Biomedical subjects

E Pellouchoud

Publications and source records attributed to E Pellouchoud.

4 recordsLinked to original sources

PubMed2001

Neurophysiological signals of working memory in normal aging.

To examine how neurophysiological signals of working memory (WM) change with normal aging, we recorded EEGs from healthy groups (n=10 each) of young (mean age=21 years), middle-aged (mean=47 years), and older (mean=69 years) adults. EEGs were recorded while subjects performed easy and difficult versions of a spatial WM task. Groups were matched for IQ (mean=123; WAIS-R) and practiced in task performance. Responses slowed with age, particularly in the more difficult task. Advanced age was associated with decreased amplitude and increased latency of the parietal P300 component of the event-related potential and an increase in the amplitude of a frontal P200 component. Spectral features of the EEG also differed between groups. Younger subjects displayed an increase in the frontal midline θ rhythm with increased task difficulty, a result not observed in older subjects. Age-related changes were also observed in the task-related alpha signal, the amplitude of which decreases as more neurons become involved in task-related processing. Young adults showed a decrease in alpha power with increased task difficulty over parietal regions but not over frontal regions. Middle-aged and older adults showed decreased alpha power with increased task difficulty over both frontal and parietal regions. This suggests that normal aging may be associated with changes in the fronto-parietal networks involved with spatial WM processes. Younger subjects appear to use a strategy that relies on parietal areas involved with spatial processing, whereas older subjects appear to use a strategy that relies more on frontal areas.

Adult↗

PubMed1999

Mental effort-related EEG modulation during video-game play: comparison between juvenile subjects with epilepsy and normal control subjects.

PURPOSE: This study investigated the effects of mental effort exerted during video-game play on features of the EEG in juvenile subjects diagnosed with seizure disorders and in age-matched clinically healthy subjects. METHODS: EEG was recorded from 14 children (9-15 years old) as they played a video game, watched another person playing a video-game, and sat quietly with their eyes open. Seven of the subjects had been clinically diagnosed with seizure disorders, three of whom had also exhibited photosensitivity. RESULTS: Three spectral components of the EEG showed cognitive load-related modulation. The amplitude of a frontal midline theta (6-7 Hz) signal increased with video-game play relative to the watching and eyes open resting conditions. A posterior alpha band (9-12 Hz) signal was attenuated during the playing and the watching conditions relative to the resting condition. A central mu (10-13 Hz) rhythm was attenuated during the game-playing condition. No significant differences were found between the patient and control groups for any of these features. Incidence of epileptiform events did not discriminate test conditions in the children with epilepsy. CONCLUSIONS: The results from this small sample suggest that video-game play tends to produce similar responses from children with epilepsy and in healthy control subjects. These responses in the juvenile population are similar to responses elicited by increased mental load in normal adult populations.

Adolescent↗

PubMed1998

A rapid method for determining standard 10/10 electrode positions for high resolution EEG studies.

This report describes the basic principle and examines the comparative accuracy of a novel method for locating 3-D coordinates of electrode positions on the head. The method involves calculation of the 3-D coordinates for any array of 10/10 electrode positions from 14 straight-line distances between 11 10/10 electrodes. In 11 subjects the 3-D coordinates of 64 scalp electrodes embedded in an electrode cap were identified with the novel method, and also with a standard commercial magnetic field digitizer. The outcomes from the two methods were compared with directly measured coordinates of all 64 positions (cf. De Munck, J.C., Vijn, P.C.M. and Spekreijse, H. A practical method for determining electrode positions on the head. Electroenceph. clin. Neurophysiol., 1991, 89: 85-87). Coordinates in 3 dimensions obtained using the new method were significantly closer to the directly measured values than those from the magnetic field digitizer. The new method was also quicker and requires less specialized instrumentation than the magnetic field digitization method. The novel method appears to be a valid and convenient tool for use with EEG analysis techniques that require specific information about 10/10 electrode positions.

Adolescent↗

PubMed1997

Implications of electrolyte dispersion for high resolution EEG methods.

The effective recording area of an EEG electrode is its electrical contact area with the scalp. With techniques that employ wet electrolyte, this area is primarily determined by the extent of electrolyte dispersion rather than by the size of the electrode. The effective recording areas of 10 widely distributed EEG electrodes embedded in an elasticized stretch hat were measured on 7 subjects using a digital multimeter. On average, conventionally prepared electrodes were associated with an electrolyte (standard gel) spread of approximately 1 cm in each of four directions (above, below, right and left of the electrode's center). This implies that EEG electrodes prepared with wet electrolyte should not be spaced less than 2 cm apart unless special precautions are taken to prevent the spread of electrolyte, and that in most circumstances there is little advantage to methods for designating the 3-D coordinates of an electrode that have a measurement error of less than 1 cm.

Adolescent↗