Biomedical subjects

K Dujardin

Publications and source records attributed to K Dujardin.

7 recordsLinked to original sources

PubMed1995

Event-related desynchronization (ERD) patterns during memory processes: effects of aging and task difficulty.

Event-related desynchronization (ERD) was studied in 10 young (mean age = 19.1) and 10 older (mean age = 62.8) subjects during two recognition tasks: verbal and visuo-spatial. The difficulty of these tasks varied according to the difficulty to distinguish between targets and distractors. EEGs recorded from 29 electrodes were used to compute ERDs from 14 source derivations in 125 msec intervals. Thereafter, they were displayed as spatio-temporal maps. The results show that desynchronization was more widespread in the visuo-spatial compared to the verbal task. This was observed in the two age groups, although it was more pronounced in the young subjects. The effect of task complexity was also influenced by the kind of material to be remembered: more differences between the two levels of difficulty were observed during the verbal task. The results revealed significant influences of the task and time variables on the ERD patterns. A distinct time course of the desynchronization phenomenon was observed to be related to the kind of recognition task. Age and task complexity interacted with the other variables.

Adolescent↗

PubMed1993

Evaluation of event-related desynchronization (ERD) during a recognition task: effect of attention.

Event-related desynchronization (ERD) was studied in 10 subjects during a verbal recognition task. The attentional load of the task varied according to the difficulty to discriminate targets and distractors. The EEG recorded from 29 electrodes was used to compute ERD from 14 source derivations in 125 msec intervals and displayed as spatio-temporal maps. The results show that large brain areas of both hemispheres are significantly activated when the attentional load is high. This cerebral activation pattern is less pronounced when the load is low. ANOVA reveals main effects of attention and time and a significant interaction between attention and time.

Adolescent↗

PubMed1993

Effect of aging on the spatio-temporal pattern of event-related desynchronization during a voluntary movement.

Event-related desynchronization (ERD) of alpha components was studied in young and elderly subjects during planning of voluntary movement. ERD was quantified from 11 source derivations covering regions of the scalp corresponding to the supplementary motor area, the left and right primary sensorimotor areas, the vertex, and the medial posterior parietal cortex. Spatio-temporal display of ERD showed a very different pattern in elderly subjects, with mainly a spatial diffusion of ERD over the parietal and frontal regions. On the contrary, ERD in young subjects was limited to the central regions. ERD was also more lasting in elderly subjects. Changes of the ERD pattern in elderly subjects could indicate a change of cortical activation during voluntary movement. The data also confirm that ERD study is a useful electrophysiological exploration to observe the changes of cortical activation during cerebral aging.

Adult↗

PubMed1990

Sleep, brain activation and cognition.

Some data have shown the presence of time-of-day effects in learning processes. We explore here whether the same phenomenon occurs during the night and how it relates to REM sleep. In an initial approach to the question, this paper points out the relationships between: 1) REM sleep and brain activation, and 2) REM sleep and information processing. The data are discussed in terms of a REM sleep implication on information processing and we examine the possibility of modifying this processing by acting on REM sleep.

Animals↗

PubMed1989

Enhancement of memory by auditory stimulation during postlearning REM sleep in humans.

REM sleep involvement in memory processes was demonstrated in animals and humans: 1) REM sleep deprivation impairs the memory fixation, 2) learning sessions are followed by modifications of REM sleep characteristics. Moreover, sleep patterns can be modified by applying auditory stimulations during REM sleep. We show that REM actual auditory stimulations significantly improve the retention of a Morse code learning task. These results are discussed in terms of brain activation.

Acoustic Stimulation↗

PubMed1989

REM sleep modifications following a Morse code learning session in humans.

Various experimental data indicate that rapid eye movement (REM) sleep is involved in learning processes. In animals, any complex task in a learning environment leads to an increase of the consecutive total REM sleep time, especially just before learning completion. In humans, the oculomotor activity during REM sleep seems to constitute an interesting marker of learning performance. In this work, we focus on the qualitative analysis of REM sleep characteristics after a Morse code learning session. Eight male subjects were polygraphically recorded during three consecutive nights. A computer aided teaching session was performed just before bedrest onset of the experimental night. The learning performance (percentage of saving) was checked on awakening. The Morse code learning led to some modifications in REM sleep components, particularly increases of REM sleep time and number of REM episodes. We did not observe any significant modification in the total number of REMs in the experimental night. However, the correlative analysis between learning performance and sleep parameters indicates a superior r for the oculomotor activity than for the tonic components. This is consistent with the information processing hypothesis in which the temporal distribution of REMs reflects the subject's ability to increase the signal-noise ratio from environmental information intake.

Adolescent↗

PubMed1988

[Memory facilitation by auditory stimulation during paradoxal sleep in man].

REM sleep involvement in memory processes was demonstrated in animals and humans. Learning sessions are followed by modifications of REM sleep patterns. Furthermore, one can modify sleep patterns by applying auditory stimulation during REM sleep oculomotor activity. We show that such a procedure facilitates the retention of Morse code learning.

Acoustic Stimulation↗