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Biomedical subjects

A R Lecours

Publications and source records attributed to A R Lecours.

At least 19 recordsLinked to original sources
PubMed2001

Two different dysgraphic syndromes in a regular orthography, spanish.

In opaque orthographies, such as English and French, three central dysgraphic syndromes have been described: surface dysgraphia, phonological dysgraphia, and deep dysgraphia. Writing breakdown patterns reveal that spelling can proceed by phoneme-to-grapheme conversion, or by a more direct or lexical approach. Ardila et al. (1989, 1991) claim that for Spanish speakers a lexical strategy for reading and writing is not an option due to the regularity of the orthography of this language. In this study we report two clear cases of dysgraphia in Spanish, one of surface dysgraphia and another of phonological dysgraphia, where a dissociation between lexical and sublexical writing can be observed, thus contradicting Ardila's position.

Aged↗
PubMed2000

The role of sublexical graphemic processing in reading.

Dual-route models of reading postulate the existence of two separate mechanisms: The lexical route allows words to be recognized in their holistic form, and the sublexical route proceeds by converting the written sublexical entities of a word or a nonword into their corresponding phonological equivalents. Sublexical reading is assumed to require three stages of processing: graphemic parsing, graphophonemic conversion, and phoneme blending. This study provides evidence in favor of the existence of a graphemic parsing process which occurs prior to grapheme-phoneme conversion. A group of normal subjects read nonwords which contained multiletter graphemes significantly more slowly than graphemically simple nonwords. These results, best interpretable in the context of a recent dual-route model of reading, confirm previous data obtained in pathology which suggest the functional independence of this cognitive procedure.

Adolescent↗
PubMed2000

[Acquired dyslexias and dysgraphias under the prism of cognitive neuropsychology: a model for the Spanish language].

The present paper discusses the different clinical manifestations of acquired disorders of reading and writing from a neurocognitive viewpoint. Based on a specific functional architecture of reading and writing--a cognitive model; presented as well--the different syndromes of acquired dyslexias and dysgraphias, that have been described in the specialized literature during the last 25 years, will be reviewed. The different pathologies are distributed along three different functional axes: a plurimodal component, including the semantic system, for the description of peripheric disorders of reading and writing; a lexical block which is justified by the findings in patients with surface dyslexia/dysgraphia; and a third, sublexical component, in order to illustrate the different functional impairments in phonological dyslexia/dysgraphia. Following the description of syndromes due to selective "functional lesions", we discuss deep dyslexia/dysgraphia, a syndrome due to multiple functional lesions. All of the syndromes will be justified and discussed with respect to the different components of the functional architecture presented and are based on cases of the literature and personal observations. Concluding remarks will evaluate the new insights gained by the presented functional arquitecture in relation to other cognitive models for the analysis of reading aloud and writing to dictation of single words.

Agraphia↗
PubMed1998

The contribution of attentional mechanisms to an irregularity effect at the graphemic buffer level.

This study analyzes acquired dysgraphia observed in a French-speaking woman. The results point to an impairment of the graphemic buffer, i.e., the processing stage where abstract orthographic representations are temporarily stored while planning the written production. However, the spelling errors were more frequent in the irregular than in the regular words. A qualitative analysis of the errors in the irregular misspelled words showed that, in general, these were not "regularization" errors, but rather the same characteristics as the phonologically implausible errors found in the regular words, such as letters substitutions, deletions, additions, and transpositions. Furthermore, in a list of regular and irregular words of same length and graphemic structure, the errors not only tended to concentrate on the irregularity itself but also tended to be more frequent elsewhere in the irregular words compared to the regular words. These finding are discussed in terms of a post-lexical sensitivity to irregular spelling. It is also shown that when focusing attention on the irregularity becomes necessary, this can cause a detriment to the surrounding graphemic constituents. Interaction between attentional resources and processing of orthographic representations at the graphemic buffer level is considered.

Aged↗
PubMed1998

Structural correlates of cognitive deficits in a selected group of patients with Alzheimer's disease.

OBJECTIVE: The objective of this study was to correlate the densities of neurofibrillary tangles (NFTs) and senile plaques (SPs) in 10 patients with Alzheimer's disease (AD) with comprehensive neuropsychological data obtained within 1 year of death. BACKGROUND: Clinicopathologic studies in AD have been essentially limited to correlate neuropathologic data with severity of dementia. Very few studies have addressed the correlations between distribution of lesions and specific cognitive deficits. This is partly due to the limitation imposed by the interval between the last neuropsychological evaluation and death. METHODS: Ten patients with a postmortem diagnosis of AD, with a mean age at death of 80.4+/-6.6 years and a mean duration of symptoms of 5.6+/-2.9 years, were selected for the study. All of these patients were submitted to neuropsychological testing within 1 year of death, including 17 tests assessing memory, language, visuoperceptual, visuospatial, and constructional abilities as well as limb praxis. The neuropathologic study was performed using a modified Bielschowsky technique. Mean densities of SPs and NFTs were determined in the hippocampal formation (CA1, subiculum, and parasubiculum) and in six neocortical areas (midfrontal, orbitofrontal, cingulum, fusiform gyrus, superior and inferior parietal cortices). Statistical correlations were determined between cognitive scores and SP and NFT densities. RESULTS: For NFTs, significant correlations emerged only between tangle density in CA1 and visuoperceptual scores. For SP density values, significant correlations were found between visuoperceptual tests and lesions in the subiculum and in the fusiform gyrus, significant correlations were found between language scores and SPs in the superior parietal cortex and between visuospatial deficits and lesions in the superior parietal cortex and fusiform gyrus. CONCLUSIONS: SPs in specific brain areas displayed a good correlation with the cognitive deficits detected in this selected group of AD patients. The association of fusiform gyrus and superior parietal lobule involvement with visuoperceptual and visuospatial deficits, respectively, is in agreement with current knowledge of the anatomic basis of visual processing.

Aged↗
PubMed1997

Educational level and neuropsychological heterogeneity in dementia of the Alzheimer type.

We retrospectively assessed the data from 24 patients with dementia of the Alzheimer type (DAT) who underwent comprehensive neuropsychological evaluations in order to determine whether there is a relationship between neuropsychological heterogeneity and educational level. Postmortem neuropathological examination results were made available for seven cases, confirming the diagnosis of DAT. Thirteen patients had < or = 8 years of schooling (less educated subgroup), and the other 11 had > or = 8 years (higher educated subgroup). There were no significant differences between the two subgroups regarding age and duration of symptoms. Performance within each subgroup was compared with that of a specific set of education-matched elderly controls. In the less educated subgroup, 10 patients evidenced a homogeneous pattern of cognitive impairment, with all cognitive areas being similarly affected. Conversely, 10 higher educated patients had at least one cognitive area relatively preserved in comparison with the others, characterizing a heterogeneous pattern of impairment. These data suggest that a high level of education may lead to a greater capacity to compensate for neuronal damage and determines specific patterns of cognitive impairment in DAT.

Aged↗
PubMed1994

Two cases of deep dyslexia in unilingual hispanophone aphasics.

This paper addresses the interaction between a particular cognitive property inherent to the human brain, i.e., the capacity to learn how to process written information in a manner such that reading words aloud can become a standard aspect of overt behavior, and some of the culture-linked characteristics of the written codes invented by the species. First, the paper reiterates that the Spanish written code is transparent to the point of entailing full graphophonemic conversion, i.e., reading behavior is possible without access to one's memory of written words (to one's "logographic lexicon"). The Ardila claim (Ardila, 1991; Ardila, Rosselli, & Pinzon, 1989) that certain clinical forms of acquired reading disorders which have been reported to occur among various cultural subgroups do not occur among unilingual readers of Spanish is then summarized. This is followed by two brief case reports of acquired aphasia in native speakers and fluent readers of Spanish; prototypical "deep dyslexia" was documented to exist in both cases (Ruiz & Ansaldo, 1990). The Ardila claim is thereafter assessed by reference to the notions of surface, phonological, and deep dyslexia; parameters such as educational background are taken into account in this discussion.

Aphasia↗
PubMed1994

Influence of affective words on lexical decision task in major depression.

In cognitive science, lexical decision task is used to investigate visual word recognition and lexical access. The issue of whether or not individuals who are depressed differ in their access to affectively laden words and specifically to words that have negative affect was examined. Based on some aspects of the Resource Allocation Model (Ellis), it was postulated that patients suffering from depression take more time to recognize items from an affective-loaded list. In order to compare their behavior in a lexical decision task, patients suffering from depression and healthy controls were studied. We hoped to find an interaction between the mood state of subjects and the categories (affective or neutral) of words. Two groups of right-handed adults served as subjects in our experiment. The first group consisted of 11 patients suffering from depression (mean age: 40.2; sd: 6.8). All of this group met the DSM-III-R and the Research Diagnostic Criteria for major depressive disorder. Severity of their disease was rated using the 24-item Hamilton Depressive Rating Scale. All patients suffering from depression were without psychotropic medication. The control group was composed of 24 subjects (mean age: 32.7; sd: 7.9). A depressive word-list and a neutral word-list were built and a computer was used for the lexical-decision task. A longer reaction time to detect the non-word stimuli (F1,33 = 11.19, p < 0.01) was observed with the patients by comparison to the normal subjects. In the analysis of the word stimuli, a group by list interaction (F1,33 = 7.18, p < 0.01) was found.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1994

Basal cortisol levels and cognitive deficits in human aging.

A group of 19 healthy elderly subjects previously shown to differ in terms of their cortisol levels over a 4 year period were administered a neuropsychological test battery assessing memory, attention, and language. Correlational analyses performed on various corticosteroid measures showed that the slope of the change in cortisol levels over time predicted cognitive deficits in this elderly population. Aged subjects showing a significant increase in cortisol levels with years and with high current basal cortisol levels were impaired on tasks measuring explicit memory and selective attention when compared to aged subjects presenting either decreasing cortisol levels with years or increasing cortisol levels with moderate current basal cortisol levels. We further showed that subjects presenting a decrease in cortisol levels with years performed as well as young healthy subjects with regard to cognitive performance. Thus, impaired cognitive performance was associated with recent evidence of hypothalamic-pituitary-adrenal (HPA) dysregulation and elevated basal cortisol levels. These results are consistent with recent animal studies showing the existence of subpopulations of aged rats that differ in HPA activity and cognitive performance. Finally, the pattern of cognitive results related to the cortisol history of subjects is in agreement with a role played by the hippocampus in age-related HPA dysfunction and cognitive performance.

Aged↗
PubMed1993

On the interdependency between attentional biases and visual field effects with bilateral presentations of stimuli.

Previous research indicates that bilateral presentations of visual stimuli yield greater visual field differences than unilateral ones. Although this fact has generally been interpreted by reference to functional models of hemispheric specialization, an alternative explanation has been offered, which suggests that it is artifactually caused by an attentional bias (AB). Indeed, consistent positive correlations between the direction of ABs and that of visual field effects have been reported. However, this relationship remains uncertain since different tasks, presented at different moments, have been used in order to document it. We report on a bilateral presentation task which controlled this potential discrepancy by mixing trials measuring ABs with those assessing visual field effects. We showed that, in a group of dextrals, the direction of the visual field effect is intimately correlated with that of the AB; subjects with a right AB showed a right visual field advantage, whereas subjects with a left AB showed a left visual field advantage; moreover, subjects with no overall AB did not show any visual field advantage. The results of this experiment confirm the fact that the formally reported correlations between the direction of ABs and visual field effects are determined by individual differences in ABs rather than by the task being used to assess them. This observation points to the necessity for further research on variables affecting the between-subjects variability in ABs with the use of bilateral presentations of visual stimuli.

Adult↗
PubMed1993

Jules Dejerine and his interpretation of pure alexia.

Dejerine's interpretation of pure alexia is routinely mentioned in all neuropsychological textbooks, yet the details of his account and the evidence on which it is based have never been subjected to a critical analysis. We provide such an evaluation in this paper, summarizing the behavioral data that Dejerine presented in his now famous case report and the theoretical framework he adopted to explain the phenomenon of alexia without agraphia. We also provide a link between Dejerine's work and current hypotheses on the nature of the syndrome.

Brain↗
PubMed1992

Educational level and the word frequency effect: a lexical decision investigation.

It is known that speed and accuracy in recognizing words are constrained by the frequency of occurrence of these words ("frequency effect"). This study examines the relationship between educational level and the word frequency effect. We postulated that individual exposure to words that are rated lower in frequency tables should be greater among subjects with higher education and therefore hypothesized that the magnitude of the frequency effect should not be as marked within such a population as among subjects with a lesser educational level. A total of 40 neurologically healthy adults, half with an average of 18 years of formal education and the other half with an average of 11 years, participated in a lexical decision experiment. Results confirmed our hypothesis; that is, significant frequency effects on reaction times were obtained in both groups but this effect was of greater magnitude for the less educated as opposed to the more educated subgroup. The significance of this finding is discussed by reference to current models of word recognition.

Adult↗
PubMed1991

[Aphasic disorders of spoken language].

Three levels of human language organization (or articulation) serve as reference for the analysis of different aphasic disorders of the oral language. They are: 1) phonetic transformations, 2) phonemic transformations, and 3) verbal transformations. From the disorders that affect the selection and integration of units corresponding to each of these three levels, the various aphasic utterances can be described. Aphasic disorders of auditory comprehension refer to a poor apprehension of the significant and/or the signified.

Aphasia↗