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Biomedical subjects

M Elton

Publications and source records attributed to M Elton.

At least 19 recordsLinked to original sources
PubMed2000

To err is human.

Explore the source record for details and available documents.

Brain↗
PubMed2000

The mismatch negativity during natural sleep: intensity deviants.

Auditory event-related potentials (ERPs) were recorded from 7 subjects who slept for a single night in the laboratory. An 'oddball' sequence of brief tone pips, differing in intensity, was used. Frequently occurring 70 dB 'standards' were presented with infrequent 80 dB intensity increment deviants and 60 dB intensity decrement deviants. The probability of each deviant was 0.1. Stimuli were presented in a random sequence every 600 ms while subjects were awake but inattentive and during stages 2 and REM of sleep. During wakefulness, the intensity increments elicited a broad fronto-central negativity with two discernable peaks. The first, peaking at approximately 120 ms, showed a polarity inversion at the mastoid and likely represented a summation of the N1 wave and the mismatch negativity (MMN). The second, peaking at approximately 330 ms, may have reflected an enhanced N2b component. In REM sleep, the increment deviants elicited a small amplitude 100-200 ms negativity but its amplitude was not significantly larger than the baseline level. It was followed by a larger and significant 300-450 ms negativity but this was considered too delayed to represent the MMN. The decrement deviants elicited a small amplitude, but statistically non-significant, MMN-like wave during both wakefulness and in REM sleep. A MMN-like wave was absent in stage 2 sleep.

Acoustic Stimulation↗
PubMed1998

Functional correlates of callosal atrophy in relapsing-remitting multiple sclerosis patients. A preliminary MRI study.

In multiple sclerosis (MS), periventricular lesions produce atrophy of the corpus callosum (CC), as evidenced by magnetic resonance imaging (MRI). We investigated whether CC atrophy in relapsing-remitting MS patients is related to functional deficits. We compared 14 mildly disabled (mean Expanded Disability Status Scale score 2.7) relapsing-remitting MS patients with 14 age- und sex-matched controls. CC size was determined using sagittal T1-weighted MRI. The function of the CC was studied using a neuropsychological battery and neurophysiological evaluation based on visual stimulation using a divided visual field paradigm. The total area of the CC in patients (mean 5.3 cm2) was significantly (P = 0.002) smaller than in controls (mean 6.6 cm2). Patients showed left ear extinction using the dichotic listening test and impaired name learning, which was correlated with atrophy of the splenium. There were no differences in interhemispheric transfer time between patients and controls. Marked atrophy of the CC can be encountered in relapsing-remitting MS patients. The associated cerebral disconnection correlated with atrophy of expected regions of the CC, thus supporting topographical organization.

Adult↗
PubMed1997

Event-related potentials to tones in the absence and presence of sleep spindles.

The present study focused on event-related potentials to tones in the presence and absence of sleep spindles. Six undergraduates were studied throughout an experimental night, following an adaptation session. The event-related potentials to tone stimuli were averaged for each subject. Separate averages were determined for trials on which no sleep spindle occurred 2 s before or after a tone and trials in which spindle activity was present. Both voltage distribution maps and multivariate analysis of the waveforms produced significant differences between these conditions, which could be seen as a higher initial positive component and sustained positively over the averaged epoch in the presence of spindles. Spectral analysis indicated that this result could not solely be ascribed to residual sigma activity in the spindle-present average. The results may provide insights into the functional role of sleep spindles in humans in addition to that suggested by a neurophysiological model of inhibition.

Adult↗
PubMed1996

Prevalence of mental illness in Germany and the United States. Comparison of the Upper Bavarian Study and the Epidemiologic Catchment Area Program.

The objective of the present study was to compare data on the prevalence of mental illness in Germany and the United States. For this purpose, data from the Upper Bavarian Study (UBS) and the Epidemiologic Catchment Area (ECA) are presented and compared. In both studies, personal interviews were administered to a sample of community residents. The UBS sample consisted of 1,847 persons aged > or = 18 years, and the ECA study consisted of 24,371 household members aged > or = 18 years in five sites; 1,876 persons from the ECA sample lived in rural sites, and they were used for comparison with the (rural) UBS sample. The diagnostic classification (according to DSM-III) obtained by clinical interviewers in the UBS and by lay interviewers in the ECA was used. The total 6-month prevalence for any axis I Diagnostic Interview Schedule mental disorder (corrected for sample stratifications and adjusted for age) was 18.5% in the (rural) UBS, 18.0% in the total ECA sample (five sites), and 13.4% in the rural sites of the ECA. High morbidity rates for substance use disorders (UBS, 5.8%; ECA rural sites, 3.4%) and affective disorders (UBS, 6.8%; ECA rural sites, 4.1%) were observed in both studies. The 6-month prevalence rates for alcohol use disorders (3.1% considered marked or severe) were 5.1% in the UBS and 2.9% in the ECA rural sites. Concerning anxiety disorders (UBS, 1.6%; ECA rural sites, 6.7%) there was a substantial difference between the studies, which mainly resulted from a higher prevalence of phobia in the ECA program. There were higher rates of dysthymia (3.8% considered marked or severe) in the UBS (5.4%) than in the ECA rural sites (2.6%), whereas the rate of major depression was somewhat lower in UBS (1.4%) as compared with the ECA rural sites (2.4%). Alcohol use disorder was the most frequent category of mental disorder for men in both studies; for women, affective disorder and phobia (in the ECA) were the most frequent categories. Despite differences in methodology concerning sampling, instruments, and case identification the similarities between the results of the two studies were considerable.

Adolescent↗
PubMed1995

Auditory event-related potentials to deviant stimuli during drowsiness and stage 2 sleep.

Twelve subjects were tested using a 3-tone auditory oddball paradigm consisting of a standard 1000 Hz tone (P = 80%) and two deviants, namely, a 1200 Hz tone and a 2000 Hz tone (both P = 10%). Testing took place in 3 conditions: (1) attend, in which the subject had to count one of the deviant tones; (2) ignore, in which the subject read a book; and (3) sleep, in which the subject was encouraged to go to sleep during presentation of the tones. In the awake conditions stimulus deviance elicited mismatch negativity (MMN) and P3. During drowsiness, no separate mismatch negativity (MMN) could be detected, but the 2000 Hz tone evoked a broad fronto-central early negative deflection, suggesting an overlap of N1 and MMN. In the same condition, P210, N330 and P430 appeared, all being sensitive to magnitude of deviance. During stage 2, the P210, N330 and P430 amplitudes increased, most notably to the large deviant. These data indicate that differential processing of auditory inputs is maintained during drowsiness and stage 2 sleep, but do not support the notion that MMN or P3 activity comparable to the waking state occurs to oddball stimuli during this stage. It is hypothesised that during light sleep, scanning of the environment is performed by a different system than in the awake state and that during drowsiness a gradual switch between these two systems takes place.

Acoustic Stimulation↗
PubMed1995

Mortality risk and mental disorders: longitudinal results from the Upper Bavarian Study.

The object of the study was the assessment of the mortality risk for persons with a mental disorder in an unselected representative community sample assessed longitudinally. Subjects from a rural area in Upper Bavaria (Germany) participated in semi-structured interviews conducted by research physicians in the 1970s (first assessment) and death-certificate diagnoses were obtained after an interval up to 13 years later. The sample consisted of 1668 community residents aged 15 years and over. Cox regression estimates resulted in an odds ratio of 1.35 (confidence interval 1.01 to 1.81) for persons with a mental disorder classified as marked to very severe. The odds ratio increased with increasing severity of mental illness from 1.04 from mild disorders, 1.30 for marked disorders, to 1.64 for severe or very severe disorders. The relative risk (odds ratio) for persons with a mental disorder only and no somatic disorder was 1.22, for persons with only a somatic disorder 2.00, and for those with both a mental and somatic disorder 2.13. The presence of somatic illness was responsible for most of the excess mortality. Somatic disorders associated with excess mortality in mental disorders were diseases of the nervous system or sensory organs, diseases of the circulatory system, diseases of the gastrointestinal tract, and diseases of the skeleton, muscles and connective tissue (ICD-8). Thus, while mental illness alone had a limited effect on excess mortality, comorbidity with certain somatic disorders had a significant effect.

Adolescent↗
PubMed1993

Effects on mortality of alcohol consumption, smoking, physical activity, and close personal relationships.

The study analyses the risks of mortality associated with alcohol consumption and smoking, as well as possible counteracting effects of physical activity and social support through close personal relationships. Data are based on the Upper Bavarian Study, a longitudinal epidemiological study of a representative community sample (n = 1668) in a rural area. Extensive semistructured psychiatric interviews by research physicians were conducted between 1975 and 1977 (n = 1536). Thirteen years after psychiatric assessment, information was obtained from the community register concerning death in the interval, data of death and cause of death according to ICD 9. This information could be ascertained for 93.1% (n = 1430) of those who had been interviewed, thus providing a good basis for generalizing the findings. Results indicate that alcohol intake and cigarette smoking increased mortality while physical activity and the availability of a steady partner had protective effects. There were no interactive effects between the four variables studied, except for a dramatically increased risk for women drinking more than 20 ml of pure alcohol a day and reporting no physical exercise at wave one assessment. The relative risks of alcohol intake and smoking, and the counteracting effects of physical activity and partnership, are exemplified in the cases of a 40-year-old female and a 40-year-old male. Specific analyses of the relationship between alcohol consumption, smoking, physical exercise and personal relationships, on the one hand, and, on the other, different causes of death, are presented.

Adolescent↗
PubMed1993

Symposium: Dream research methodology: Methodological issues affecting the collection of dreams.

This article focuses attention on the perennial issue of home versus laboratory recording situations for the garnering of dream reports. Studies into the experimental control over procedures for both waking and interviewing are reviewed. Against this background, an experiment into the relationship between REM/NREM sleep and visual imagery is reported. We found that, having corrected for total word count, visual imagery still made an independent contribution to REM reports. This finding is evaluated in the light of differential cognitive mechanisms underlying dream formation during sleep.

Journal Article↗
PubMed1993

EEG spectral power analysis of phasic and tonic REM sleep in young and older male subjects.

EEG spectral power was studied during periods of rapid eye movements (REMs) and tonic intervals in REM sleep of 7 young and 7 older male subjects. Significant symmetrical decreases in alpha and beta1 power at central and occipital sites, concurrent with an increase in frontal theta power, were observed during the production of REMs. The former findings are discussed as sleep analogues to changes in alpha and beta1 during waking, showing increased information processing and behavioural activation, and that of theta is tentatively presented as reflecting an increase in afferent thresholds. Independent of the phasic-tonic REM distinction, total EEG power markedly decreased as a function of time of night and did not interact with age. Significant age differences in the overall spectral composition of the EEG were obtained, namely, a lower level of delta power and a relative shift towards more power in frequencies above 12 Hz for the older group. Further, older subjects also demonstrated a more uniform topographical distribution of alpha and sigma power.

Journal Article↗
PubMed1992

Removal of ocular artifacts from the REM sleep EEG.

The present report concerns the first study in which electrooculographic (EOG) contamination of electroencephalographic (EEG) recordings in rapid eye movement (REM) sleep is systematically investigated. Contamination of REM sleep EEG recordings in six subjects was evaluated in the frequency domain. REM-active and REM-quiet series were obtained for each subject. Transfer coefficients and power spectra of EOG and EEG indicated that (a) increases in transfer coefficients beyond 4.5 Hz are brought about by residual EEG in the EOG, and (b) EOG-EEG contamination in the delta band is most pronounced in frontal, intermediate in central and negligible in occipital leads. It was found that correction of the REM-active series resulted in significant (c) reductions in power, (d) increases in interhemispheric coherences and (e) reductions in degree of lateral asymmetry. These effects were largest for frontal leads, but still marked for central ones. The results are discussed in the light of previous findings concerning models of hemispheric functioning during REM sleep.

Adult↗
PubMed1990

Overall functioning and criteria of progress in rehabilitation of alcohol abusers: longitudinal analyses of changes.

The aim was to compare alcohol consumption and vocational adjustment as criteria of rehabilitation progress of alcoholics, with regard to links to concomitant changes in functioning in other life areas. Thirty-four advanced alcohol abusers in rehabilitation were examined twice with an interval of 2 years between each examination. Change scores in alcohol consumption and work capacity were correlated with change scores in social network, activities, life-satisfaction, psychological well-being, psychiatric symptoms, and biomedical functioning. Improved drinking habits were connected with some changes in overall functioning, however not solely in a favorable direction. Negative mood changes were especially noteworthy. Improvements in vocational adjustment, on the other hand, appeared to be somewhat more unequivocally and encompassingly associated with amelioration in the wider range of functioning. The results indicate that drinking measures alone are not sufficient indicators of progress in rehabilitation and underscores the need of more global criteria of general adjustment.

Activities of Daily Living↗