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Biomedical subjects

A R Lecours

Publications and source records attributed to A R Lecours.

At least 37 records · Page 2Linked to original sources
PubMed1991

Visual neglect and left-sided context effects.

Patients with visual neglect generally fail to respond to an item placed on the left of a target location, even when both stimuli are situated in the right visual field. Little is known, however, about the level of processing for the unattended items. Two patients with left visual neglect served as subjects in several experiments measuring passive contextual effects of a left-sided item on responses to a focal target. The results reveal that a neglected item may influence the speed of responding. The findings are interpreted relative to the loci of context effects in normal subjects.

Aged↗
PubMed1990

Re-evaluating the effect of unilateral brain damage on simple reaction time to auditory stimulation.

Results of a previous experiments designed to test if there is a right hemisphere superiority over the left hemisphere in the capacity to react quickly to a stimulus have not lead to an unambiguous conclusion, although the majority of studies indicate that right-brain-damaged patients are generally slower than left-brain-damaged patients. The present experiment re-examines the speed of reaction time to auditory stimulation in a population of brain-damaged patients. Each case was presented with 120 auditory events and variable inter-trial intervals (from 1 s to 15 s). To ensure homogeneity of the population tested, only patients with a cerebro-vascular accident were chosen. The results show that the right-brain-damaged patients were not generally slower than left-brain-damaged patients. However, a marked deterioration in performance over time was observed in the right-hemisphere group while a small amount of improvement was found in the normal and left-brain-damaged patients. The outcome is discussed in terms of a sustained attention deficit associated with right-hemisphere damage.

Acoustic Stimulation↗
PubMed1989

Aging and the word frequency effect: a lexical decision investigation.

It is known that speed and accuracy in recognizing words are constrained by their frequency of occurrence ("frequency effect"). This study bears on the diachrony of the word frequency effect. Our postulates in this respect were (1) that a significant frequency effect should be present throughout adulthood, irrespective of age, and (2) that the magnitude of this effect should be greater among the elderly. Twenty young and 20 older healthy adults were submitted to a lexical decision experiment. Results confirmed our first postulate but invalidated the second one, that is, significant frequency effects were found in both groups but these effects were documented to be of identical magnitude. An attempt is made at explaining the latter result from a theoretical standpoint. The former is interpreted as further evidence that senescence (normal aging) does not interfere with passive, automatic and unconscious mental processes. Moreover, it is suggested that--if observed among otherwise apparently healthy elderly adults--modifications of the frequency effect might be taken as a cognitive marker of disease.

Adult↗
PubMed1988

Illiteracy and brain damage. 3: A contribution to the study of speech and language disorders in illiterates with unilateral brain damage (initial testing).

This report bears on the behavior of 188 unilateral stroke subjects when administered an aphasia screening test comprising a short interview as well as naming, repetition, word-picture matching and sentence-picture matching tasks. All subjects were unilingual lusophone adult (40 yr of age or older) right-handers. Furthermore, they were either totally unschooled illiterates or they had received school education and thereafter retained writing skills and reading habits. Subjects were tested less than 2 months after a first unilateral stroke. In all tasks, global error scores were greater among left and right brain-damaged illiterate and literate subjects than among their controls. In repetition and matching, these differences were statistically significant for the left but not for the right-stroke groups, irrespective of the literacy factor. In naming, on the other hand, significant differences were found not only for the two left-stroke groups but also for the right-stroke illiterate group although not for the right-stroke literate one. Likewise, some degree of word-finding difficulty and of reduction in speech output as well as sizeable production of phonemic paraphasias were observed in the interviews of several right-stroke illiterates, clearly less in those of right-stroke literates. These findings lead us to suggest that cerebral representation of language is more ambilateral in illiterates than it is in school educated subjects although left cerebral "dominance" remains the rule in both.

Aphasia↗
PubMed1988

Agrammatism in sentence production without comprehension deficits: reduced availability of syntactic structures and/or of grammatical morphemes? A case study.

A French-speaking patient with Broca's aphasia--following a left-hemisphere lesion involving the sylvian region but sparing Broca's area--is presented. Like G. Miceli, A. Mazzuchi, L. Menn, and H. Goodglass's (1983, Brain and Language, 19, 65-97) case 2, this patient produces agrammatic speech in the absence of any comprehension deficit. Unlike Miceli's patient, though, agrammatic speech can be observed in all sentence production tasks (from spontaneous speech to repetition, oral reading, and writing) whereas production of individual words--be they open class or closed class--is almost always intact. On the basis of extensive (psycho)linguistic testing, it is argued that this patient's deficit is not central and not crucially syntactic (at least) at the level of knowledge but seems to disrupt specifically those (automatic?) processes responsible for both retrieval and production of free-standing grammatical morphemes whenever they have to be inserted into phrases and sentences.

Aphasia↗
PubMed1987

Illiteracy and brain damage--1. Aphasia testing in culturally contrasted populations (control subjects).

One hundred neurologically healthy adults were tested for their pointing (choosing one of four or six line drawings as the match to an auditorily presented linguistic stimulus), naming (from line drawings), and repetition abilities. All subjects were unilingual adult right-handers. Fifty-seven subjects were totally unschooled illiterates and 43 were fluent readers. Statistically significant differences were found to exist between the scores of the illiterate and literate subpopulations across all tasks. With the focus being placed on these cultural differences, the discussion bears on: (a) the interaction between linguistic and iconographic factors in certain types of naming and pointing tasks currently used in clinical and research aphasiology, (b) some of the linguistic parameters which are apparently at stake in repetition behavior, and (c) the circumstances in which aphasiological research dealing with groups of patients cannot yield reliable data without reference to neurologically healthy controls. It is argued that, when testing brain-damaged patients of different cultural backgrounds, one runs the risk of over- or underestimating the frequency of aphasia if one does not refer to norms which explicitly take educational level into account.

Adult↗
PubMed1987

Illiteracy and brain damage. 2. Manifestations of unilateral neglect in testing "auditory comprehension" with iconographic materials.

This report concerns the sentence-picture matching behavior of 100 neurologically healthy and 169 brain-damaged subjects, all of whom were unilingual adult right-handers. Within this population, 144 subjects were totally unschooled illiterates and the remaining 125 had received school education and thereafter had retained writing skills and reading habits. Brain-damaged subjects were tested less than 2 months after a first left- or right-hemisphere stroke. All subjects were administered an aphasia screening battery including, among other subtests, a set of six sentence-picture matching stimuli. For each of these six stimuli, subjects heard a sentence uttered by the examiner and were then requested to match this sentence with one of four drawings presented within a single display divided into four quadrants of equal surface. Three sentences were syntactically "simple" (noun subject + verb) and three were relatively more "complex" (noun subject + verb + one or two noun complements). Evidence of unilateral neglect was found in both left- and right-brain-damaged illiterates and literates. Moreover, the right neglect of left-brain-damaged subjects was manifest mostly when target sentences were relatively "complex" whereas the left neglect of right-brain-damaged subjects was manifest irrespective of the syntactic complexity of target sentences. Our data are interpreted as indicative of an interaction between two cognitive disorders resulting from dysfunctions of asymmetrically represented cognitive mechanisms. The implications of these findings with respect to clinical and research aphasia testing are discussed.

Attention↗
PubMed1985

Anatomoclinical correlations of the aphasias as defined through computerized tomography: exceptions.

We have studied the frequency of exceptions to classical aphasia localizations in right-handed, literate, adult, native speakers of Italian with focal vascular left-hemisphere lesions, correlating clinical and computerized tomography data. Two hundred sixty-seven subjects were given computerized tomography (CT) examinations; lesions were mapped onto lateral diagrams and the sites of the lesions were defined. Patients were then classified as nonfluent aphasics, fluent aphasics, and nonaphasics. Patients with negative CT scans (n = 10) or only "deep" lesions (n = 50) were not studied for anatomoclinical correlations. Of the remaining 207 patients, 36 presented unexpected findings. There were seven cases of fluent aphasia and "anterior" CT lesions and six cases with nonfluent aphasia and "posterior" CT lesions among them. The significance of these findings is discussed.

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PubMed1985

[To the letter].

Explore the source record for details and available documents.

Adult↗
PubMed1983

Language in right-handers with right-hemisphere lesions: a preliminary study including anatomical, genetic, and social factors.

A comprehensive test battery was devised to study the effects of right hemisphere lesions on the speech and language of "nonaphasic" dextrals. Data were thus obtained for 62 subjects, 20 of them neurologically healthy and 42 with a focal right hemisphere lesion resulting from a cerebro-vascular accident. A preliminary global analysis of these data is reported. Anomalies were observed in 33 brain-damaged subjects. Although discreet in all cases, these anomalies were shown to have various degrees of severity. Given the population submitted to this study, the subject most likely to show such anomalies was defined, genetically, as a right-handed adult with a family history of ambidextrality or left-handedness and, socially, as one with a relatively limited education. The implications of these findings are discussed together with the problem of the anatomo-clinical correlations of language disorders resulting from right hemisphere lesions in "nonaphasic" dextrals.

Aged↗
PubMed1982

[Crossed aphasia in right-handed patients. I. Review of the literature].

More than 70 cases of crossed dextral aphasia have been reported in the literature since the end of the XIXth century. If a genetic, environmental or even pathological factor--or lack of information about it--could be suspected to be responsible of a majority of these cases, 10 of them in which all these factors were eliminated still remain. A summary of the neurological, neuropsychological and neurolinguistic features of these 10 cases shows, among other things: 1. that nearly all of them present a (left) motor deficit associated with a quite large and deep right-hemispheric lesion; 2. that most of them also report the presence of one or the other of the neuropsychological signs usually seen in right hemisphere lesions in dextrals; 3. that if reduction and agrammatism are frequent aphasic signs, fluent jargon is also reported, more so in written than in oral expression. Some of the hypotheses put forward to explain crossed aphasia in dextrals are discussed in the light of these facts. It appears that none of these hypotheses can satisfactorily account for the occurrence of a right hemisphere aphasia in some dextrals.

Adult↗
PubMed1982

[Crossed aphasia in right-handed patients. II. Neuropsychological and neurolinguistic study of a case. Evolution over a 2 year period].

We present an unusual case of crossed aphasia in a doctor who is totally right handed, following an infarction which almost completely destroyed his right hemisphere. The observations--linguistic and extra linguistic--during a study over two years are presented. The aphasia evolved in three stages, taking semiological and evolutive aspects not commonly met with. In speech and writing there were: 1. an oral agrammatism and a written dyssyntaxia in the initial stage; 2. the evolution of a non-fluent speech typically agrammatic leading to a jargonaphasia; 3. a dissociation between oral and written language, characterised by phonemic paraphasias in speech and dyssyntaxia in writing. Comprehension was good except for a verbal class called "empty signs" of language, in which the lexic which refers to the notion of space and time has a primary role. On an extra linguistic level some of the usual signs of right hemisphere lesions were present indicating disturbances of a spatial type. The patient could no longer grasp the concept of numerical value and showed severe difficulties in relation to time. On a linguistic level, the discussion is first considered from a typological point of view; this allows to compare our patient's disorders with a Broca's then with a conduction aphasia, Secondly, the discussion is considered from a semiological point of view, taking into consideration the 10 selected cases in the literature and adding our own; a semiological formula of crossed aphasia is given: agrammatism and/or dyssyntaxia + phonemic paraphasia and/or dysorthographia. A suggestion concerning the role of each hemisphere in the language of our patient is proposed: the possible role played by a congenital deafness in the right ear (discovered in the patient at the age of 8) to explain this abnormal hemispherical functional specialisation is discussed. Original comprehension difficulties concerning the time-space lexic are replaced by a perspective of a cognitive type. We conclude that in our patient, there was a "breakdown" of time and space which comes close to the "indifferenciation" of spatial order and time which Piaget has described in children.

Aphasia↗