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Biomedical subjects

H Bastuji

Publications and source records attributed to H Bastuji.

At least 19 recordsLinked to original sources
PubMed2000

Functional dissociation of the early and late portions of human K-complexes.

We analyzed K-complexes (KCs) evoked during sleep stage II by the subject's own name and by other names. KCs were composed either of four consecutive waves (full KCs, N2-P3-N3-P4) or of the two first components only (N2-P3). The amplitude of the late phase of KCs (N3-P4) was identical to all stimuli; conversely, own names enhanced selectively the N2-P3 waves, whether they were or not part of a full KC. Two independent phenomena appear to coexist during a full KC, one being connected to the physical characteristics of the stimulus (N3-P4) and the other to its intrinsic significance. This latter may appear either within a full KC or in isolation, and in this case it is reminiscent of the N200-P300 complex observed in wakefulness.

Acoustic Stimulation↗
PubMed1999

Evoked potentials as a tool for the investigation of human sleep.

This review summarizes studies of evoked potentials (EPs) applied to the investigation of human sleep and of sleep disorders. The first part is devoted to studies dealing with the nature, mechanisms and extent of information processing during sleep. EP studies suggest that the brain's ability to detect salient stimuli persists during even the deepest sleep stages, while discrimination of the stimulus' intrinsic significance and/or semantic content may persist only in stage II and paradoxical sleep (PS). Deviance detection in non-rapid eye movement (NREM) sleep is reflected by amplitude recovery of K-complexes elicited by stimulations that differ from the background. The evoked K-complex appears to be formed by two functionally different modules. The first may be related to the discrimination of relevant information. The second appears more sensitive to stimulus salience than to its intrinsic significance. In PS, the EP signs of stimulus discrimination are similar to those observed during waking. Thus, if the possibilities of information processing are fairly similar during stage II and PS, their respective neural mechanisms are not the same, as judged by their electrophysiological counterparts. The second part of the paper reviews clinical application of EPs to the study of sleep/wake disorders. While early potentials are of little use for diagnosis of sleep disorders, the cognitive P300 may help to quantify cognitive slowing and pathological sleepiness. However, intersubject variability restrains the use of these techniques in individual patients. A promising approach is the utilization of late responses to the study of sleep inertia with the use of "forced awakening" recording paradigms.

Journal Article↗
PubMed1999

A differential brain response to the subject's own name persists during sleep.

METHODS: Auditory evoked potentials (AEPs) to the subject's own name and to seven other first names were recorded in ten normal adults during wakefulness, in both passive listening and active detection conditions, and during sleep stage II (SII) and paradoxical sleep (PS). All stimuli were disyllabic, equiprobable and presented in random order. RESULTS: During wakefulness, a parietal positive 'P3' component, peaking at about 500 ms, probably equivalent to the endogenous P300 wave, was enhanced in response to the subject's own name, even in the passive condition. During SII, K-complexes (KCs) were evoked by all first names and were formed by two biphasic consecutive waveforms. While the amplitude of the late complex (N3/P4) was identical for both types of stimuli, the early portion of the KC (N2/P3), and notably the positive wave 'SII-P3' at about 600 ms, was selectively enhanced after the subject's own name. This supports the hypothesis that at least two distinct neuronal systems are activated in parallel in response to auditory stimuli during SII, one reflecting the detection of stimulus' salience and the other the processing of its intrinsic relevance. During PS, the AEP morphology was comparable to that observed in wakefulness. Notably, a posterior 'PS-P3' wave appeared exclusively in response to own names at about 550 ms, and was considered as an equivalent of the waking P300. CONCLUSIONS: These results suggest that the sleeping brain, during SII and PS, elicits a differential cognitive response to the presentation of the subject's own name, comparable to that occurring during wakefulness, and therefore that the sleeping brain is able to detect and categorize some particular aspects of stimulus significance.

Acoustic Stimulation↗
PubMed1999

Sleep/wake abnormalities in patients with periodic leg movements during sleep: factor analysis on data from 24-h ambulatory polygraphy.

Periodic Leg Movements (PLM) in sleep occur in a wide variety of sleep/wake disorders but their relationship with sleep disturbance, and notably with the concomitant existence of a 'restless legs' syndrome (RLS) remains unclear. We performed 24-h ambulatory polygraphy in a population of 54 consecutive, unselected patients with PLMs (Coleman's index greater than 5/h) who complained of different sleep disorders. A Principal Component Analysis (PCA) was conducted on seven variables from the sample, namely PLM index, patient's age, sleep stage changes per hour, sleep depth index (SWS+PS/TST), diurnal sleep time, number of awakenings exceeding 2 min and presence of a RLS. PCA yielded four independent factors. The PLM index and the changes of sleep stage clustered in a single factor, linking therefore sleep fragmentation to the frequency of PLMs. The second factor appeared to reflect a circadian sleep/wake disorder, combining diurnal sleep time with the number of long night awakenings. The third factor was mainly loaded by the patients' age and the sleep depth index, thus reflecting a well known relationship. Finally, the variable reflecting the existence of a RLS appeared isolated in a single factor, independent from the three previously described. These results confirm and extend the link between PLMs and sleep fragmentation, as well as the recently described dissociation between PLMs and diurnal somnolence. On the other hand, our analysis suggests that in PLM patients the concomitant existence of a RLS is not related to the frequency of occurrence of PLMs, at least when these latter are quantified independently of their arousal index.

Adult↗
PubMed1998

Effect of modafinil on plasma melatonin, cortisol and growth hormone rhythms, rectal temperature and performance in healthy subjects during a 36 h sleep deprivation.

Modafinil is an alerting substance which has been used successfully to treat narcolepsy. Nothing is known about its effect on hormone secretions. For this purpose, eight healthy young men were enrolled in a double blind trial to test the effects of modafinil on daily plasma melatonin, cortisol and growth hormone (GH) rhythms. Blood was sampled for hormone assays, every hour during the daytime and every 30 min during the nighttime. In addition, rectal temperature and mental performances were determined during the study which comprised 3 sessions, two weeks apart: a 24 h control session including a night with sleep (S1) and two 48 h sessions S2 and S3 with a sleep-deprived night (N1) followed by a recovery night (N2). Modafinil (300 mg x 2) or placebo were randomly attributed during N1 at 22 h and 8 h. As expected, performance was improved after modafinil administration and body temperature was maintained or increased. Plasma melatonin and cortisol profiles were similar after modafinil and placebo administration. The levels observed during the recovery and the control nights (N2) displayed no difference. For GH, during both sleep deprived nights, secretion was dramatically reduced compared with the control one, although the number of secretory episodes was unchanged. These data show that the alerting property of modafinil is not related to an alteration of hormone profiles and suggest that the acute modafinil administration is devoid of short-term side-effects.

Adult↗
PubMed1997

Sleep ontogenesis revisited: a longitudinal 24-hour home polygraphic study on 15 normal infants during the first two years of life.

The sleep organization of 15 normal infants (seven boys, eight girls) was studied at their homes during six 24-hour periods, i.e. at 3, 6, 9, 12, 18, and 24 months of age, using the Oxford Medical System. Sleep states and stages were scored visually at 30-second intervals, according to Rechtschaffen and Kales' criteria, adapted for children by Guilleminault. All sleep parameters were analyzed for the entire 24-hour period, i.e. during both the nocturnal and the diurnal part of the nycthemere. The results showed a continuous decrease in total sleep time, rapid eye movement (REM) sleep, and indeterminate sleep, and also an increase in waking time, quiet sleep, and stages 1 and 2 sleep. Except for slow-wave sleep, which remained very stable for the different ages, analysis of variance applied to the data showed clear age and day-night effects on sleep ontogenesis. Modifications with age were more precocious and more pronounced for the diurnal part of the nycthemere, especially as regards REM sleep. For the nocturnal part, there was a significant increase in sleep efficiency and in the length of the REM period after 12 months of age, while total sleep duration and number of awakenings decreased. In addition to normative data for clinical use, this study provides three new interesting results related to the maturation of sleep mechanisms and functions: 1) the high stability of the percentage of slow-wave sleep along these 2 years, 2) the presence (from 12 months of age) of a stage 2/REM sleep ratio equal to one, and a sleep change occuring earlier, during the diurnal rather than the nocturnal part of the nycthemere. The first two points could be regarded as indexes of sleep maturation reflecting developmental and neurophysiological changes in central nervous system structures. The third point underlines the importance of the circadian rhythm and the concept of "experience" in the maturation of sleep.

Child, Preschool↗
PubMed1995

Brain processing of stimulus deviance during slow-wave and paradoxical sleep: a study of human auditory evoked responses using the oddball paradigm.

Auditory evoked potentials (AEPs) to frequent (90%) and deviant (10%) tones were recorded during both wakefulness and all-night sleep in eight drug-free volunteers. During presleep waking (10:00-11:00 p.m.), deviant stimuli elicited, in all subjects, a prominent "P300" wave of parieto-central topography, culminating at 344 ms (average), which was absent in response to frequent tones. This "presleep P300" was delayed and reduced relative to values obtained during full wakefulness (3:00-7:00 p.m.) in a control group. Passage from waking to sleep stage I was characterized by a progressive attenuation and delay of the P300 wave in response to deviant stimuli, without major changes in AEP morphology as compared to the waking state. Thus, in terms of cognitive evoked potentials (EPs), sleep stage I appeared more as a "weak" state of wakefulness than a true phase of sleep. During sleep stages II, III, and IV, both frequent and deviant tones evoked AEPs that closely resembled K-complexes. Responses to rare stimuli were four-to-five times larger than those to frequent tones, this likely being the result of K-complex habituation to monotonous stimuli. During paradoxical sleep (PS), AEP morphology again became comparable to that of wakefulness. Notably, a "P3" wave with similar topography as the waking P300 appeared in response to deviant stimuli exclusively. Thus, even though the brain seems able to detect stimulus deviance during all sleep stages, only during stage I and PS were the electrophysiological counterparts of deviance detection comparable to those of the waking state. Our results support the view that PS is not a state of "sensory isolation"; failure to respond to external stimuli during this stage may depend upon mechanisms occurring only after the sensory input has undergone cognitive analysis.

Adult↗
PubMed1994

[Rhythms of falling asleep persisting in adults. Two cases without mental deficiency].

Nocturnal rhythmic movements (jactatio capitis nocturnus, JCN) are very frequent in young children but persist only rarely in adults; studies including sleep recordings are exceptional in those cases. We report two new cases of young adults with JCN persisting since the first year of life, associated with restless sleep and diurnal sleepiness. Several episodes of JCN were recorded in each of the two patients; they always occurred after a period of paradoxical sleep, the waking phase preceding the rhythmic movements which are sometimes very short (1 s). The pathophysiology of adult JCN is discussed as a behavioral disorder of sleep onset conditioning or a disorder of sleep maintenance.

Adult↗
PubMed1989

[Nocturnus terrors--somnambulism].

Among disorders of sleep in children, pavor nocturnus ("night terrors") is common and considered harmless. Yet the clinical picture, the child's personality and the polygraphic electroencephalographic recordings suggest that it should be treated sooner and more often than is usually done. Somnambulism ("sleep walking") also is very frequent. It has no consequences in most cases, but it may be the cause of serious events such as falling out of a window which is rare but may result in death or disablement. Some children have repeated attack of somnambulism, and these constitute a true pathology of sleep requiring a specific treatment that will cure or improve. All this must be known to the practitioner who will inform the parents.

Adolescent↗
PubMed1989

Changes of middle latency auditory evoked potentials during natural sleep in humans.

During natural nocturnal sleep, Na and Pa middle latency auditory evoked potentials (MLAEPs) underwent significant variations which were related to sleep stages. The deepening of sleep from stage II to stage IV was paralleled by a latency shift and an amplitude decrease of Na and Pa, while MLAEPs were similar in wakefulness and REM sleep. Moreover, Na and Pa components tended to shift over the hemisphere contralateral to the stimulated ear during sleep. These findings demonstrate that the responsiveness of the auditory cortex to acoustic stimuli is modulated during sleep. Vigilance should be monitored during MLAEP recordings in patients.

Adult↗
PubMed1988

BAEP latency changes during nocturnal sleep are not correlated with sleep stages but with body temperature variations.

Serial BAEPs and polysomnograms were recorded during nocturnal sleep in 8 normal subjects. Wave V latency and the I-V interval were found to increase significantly during stages II, III + IV and paradoxical sleep when compared to waking. Trend curves of BAEP latencies showed that these shifts were independent of sleep stages and reversed at the end of the night. BAEP changes were found to be related to physiological hypothermia during the night.

Adult↗
PubMed1988

Successful treatment of idiopathic hypersomnia and narcolepsy with modafinil.

1. Modafinil, a putative central alpha 1 adrenergic agonist, was tested in idiopathic hypersomnia and narcolepsy. 2. Sleep attacks and drowsiness were significantly decreased in 83% of 18 hypersomniac subjects and 71% of 24 narcoleptics. 3. When cataplectic episodes were not totally suppressed the association of a low dose of Clomipramine was successful in improving them. 4. Modafinil, used for at least 3 years in some patients, produces, in most cases, no peripheric sides effects, does not disturb night sleep and is never responsible of tolerance of drug dependence.

Adrenergic alpha-Agonists↗
PubMed1988

[HLA and narcolepsy. Apropos of 28 cases including 2 negative HLA-DR2].

Association between narcolepsy and HLA-DR2 antigen is the strongest so far described between an HLA antigen and a disease. Among 28 narcoleptic patients, we found two HLA-DR2 negative cases: a caucasoid woman also suffering from dystrophia myotonica and a negroid. All of our patients were HLA-DQW1 positive. An hypothetical narcolepsy susceptibility gene could be located in the HLA region, closer to the DQ than to the DR gene. It could be a pathologic allele of a sleep controlling gene in linkage disequilibrium with DQW1. Presence of DQW1 is a quasi-requisite for the expression of narcolepsy. It is not sufficient as it is observed in 70 p. 100 of controls.

Adolescent↗
PubMed1986

[Comparison between good and poor sleep in the 20 to 30-year-old age range: polygraphic findings and psychopathologic aspects].

Fifty-six poor sleepers, aged from 20 to 30, were compared with 46 good sleepers of the same age regarding objective sleep parameters and personality. A gradation of sleep disorders was observed. The degree of sleep disorders was found to be directly proportional to the degree of psychological disturbance. Psychophysiological group of poor sleepers exhibited objective differences from good sleepers during the first cycle only (lack of SWS and REM sleep). Sleep organization in the first cycle seemed important for the estimation of poor or good sleep by the sleeper.

Adult↗
PubMed1986

Nocturnal continuous infusion of growth hormone (GH)-releasing hormone results in a dose-dependent accentuation of episodic GH secretion in normal men.

Fluctuations in plasma GH levels have been found in patients with acromegaly who have continuously elevated levels of ectopically produced GH-releasing hormone (GHRH). Likewise, plasma GH fluctuations have been found in normal subjects receiving continuous GHRH infusions. We report the effects of two doses of GHRH, administered by constant infusion, on nocturnal GH secretion in six normal young men. Each received, in random order, 2.5 ng/kg X min GHRH, 15 ng/kg X min GHRH, and 0.15 M NaCl. During both GHRH doses, a highly significant increase in total nocturnal GH secretion was found (P less than 0.001) as well as an increase in GH secretion during different periods of the night. Nocturnal GH secretion was episodic during the GHRH infusions, with an increase in the number and magnitude of the peaks compared to those during the NaCl infusion. Plasma immunoreactive GHRH concentrations plateaued at 1 h during the high dose and at 3 h during the low dose GHRH infusion. Sleep parameters, including total sleep time, sleep latency, and duration and timing of the different sleep stages, were not affected by GHRH infusions. We conclude that GHRH, continuously infused, increases nocturnal GH secretion according to the dose, while the episodic pattern of GH secretion is maintained.

Adult↗