006

Sensorimotor training in a virtual reality environment: does it improve functional recovery poststroke?

OBJECTIVE: To investigate the effectiveness of computerized virtual reality (VR) training of the hemiparetic hand of patients poststroke using a system that provides repetitive motor reeducation and skill reacquisition. METHODS: Eight subjects in the chronic phase poststroke participated in a 3-week program using their hemiparetic hand in a series of interactive computer games for 13 days of training, weekend breaks, and pretests and posttests. Each subject trained for about 2 to 2.5 h per day. Outcome measures consisted of changes in the computerized measures of thumb and finger range of motion, thumb and finger velocity, fractionation (the ability to move fingers independently), thumb and finger strength, the Jebsen Test of Hand Function, and a Kinematic reach to grasp test. RESULTS: Subjects as a group improved in fractionation of the fingers, thumb and finger range of motion, and thumb and finger speed, retaining those gains at the 1-week retention test. Transfer of these improvements was demonstrated through changes in the Jebsen Test of Hand Function and a decrease after the therapy in the overall time from hand peak velocity to the moment when an object was lifted from the table. CONCLUSIONS: It is difficult in current service delivery models to provide the intensity of practice that appears to be needed to effect neural reorganization and functional changes poststroke. Computerized exercise systems may be a way to maximize both the patients' and the clinicians' time. The data in this study add support to the proposal to explore novel technologies for incorporation into current practice.

Aged↗