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Biomedical subjects

C W Erwin

Publications and source records attributed to C W Erwin.

At least 55 records · Page 3Linked to original sources
PubMed1981

Evaluation of a syntactic pattern recognition approach to quantitative electroencephalographic analysis.

This paper reports an experiment designed to evaluate the usefulness of a syntactic pattern recognition approach to quantitative EEG analysis. This approach provides a systematic way of organizing and interpreting spatially and temporally distributed activity in an EEG record. Many automated scoring systems evaluate only background activity, ignoring the significant transient events that may occur in an EEG. In contrast, syntactic methods allow evaluation of background activity in combination with transient events. In this paper, 454 EEGs recorded from a population of renal patients are evaluated using (1) the syntactic approach, and (2) a method based on discriminant analysis. The main finding is that the syntactic approach outperforms the discriminant analysis method when each technique is compared to visual scoring.

Electroencephalography↗
PubMed1981

Effect of ethyl alcohol on visual evoked potentials.

Effects of ethyl alcohol evoked potentials were studied in 12 healthy volunteers. Alcohol significantly reduced the amplitude and prolonged the latency of the N2-P2 components of the centrally derived flash evoked potential. Amplitude attenuation was positively correlated with alcohol doses of 0.8 and 1.2 g/kg. Analysis of subsets of data revealed the amplitude attenuation to be time related and not present in the initial five responses after alcohol. Possible neurochemical mechanisms related to the amplitude attenuation are discussed.

Adult↗
PubMed1981

Effects of ethanol and psychomotor tests on state anxiety: interaction with menstrual cycle in women.

10 non-alcoholic women (ages 20 to 25 yr.) were administered drinks containing ethanol 0.0, 0.5, 0.8, and 1.2 g/kg. They then performed four complex psychomotor tasks. Immediately prior to drinking and after completing the tasks they were given the Spielberger State-Anxiety Inventory. Women were tested both during follicular and the luteal phases of their menstrual cycle. A significant positive correlation was found between increments in anxiety scores and blood ethanol levels in the luteal but not in the follicular phase.

Adult↗
PubMed1980

Hyperventilation induced abnormalities in the electroencephalogram of children with Moyamoya disease.

Two cases of Moyamoya disease in children are presented. The EEG of each child demonstrated minimal abnormalities at rest. However, during 3 min of hyperventilation, the record developed rhythmic delta activity which persisted in excess of 5 min after termination of over breathing. This activity did not respond to glucose administration and was maximal in the areas correlating with the clinical symptoms. It appears to represent a physiologic correlate of an abnormal vascular response to hypocapnia. Although admittedly a non-specific response, the persistence of delta activity easily provoked by hyperventilation, the topographic correspondence to the ultimately demonstrated vascular anomaly, and the lack of response to glucose ingestion represent a combination of factors which, in the appropriate clinical setting, are distinctive and of diagnostic value. Currently, invasive arteriography is required for definitive diagnosis of Moyamoya. Improved selection of children for invasive studies may be accomplished by EEG screening.

Adolescent↗
PubMed1980

Effects of alcohol on psychomotor performance of women: interaction with menstrual cycle.

The effects of alcohol on performance were investigated in 10 ovulating young women. Placebo drink and three doses of alcohol were administered in a random order both during follicular and luteal phases of the menstrual cycle. The women had significantly slower verbal information processing rate and poorer visual detection performance during the follicular than the luteal phase of the menstrual cycle. In psychomotor tasks other than tracking, dose--response relationships of alcohol were different during the different phases of the menstrual cycle.

Adult↗
PubMed1979

Biofeedback control of skin potential level.

This study explored the possibility of using biofeedback to arrest spontaneous declines in tonic electrodermal levels. For 3 days, 10 subjects (S) received 20 minutes of training in increasing skin potential level (SPL) negativity (arrested declines), followed by 20 minutes of training in decreasing SPL negativity (facilitating declines), with reverse order for half of the Ss. Simultaneous analogue and binary feedback of SPL were used. Training in the direction of SPL increases resulted in arrest of spontaneous declines in SPL negativity but did not result in large-magnitude increases above baseline. Training in the direction of SPL decreases facilitated declines in SPL. The absolute mean difference between the increase condition and the decrease condition on the 3rd day was 8.28 mV. Correlations suggested that considerable intraindividual variability may have been independently related to the Locus of Control personality dimension and to a Law of Initial Values limitation on SPL change. It was concluded that SPL was controllable to the extent of facilitating or arresting spontaneous declines.

Action Potentials↗
PubMed1978

Effect of alcohol consumption on state anxiety changes in male and female nonalcoholics.

Ten male and 10 female nonalcoholic college students were given drinks having alcohol levels of 0, 0.5, 0.8, and 1.2 g/kg. They were then given four complex psychomotor tests, immediately before and after which they were given the Spielberger State Anxiety Inventory, and asked to rate their performance on a five-point scale. Mean anxiety change scores were -.90, .75, 4.75, and 5.55 for the four alcohol doses, respectively. There was no significant correlation between anxiety change and actual performance on the visual vigilance task, but for males there was a significant correlation between anxiety change and perceived level of impairment.

Alcohol Drinking↗
PubMed1976

Evoked potential analysis: on-line signal optimization using a mini-computer.

An automated computer-based system is described for the analysis of evoked potentials. All procedures are carried out in real-time A small computer performs the following functions; timing of random stimulus presentation, rejection of artifact contaminated responses, collection of digital data, computation of averaged evoked responses, computation of the Wiener filter, storage of the filtered and unfiltered averages and display of the resultant averages. The Wiener filter as described by Walter (1969) and Doyle (1975) is used to improve the estimate of the evoked potential by discriminating against frequencies likely to be contaminated with noise. The defining equation for the Wiener filter states that information at any frequency is to be weighted by the ratio of the power known to be in the signal (response) at that frequency over the corresponding power known to be in both the signal (response) and the noise (background EEG) at the same frequency. The technique requires the computation of the Fourier transform for each response in order to produce the power spectra necessary for the Wiener filter. Earlier reports dealing with this technique have usee large computers to analyze the evoked potential data off-line. The system described here allows for greater routine utilization of this powerful technique and the concomitant automated rejection of artifact contaminated responses. Highly improved estimates of the evoked potential are resultant using a minimal number of stimuli.

Computers↗