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P Etevenon

Publications and source records attributed to P Etevenon.

At least 19 recordsLinked to original sources
PubMed1995

Topographic EEG activations during timbre and pitch discrimination tasks using musical sounds.

Successive auditory stimulation sequences were presented binaurally to 18 young normal volunteers. Five conditions were investigated: two reference tasks, assumed to involve passive listening to couples of musical sounds, and three discrimination tasks, one dealing with pitch, and two with timbre (either with or without the attack). A symmetrical montage of 16 EEG channels was recorded for each subject across the different conditions. Two quantitative parameters of EEG activity were compared among the different sequences within five distinct frequency bands. As compared to a rest (no stimulation) condition, both passive listening conditions led to changes in primary auditory cortex areas. Both discrimination tasks for pitch and timbre led to right hemisphere EEG changes, organized in two poles: an anterior one and a posterior one. After discussing the electrophysiological aspects of this work, these results are interpreted in terms of a network including the right temporal neocortex and the right frontal lobe to maintain the acoustical information in an auditory working memory necessary to carry out the discrimination task.

Adolescent↗
PubMed1988

[Caffeine and EEG mapping: effects of visuo-spatial task in healthy volunteers].

A group of 10 subjects, normal volunteers (6 men, 4 women), mean age 27.2 years, right-handers, has been selected for a double-blind study of caffeine effects (400 mg per os) versus placebo. One week delay separated the two EEG sessions quantified by spectral analysis. During each session (16 EEG channels, common reference), each subject was recorded four times: 2.5 min, in eyes-closed condition, under diffuse attention, followed by 2.5 min, during a visuo-spatial task ("eyes open" condition: presentation of a picture). These two EEG recordings were obtained before the oral administration and repeated 1 hr after the administration of caffeine or placebo. Individual and group results presented globally: 1) an increase in mean frequencies of alpha activity in "eyes closed" condition, and of delta activity in "eyes open" condition; 2) a decrease of alpha activity amplitudes (both RMS and % values) in both conditions; 3) a decrease of total RMS amplitudes in "eyes closed" condition; 4) an increase of relative % amplitudes for beta 2% fast activity in the "eyes open condition". These results characterize the psycho-stimulant effects of caffeine, especially over the left temporal area which was confirming an initial statistical hypothesis of specific cerebral local activation. The non-parametric permutation tests of Fisher, were not always reaching statistical significance for the same EEG channel quantified by one of the 17 analyzed spectral parameters, except on the left temporal area. During the visuo-spatial task, the decrease in alpha amplitudes (RMS and %) was also statistically significant, but over larger areas: over left and right temporal, central and parietal regions. In both conditions, eyes closed and eyes open, the alpha RMS amplitude was also decreased over the right anterior frontal area.

Administration, Oral↗
PubMed1986

EEG cartography of a night of sleep and dreams. A longitudinal study with provoked awakenings.

A night of sleep has been recorded under the conditions of a sleep laboratory. The subject was a woman of 55 years, well-trained in dream recall. The subject was awakened three times at the end of sleep cycles. EEG was monitored for 7 h with a 16-channel polygraph (REEGA 16, Alvar) connected to two systems of EEG cartography: minicomputers (HP Fourier Analyser 5451 C and HP 1000) and a microinformatic system (Cartovar, Alvar). A second 8-channel polygraph (Mini-huit, Alvar) was used in parallel for polygraphy (EOG, EMG, respiration, actogram, EKG). Based on immediate visual inspection of EEG and polygraphic tracings, 500 EEG recordings of selected epochs (of 6, 30 or 60 s length) have been quantified, submitted on-line to spectral analysis (on Cartovar) and stored on floppy disks for further printing of EEG maps. The 16 EEG channels were placed over the scalp according to the 10/20 system and following Giannitrapani's placement. We have chosen a common average electrode. For each of the 500 EEG epochs, four EEG maps were edited (raw EEG between 0 and 30 Hz, 0 and 7 Hz, 8 and 12 Hz, 13 and 30 Hz). Each of these 2,000 maps has been checked visually in comparison with the polygraphic recordings for visual rejection of artifacts or transitory states. The remaining EEG epochs and EEG maps, scored by 2 independent trained sleep scorers, were classified into stages I, II, III-IV, and REM, apart from control runs of active wakefulness with eyes open (EO) and quiet wakefulness with eyes closed (EC), which were undertaken on mini- and microsystems of EEG analysis.(ABSTRACT TRUNCATED AT 250 WORDS)

Brain Mapping↗
PubMed1985

Electroencephalographic cartography. II. By means of statistical group studies-activation by visual attention.

10 male volunteers, right-handers, mean age 30.4 years, were recorded in four successive sequences: under 'eyes closed' conditions, right and then left hemisphere, followed by an 'eyes open' situation with visual attention fixed on a cartoon, right and then left hemisphere recordings. Each EEG recording was made simultaneously over 16 EEG channels for each hemisphere, according to a protocol previously described as well as Fourier analysis and EEG mapping on a minicomputer (HP 5451 C, HP 1000). Each EEG recording was stored on a cartography data base, and 90 maps could be drawn from 10 spectral parameters applied to the raw EEG and 5 frequency bands. Permutation paired Fisher tests were applied to three main EEG parameters: mean centroid frequencies, RMS amplitudes in microvolts and relative (%) amplitudes. Activation of EEG in the 'eyes open' situation during visual fixation was found compared to the 'eyes closed' situation: decreasing dominant EEG frequency and low delta and theta mean frequencies, no change in a mean alpha frequency; increasing fast mean beta frequencies, together with a major decrease in theta, alpha, beta 1 amplitudes, and a concomitant increase in raw EEG, delta and beta 2 amplitudes. Finally, the percent alpha amplitude was decreased when other percent amplitudes were increased in delta, theta, beta 1 and beta 2 frequency bands. A symmetry between hemispheres was observed in the 'eyes closed' situation. Averaged EEG maps between subjects illustrate these findings, especially relative (%) alpha amplitude maps and also maps of coefficients of resonance of the alpha rhythm.

Adult↗
PubMed1985

Electroencephalographic Cartography. I. By means of mini- or microcomputers. Reliability and interest of this electrical non-invasive brain imagery.

We have recorded control subjects, neurological and psychiatric patients (n = 217 sequences recorded over both hemispheres). Minicomputers (HP Fourier analyzer, HP 1000) for spectral analysis provided 10 spectral parameters over 5 spectral frequency bands (delta, theta, alpha, beta 1, beta 2, raw EEG). For each recorded sequence, 90 EEG maps could be computed over both hemispheres. Topo-EEGs were stored in an EEG image data bank. An EEG mapping microcomputer system linked with a digital polygraph (Alvar Electronic, REEGA 2000) has been used simultaneously. White noises have been fed into both computers for testing spatial resolution. Ten topo-EEGs have been recorded in control subjects and patients. The microcomputer system has provided very reliable topographical results when compared to similar maps generated by the minicomputer. A common average reference has been used. First clinical applications have been studied (brain strokes, brain tumors). The method appears very reliable in comparison with CT scans.

Adult↗
PubMed1984

Intra and inter-hemispheric changes in alpha intensities in EEGs of schizophrenic patients versus matched controls.

62 EEGs of 5 min recordings, over C4-P4, P4-02, C3-P3, P3-01, have been recorded from 31 schizophrenic patients and 31 controls, matched for age (27 years) and sex (males). Patients were clinically classified into 3 sub-groups: paranoid-type P(7), residual type R(10) and others O(14). Controls were statistically classified into 2 sub-groups as high alpha subjects HA(15) or low alpha subjects LA(16). Following computer Fourier statistical analysis, evolutive power spectra, averaged power spectra and spectral variances were obtained for each EEG recording. Date reduction provided for each EEG: Mean frequencies, mean amplitudes in microvolts and percentage asymmetries, resonance, spectral parameters; theta/alpha, with their variabilities. Power spectra were averaged between patients or between subjects for each sub-group. The alpha peak and the mean RMS amplitude was higher over P3-01 than over P4-02 for the residual-type of schizophrenic patients, when compared to his matched control sub-group of high-alpha subjects which presented almost symmetrical occipital alpha peaks and RMS amplitudes. However, the most important changes appear to be intra-hemispheric. The alpha peaks and RMS amplitudes were almost equal between C3-P3 and P3-O1 for the paranoid type of schizophrenic patients in contrast to other sub-groups and especially both control sub-groups. This seems to imply left hemispheric changes in terms of EEG spectral alpha intensities, when tracings of schizophrenics were compared with recordings of volunteers.

Adult↗
PubMed1984

Computerized topo-EEG spectral maps: difficulties and perspectives.

An electric potential measurement tells us only about the difference between two electrode locations. When prior experiments or present measurements prove that an electrode's location is inactive (especially in 'mono-polar' or scalp-to-reference technique), then EEG records and EEG maps can be interpreted regionally near each electrode location. Topographical mapping requires spatial interpolation which is one factor involved in spatial resolution. The interpolation algorithm has been studied by changing the power exponent n of the interelectrode distance d. When n is close to zero, interpolated values are all equal to the average of the four electric potential measurement Vs bounding the quadrilateral in which the interpolated points of the EEG map are located. When n is very high (n = 20 or higher), the values are essentially equal to the V which is at the minimum distance d. For n = 1, the map seems unlikely to represent the true scalp field. The choice between n = 2 and n = 3 is difficult, but n = 3 EEG mapping looks better (more plausible) and is our regular choice. The choice of recording/reporting method has also been studied. If the quantitative EEG map is linearly calculated from observations, the interpretation of record activity resulting from charge separation near the non-reference electrode attached to a particular channel is only possible when inactivity can be assured. This is completely different when the quantity mapped is not linearly calculated from observations (like power values or rms amplitudes in microvolts).(ABSTRACT TRUNCATED AT 250 WORDS)

Brain Mapping↗
PubMed1983

[Computerized quantitative topo-electroencephalography].

A method is described which has been developed to topographically display the values of spectral EEG analysis from 11 electrodes on each hemisphere and 5 electrodes on the midline. The EEG from 16 channels at a time is multiplexed and sampled at 3.2 kHz. From power spectra averaged every 10 sec for 5 min a few spectral parameters are computed among which are the spectral intensities within the delta, theta, alpha and beta bands. The whole values are then displayed on maps representing lateral views of cerebral hemispheres by means of spectral iso-intensity surfaces with extrapolation of the intermediate points. Different spectral intensities are coded by means of different gray levels. These maps clearly illustrate the topographical distribution of EEG rhythms and their peculiarities related to the side of the head recorded.

Alpha Rhythm↗
PubMed1983

[Topographic aspects of drug-induced fast rhythms in quantitative topo-electroencephalography].

The topographical aspects of fast rhythms induced by different psychotropic drugs have been studied in patients by means of a previously described method. This method is based on the spectral analysis of 28 EEG channels over both cerebral hemispheres. The spectral parameters, computed over 2 min 40 sec, are put into a data base. The clinician can then decide which of these parameters will be extracted from the data base and then displayed by means of maps on a graphic terminal. Those maps are useful for immediate comparison not only of the fast rhythms' characteristic values but also of those from other spectral bands. As quantitative EEG analysis is more and more frequently used in psychotropic drug studies, a good knowledge of the topography of the rhythms induced by these drugs will help in the selection of the most useful derivations.

Adult↗
PubMed1982

[Value of quantitative electroencephalography in psychiatry].

Computerized quantitative EEG processes the signal in four sequential steps: 1) EEG sampling with rejection of artefacts; 2) Fourier analysis (power spectrum according to frequency); 3) data reduction with computation of spectral parameters in five-minute recordings on at least four EEG channels (mean frequencies, mean amplitudes in microvolts and %, with standard deviations for delta, theta, alpha and beta frequency bands); 4) data base and multivariate statistical analyses. Five main results are obtained by computerized quantitative EEG analysis in psychiatry and clinical pharmacology: 1) longitudinal studies of patients before and after treatment; 2) transversal studies of homogeneous EEG groups (discrimination between tracings of residual-type or paranoid-type schizophrenic patients) comparatively with control groups (high and low alpha subjects); 3) study of psychotropic drugs: profiles, prediction of action, dose-effect curves, pharmacokinetic studies, biodisponibility, correlations with plasmatic levels and behavioural or clinical psychiatric rating scales; 4) typologic classification and discrimination by multivariate analysis, studies of functional activities: functional interhemispheric lateralisation of amplitudes and its variations during the course of psychotic processes; 5) new techniques: computerized topo-electroencephalography (CT-EEG, BEAM technique) based on 16 EEG recordings, comparison with other imaging techniques.

Computers↗
PubMed1982

[Multivariate correspondence analysis of a visually screened EEG. Application to a study of psychotropic drugs compared with placebos (author's transl)].

Eighty-seven EEG recordings were obtained from 9 healthy volunteers, medical students who were part of a controlled, double-blind, randomized study. After a first control recording, they received orally, at 1 week interval, either 3 placebos or 3 compounds: yohimbine chlorhydrate (4 mg), propranolol (40 mg), a psychotropic compound in experimentation. The polygraphic recordings were obtained 2 or 6 h after placebos or active compounds. Four EEG channels were recorded simultaneously (T4-C4, T3-C3, P4-O2, P3-O1). The EEGs were sampled at 200 Hz, for 120 successive epochs, free of artifacts. The recordings of 5 min were then submitted to spectral analysis followed by data reduction providing characteristic spectral parameters. A descriptive questionnaire of EEG made of 100 items was filled out by two electroencephalographists for each of 87 recordings. The items, with dichotomic choices, described 4 EEG frequency bands: delta, theta, alpha, and fast frequencies (beta). For each frequency band the following was evaluated: frequency, amplitude, asymmetry, morphology, relative abundance, irregularity, lability of frequency, diffusion, dominant localization, EMG activity and superposition of rhythms. The number of periods of drowsiness in 5 min and fluctuations of rhythms were also ascertained in the same way. The items were coded on punch cards and submitted to a first analysis of correspondences. The 3 factorial planes were plotted with the projections of each item together with the centers of gravity of placebos and treatments. The first factor can be interpreted as a bipolar axis 'mental activation-diffused vigilance', the first pole being characterized by a 'beta cluster' and the second by alpha and theta superimposed clusters. The second factor can be also considered as a bipolar axis 'drowsiness -quiet wakefulness', the first pole being characterized by a 'theta cluster' and a larger 'delta cluster' containing a smaller 'alpha cluster' of labile alpha rhythm intermingled with slower rhythms. In respect to the barycentric centers of gravity, yohimbine and propranolol are opposed to the placebo center along the factor-two axis. This may be considered as an 'anti-sedation effect'. However, along the first factor axis, the propranolol center can be associated with a greater diffusion of vigilance than the yohimbine center.

Adult↗
PubMed1981

Intellectual efficiency in manic-depressive patients treated with lithium. A control study.

A longitudinal study of 21 non-hospitalized manic-depressive subjects treated with lithium was carried out over a 3-year period: year 1 (Y1), year 2 (Y2), year 3 (Y3). A control group C of 21 subjects matched for age, sex and educational level was compared to Y1, Y2 and Y3 using the Cattell Intelligence Scale, the immediate memory recall test of numbers, the Code Test (WAIS), the 15-Word Test and the Benton Visual Retention Test. The vocabulary test of Binois and Pichot was first applied to C and Y1 to test the homogeneity of intellectual level between these two groups. A strategy of variance analysis followed by non-parametric Mann-Whitney and Wilcoxon tests was applied for statistical analysis of the results. Generally, except for the Cattell test, the patients presented lower scores than the control group. This decrease was not accentuated as time elapsed; the non-verbal were not affected more than the verbal tests. A clinical analysis was carried out relating the importance of the criteria "deterioration" to four other criteria: "age", "gravity and duration of illness ", "history of E.C.T." and "insufficient mood stabilization". The factor "gravity of the illness" was slightly more frequently associated with factor deterioration.

Adult↗
PubMed1979

Intra- and interhemispheric EEG differences quantified by spectral analysis. Comparative study of two groups of schizophrenics and a control group.

In this work we have studied comparatively the relationships between alpha intensity, alpha frequency, root-mean-square amplitude and their standard deviations, versus the location of the four recorded EEG channels: left and right rolando-parietal, left and right parieto-occipital. Twenty-four spectral parameters were computed for each 5-min EEG recording, in the eyes closed situation. The hebephrenic group (36 EEGs from six patients) presented higher values of alpha intensity and RMS amplitudes with low coefficient of variation when compared with the other groups. The left/right rolando-parietal amplitude ratio was 0.73 versus 1.52 for the parieto-occipital ratio. An amplitude hypovariability in the central regions, probably associated with hyperarousal, especially in the left hemisphere, can then be observed in hebephrenics, together with high alpha intensity on the left parieto-occipital area. The two groups of schizophrenics differ from the control group (27 EEGs from 12 subjects) in terms of spectral parameters, the hebephrenic group presenting a possible interhemispheric dysfunction.

Adult↗
PubMed1978

[Alpha activity in a group of schizophrenics: spectral analysis and comparison with a control group (author's transl)].

Spectral analysis of tracings from four leads; C3-P3, P3-O1, C4-P4, and P4-O2, were used to compare the results of fiftyseven electroencephalograms from 10 schizophrenics, and 14 normal subjects used as controls. The results show that the mean frequencies of the alpha waves are identical in schizophrenics and controls. Patients with hebephrenia show the lowest variations in alpha wave frequency but with the highest voltage, whereas paranoid schizophrenics have tracings with the lowest amplitude and the greatest variation in frequency. There is also better left intrahemispheric correlation of relative alpha intensities in those patients with the lowest variation in right alpha intensity in relation to controls. The preliminary results suggest that there is a reduction in functional asymmetry of the hemispheres in the electroencephalograms from schizophrenics, when looking at the alpha activity.

Adult↗
PubMed1978

[Statistical spectral study of alpha rhythms: modifications due to the tardive action of a hypnotic (author's transl)].

In a simple blind study to evaluate electroencephalographic criteria objectively, and to continue characterization of psychotropic compounds, 5 mg of nitrazepam, a hypnotic derivative, was given to seven subjects the night before the recording. We noted that in most subjects there was a reduction in the spectral intensity of the alpha rhythm, associated with a greater frequency instability, several hours after the absorption of nitrazepam. This corresponds to the tardive hypnotic action of the psychotrope, the importance of which is wellknown at the present time. In the same way as the increase in rapid rhythms, the slipping of 0.5 c/s of the dominant alpha frequency to the top could be characteristic of the action of nitrazepam.

Adult↗