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Biomedical subjects

L Collet

Publications and source records attributed to L Collet.

At least 145 records · Page 8Linked to original sources
PubMed1990

Age-related changes in evoked otoacoustic emissions.

Outer hair cells of the organ of Corti play an important part in the genesis of evoked otoacoustic emissions (EOAEs), which are related to cochlear biomechanics. The aim of this study was to investigate the age factor in relation to EOAEs in 166 ears of subjects between 6 weeks and 83 years of age. The results show that when age increases, the presence of EOAEs by age group and the frequency peak in spectral analysis decrease, and EOAE threshold increases. Thus, there is an effect of age upon EOAEs, and it seems linked with alteration of cochlear biomechanics and/or hair cell loss. Such an effect has to be taken into consideration when EOAEs are used in clinical applications, and limits the use of EOAEs in older subjects.

Adolescent↗
PubMed1990

Minnesota Multiphasic Personality Inventory in tinnitus disorders.

The relation between Minnesota Multiphasic Personality Inventory (MMPI) and tinnitus was examined in 100 subjects with tinnitus disorders. The overall profile of tinnitus sufferers on the MMPI was normal. Higher scores on the depression scale were obtained in males. High hypochondria scores were related to long duration of tinnitus. High psychoasthenia scores were associated with hearing loss. Despite an analogy previously described between chronic pain and tinnitus, the psychometric parameters of tinnitus and of headaches are quite different.

Adult↗
PubMed1990

[Effect of attention on audition. Contribution of the study of the olivocochlear efferent system].

It is possible by studying the Evoked Otoacoustic Emissions (EOAEs) to detect an effect of selective attention on the cochlea. The authors present the main data of the literature and the results of their works. They show an effect of visual attention as well as auditory attention on the EOAEs. This effect is not the same whether attention is visual or auditory. There is a result of selective attention as early as the cochlear level.

Attention↗
PubMed1989

Evoked otoacoustic emissions and sensorineural hearing loss.

Following Kemp's original studies, several others have confirmed the existence of otoacoustic emissions. Their clinical relevance remains, however, to be clarified. The various published studies have concerned small series. This study sought to specify otoacoustic emission characteristics in relation to sensorineural hearing loss (148 ears of 76 subjects). The results show that the presence of otoacoustic emissions drops as a function of hearing loss and that there is a highly statistically significant correlation between otoacoustic emission threshold and hearing loss at the 1000-Hz frequency. Otoacoustic emissions are never found when hearing loss at 1000 Hz exceeds 40 dB hearing level and when the mean audiometric hearing loss (at 500, 1000, 2000, and 4000 Hz) exceeds 45 dB hearing level. The main practical conclusion is that otoacoustic emission presence indicates middle frequency functional integrity of the outer hair cells of Corti's organ. Absence of otoacoustic emissions is harder to interpret.

Adolescent↗
PubMed1989

Are click-evoked BAEPs useful in case of neonate hyperbilirubinemia?

There is still controversy about the usefulness of click-evoked brainstem auditory evoked potentials (BAEPs) for the investigation of neonatal hyperbilirubinemia. The present work concerns the study of click-evoked BAEP responses in a population of 72 hyperbilirubinemic children (conceptional age between 33 and 42 weeks). Their bilirubinemia rates were between 219 and 600 mumol/l. The waves I, III and V were always present, and click BAEP thresholds were normal in all subjects. Latency anomalies were found only for 8 of the 72 subjects. The comparison of subjects having the higher (greater than 307 mumol/l) bilirubin levels with the group having the lower ones failed to show any significant differences for the I-III and I-V intervals. The influence of prematurity in BAEP alteration has not been demonstrated in this study. These data show, on the one hand, normal click-BAEP thresholds but, on the other hand, alterations of central conduction time in some hyperbilirubinemic newborns. It seems that other factors than hyperbilirubinemia might be operating.

Acoustic Stimulation↗
PubMed1989

Is there a difference between extrauterine and intrauterine maturation on BAEP?

A difference between extrauterine and intrauterine maturation on BAEP has not been established, remaining a subject of controversy. The present study involved 76 children, aged between 36 and 37 weeks (conceptional age), with an extrauterine life duration of equal to or less than 2 weeks (N = 46) or more than 2 weeks (N = 30). The latencies for waves III and V, and the I-III and I-V intervals were significantly shorter for the neonates with a greater extrauterine life duration. An explanation for this finding is discussed: the head size is significantly smaller in the group with a greater extrauterine life duration. An influence of extrauterine life duration on BAEP is thus shown, but it seems to reflect the anatomical consideration and not to peripheral auditory system maturation.

Aging↗
PubMed1989

Validity of bone conduction stimulated ABR, MLR and otoacoustic emissions.

The present study considers the validity of objective auditory investigation via bone conduction. Auditory Brainstem Responses (ABR) and Middle Latency Responses (MLR) were recorded in response to a bone vibrator stimulation with or without continuous bilateral air white noise masking. In all cases, such masking was found to result in an absence of recorded evoked potentials. It shows that under bone-conducted stimulation the evoked potential recorded is purely auditory, with no additional mechanical somatosensory component. In a further study, the feasibility of oto-acoustic emissions (OAEs) via bone conduction is demonstrated. These OAEs are, for a given subject, comparable to those found for air-transmission stimulation.

Adolescent↗
PubMed1989

[Effect of age on otoacoustic emissions].

The aim of this work was to study the age-effect on otoacoustic emissions (OAE) (93 subjects, 166 ears). The results show that when age increases the presence of OAE by age group decreases as well as the frequency peak in spectral analysis. The OAE threshold increases with age. So there is an effect of age upon OAE. The effect seems linked with alteration hair cell loss and/or alteration of cochlear biomechanics.

Acoustics↗
PubMed1988

Effect of sleep on middle latency response (MLR) in infants.

Auditory middle latency responses (MLR), with two click-rates (1.3 Hz, 8.9 Hz) and simultaneous polygraphic recording with EEG, EOG, EMG, ECG and respiratory rhythm have been recorded in 16, 6 or 7 week old infants to study the effect of sleep on the amplitudes of MLR. For both click-rates, response amplitude depended upon waking and sleep states, the Na-Pa complex being always greater during waking states. It is of very low amplitude during quiet and active sleep but significantly lower in quiet sleep. In some infants it disappears entirely in quiet sleep. MLRs have been said to be hard to reproduce in infants. Our results would suggest that this is due to a strong alertness effect on MLRs in infants.

Age Factors↗
PubMed1988

Effect of brainstem auditory evoked potential stimulus intensity variations in neonates of small for gestational age.

The latencies of brainstem auditory evoked potentials were compared first in 25 small for gestational age (SGA) neonates (conceptional age less than 43 weeks) matched with 25 appropriate for gestational age (AGA) neonates, and then in the 8 younger SGA neonates (less than 37 weeks) matched with 8 AGA neonates. In this last subgroup the results showed that the I-V interval is shorter in SGA than in AGA neonates, as previously described. This shortening effect is essentially linked to a lengthening of wave I. So the results are discussed in terms of immaturity of the basal end of the cochlea, rather than of precocious development of the auditory brainstem neural function in SGA infants.

Brain Stem↗
PubMed1988

Cerebral evoked potentials after endorectal mechanical stimulation in humans.

Although numerous clinical studies have proved that impaired rectal sensation is a major factor in fecal continence dysfunctions, objective studies in this field are still lacking. To provide information on normal rectal afferents, a study of cerebral potentials evoked by mechanical stimulation of the rectal wall was carried out in 10 healthy volunteers (5 male, 5 female; age, 33-52 yr). The stimulating device consisted of a rectal balloon rhythmically inflated and deflated by means of an animal breathing ventilator. Recordings were obtained 2 cm behind the vertex (C'z, International system 10-20). The responses were averaged from 300 to 800 sweeps. The average was triggered either on inflation ("on effect") or on deflation ("off effect"). Inflation volume and pressure were adjusted to induce a clear but not painful pulsing sensation. Reproducible responses were recorded by both on and off effects. The evoked potentials were polyphasic with a succession of positive and negative waves (peak latencies between 78 and 310 ms). The shape of the response (morphology, latency, and amplitude) was perfectly reproducible in the same subject. With regard to intrasubject reproducibility, variability was displayed: only the early waves (latency less than 100 ms) were perfectly reproducible; late waves exhibited variable latency and morphology. The present findings are the first demonstration of the possibility of recording an evoked potential on the scalp after a mechanical stimulation of the rectum.

Adult↗
PubMed1988

Effect of stimulus intensity variation on brainstem auditory evoked potentials. Maturational changes.

The effect of stimulus intensity variation on brainstem auditory evoked potentials in premature and full-term neonates has been studied in two experiments. They show that the effects are different according to age and to waves. The variation of latencies is greater the younger the child and it is clearer with wave I than waves III and V. The findings are discussed in terms of the maturation of the basal part of the cochlea.

Acoustic Stimulation↗
PubMed1988

Are BAEP and MLR suited for the study of a hypothetic peripheral selective attention effect?

BAEPs and MLRs for clicks were recorded for situations of selective attention, ignoring stimuli and mental arithmetic. Certain studies have shown no attention effect on these evoked potentials, but several others have shown reduction of latency and increase in amplitude under selective attention. Our study finds no significant difference in latency or amplitude for BAEP waves I, III and V, nor in Na or Pa latency or NaPa amplitude for MLR. What we know anatomically of cochlear innervation, particularly efferent innervation, would seem to show that efferent projection is basically onto the outer hair cells which have been little if at all explored by BAEPs and MLRs under standard conditions. A study of outer hair cell functioning under various attention situations would be needed in order to find any peripheral selective attention effect.

Acoustic Stimulation↗
PubMed1988

Relationships between verbal intelligence, educational level and reconstitution of linguistic messages in schizophrenia.

The authors studied the influence of educational and verbal intelligence levels on a linguistic messages reconstitution test with schizophrenics. The two studies undertaken showed significantly lower sentence completion test scores for schizophrenics than for control subjects matched for verbal intelligence, educational level, age and sex. There appears to be an alteration of the cognitive processes underlying the processing and reconstitution of simple messages. This alteration is neither affected by educational level nor verbal intelligence level.

Adult↗
PubMed1987

Psychological factors affecting outcome of treatment after transcutaneous electrotherapy for persistent tinnitus.

We used transcutaneous electrotherapy to treat 27 patients with persistent tinnitus. Each patient was tested with the short form of the Minnesota Multiphasic Personality Index test (MMPI) prior to the commencement of treatment. The "unimproved" group of patients (n = 15) showed higher pretreatment scores for depression (P less than 0.05), psychasthenia (P less than 0.05) and schizophrenia (P less than 0.02). Our findings indicate that patients having significantly pathological scores on at least one of these three scales will fail to benefit from treatment. These findings also show that there appear to be psychological prognostic factors that can be used to evaluate patients receiving transcutaneous electrotherapy for persistent tinnitus.

Adult↗
PubMed1987

Hemispheric lateralization of emotions: absence of electrophysiological arguments.

EEG lateralization was examined during happy and sad emotional expression in 24 subjects. Happy and sad emotional states were induced by asking subjects to mentally review previously shown film-sequences. Our results failed to replicate those of previous studies, in that they showed no frontal alpha lateralization as a function of emotion. The authors discuss the literature and suggest caution before asserting the existence of electrophysiological arguments in favor lateralization of emotions in humans.

Adolescent↗