Biomedical subjects

G Delapierre

Publications and source records attributed to G Delapierre.

5 recordsLinked to original sources

PubMed1997

Normal and pathological changes in alpha rhythms.

Normal alpha rhythm begins to appear at three months. It was possible to observe successively, the rhythmicity, visual reactivity, occipital topography, and at the end of the first year, the first bursts of 7-8 Hz waves. Evolution of alpha was not linear with the age. Alpha frequency acceleration was important before the age of 11 years. In adults it decreased from 20 to 55, then there was a tendency to increase with aging. Amplitude was highest at 11-12 years, then its tendency was to decrease until 40, and to increase later. In pathology, for instance, alpha could be observed too early in newborn and infants with malformations, in children, in some psychiatric diseases, in adults and old people, alpha was replaced by theta waves in dementia: it seemed to be a very reliable sign, at the beginning of the disease.

Adolescent↗

PubMed1992

[Automatic analysis of sleep-wake states during the first year of life].

Automatic analysis on infant sleep tracing was first considered as an aid to the rapid construction of hypnograms. It has long been thought more complicated than in adults, because of the significant changes in electrogenesis during the first year of life, resulting in difficulty to adapt to the criteria of Rechtschaffen and Kales (1968), even if modified, or to those of Anders et al (1971). In fact, these studies have shown that automatic analysis of sleep EEG tracings permit an easier analysis of the changes in electrogenesis according to subject age, sleep stage and time of night. Moreover, automatic analysis of parameters which change with the sleep-wake stages shows the continuity of these changes, and therefore the somewhat arbitrary nature of conventional hypnogram classification. The mathematical treatment of this information facilitates their visualisation, and permits a better analysis of circadian and ultradian variations that could scarcely be formalized by classical hypnogram analysis. In the study of maturation occurring during the first months of life, automatic signal processing will require adaptation that will lead to new forms of reasoning.

Circadian Rhythm↗

PubMed1991

Effects of stimulus intensity increase on short-latency somatosensory evoked potentials: application of polynomial curvature coefficients.

We assessed the influence of increasing stimulus intensity from motor threshold to pain threshold on short latency somatosensory evoked potentials recorded over the parietal and frontal scalp in 14 subjects during median nerve stimulation at the wrist. We used the curvature polynomial coefficient to evaluate alterations of the main components. The N20 and P27 curvature coefficients are not modified. The change of the N30 curvature coefficient is the result of shortened P45 latency. The increase of N60 curvature coefficient shows a great interindividual variability, probably due to a central amplification and synchronization or to involvement of nerve fibres with different excitability.

Adult↗

PubMed1988

Sleep organization in children at risk for sudden infant death syndrome.

The organization of sleep was studied in four groups of 6-month-old babies: monitored near-miss babies (NM), monitored siblings (HR), nonmonitored siblings (LR), and siblings considered at low risk but monitored because of marked parental anxiety (PA). It was studied using the method of cumulated occurrences and orthogonal polynomial fitting introduced for the analysis of sleep by Gaillard and Martinoli in 1976. No monitoring effect was found. We also found no difference between the groups when the usual sleep scores were used. However, differences were found with the polynomial adjustment method: there was more quiet sleep stage 3 in NM than in any other group. There was less waking state and more paradoxical sleep at the end of the night in PA and NM than in HR or LR babies. This suggests that the differences may not be related so much to real risk as to parental comportment.

Cerebral Cortex↗

PubMed1986

[Development of a criterion for the automatic detection of sleep spindles in the infant].

The authors present a model for automatic detection of spindles during the different sleep stages. Baseline spindle-free EEG was modelized on a 10 sec recording using an autoregressive model. Spindles were thereafter detected using the quadratic error from this baseline model on successive 1 sec periods. This automatic detection is in a 95.7% agreement with visual analysis.

Computers↗