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Biomedical subjects

P Goulet

Publications and source records attributed to P Goulet.

15 recordsLinked to original sources
PubMed2001

The effects of left- versus right-hemisphere lesions on the sensitivity to intra- and interconceptual semantic relationships.

Studies on split-brain, normal and brain-damaged subjects suggest differences in the processing of semantic relationships by the two hemispheres. Various authors have conceived of this distinction in terms of the paradigmatic/syntagmatic dissociation, and the connotative and denotative meanings of words, and as reflecting different types of links between words. Drews has suggested that a left-hemisphere lesion would affect the processing of intraconceptual relationships, while a right-hemisphere lesion would impair the processing of interconceptual relationships. The goal of this study was to test this hypothesis, using a number of intra- and interconceptual semantic relationships. Pairs of common words were submitted to left-hemisphere brain-damaged and right-hemisphere brain-damaged subjects. The task required subjects to indicate whether or not there was any relationship between the words. The results only partially support the hypothesis. The right/left opposition applied to only one of three types of intraconceptual relationships (whole-part relation) and to one of two types of interconceptual relationship (same location relation). This partially unexpected result is discussed in reference to other studies.

Aged↗
PubMed1999

Age-related evolution of the contribution of the right hemisphere to language: absence of evidence.

The age difference observed between Wernicke's and Broca's aphasics has been understood by some authors as an indication of a progressive diminution of the contribution of the right hemisphere to language throughout the life span. To test this hypothesis, 24 right-hemisphere-damaged (RHD) and 24 normal control adults were submitted to six tasks looking at different aspects of language abilities. Results showed that RHDs performed less well than normal subjects on 3 of these tasks, but that this difference was not linked with age (younger than 55 versus older than 65 years). Consequently, these results do not support models of functional brain organization suggesting a decreasing contribution of the right hemisphere to language abilities with age.

Acoustic Stimulation↗
PubMed1997

Word fluency after a right-hemisphere lesion.

Joanette and Goulet (Neuropsychologia, 1986, 24, 875-879) reported that right-handed patients suffering from a right-hemisphere stroke were impaired on semantic but not on orthographic criteria when they were submitted to a word fluency task. The interpretation of this dissociation was that the right hemisphere would subtend a particular contribution to the semantic component of word processing in right handers. The goal of the research reported here was to challenge this dissociation. In contrast with the first study, the production criteria were presented randomly and their level of productivity was a controlled factor. The semantic-orthographic dissociation was not replicated under these conditions.

Adult↗
PubMed1994

Sentence completion task in right-brain-damaged right-handers: Eisenson's study revisited.

This study investigated Eisenson's claim (Eisenson, 1962, 1973) that right-brain-damaged right-handers (RBDs) are impaired on a sentence completion task especially when they have to look for abstract words. Five sentences to be completed with concrete nouns and five sentences asking for abstract nouns were presented to 34 right-brain-damaged patients and to 19 normal control subjects. RBDs' performance differed from that of normals on both types of sentences when expected words were considered as the only acceptable answers, but was judged defective only for the sentences to be completed with abstract nouns when both expected words and adequate words were accepted. Moreover, of the RBDs, only 50% performed less well than 95% of the control subjects under this last condition. Factors such as age, education, and lesion site failed to characterize this subgroup of RBDs.

Brain Damage, Chronic↗
PubMed1994

Is there a decline in picture naming with advancing age?

This review of 25 studies of the picture-naming accuracy of normal aging individuals shows that an age-related decline in picture naming is an inconsistent finding. Naming performance of older adults varied throughout the studies reviewed in this paper. This variability is attributed to the research methods used and to subject characteristics. To date, there are no studies that have considered all "nuisance factors" (e.g., health status, medication) in such a way that would allow support for a decrease in picture-naming accuracy associated with primary aging.

Adolescent↗
PubMed1993

[Age and type of aphasia].

According to many studies, Broca's (or non fluent) aphasic patients are younger than Wernicke's (or fluent). Different hypotheses have been proposed to explain this age difference. However, since the studies in which an age difference was observed have not controlled all the variables--such as schooling and handedness--that may have an influence on speech and language impairments following cerebral lesion, it is legitimate to ask whether or not the explanations proposed are of any relevance. Accordingly, the present study aimed to investigate the age difference between Broca's and Wernicke's aphasics while achieving better control over potentially confounding variables. The subjects (9 Broca's and 14 Wernicke's) were selected from a data base according to the following selection criteria: aphasia type, handedness, localization of lesion and etiology (first CVA). The two groups revealed to be equivalent for sex distribution and schooling; post onset time was superior to three weeks for all subjects but one. Results showed that the distribution of age between Broca's and Wernicke's group were significantly different: there was a small representation of Broca's aphasics in older subjects while Wernicke's aphasia occurred at all ages.

Aged↗
PubMed1991

Text-level representations as one determinant for lexical retrieval and sentence production deficits in aphasia: comments on L. B. Zingeser and R. Sloan Berndt "Retrieval of nouns and verbs in agrammatism and anomia".

This note discusses the explanation put forward by Zingeser and Berndt (1990) in their attempt to account for agrammatism by reference to word-level representations. These authors have suggested that agrammatism could be the expression of some particular difficulties with the lexical retrieval of verbs. The present discussion suggests an alternative explanation making reference to text-level representations, and particularly to the lexicalization of predicates.

Anomia↗
PubMed1990

Discourse analysis in neuropsychology: comment on Chapman and Ulatowska.

This paper discusses a recent article by Chapman and Ulatowska (1989, Brain and Language, 36, 651-658) on discourse analysis in aphasia. As such, the research in this area is interdisciplinary drawing from neuropsychology, as well as cognitive psychology, and, in part, aging. We illustrate problems that can arise when theoretical constructs and methodological considerations in this interdisciplinary approach are not rigorously observed. It is argued that definitive conclusions regarding the functional organization of the brain and discourse can be offered only when discourse analysis uses the state of the art from neuropsychology and cognitive psychology.

Adult↗
PubMed1990

[Formal and semantic lexical evocation in normal subjects. Performance and dynamics of production as a function of sex, age and educational level].

A protocol of formal lexical evocation (words beginning with a letter) and semantic evocation was applied to 168 normal subjects evenly distributed on the basis of three factors (sex, three age classes and two levels of education). Correct answers, their distribution within the allotted time (proportions of correct answers in four thirty-second periods) and errors were analysed globally and in relation to the said factors. Level of education had a decisive influence in all tests; age had no influence on performance in formal evocation, whereas the subjects in the middle age class presented the best performance in semantic evocation. Distribution of the answers over time was unrelated to any of the factors considered. Errors were related to age in half the test.

Adult↗
PubMed1988

Impaired word naming in right-brain-damaged right-handers: error types and time-course analyses.

The purpose of this study is to search for cues that could account for the fact that right-hemisphere lesions affect word naming when the criterion for naming is semantic. The authors analyzed the errors as well as the time course of productions of 35 vascular right-brain-damaged subjects (RBD) and 20 control subjects (C) in a semantic-based word-naming task. Results show that there are no differences between groups in terms of (a) the number of errors produced and, (b) the patterns of error types. However, results also show a reduction of verbal fluency for semantic criteria in RBD-subjects present only after the first 30 seconds of production. These results indicate that reduction of word production in RBD-subjects is not the consequence of nonspecific factors such as perseveration or spontaneity, but reflects problems with the less automatized processes permitting exploration of semantic organization, either because scanning process are affected, or because the presence of a discreet semantic impairment prevents scanning from being as efficient. Given that efficient exploration of semantic knowledge is important for lexico-semantic functioning, the present results suggest that the right hemisphere contributes to some aspects of lexico-semantic processing necessary for language production.

Brain Damage, Chronic↗
PubMed1986

Criterion-specific reduction of verbal fluency in right brain-damaged right-handers.

Thirty-five vascular right brain-damaged (RBD) and 20 control (C) subjects were submitted to a verbal fluency task for which acceptability criteria were either semantic or formal. Results showed that subjects with a vascular lesion limited to the right hemisphere do show a statistically significant reduction of verbal fluency as compared to controls, that this reduction in verbal fluency is only present when the criterion is semantic, and that such a reduction is independent from the frontal or non-frontal topography of the lesion. These results tend to agree with the general conception of a--non-exclusive--right-hemisphere contribution to lexico-semantic processing, and more specifically to its semantic aspects.

Brain↗
PubMed1986

Informative content of narrative discourse in right-brain-damaged right-handers.

Thirty-six right-brain-damaged (RBD) right-handers and 20 controls (C) were submitted to a narrative production task using the pictorial representation of a trivial story. Each subject's narrative was analyzed, using a "propositional analysis," in order to study amount as well as nature of informative content. Results show that RBD subjects' narratives contain a smaller amount of information that did not appear to be related to a smaller amount of verbal output or to the presence of a visual neglect, that the information contained in RBD subjects' narratives appears to be a subset of that contained in C subjects' narratives, and that these results do not pertain to all C or RBD subjects, since both groups are nonhomogeneous. Even though these results are not linked to the presence of some visual neglect or visual agnosia per se, they could be, at least in part, the expression of some degree of perceptive difficulties of the iconography. However, they are also interpreted as expressing a problem with the organization of narrative discourse at levels of cognitive processing which may not be exclusive to language, but which are nonetheless essential for discourse organization.

Brain Damage, Chronic↗
PubMedDate not supplied

Resolution of pinhole collimators used with gamma cameras.

The line spread function (LSF) of an imaging system incorporating a pinhole of 0.275 cm radius and a scintillation camera has been measured and its full width at half maximum (FWHM) compared to the values predicted by an expression based on the resolution index of Anger. In most cases, the actual resolution of the system is approximately 20% superior to that predicted by the above expression. However, good agreement is observed between our measured LSFs and those computed using a frequency domain method. Based on these computed LSFs, an empirical expression relating the FWHM of the total system to pinhole and camera parameters with an accuracy of +/- 3% is presented. This expression is applicable to most pinhole imaging systems in use today.

Gamma Rays↗