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At least 703 records · Page 39Linked to original sources

PubMed1997

Virtual reality for orthognathic surgery: the augmented reality environment concept.

PURPOSE: The objective of this study was to apply virtual reality technology to osteotomies of the facial skeleton. MATERIALS AND METHODS: Augmented reality can be considered a hybrid of virtual and real environment spaces, which are coregistered and simultaneously visualized. Using a see-through HMD (head-mounted display) and Interventional Video Tomography intraoperatively, partial visual immersion into a patient-related virtual data space augments the surgeon's perception as shown in an experimental study and clinical applications. RESULTS: Without limiting the surgical judgment, offering continuous observation of the operating field, the presented technology additionally provides visual access to invisible data of anatomy, physiology, and function and thus guarantees unencumbered and fluent surgery. CONCLUSION: Despite current shortcomings, augmented reality technology proved to be particularly well suited for use in osteotomies of the facial skeleton.

Anatomy, Cross-Sectional↗

PubMed1996

A haptic interface for virtual simulation of endoscopic surgery.

Virtual reality can be described as a convincingly realistic and naturally interactive simulation in which the user is given a first person illusion of being immersed within a computer generated environment While virtual reality systems offer great potential to reduce the cost and increase the quality of medical training, many technical challenges must be overcome before such simulation platforms offer effective alternatives to more traditional training means. A primary challenge in developing effective virtual reality systems is designing the human interface hardware which allows rich sensory information to be presented to users in natural ways. When simulating a given manual procedure, task specific human interface requirements dictate task specific human interface hardware. The following paper explores the design of human interface hardware that satisfies the task specific requirements of virtual reality simulation of Endoscopic surgical procedures. Design parameters were derived through direct cadaver studies and interviews with surgeons. Final hardware design is presented.

Computer Simulation↗

PubMed2003

Virtual reality: new method of teaching anorectal and pelvic floor anatomy.

PURPOSE: A clear understanding of the intricate spatial relationships among the structures of the pelvic floor, rectum, and anal canal is essential for the treatment of numerous pathologic conditions. Virtual-reality technology allows improved visualization of three-dimensional structures over conventional media because it supports stereoscopic-vision, viewer-centered perspective, large angles of view, and interactivity. We describe a novel virtual reality-based model designed to teach anorectal and pelvic floor anatomy, pathology, and surgery. METHODS: A static physical model depicting the pelvic floor and anorectum was created and digitized at 1-mm intervals in a CT scanner. Multiple software programs were used along with endoscopic images to generate a realistic interactive computer model, which was designed to be viewed on a networked, interactive, virtual-reality display (CAVE or ImmersaDesk). A standard examination of ten basic anorectal and pelvic floor anatomy questions was administered to third-year (n = 6) and fourth-year (n = 7) surgical residents. A workshop using the Virtual Pelvic Floor Model was then given, and the standard examination was readministered so that it was possible to evaluate the effectiveness of the Digital Pelvic Floor Model as an educational instrument. RESULTS: Training on the Virtual Pelvic Floor Model produced substantial improvements in the overall average test scores for the two groups, with an overall increase of 41 percent (P = 0.001) and 21 percent (P = 0.0007) for third-year and fourth-year residents, respectively. Resident evaluations after the workshop also confirmed the effectiveness of understanding pelvic anatomy using the Virtual Pelvic Floor Model. CONCLUSION: This model provides an innovative interactive educational framework that allows educators to overcome some of the barriers to teaching surgical and endoscopic principles based on understanding highly complex three-dimensional anatomy. Using this collaborative, shared virtual-reality environment, teachers and students can interact from locations world-wide to manipulate the components of this model to achieve the educational goals of this project along with the potential for virtual surgery.

Anal Canal↗

PubMed1987

Isolation distress in two-week-old rats: influence of home cage, social companions, and prior experience with littermates.

Behavioral and autonomic manifestations of acute isolation distress were studied in 2-week-old rats under novel and home-cage conditions. Levels of ultrasonic vocalization, heart rate, self-grooming, and rises were higher in novel surroundings, while locomotion and digging were more frequent in home cages. Next, we found that a group of 8 unanesthetized agemate pups was just as effective as an anesthetized dam in reducing (by 80-90%) all behaviors of isolated pups in novel surroundings. Finally, singletons reared without littermates during postnatal days 7-14 showed normal isolation responses, and these were as effectively alleviated by littermates as those of normally reared pups. Thus, isolation distress in rats this age is a complex response, modulated over time by aspects of the pups' environment and virtually prevented by the presence of cues common to both mother and littermates.

Animals↗

PubMed2005

Learning in a web-based system in medical education.

New learning environments such as distance education and computer-aided instruction promise to bring a change in today's learning environments by adjusting the relationship between the learner, the educational content and the organization of education. In this study, we explored whether students' approaches to learning related to their perception of a particular virtual learning environment. Scales of the ASSIST questionnaire were loaded in a two-principal component solution, surface and deep-strategic. We found statistically significant correlations between the approaches to learning and the student's attitudes towards ICT. Early identification of approaches to learning and attitudes towards ICT may prove to be important in order to provide assistance to aid the transition of students with diverse individual characteristics and to the design of new learning environments.

Attitude to Computers↗

PubMed2006

Enhanced visual experiences and seeing hardware for reduced vision: a pilot study.

BACKGROUND: Persons with vision loss may have limited ability to experience visual arts and difficulty navigating unfamiliar environments. The Center for Advanced Visual Studies at Massachusetts Institute of Technology developed a Retinal Imaging Machine Vision System (RIMVS) "seeing machine" to project "word-images" onto the retina and permit navigation through virtual architectural environments. METHODS: Ten subjects with visual acuity < or = 20/70 in the better-seeing eye were recruited. Subjects viewed word-images that were projected on the retina of the better-seeing eye and asked to interpret the images. Subsequently, they were asked to recall as many images as possible. Participants also practiced navigation through a computer-modeled building that was projected onto the retina. A survey elicited subject response to the RIMVS. RESULTS: Six subjects correctly interpreted all 10 word-images; no subject interpreted fewer than 8 correctly. Seven subjects felt that the word images afforded easy recall, and 7 subjects responded that the technology might assist subsequent navigation in unfamiliar environments. CONCLUSIONS: Responses reflect a general interest and potential with the RIMVS. Further studies are warranted to explore the value of the RIMVS as a tool to enable visually compromised persons to experience and appreciate visual arts and as a navigation aid.

Adult↗

PubMed1997

3-D surface reconstruction of patient specific anatomic data using a pre-specified number of polygons.

Virtual reality environments provide highly interactive, natural control of the visualization process, significantly enhancing the scientific value of the data produced by medical imaging systems. Due to the computational and real time display update requirements of virtual reality interfaces, however, the complexity of organ and tissue surfaces which can be displayed is limited. In this paper, we present a new algorithm for the production of a polygonal surface containing a pre-specified number of polygons from patient or subject specific volumetric image data. The advantage of this new algorithm is that it effectively tiles complex structures with a specified number of polygons selected to optimize the trade-off between surface detail and real-time display rates.

Algorithms↗

PubMed2003

Ambient intelligence in health care.

Ambient Intelligence (AmI) is a new paradigm in information technology, in which people are empowered through a digital environment that is aware of their presence and context, and is sensitive, adaptive, and responsive to their needs, habits, gestures and emotions. The most ambitious expression of AmI is Intelligent Mixed Reality (IMR), an evolution of traditional virtual reality environments. Using IMR, it is possible to integrate computer interfaces into the real environment, so that the user can interact with other individuals and with the environment itself in the most natural and intuitive way. How does the emergence of the AmI paradigm influence the future of health care? Using a scenario-based approach, this paper outlines the possible role of AmI in health care by focusing on both its technological and relational nature. In this sense, clinicians and health care providers that want to exploit AmI potential need a significant attention to technology, ergonomics, project management, human factors and organizational changes in the structure of the relevant health service.

Electronics↗

PubMed1999

The Virtual Pelvic Floor, a tele-immersive educational environment.

This paper describes the development of the Virtual Pelvic Floor, a new method of teaching the complex anatomy of the pelvic region utilizing virtual reality and advanced networking technology. Virtual reality technology allows improved visualization of three-dimensional structures over conventional media because it supports stereo vision, viewer-centered perspective, large angles of view, and interactivity. Two or more ImmersaDesk systems, drafting table format virtual reality displays, are networked together providing an environment where teacher and students share a high quality three-dimensional anatomical model, and are able to converse, see each other, and to point in three dimensions to indicate areas of interest. This project was realized by the teamwork of surgeons, medical artists and sculptors, computer scientists, and computer visualization experts. It demonstrates the future of virtual reality for surgical education and applications for the Next Generation Internet.

Anatomy↗

PubMed2000

Localization of a time-delayed, monocular virtual object superimposed on a real environment.

Observers adjusted a pointer to match the depicted distance of a monocular virtual object viewed in a see-through, head-mounted display. Distance information was available through motion parallax produced as the observers rocked side to side. The apparent stability of the virtual object was impaired by a time delay between the observers' head motions and the corresponding change in the object position on the display. Localizations were made for four time delays (31 ms, 64 ms, 131 ms, and 197 ms) and three depicted distances (75 cm, 95 cm, and 113 cm). The errors in localizations increased systematically with time delay and depicted distance. A model of the results shows that the judgment error and lateral projected position of the virtual object are each linearly related to time delay.

Adolescent↗

PubMed1993

Binocular vision in a virtual world: visual deficits following the wearing of a head-mounted display.

The short-term effects on binocular stability of wearing a conventional head-mounted display (HMD) to explore a virtual reality environment were examined. Twenty adult subjects (aged 19-29 years) wore a commercially available HMD for 10 min while cycling around a computer generated 3-D world. The twin screen presentations were set to suit the average interpupillary distance of our subject population, to mimic the conditions of public access virtual reality systems. Subjects were examined before and after exposure to the HMD and there were clear signs of induced binocular stress for a number of the subjects. The implications of introducing such HMDs into the workplace and entertainment environments are discussed.

Computer Simulation↗

PubMed1970

The hovercraft environment.

In just over a decade the hovercraft has progressed from first prototype to a successful commercial form of transport which also has the ability to penetrate many environments hitherto virtually inaccessible to manned vehicles. Comparison with rival short range vehicles such as the helicopter and hydrofoil show that the hovercraft has become one of the most versatile forms of transport available. This versatility and ability to operate in unusual or extreme environments has been accompanied by the problems of control and of protection of the occupants of the hovercraft from the hazards associated with these environments. Several of these problems are discussed, together with their possible solutions. This article is based on a paper given to the Nederlands Vereniging Voor Ergonomie/Ergonomics Research Society joint conference at Noordwijk in Holland, 11-13 June, 1969.

Journal Article↗

PubMed2001

Bilateral hippocampal pathology impairs topographical and episodic memory but not visual pattern matching.

A virtual reality environment was used to test memory performance for simulated "real-world" spatial and episodic information in a 22-year-old male, Jon, who has selective bilateral hippocampal pathology caused by perinatal anoxia. He was allowed to explore a large-scale virtual reality town and was then tested on his memory for spatial layout and for episodes experienced. Topographical memory was tested by assessing his ability to navigate, recognize previously visited locations, and draw maps of the town. Episodic memory was assessed by testing the retrieval of simulated events which consisted of collecting objects from characters while following a route through the virtual town. Memory for the identity of objects, as well as for where they were collected, from whom, and in what order, was also tested. While the first task tapped simple recognition memory, the latter three tested memory for context. Jon was impaired on all topographical tasks and on his recall of the context-dependent questions. However, his recognition of objects from the virtual town, and of "topographical" scenes (as evaluated by standard neuropsychological tests), was not impaired. These findings are consistent with the view that the hippocampus is involved in navigation, recall of long term allocentric spatial information and context-dependent episodic memory, but not visual pattern matching.

Adult↗

PubMed1993

Electromagnetic field interactions with biological systems.

This is a report on Symposia organized by the International Society for Bioelectricity and presented at the 1992 FASEB Meeting. The presentations summarized here were intended to provide a sampling of new and fruitful lines of research. The theme topics for the Symposia were cancer, neural function, cell signaling, pineal gland function, and immune system interactions. Living organisms are complex electrochemical systems that evolved over billions of years in a world with a relatively simple weak magnetic field and with few electromagnetic energy emitters. As is characteristic of living organisms, they interacted with and adapted to this environment of electric and magnetic fields. In recent years there has been a massive introduction of equipment that emits electromagnetic fields in an enormous range of new frequencies, modulations, and intensities. As living organisms have only recently found themselves immersed in this new and virtually ubiquitous environment, they have not had the opportunity to adapt to it. This gives us, as biologists, the opportunity to use these electromagnetic fields as probes to study the functioning of living systems. This is a significant opportunity, as new approaches to studying living systems so often provide the means to make great leaps in science. In recent years, a diversity of biologists have carried out experiments using electromagnetic fields to study the function of living cells and systems. This approach is now becoming quite fruitful and is yielding data that are advancing our knowledge in diverse areas of biology.

Animals↗

PubMed1996

Mutagenic DNA base modifications are correlated with lesions in nonneoplastic hepatic tissue of the English sole carcinogenesis model.

Hydroxyl radical-induced mutagenic base modifications have been linked to neoplasia in a number of biological systems, including English sole from chemically contaminated urban environments. However, virtually no information exists on the relationship between the mutagenic base modifications and preneoplastic and other lesions found in tumor-free tissues prone to cancer. We studied six hepatic lesions in immature, neoplasm-free English sole exposed to an urban and reference environment and established correlations between the lesion incidence and concentrations of the mutagenic base modifications 8-hydroxyguanine and 8-hydroxyadenine. The lesions were putatively preneoplastic basophilic foci, hepatocellular karyomegaly, megalocytic hepatosis, hepatocellular vacuolar change, hyalin droplet formation, and apoptosis. With the exception of hepatocellular vacuolar change, significant positive correlations were found between the lesions and the mutagenic base modifications. The hydroxyl radical may be a common etiological factor in the formation of the base modifications and hepatic lesions.

Adenine↗

PubMed2005

A strategic approach to developing e-learning capability for healthcare.

OBJECTIVES: This article examines a strategic approach to developing e-learning capability to enhance learning opportunities for the workforce of a healthcare organization. Emphasis is given to the procurement of a bespoke Managed Learning Environment (MLE). Strategic organizational issues impacting on future e-learning developments are considered. METHODS: The 2-year implementation plan was evaluated through a two phase external research project. The first phase focused on the effectiveness of a training programme designed to build capacity for e-learning within the Northern area and also included a virtual learning environment usability study which informed the MLE specification. The second phase evaluation is ongoing during 2005 and interim findings are presented. RESULTS: The MLE has been piloted and on-line learning packages have been acquired. There has been a phased take-up of e-learning opportunities and e-tutor training. Some virtual Communities of Practice have been established. Key organizational issues have been identified and ongoing findings are informing strategic planning. CONCLUSIONS: The healthcare MLE is offering enhanced learning opportunities and assisting area healthcare providers in training their dispersed workforces. Blended learning strategies are most successful. The need for protected time for e-learning is a key issue, financial savings are available. Progress has been slowed by identified organizational constraints-the MLE's benefits are widely recognized.

Community Networks↗

PubMed2004

Neural foundations of emerging route knowledge in complex spatial environments.

Behavioral evidence suggests that spatial knowledge derived from ground-level navigation can consist of both route and survey knowledge. Neuroimaging and lesion studies aiming to identify the neural structures responsible for topographical learning in humans have yielded partially inconsistent results, probably due to the lack of an effective behavioral parameter allowing for a reliable distinction between different representations. Therefore, we employed a novel virtual reality environment that provides accuracy and reaction time measures precisely indicating the emergence of route vs. survey knowledge. Functional magnetic resonance imaging (fMRI) was used to localize brain regions involved in the acquisition of pure route knowledge in the form of associations between consecutive landmark views and the direction of intermediate movements. Participants were scanned during repeated encoding of the complex environment from a first-person, ground-level perspective. Behavioral data revealed emerging route knowledge in 11 out of 14 subjects. Overall comparisons between encoding and control conditions identified activation in medial frontal gyrus, retrosplenial cortex and posterior inferior parietal cortex. Most importantly, only posterior inferior parietal regions showed increasing activation across sessions, thus paralleling behavioral measures of route expertise. Given the established role of the posterior parietal cortex in spatial processing, this area is thought to provide the pivotal spatial link between two landmarks encountered in immediate temporal succession.

Adult↗

PubMed1995

Ethical issues in the application of virtual reality to medicine.

Virtual reality (VR) will be increasingly used as a research tool in medicine. Examples include the computer modelling of complex pathological regulatory systems in disease; the integration of massive data bases derived from structural imaging of diseased organs and simultaneous functional mapping of the same organ; the development of neural prosthetic devices in sensory and/or mental impairment and the assessment or modification of major behavioural abnormalities in selected individuals. In time, advances in VR will lead to increasing pressure to introduce patients to a virtual reality environment and it is here that ethical problems will most frequently be encountered. Early examples would include the monitoring of anaesthesia and intensive care procedures but may extend to the support and enrichment of life of those patients who suffer chronic disabilities. In the setting of virtual reality, they may be able to experience much improved educational, recreational or pleasurable pursuits. Whilst the ultimate goal of improvement of the human condition will be cited to justify any human costs encountered in the development, testing and introduction of VR machines to patient care, pertinent ethical problems must simultaneously be addressed. These include the possibility that some researchers place their own advancement above the interests of a particular patient. Some other researchers may be unduly paternalistic especially when making decisions about patients who because of mental impairment or illness are unable to give their informed consent. Potentially, VR machines may be prone to errors such that they introduce into the mental life of susceptible individuals specific distortions that serve to exacerbate the symptoms of mental illness or induce such symptoms when none were previously present.(ABSTRACT TRUNCATED AT 250 WORDS)

Behavioral Research↗