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At least 307 records · Page 17Linked to original sources

PubMed2006

Intelligent inferencing and haptic simulation for Chinese acupuncture learning and training.

This paper presents an intelligent virtual environment for Chinese acupuncture learning and training using state-of-the-art virtual reality technology. It is the first step toward developing a comprehensive virtual human model for studying Chinese medicine. Students can learn and practice acupuncture in the proposed 3-D interactive virtual environment that supports a force feedback interface for needle insertion. Thus, students not only "see" but also "touch" the virtual patient. With high performance computers, highly informative and flexible visualization of acupuncture points of various related meridian and collateral can be highlighted to guide the students during training. A computer-based expert system using our newly proposed intelligent fuzzy petri net is designed and implemented to train the students to treat different diseases using acupuncture. Such an intelligent virtual reality system can provide an interesting and effective learning environment for Chinese acupuncture.

Acupuncture↗

PubMed2002

On defining metrics for assessing laparoscopic surgical skills in a virtual training environment.

One of the key components of any training environment for surgical education is a method that can be used for assessing surgical skills. Traditionally, defining such a method has been difficult and based mainly on observations. However, through advances in modeling techniques and computer hardware and software, such methods can now be developed using combined visual and haptic rendering of a training scene. This paper presents some ideas on how metrics may be defined and used in the assessment of surgical skills in a virtual laparoscopic training environment.

Animals↗

PubMed2004

Phantom-based multimodal interactions for medical education and training: the Munich Knee Joint Simulator.

Simulation environments based on virtual reality technologies can support medical education and training. In this paper, the novel approach of an "interactive phantom" is presented that allows a realistic display of haptic contact information typically generated when touching and moving human organs or segments. The key idea of the haptic interface is to attach passive phantom objects to a mechanical actuator. The phantoms look and feel as real anatomical objects. Additional visualization of internal anatomical and physiological information and sound generated during the interaction with the phantom yield a multimodal approach that can increase performance, didactic value, and immersion into the virtual environment. Compared to classical approaches, this multimodal display is convenient to use, provides realistic tactile properties, and can be partly adjusted to different, e.g., pathological properties. The interactive phantom is exemplified by a virtual human knee joint that can support orthopedic education, especially for the training of clinical knee joint evaluation. It is suggested that the technical principle can be transferred to many other fields of medical education and training such as obstetrics and dentistry.

Computer Graphics↗

PubMed2003

The use of virtual reality in memory rehabilitation: current findings and future directions.

There is considerable potential for using virtual reality (VR) in memory rehabilitation which is only just beginning to be realized. PC-based virtual environments are probably better suited for this purpose than more immersive virtual environments because they are relatively inexpensive and portable, and less frightening to patients. Those exploratory studies that have so far been performed indicate that VR involvement would be usefully directed towards improving assessments of memory impairments and in memory remediation using reorganization techniques. In memory assessment, the use of VR could provide more comprehensive, ecologically-valid, and controlled evaluations of prospective, incidental, and spatial memory in a rehabilitation setting than is possible using standardized assessment tests. The additional knowledge gained from these assessments could more effectively direct rehabilitation towards specific impairments of individual patients. In memory remediation, VR training has been found to promote procedural learning in people with memory impairments, and this learning has been found to transfer to improved real-world performance. Future research should investigate ways in which the procedural knowledge gained during VR interaction can be adapted to offset the many disabilities which result from different forms of memory impairment.

Humans↗

PubMed1997

Can hazard risk be communicated through a virtual experience?

Cyberspace, defined by William Gibson as a consensual hallucination, now refers to all computer-generated interactive environments. Virtual reality, one of a class of interactive cyberspaces, allows us to create and interact directly with objects not available in the everyday world. Despite successes in the entertainment and aviation industries, this technology has been called a 'solution in search of a problem'. The purpose of this commentary is to suggest such a problem: the inability to acquire experience with a hazard to motivate mitigation. Direct experience with a hazard has been demonstrated as a powerful incentive to adopt mitigation measures. While we lack the ability to summon hazard events at will in order to gain access to that experience, a virtual environment can provide an arena where potential victims are exposed to a hazard's effects. Immersion as an active participant within the hazard event through virtual reality may stimulate users to undertake mitigation steps that might otherwise remain undone. This paper details the possible direction in which virtual reality may be applied to hazards mitigation through a discussion of the technology, the role of hazard experience, the creation of a hazard stimulation and the issues constraining implementation.

Computer Simulation↗

PubMed2004

Molecular surface point environments for virtual screening and the elucidation of binding patterns (MOLPRINT 3D).

A novel method (MOLPRINT 3D) for virtual screening and the elucidation of ligand-receptor binding patterns is introduced that is based on environments of molecular surface points. The descriptor uses points relative to the molecular coordinates, thus it is translationally and rotationally invariant. Due to its local nature, conformational variations cause only minor changes in the descriptor. If surface point environments are combined with the Tanimoto coefficient and applied to virtual screening, they achieve retrieval rates comparable to that of two-dimensional (2D) fingerprints. The identification of active structures with minimal 2D similarity ("scaffold hopping") is facilitated. In combination with information-gain-based feature selection and a naive Bayesian classifier, information from multiple molecules can be combined and classification performance can be improved. Selected features are consistent with experimentally determined binding patterns. Examples are given for angiotensin-converting enzyme inhibitors, 3-hydroxy-3-methylglutaryl-coenzyme A reductase inhibitors, and thromboxane A2 antagonists.

Angiotensin-Converting Enzyme Inhibitors↗

PubMed2004

Hippocampal function and spatial memory: evidence from functional neuroimaging in healthy participants and performance of patients with medial temporal lobe resections.

Several strategies can be used to find a destination in the environment. Using a virtual environment, the authors identified 2 strategies dependent on 2 different memory systems. A spatial strategy involved the use of multiple landmarks available in the environment, and a response strategy involved right and left turns from a given start position. Although a probe trial provided an objective measure of the strategy used, classification that was based on verbal reports was used in small groups to avoid risks of misclassification. The authors first demonstrated that the spatial strategy led to a significant activity of the hippocampus, whereas the response strategy led to a sustained activity in the caudate nucleus. Then, the authors administered the task to 15 patients with lesions to the medial temporal lobe, showing an impaired ability using the spatial strategy. Imaging and neuropsychological results are discussed to shed light on the human navigation system.

Adult↗

PubMedDate not supplied

Data streaming in telepresence environments.

In this paper, we discuss data transmission in telepresence environments for collaborative virtual reality applications. We analyze data streams in the context of networked virtual environments and classify them according to their traffic characteristics. Special emphasis is put on geometry-enhanced (3D) video. We review architectures for real-time 3D video pipelines and derive theoretical bounds on the minimal system latency as a function of the transmission and processing delays. Furthermore, we discuss bandwidth issues of differential update coding for 3D video. In our telepresence system-the blue-c-we use a point-based 3D video technology which allows for differentially encoded 3D representations of human users. While we discuss the considerations which lead to the design of our three-stage 3D video pipeline, we also elucidate some critical implementation details regarding decoupling of acquisition, processing and rendering frame rates, and audio/video synchronization. Finally, we demonstrate the communication and networking features of the blue-c system in its full deployment. We show how the system can possibly be controlled to face processing or networking bottlenecks by adapting the multiple system components like audio, application data, and 3D video.

Computer Communication Networks↗

PubMed2004

Improving left hemispatial neglect using virtual reality.

BACKGROUND: In hemispatial neglect, space can be dissociated on the basis of "near" peripersonal vs "far" extrapersonal space. The clinical manifestations of neglect can be modified by having patients use a tool to explore "far" extrapersonal space. An explanation for this is that the use of a stick produced an extension of body space resulting in a remapping of "far" space as "near" space. OBJECTIVE: S: To determine whether the remapping of space can be generalized to the amelioration of the "affected" vs the "nonaffected" space, rather than being confined to the selective amelioration of "far" vs "near" neglect; and to determine whether tool use is a necessary condition for the remapping of space. METHODS: Using virtual reality, the authors asked six hemispatial neglect patients to reach and grasp a real object while simultaneously observing the grasping of a virtual object located within a virtual environment by a virtual hand. The virtual hand was commanded in real time by their real hand. RESULTS: After a period of adaptation, hemispatial neglect patients coded the visual stimuli within the neglected space in an identical fashion as those presented within the preserved portions of space. CONCLUSIONS: It is possible to re-create links between the affected and the nonaffected space. Wielding a tool is not a necessary condition in reopening neglected space.

Aged↗

PubMed2006

Virtual reality applications for the remapping of space in neglect patients.

PURPOSE: The aims of the present article were the following: (i) to provide some evidence of the potential of virtual reality (VR) for the assessment, training and recovery of hemispatial neglect; (ii) to present data from our laboratory which seem to confirm that the clinical manifestation of neglect can be improved by using VR techniques; and (iii) to ascertain the neural bases of this improvement. METHODS: We used a VR device (DataGlove) interfaced with a specially designed computer program which allowed neglect patients to reach and grasp a real object while simultaneously observing the grasping of a virtual object located within a virtual environment by a virtual hand. The virtual hand was commanded in real time by their real hand. RESULTS: After a period of training, hemispatial neglect patients coded the visual stimuli within the neglected space in an identical fashion as those presented within the preserved portions of space. However it was also found that only patients with lesions that spared the inferior parietal/superior temporal regions were able to benefit from the virtual reality training. CONCLUSIONS: It was concluded that using VR it is possible to re-create links between the affected and the nonaffected space in neglect patients. Furthermore, that specific regions may play a crucial role in the recovery of space that underlies the improvement of neglect patients when trained with virtual reality. The implications of these results for determining the neural bases of a higher order attentional and/or spatial representation, and for the treatment of patients with unilateral neglect are discussed.

Aged↗

PubMed2006

Fuzzy approach to the intelligent management of virtual spaces.

This paper presents research carried out toward the improvement of current virtual environments from an intelligent systems approach. A novel architecture to solve vague queries that allows users to find objects and scenes in virtual environments is described. As a base, a new virtual worlds representation model and an associated fuzzy querying approach are used. The new representation model adds a semantic level to the usual models, providing more suitable environments for the interaction with users. The query solver is able to work with queries expressing the vagueness inherent to human conceptualization of visual perception (for example, tall tree, a park with many tall trees, or a park bench near approximately five tall trees). The system has been developed and evaluated with user experiments, where comparison with navigation and keyword-based query approaches have been realized. The results of this study show that the proposed architecture is more powerful and intuitive for finding the targets.

Algorithms↗

PubMedDate not supplied

Development of a Remote Accessibility Assessment System through three-dimensional reconstruction technology.

A Remote Accessibility Assessment System (RAAS) that uses three-dimensional (3-D) reconstruction technology is being developed; it enables clinicians to assess the wheelchair accessibility of users' built environments from a remote location. The RAAS uses commercial software to construct 3-D virtualized environments from photographs. We developed custom screening algorithms and instruments for analyzing accessibility. Characteristics of the camera and 3-D reconstruction software chosen for the system significantly affect its overall reliability. In this study, we performed an accuracy assessment to verify that commercial hardware and software can construct accurate 3-D models by analyzing the accuracy of dimensional measurements in a virtual environment and a comparison of dimensional measurements from 3-D models created with four cameras/settings. Based on these two analyses, we were able to specify a consumer-grade digital camera and PhotoModeler (EOS Systems, Inc, Vancouver, Canada) software for this system. Finally, we performed a feasibility analysis of the system in an actual environment to evaluate its ability to assess the accessibility of a wheelchair user's typical built environment. The field test resulted in an accurate accessibility assessment and thus validated our system.

Computer Graphics↗

PubMed2005

Design of functional simulation of renal cancer in virtual reality environments.

OBJECTIVES: The preoperative planning of partial nephrectomy can be facilitated by the ability to view the tumor and surrounding tissue in three-dimensional (3D) virtual reality (VR). A technique to convert Digital Imaging and Communications in Medicine computed tomography scan data into a fully 3D VR environment was developed. The model can be transferred to a personal computer, allowing the surgeon to view the 3D model in the operating room. METHODS: Computed tomography data from a patient with multifocal renal masses was converted into a 3D polygonal mesh using Amira running on a desktop personal computer with Windows XP Professional. A Silicon Graphics Monster Onyx2 running the Linux operating system was used to view the 3D stereo model in the VR environments: either the CAVE or a specialized desk called the Immersadesk. An application to view and interact with the model on a desktop personal computer was written in C++. RESULTS: A 3D model of the kidney, the multiple tumors, and the associated systems was created. The model could be viewed and manipulated in a true VR environment and on a desktop personal computer. CONCLUSIONS: This project completed two major goals. First, a 3D model of a kidney containing multiple masses was created and viewed in a VR environment. Second, an interface to display the model on a desktop personal computer in the operating room was created. This is the first step in bringing VR technology to the operating room to assist the surgeon directly.

Aged↗

PubMed1998

Uses of virtual reality in clinical training: developing the spatial skills of children with mobility impairments.

In this chapter we review some of the ways in which the skills learned in virtual environments (VEs) transfer to real situations, and in particular how information about the spatial layouts of virtual buildings acquired from the exploration of three-dimensional computer-simulations transfers to their real equivalents. Four experiments are briefly described which examined VR use by disabled children. We conclude that spatial information of the kind required for navigation transfers effectively from virtual to real situations. Spatial skills in disabled children showed progressive improvement with repeated exploration of virtual environments. The results are discussed in relation to the potential future benefits of VR in special needs education and training.

Computer Simulation↗

PubMed2004

New technologies for providing remote psychological treatments.

New technologies lead us to a series of new applications that we could not imagine just a few years before. Many services have appeared for Internet, the global computer network: FTP, e-mail, World Wide Web. Psychological treatments are one of the multiple applications that can be developed using these tools. Dynamic web pages that include information prepared by the therapist for different patients and that receive information from them can be generated. Other tools such as e-mail or chats can be used to provide a direct communication. Databases can be integrated in web applications for storing data about different patients. Several formats can be used for storing the information, and some of them such as XML provide a promising method of psychological data standardization. Using different development tools, virtual environments can also be generated and integrated in web pages, so new psychological treatments such as virtual environment exposure are also possible from web applications. This entire basis provides the structure that allows that new applications can be imagined and developed. In a few years, new trends will appear, probably one of them will be the use of wireless devices to provide psychological treatment and help at any place and any time.

Internet↗

PubMed1999

Interactive navigation and bronchial tube tracking in virtual bronchoscopy.

An interactive virtual environment for simulation of bronchoscopy is developed. Medical doctor can safely plan their surgical bronchoscopy using the virtual environment without any invasive diagnosis which may risk the patient's health. The 3D pen input device of the system allows the doctor to navigate and visualize the bronchial tree of the patient naturally and interactively. To navigate the patient's bronchial tree, a vessel tracking process is required. While manual tracking is tedious and labor-intensive, fully automatic tracking may not be reliable. We propose a semi-automatic tracking technique called Intelligent Path Tracker which provides automation and enough user control during the vessel tracking. To support an interactive frame rate, we also introduce a new volume rendering acceleration technique, named as IsoRegion Leaping. The volume rendering is further accelerated by distributed rendering on a TCP/IP-based network of low-cost PCs. With these approaches, a 256 x 256 x 256 volume data of human lung, can be navigated and visualized at a frame rate of over 10 Hz in our virtual bronchoscopy system.

Bronchoscopy↗

PubMed2006

Responses to a virtual reality grocery store in persons with and without vestibular dysfunction.

People with vestibular dysfunction often complain of having difficulty walking in visually complex environments. Virtual reality (VR) may serve as a useful therapeutic tool for providing physical therapy to these people. The purpose of this pilot project was to explore the ability of people with and without vestibular dysfunction to use and tolerate virtual environments that can be used in physical therapy. We have chosen grocery store environments, which often elicit complaints from patients. Two patients and three control subjects were asked to stand and navigate in VR grocery stores while finding products. Perceived discomfort, simulator sickness symptoms, distance traveled, and speed of head movement were recorded. Symptoms and discomfort increased in one subject with vestibular dysfunction. The older subjects traveled a shorter distance and had greater speed of head movements compared with young subjects. Environments with a greater number of products resulted in more head movements and a shorter distance traveled.

Activities of Daily Living↗

PubMed2006

Navigation-associated medial parietal neurons in monkeys.

To examine the neural basis of route knowledge by which one can reach one's destination, we recorded the activity of 580 neurons in the monkey medial parietal region (MPR) while monkeys actively navigated through a virtual environment. One hundred eighty of these neurons (31%) showed significant responses to the monkeys' movements in the virtual environment. Of these responsive neurons, 77% (139/180) showed responses associated with a specific movement at a specific location (navigation neurons), 8% (14/180) showed responses associated with a specific movement (movement-selective neurons), and the remaining 27 neurons (15%) were nonselective. We found navigation neurons whose responses to the same movement at the same location were modulated depending on the route that the monkey was currently taking, that is, in a route-selective manner (32 of 59 tested neurons among 139 navigation neurons, route-selective navigation neurons). The reversible inactivation of MPR neurons by muscimol resulted in a monkey becoming lost during the navigation task trial. These results suggest that MPR plays a critical role in route-based navigation by integrating location information and self-movement information.

Animals↗