Ralph Mager

Immersive virtual environments in cue exposure.

Cue reactivity to drug-related stimuli is a frequently observed phenomenon in drug addiction. Cue reactivity refers to a classical conditioned response pattern that occurs when an addicted subject is exposed to drug-related stimuli. This response consists of physiological and cognitive reactions. Craving, a subjective desire to use the drug of choice, is believed to play an important role in the occurrence of relapse in the natural setting. Besides craving, other subjective cue-elicited reactions have been reported, including withdrawal symptoms, drug-agonistic effects, and mood swings. Physiological reactions that have been investigated include skin conductance, heart rate, salivation, and body temperature. Conditioned reactivity to cues is an important factor in addiction to alcohol, nicotine, opiates, and cocaine. Cue exposure treatment (CET) refers to a manualized, repeated exposure to drug-related cues, aimed at the reduction of cue reactivity by extinction. In CET, different stimuli are presented, for example, slides, video tapes, pictures, or paraphernalia in nonrealistic, experimental settings. Most often assessments consist in subjective ratings by craving scales. Our pilot study will show that immersive virtual reality (IVR) is as good or even better in eliciting subjective and physiological craving symptoms as classical devices.

Age-related changes in cognitive conflict processing: An event-related potential study

Cognitive tasks involving conflicting stimuli and responses are associated with an early age-related decline in performance. Conflict and conflict-induced interference can be stimulus- or response-related. In classical stimulus-response compatibility tasks, such as the Stroop task, the event-related potential (ERP) usually reveals a greater negativity on incongruent versus congruent trials which has often been linked with conflict processing. However, it is unclear whether this negativity is related to stimulus- or response-related conflict, thus rendering the meaning of age-related changes inconclusive. In the present study, a modified Stroop task was used to focus on stimulus-related interference processes while excluding response-related interference. Since we intended to study work-relevant effects ERPs and performance were determined in young (about 30 years old) and middle-aged (about 50 years old) healthy subjects (total n=80). In the ERP, a broad negativity developed after incongruent versus congruent stimuli between 350 and 650 ms. An age-related increase of the latency and amplitude of this negativity was observed. These results indicate age-related alterations in the processing of conflicting stimuli already in middle age.

Safety of injectable opioid maintenance treatment for heroin dependence

BACKGROUND There is a growing debate about injectable opioid treatment programs in many Western countries. This is the first placebo-controlled study of the safety of injectable opioids in a controlled treatment setting. METHODS Twenty-five opioid-dependent patients on intravenous (IV) heroin or IV methadone maintenance treatment were randomly assigned to either their individual prescribed IV maintenance dose or placebo. Acute drug effects were recorded, focusing on electrocardiography, respiratory movements, arterial blood oxygen saturation, and electroencephalography (EEG). RESULTS After heroin injection, marked respiratory depression progressing to a Cheyne-Stokes pattern occurred. Peripheral arterial blood oxygenation decreased to 78.9 +/- 8.7% (mean +/- SD) ranging from 52%-90%. During hypoxia, 7 of the 16 subjects experienced intermittent and somewhat severe bradycardia. Five subjects exhibited paroxysmal EEG patterns. After methadone injection, respiratory depression was less pronounced than after heroin injection. No relevant bradycardia was noted. CONCLUSIONS Opioid doses commonly prescribed in IV opioid treatment induce marked respiratory and circulatory depression, as well as occasionally irregular paroxysmal EEG activity. Further studies are needed to optimize the clinical practice of IV opioid treatment to prevent serious complications. Moreover, the extent of the observed effects raises questions about the appropriateness of IV opioid treatment in the present form.

Mismatch and conflict: Neurophysiological and behavioral evidence for conflict priming

Conflict-related cognitive processes are critical for adapting to sudden environmental changes that confront the individual with inconsistent or ambiguous information. Thus, these processes play a crucial role to cope with daily life. Generally, conflicts tend to accumulate especially in complex and threatening situations. Therefore, the question arises how conflict-related cognitive processes are modulated by the close succession of conflicts. In the present study, we investigated the effect of interactions between different types of conflict on performance as well as on electrophysiological parameters. A task-irrelevant auditory stimulus and a task-relevant visual stimulus were presented successively. The auditory stimulus consisted of a standard or deviant tone, followed by a congruent or incongruent Stroop stimulus. After standard prestimuli, performance deteriorated for incongruent compared to congruent Stroop stimuli, which were accompanied by a widespread negativity for incongruent versus congruent stimuli in the event-related potentials (ERPs). However, after deviant prestimuli, performance was better for incongruent than for congruent Stroop stimuli and an additional early negativity in the ERP emerged with a fronto-central maximum. Our data show that deviant auditory prestimuli facilitate specifically the processing of stimulus-related conflict, providing evidence for a conflict-priming effect.

Real-time monitoring of brain activity in patients with specific phobia during exposure therapy, employing a stereoscopic virtual environment.

Exposure therapy is a behavioral technique that is reported to be the most effective, long-lasting treatment for patients suffering from specific phobia. During the performance in enclosed spaces, the patients show a strong psychophysiological response to the phobic stimulus that is normally avoided. This psychophysiological response changes characteristically during the course of exposure. We implemented an electroencephalographic monitoring focusing on event-related potentials to resolve the modulation of preattentive information processing by the anxiety state of the subject. Therefore, mismatch-negativity (MMN) was chosen as parameter using a passive auditory oddball paradigm that does not interfere with performance in the virtual environment. The results of this neurophysiological monitoring are demonstrated in one patient suffering from claustrophobia.

Monitoring Brain Activity During Use of Stereoscopic Virtual Environments

Performance in virtual environments (VEs) is strongly modulated by attention-related factors such as the preattentive state of the brain. Because this state changes over time and might also be infl...

75.4: Evaluation of Human Reactions on Displays with LED Backlight and a Technical Concept of a Circadian Effective Display

We present the results of clinical user studies comparing the effects of LED- vs. CCFL-backlit displays on humans, resulting from the emitted amount of 464 nm light. The LED-lit display causes significant effects on the user. We present a concept of a display with controllable 464 nm emission.

LED‐backlit computer screens influence our biological clock and keep us more awake

— In commodity LC flat-panel displays, the traditional CCFL backlight is being replaced more and more by LEDs. The typical spectrum of LED-lit displays shows a significantly higher amount of blue light in the range around 464 nm. Blue light in this wavelength area suppresses the melatonin level in humans and thus effects the biological clock. Our hypothesis was that the amount of blue light reaching the human eye from a LED-backlit display is sufficient to have a significant effect on the biological clock. The results of clinical user studies comparing the effects of LED- vs. CCFL-backlit displays on humans, resulting from the emitted amount of 464-nm light, will be presented. It was found that the LED-backlit display causes significant suppression of melatonin, which effects the biological clock of the test persons, indicating the necessity for displays with a controllable 464-nm emission. A technical concept for a display with such functionality will be presented.

Monitoring Human-Virtual Reality Interaction: A Time Series Analysis Approach

Optimization of Virtual Environments (VEs) in the Mental Health field as well as in other application areas depends heavily on the exact knowledge of the technologys impact on mental work load, st...

Beschwerdenvalidierung in der versicherungsmedizinischen Begutachtung

High prevalence rates of non-authentic complaints identified by experts in the field of insurance medicine draw attention to the risk of services, which are of limited availability and financially compensated, being used in ways that are not goal-oriented. Therefore, symptom validity testing has become a growing issue to prevent non-targeted monetary compensations. This paper outlines the best-evaluated methods and instruments. Based on the data currently available, their validity, in particular in the context of medico-legal assessment, is assessed. It is concluded that symptom validity assessment allows inferences about the degree of certainty of clinical judgements on the authenticity of reported symptoms. Thus, the application of the suggested instruments enhances significantly the quality of medical and psychological expertise. However, the integration of the additional results into the overall assessment is challenging and needs to be further clarified.