Biomedical subjects

H Platel

Publications and source records attributed to H Platel.

7 recordsLinked to original sources

PubMed2001

Contributions of frontal and medial temporal regions to verbal episodic memory: a PET study.

Using PET, subtraction and correlation analysis were jointly employed to determine the specific and complementary contributions of frontal and medial temporal regions to verbal episodic encoding and retrieval processes. Subtraction analysis highlighted prefrontal rCBF increases which were predominantly left-sided during intentional encoding and exclusively right-sided during retrieval, the latter being moreover associated with bilateral precuneus activation. However, significant correlation between rCBF values obtained during intentional encoding and performance scores obtained during retrieval concerned, among other regions, the left parahippocampal gyrus, which indicated that the higher the neuronal activity in this medial temporal region during encoding, the better the retrieval performance.

Adult↗

PubMed1998

Preservation of the attribute knowledge of concepts in normal aging groups.

The aim of this study was to detect possible alterations in semantic representation during normal aging. Forty young subjects (aged 20 to 30 years) and 40 elderly ones (divided into two groups of 60 to 70 years and 70 to 80 years), all in good health and with high education, completed a test protocol used for assessing semantic knowledge in the study of Alzheimer's disease. The same list of 42 words belonging to three different semantic categories was presented visually three times to the subjects, each time with different instructions: (a) find the words with one letter N (or more) (training task); (b) find the names of animals (test of categorical knowledge); (c) find the words representing something that prick (test of attribute knowledge of concepts). A two-way analysis of variance showed an effect of task (the times taken were significantly longer for the attribute-knowledge test), a group effect (the elderly subjects were slower) and an absence of interaction (the elderly subjects had the same profile as the young group). The results indicate the preservation of the semantic memory in normally aging groups and the usefulness is emphasized in the context of the data given in the literature on Alzheimer's disease.

Adult↗

PubMed1997

The structural components of music perception. A functional anatomical study.

This work explores the cerebral structures involved in the appreciation of music. We studied six young healthy subjects (right handed, French, without musical talent), using a high resolution PET device (CTI 953B) and 15O-labelled water. In three tasks, we studied the effects of selective attention to pitch, timbre and rhythm; a final task studied semantic familiarity with tunes (considered as divided attention for pitch and rhythm). These four tasks were performed on the same material (a tape consisting of 30 randomly arranged sequences of notes). We selected a paradigm, without a reference task, to compare the activations produced by attention to different parameters of the same stimulus. We expected that the activations recorded during each task would differ according to the differences in cognitive operations. We found activations preferentially in the left hemisphere for familiarity, pitch tasks and rhythm, and in the right hemisphere for the timbre task. The familiarity task activated the left inferior frontal gyrus, Brodmann area (BA) 47, and superior temporal gyrus (in its anterior part, BA 22). These activations presumably represent lexico-semantic access to melodic representations. In the pitch task, activations were observed in the left cuneus/precuneus (BA 18/19). These results were unexpected and we interpret them as reflecting a visual mental imagery strategy employed to carry out this task. The rhythm task activated left inferior Broca's area (BA 44/6), with extention into the neighbouring insula, suggesting a role for this cerebral region in the processing of sequential sounds.

Adult↗

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↗

PubMed1993

Characteristics and evolution of writing impairment in Alzheimer's disease.

Rapcsak et al. (Archs Neurol. 46, 65-67, 1989) proposed a hypothesis describing the evolution of agraphic impairments in dementia of the Alzheimer type (DAT): lexico-semantic disturbances at the beginning of the disease, impairments becoming more and more phonological as the dementia becomes more severe. Our study was conducted in an attempt to prove this hypothesis on the basis of an analysis of the changes observed in the agraphia impairment of patients with DAT. A writing test from dictation was proposed to 22 patients twice, with an interval of 9-12 months between the tests. The results show that within 1 year there was little change in the errors made by the patients in the writing test. The changes observed however were all found to develop within the same logical progression (as demonstrated by Correspondence Analysis). These findings made it possible to develop a general hypothesis indicating that the agraphic impairment evolves through three phases in patients with DAT. The first one is a phase of mild impairment (with a few possible phonologically plausible errors). In the second phase non-phonological spelling errors predominate, phonologically plausible errors are fewer and the errors mostly involve irregular words and non-words. The last phase involves more extreme disorders that affect all types of words. We observe many alterations due to impaired graphic motor capacity. This work would tend to confirm the hypothesis proposed by Rapcsak et al. concerning the development of agraphia, and would emphasize the importance of peripheral impairments, especially grapho-motor impairments which come in addition to the lexical and phonological impairments.

Agraphia↗

PubMed1984

[A pneumatic transfusion accelerator].

A new simple device using piped medical gases for the inflation of pressure cuffs used for rapid intravenous infusions is described. The pressure cuffs are maintained inflated with piped medical oxygen delivered by an adjustable pressure regulator. Operating advantages of this device were: 1) inflation time for the cuff and infusion time for fluids kept in collapsible PVC bags (whole blood, plasma, cellular concentrates or other fluids) were considerably shortened, not requiring any manual manipulation throughout the infusion; 2) when the bag is emptied, the large bore tubing used allowed rapid deflation of the cuffs; 3) the procedure was as safe as manual acceleration of transfusion, and simpler, requiring a simple three-way stopcock.

Air Pressure↗

PubMedDate not supplied

[Neuropsychology of musical identification].

Several neuropsychological observations have suggested that disturbances of the process involved in identifying music is related to lesions of the dominant cerebral hemisphere. The studies have been confirmed by different data from experimental psychology and functional brain imaging techniques. Based on these inference sources we propose different hypotheses to describe the cognitive processes involved in identifying music.

Cognition↗