Ursula Voss

The effects of experimenter characteristics on pain reports in women and men

Abstract The present study investigated the effects of two attributes of the experimenter (gender and professional status) on the report and tolerance of pain in male and female subjects. 160 non‐psychology students (80 male and 80 female, aged 17–59 years) participated in a cold‐pressor task. Subjects were assigned to one of 8 groups: male (M) and female (F) experimenters tested male (m) and female (f) students. In each combination (Mm, Mf, Fm, Ff), the cold‐pressor task was conducted by either one of two faculty members (high professional) or one of two students (low professional). Subjects were asked to immerse their non‐dominant hand as long as possible in cold water (−1 °C). Dependent variables were pain threshold, pain tolerance, and pain intensity. Results indicated a significant main effect for professional status of the experimenter on pain tolerance. Subjects tolerated pain longer when they were tested by a professional experimenter. Further, a significant interaction of experimenter gender and subject gender on pain tolerance indicated that subjects also tolerated pain longer when they were tested by an experimenter of the opposite sex. Additionally, a significant main effect for experimenter gender showed higher pain intensities for subjects tested by female experimenters. The observation that pain responsivity is influenced by the professional status of the experimenter might have implications for the study of pain in general and should be addressed in more detail in future experiments.

Induction of self awareness in dreams through frontal low current stimulation of gamma activity

Recent findings link fronto-temporal gamma electroencephalographic (EEG) activity to conscious awareness in dreams, but a causal relationship has not yet been established. We found that current stimulation in the lower gamma band during REM sleep influences ongoing brain activity and induces self-reflective awareness in dreams. Other stimulation frequencies were not effective, suggesting that higher order consciousness is indeed related to synchronous oscillations around 25 and 40 Hz.

Measuring consciousness in dreams: The lucidity and consciousness in dreams scale

In this article, we present results from an interdisciplinary research project aimed at assessing consciousness in dreams. For this purpose, we compared lucid dreams with normal non-lucid dreams from REM sleep. Both lucid and non-lucid dreams are an important contrast condition for theories of waking consciousness, giving valuable insights into the structure of conscious experience and its neural correlates during sleep. However, the precise differences between lucid and non-lucid dreams remain poorly understood. The construction of the Lucidity and Consciousness in Dreams scale (LuCiD) was based on theoretical considerations and empirical observations. Exploratory factor analysis of the data from the first survey identified eight factors that were validated in a second survey using confirmatory factor analysis: INSIGHT, CONTROL, THOUGHT, REALISM, MEMORY, DISSOCIATION, NEGATIVE EMOTION, and POSITIVE EMOTION. While all factors are involved in dream consciousness, realism and negative emotion do not differentiate between lucid and non-lucid dreams, suggesting that lucid insight is separable from both bizarreness in dreams and a change in the subjectively experienced realism of the dream.

The Spectrum of Syndromes and Manifestations in Individuals Screened for Suspected Marfan Syndrome

The diagnosis of Marfan syndrome (MFS) is based on evaluating a large number of clinical criteria. We have observed that many persons presenting in specialized centers for “Marfan‐like” features do not have MFS, but exhibit a large spectrum of other syndromes. The spectrum of these syndromes and the distribution of “Marfan‐like” features remain to be characterized. Thus, we prospectively evaluated 279 consecutive patients with suspected MFS (144 men and 135 women at a mean age of 34 ± 13 years) for presence of 27 clinical criteria considered characteristic of MFS. The most frequent reasons to refer individuals for suspected MFS were skeletal features (31%), a family history of MFS, or aortic complications (29%), aortic dissection or aneurysm (19%), and eye manifestations (9%). Using established criteria, we confirmed MFS in 138 individuals (group 1) and diagnosed other connective tissue diseases, both with vascular involvement in 30 (group 2) and without vascular involvement in 39 (group 3), and excluded any distinct disease in 72 individuals (group 4). Clinical manifestations of MFS were present in all four patient groups and there was no single clinical criterion that exhibited positive and negative likelihood ratios that were per se sufficient to confirm or rule out MFS. We conclude that “Marfan‐like” features are not exclusively indicative of MFS but also of numerous, alternative inherited diseases with many of them carrying a hitherto poorly defined cardiovascular risk. These alternative diseases require future study to characterize their responses to therapy and long‐term prognosis.

Arousal thresholds during human tonic and phasic REM sleep.

The goal of the present study was to investigate arousal thresholds (ATs) in tonic and phasic episodes of rapid eye movement (REM) sleep, and to compare the frequency spectrum of these sub‐states of REM to non‐REM (NREM) stages of sleep. We found the two REM stages to differ with regard to behavioural responses to external acoustic stimuli. The AT in tonic REM was indifferent from that in sleep stage 2, and ATs in phasic REM were similar to those in slow‐wave sleep (stage 4). NREM and REM stages of similar behavioural thresholds were distinctly different with regard to their frequency pattern. These data provide further evidence that REM sleep should not be regarded a uniform state. Regarding electroencephalogram frequency spectra, we found that the two REM stages were more similar to each other than to NREM stages with similar responsivity. Ocular activity such as ponto‐geniculo‐occipital‐like waves and microsaccades are discussed as likely modulators of behavioural responsiveness and cortical processing of auditory information in the two REM sub‐states.

Sleep Disorders in Spinocerebellar Ataxia Type 2 Patients

Background: Sleep disturbances are common features in spinocerebellar ataxias (SCAs). Nevertheless, sleep data on SCA2 come from scarce studies including few patients, limiting the evaluation of the prevalence and determinants of sleep disorders. Objective: To assess the frequency and possible determinants of sleep disorders in the large and homogeneous SCA2 Cuban population. Methods: Thirty-two SCA2 patients and their age- and sex-matched controls were studied by video-polysomnography and sleep interviews. Results: The most striking video-polysomnography features were rapid eye movement (REM) sleep pathology and periodic leg movements (PLMs). REM sleep abnormalities included a consistent reduction of the REM sleep percentage and REM density as well as an increase in REM sleep without atonia (RWA). REM sleep and REM density decreases were closely related to the increase in ataxia scores, whereas the RWA percentage was influenced by the cytosine-adenine-guanine (CAG) repeats. PLMs were observed in 37.5% of cases. The PLM index showed a significant association with the ataxia score and disease duration but not with CAG repeats. Conclusions: REM sleep pathology and PLMs are closely related to SCA2 severity, suggesting their usefulness as disease progression markers. The RWA percentage is influenced by the CAG repeats and might thus be a sensitive parameter for reflecting polyglutamine toxicity. Finally, as PLMs are sensible to drug treatment, they represents a new therapeutic target for the symptomatic treatment of SCA2.

Lucid dreaming: an age-dependent brain dissociation

The current study focused on the distribution of lucid dreams in school children and young adults. The survey was conducted on a large sample of students aged 6–19 years. Questions distinguished between past and current experience with lucid dreams. Results suggest that lucid dreaming is quite pronounced in young children, its incidence rate drops at about age 16 years. Increased lucidity was found in those attending higher level compared with lower level schools. Taking methodological issues into account, we feel confident to propose a link between the natural occurrence of lucid dreaming and brain maturation.

Functions of sleep architecture and the concept of protective fields.

This article focuses on the function of human sleep architecture and, where it adjoins, on the ultradian rhythm of NREM and REM cycles. In healthy adult human sleep, NREM and REM sleep succeed each other in 90-110 min intervals. This ultradian pattern of NREM/REM succession is cyclical. Sleep architecture relates to the shifting between sleep stages of varying sleep intensity and arousal thresholds. It has been found to follow a typical but non-cyclical pattern throughout the night. In the first third of the night, light sleep alternates predominantly with slow wave sleep (SWS). As sleep progresses, the amount of SWS typically decreases and REM sleep increases. In the last third of the night, light sleep almost exclusively alternates with REM sleep. The author postulates that one function of the non-cyclical succession of sleep stages is the erection and maintenance of a protective field around the sleeper. A protective field is to be understood as an area of relative safety, minimizing the chances for an intruder to enter the field without detection. The frequent shifts between sleep phases with low and high arousal thresholds allow a periodic screening of the sleep environment for danger signals. The relevant literature on sleep architecture, ultradian rhythms and its determinants is reviewed and the implications of the concept of protective fields are discussed.

Information processing and coping style during the wake/sleep transition

Information processing of meaningful events (subjects own name, neutral name and tones) was studied during the transition from wakefulness to sleep in two groups of subjects with opposing information processing styles, Monitors and Blunters. In two experimental sets, subjects were instructed to execute a fingerlift response to a predetermined stimulus type. Subjects own name produced the greatest number of K‐complexes and arousals relative to other name and tones. A task relevance effect was found for arousals but not for K‐complexes. The overall P3 amplitude was larger for Monitors than for Blunters, whereas Blunters showed a larger N350 to target stimuli than Monitors. The findings suggest that higher level processing continues during light sleep and that N350 may reflect a process related to sleep maintenance.

Waking and dreaming: Related but structurally independent. Dream reports of congenitally paraplegic and deaf-mute persons

Models of dream analysis either assume a continuum of waking and dreaming or the existence of two dissociated realities. Both approaches rely on different methodology. Whereas continuity models are based on content analysis, discontinuity models use a structural approach. In our study, we applied both methods to test specific hypotheses about continuity or discontinuity. We contrasted dream reports of congenitally deaf-mute and congenitally paraplegic individuals with those of non-handicapped controls. Continuity theory would predict that either the deficit itself or compensatory experiences would surface in the dream narrative. We found that dream form and content of sensorially limited persons was indifferent from those of non-handicapped controls. Surprisingly, perceptual representations, even of modalities not experienced during waking, were quite common in the dream reports of our handicapped subjects. Results are discussed with respect to feedforward mechanisms and protoconsciousness theory of dreaming.