Evaluation of electrochemical methods for tonic dopamine detection in vivo

Dysfunction in dopaminergic neuronal systems underlie a number of neurologic and psychiatric disorders such as Parkinson's disease, drug addiction, and schizophrenia. Dopamine systems communicate via two mechanisms, a fast "phasic" release (sub-second to second) that is related to salient stimuli and a slower "tonic" release (minutes to hours) that regulates receptor tone. Alterations in tonic levels are thought to be more critically important in enabling normal motor, cognitive, and motivational functions, and dysregulation in tonic dopamine levels are associated with neuropsychiatric disorders. Therefore, development of neurochemical recording techniques that enable rapid, selective, and quantitative measurements of changes in tonic extracellular levels are essential in determining the role of dopamine in both normal and disease states. Here, we review state-of-the-art advanced analytical techniques for in vivo detection of tonic levels, with special focus on electrochemical techniques for detection in humans.

The development of virtual reality therapy (VRT) system for the treatment of acrophobia and therapeutic case

Virtual reality therapy (VRT), based on this sophisticated technology, has been recently used in the treatment of subjects diagnosed with acrophobia, a disorder that is characterized by marked anxiety upon exposure to heights and avoidance of heights. Conventional VR systems for the treatment of acrophobia have limitations, over-costly devices or somewhat unrealistic graphic scenes. The goal of this study was to develop an inexpensive and more realistic virtual environment (VE) in which to perform exposure therapy for acrophobia. It is based on a personal computer, and a virtual scene of a bunge-jump tower in the middle of a large city. The virtual scenario includes an open lift surrounded by props beside a tower, which allows the patient to feel a sense of heights. The effectiveness of the VE was evaluated through the clinical treatment of a subject who was suffering from the fear of heights. As a result, it was proved that this VR environment was effective and realistic at overcoming acrophobia according not only to the comparison results of a variety of questionnaires before and after treatment but also to the subject's comments that the VE seemed to evoke more fearful feelings than the real situation.

The treatment of fear of flying: a controlled study of imaginal and virtual reality graded exposure therapy

The goal of this study was to determine if virtual reality graded exposure therapy (VRGET) was equally efficacious, more efficacious, or less efficacious, than imaginal exposure therapy in the treatment of fear of flying. Thirty participants (Age = 39.8 +/- 9.7) with confirmed DSM-IV diagnosis of specific phobia fear of flying were randomly assigned to one of three groups: VRGET with no physiological feedback (VRGETno), VRGET with physiological feedback (VRGETpm), or systematic desensitization with imaginal exposure therapy (IET). Eight sessions were conducted once a week. During each session, physiology was measured to give an objective measurement of improvement over the course of exposure therapy. In addition, self-report questionnaires, subjective ratings of anxiety (SUDs), and behavioral observations (included here as flying behavior before beginning treatment and at a three-month posttreatment followup) were included. In the analysis of results, the Chi-square test of behavioral observations based on a three-month posttreatment followup revealed a statistically significant difference in flying behavior between the groups [chi(2) (4) = 19.41, p < 0.001]. Only one participant (10%) who received IET, eight of the ten participants (80%) who received VRGETno, and ten out of the ten participants (100%) who received VRGETpm reported an ability to fly without medication or alcohol at three-month followup. Although this study included small sample sizes for the three groups, the results showed VRGET was more effective than IET in the treatment of flying. It also suggests that physiological feedback may add to the efficacy of VR treatment.

Virtual reality system for treatment of the fear of public speaking using image-based rendering and moving pictures

The fear of speaking is often cited as the world's most common social phobia. The rapid growth of computer technology enabled us to use virtual reality (VR) for the treatment of the fear of public speaking. There have been two techniques used to construct a virtual environment for the treatment of the fear of public speaking: model-based and movie-based. Virtual audiences and virtual environments made by model-based technique are unrealistic and unnatural. The movie-based technique has a disadvantage in that each virtual audience cannot be controlled respectively, because all virtual audiences are included in one moving picture file. To address this disadvantage, this paper presents a virtual environment made by using image-based rendering (IBR) and chroma keying simultaneously. IBR enables us to make the virtual environment realistic because the images are stitched panoramically with the photos taken from a digital camera. And the use of chroma keying allows a virtual audience to be controlled individually. In addition, a real-time capture technique was applied in constructing the virtual environment to give the subjects more interaction, in that they can talk with a therapist or another subject.

Development and validation of virtual driving simulator for the spinal injury patient

We developed a virtual reality (VR) driving simulator in order to safely evaluate and improve the driving ability of spinal injury patients. The simulator is composed of an actual car, a beam projector, and a large screen. For the interface of our driving simulator, an actual car was adapted and then connected to a computer. We equipped the car with hand control driving devices especially adapted for spinal injury patients. A beam projector was used so that the subjects could see the virtual scene on a large screen set up in front of them. The virtual environment (VE) consisted of 18 sections (e.g., a speed-limited road, a straight road, a curved road, a left turn) and each section was linked naturally to the next. The subjects selected for this trial were 10 normal drivers with valid driving licenses and 15 patients with thoracic or lumbar cord injuries who had prior driving experience. For evaluation, five driving skills were measured, including average speed, steering stability, centerline violations, traffic signal violations, and driving time in various road conditions such as straight and curved roads. The normal subjects manipulated the gas pedal and the brake with their feet, while the patients manipulated a hand control with their hands. After they finished driving the whole course, the participants answered the questions such as "How realistic did the virtual reality driving simulator seem to you?" and "How much was your fear reduced?" In this study, we found that the difference in manipulation method (i.e., the patient group's hand control versus the normal driver's foot controls) does not seem to influence relative performance in the VR driving simulator, though training to improve the use of hand controls in the VR driving simulator would be useful to reduce the fear that the patients feel while driving.

Analysis of physiological response to two virtual environments: driving and flying simulation

As virtual reality technology continues to attract significant attention in clinical psychology, especially in the treatment of phobias, physiological monitoring is increasingly considered as an objective measurement tool for studying participants. There are few studies, however, of the normal physiological response to virtual environments or reactions to different virtual environments. The goal of this study is to analyze nonphobic participants' physiological reactions to two virtual environments: driving and flying. Eleven nonphobic participants were exposed to each virtual environment for 15 min. Heart rate, skin resistance, and skin temperature were measured during physiological monitoring, and the Presence and Simulator Sickness Questionnaire scores were obtained after each exposure. This study found that skin resistance and heart rate variability can be used to show arousal of participants exposed to the virtual environment experience and that such measures generally returned to normal over time. The data suggest that skin resistance and heart rate can be used as objective measures in monitoring the reaction of non-phobic participants to virtual environments. We also noted that heart rate variability could be useful for assessing the emotional states of participants.

Physiological monitoring as an objective tool in virtual reality therapy

The goals of this study were twofold: (1) to investigate nonphobics' and phobics' physiological response in virtual environments, and (2) to analyze the trend of phobics' physiology during virtual reality (VR) treatment. As a measure of physiology, heart rate, skin resistance, and skin temperature were acquired. The data for two groups of participants were analyzed: 22 nonphobic participants (mean = 32 +/- 9.4 years) and 36 subjects with fear of flying (mean = 40 +/- 12.1 years) who met the DSM-IV criteria for fear of flying. As a result, skin resistance showed significant differences between nonphobics and phobics, T(56) = 2.978 and p < 0.01, respectively. The physiological response of 33 phobic participants, who were able to fly without medicine after VR treatment, showed a gradual trend toward the nonphobics' physiological responses as therapy sessions progressed. In this study, physiological monitoring, in particular skin resistance, appeared to be useful both in understanding the physiological state of phobic individuals and in evaluating the results of treatment in VR psychotherapy.

An investigation of immersiveness in virtual reality exposure using physiological data

As virtual reality technology is increasingly attracting significant attention in clinical psychology, especially in the treatment of phobias, physiological monitoring is increasingly considered as an objective measuring tool for studying participants. However, there are few studies of the normal individual's physiological response to virtual environments, or their reactions to different virtual environments. The goal of this study is to analyze non-phobic participants' physiological reaction to two virtual environments: driving and flying and to investigate the usefulness of heart rate variability. Eleven non-phobic participants were exposed to each virtual environment for 15 minutes. Heart rate, skin resistance, and skin temperature measurements were taken for physiological monitoring and Presence and Simulator Sickness Questionnaires were obtained after each exposure. This study found that skin resistance and heart rate variability can be used to show arousal of participant exposed to virtual environments experience and that such measures generally returned to normal as time went by. The Study showed that skin resistance and heart rate can be used as objective measures in monitoring the reaction of non-phobic participants to virtual environments. Significantly, heart rate variability analysis in virtual environments showed that it could be useful for assessing the emotional states of participants.

Development of a virtual speaking simulator using Image Based Rendering

The fear of speaking is often cited as the world's most common social phobia. The rapid growth of computer technology has enabled the use of virtual reality (VR) for the treatment of the fear of public speaking. There are two techniques for building virtual environments for the treatment of this fear: a model-based and a movie-based method. Both methods have the weakness that they are unrealistic and not controllable individually. To understand these disadvantages, this paper presents a virtual environment produced with Image Based Rendering (IBR) and a chroma-key simultaneously. IBR enables the creation of realistic virtual environments where the images are stitched panoramically with the photos taken from a digital camera. And the use of chroma-keys puts virtual audience members under individual control in the environment. In addition, real time capture technique is used in constructing the virtual environments enabling spoken interaction between the subject and a therapist or another subject.

The development of the virtual reality system for the treatment of the fears of public speaking

The fear of public speaking is a kind of social phobias. The patients having the fear of public speaking show some symptoms like shame and timidity in the daily personal relationship. They are afraid that the other person would be puzzled, feel insulted, and they also fear that they should be underestimated for their mistakes. For the treatment of the fear of public speaking, the cognitive-behavioral therapy has been generally used. The cognitive-behavioral therapy is the method that makes the patients gradually experience some situations inducing the fears and overcome those at last. Recently, the virtual reality technology has been introduced as an alternative method for providing phobic situations. In this study, we developed the public speaking simulator and the virtual environments for the treatment of the fear of public speaking. The head-mounted display, the head-tracker and the 3 dimensional sound system were used for the immersive virtual environment. The imagery of the virtual environment consists of a seminar room and 8 virtual audiences. The patient will speak in front of these virtual audiences and the therapist can control motions, facial expressions, sounds, and voices of each virtual audience.

Highly diastereoselective Michael addition of alpha-hydroxy acid derivatives and enantioselective synthesis of (+)-crobarbatic acid

[reaction: see text]. Michael addition of enolates of 2a and 2b to alpha,beta-unsaturated esters took place selectively on different faces (Si and Re, respectively) of the double bond to give the corresponding products 4 and 5, respectively, with >98% de. Subsequent hydrolysis of these Micheal adducts gives 3,4-disubstituted gamma-lactones with high enantiomeric excesses.

Virtual endoscopy using surface rendering and perspective volume rendering

Noninvasive virtual endoscopy is a new method of diagnosis using computer processing of 3-D image data sets (such as CT or MRI scans). Conventionally, two methods have been used in virtual endoscopy. One is 3-D surface rendering method. 3-D surface of human organs can be explored in real time by using this method, but surface rendering algorithm has disadvantages such as the low quality of visualized image and the loss of the volume data. The other is perspective volume rendering method. The power of perspective volume rendering is that the intrinsic 3-D richness of the volume data is preserved. However, there are the difficulty in planning flight-path and the disability of real time flight for a computationally intense procedure. This paper presents virtual endoscopy using both surface and perspective volume rendering. By combining each merits of two methods, a user can not only process virtual endoscopy interactively in real time but also view lossless and high-resolution image using the flight path defined by surface rendering. As a result, the use of common fly-paths removes the burden to define a flight-path in conventional perspective rendering method. Also 3-D object is explored in real time and viewed as lossless and detail cine sequences.