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Biomedical subjects

Y Joanette

Publications and source records attributed to Y Joanette.

At least 19 recordsLinked to original sources
PubMed2004

Neural basis of emotional self-regulation in childhood.

Emotional self-regulation plays a pivotal role in socialization and moral development. This capacity critically depends on the development of the prefrontal cortex (PFC). The present functional magnetic resonance imaging study was conducted to identify the neural circuitry underlying voluntary self-regulation of sadness in healthy girls (aged 8-10). A 2 x 2 factorial design was implemented with Emotion (No Sadness vs. Sadness) and Regulation (No Reappraisal vs. Reappraisal) as factors. In the No Reappraisal conditions, subjects were instructed to react normally to neutral and sad film excerpts whereas in the Reappraisal conditions, subjects were asked to voluntarily suppress any emotional reaction in response to comparable stimuli. A significant interaction of the Emotion and Regulation factors revealed that reappraisal of sad film excerpts was associated with bilateral activations of the lateral PFC (LPFC; Brodmann areas [BA] 9 and 10), orbitofrontal cortex (OFC; BA 11), and medial PFC (BA 9 and 10). Significant loci of activations were also detected in the right anterior cingulate cortex (BA 24/32) and right ventrolateral PFC (BA 47). In an identical study previously conducted by our group in adult women [Biol Psychiatry 53 (2003) 502], reappraisal of sad film excerpts was associated with activation of the right OFC (BA 11) and right LPFC (BA 9). The greater number of prefrontal loci of activation found in children relative to adults during voluntary self-regulation of sadness may be related to the immaturity of the prefronto-limbic connections in childhood.

Behavior↗
PubMed2004

Coexistence of reactive plasticity and neurodegeneration in Alzheimer diseased brains.

Alzheimer's disease (AD) is a pathological process characterized by neuron degeneration and, as recently suggested, brain plasticity. In this work, we compared the reactive plasticity in AD brains associated to O-glycosydically linked glycans, recognized by lectins from Amaranthus leucocarpus (ALL) and Macrobrachium rosenbergii (MRL), and the tau neuritic degeneration. The neuritic degenerative process was evaluated by the quantification of aggregated neuritic structures. Lesions were determined using antibodies against hyperphosphorylated-tau (AD2), amyloid-beta, and synaptophysin. In these conditions, we classified and quantified three pathological structures associated to the neuritic degenerative process: 1) Amyloid-beta deposits (AbetaDs), 2) Classic neuritic plaques (NPs), and 3) Dystrophic neurites clusters (DNCs) lacking amyloid-beta deposits. Reactive plasticity structures were constituted by meganeuritic clusters (MCs) and peri-neuronal sprouting in neurons of the CA4 region of the hippocampus, immunoreactive to synaptophysin (exclusively in AD brains) and GAP-43. Besides, MCs were associated to sialylated O-glycosydically linked glycans as determined by positive labeling with ALL and MRL. Considering that these lectins are specific for the synaptic sprouting process in AD, our results suggest the co-occurrence of of several areas of reactive plasticity and neuron degeneration in AD.

Aged↗
PubMed2003

Neural correlates of sad feelings in healthy girls.

Emotional development is indisputably one of the cornerstones of personality development during infancy. According to the differential emotions theory (DET), primary emotions are constituted of three distinct components: the neural-evaluative, the expressive, and the experiential. The DET further assumes that these three components are biologically based and functional nearly from birth. Such a view entails that the neural substrate of primary emotions must be similar in children and adults. Guided by this assumption of the DET, the present functional magnetic resonance imaging study was conducted to identify the neural correlates of sad feelings in healthy children. Fourteen healthy girls (aged 8-10) were scanned while they watched sad film excerpts aimed at externally inducing a transient state of sadness (activation task). Emotionally neutral film excerpts were also presented to the subjects (reference task). The subtraction of the brain activity measured during the viewing of the emotionally neutral film excerpts from that noted during the viewing of the sad film excerpts revealed that sad feelings were associated with significant bilateral activations of the midbrain, the medial prefrontal cortex (Brodmann area [BA] 10), and the anterior temporal pole (BA 21). A significant locus of activation was also noted in the right ventrolateral prefrontal cortex (BA 47). These results are compatible with those of previous functional neuroimaging studies of sadness in adults. They suggest that the neural substrate underlying the subjective experience of sadness is comparable in children and adults. Such a similitude provides empirical support to the DET assumption that the neural substrate of primary emotions is biologically based.

Behavior Therapy↗
PubMed2002

[Mild cognitive impairments in the elderly: a critical review].

The aging of the population leads to increased awareness of problems associated with age-related degenerative dementias. Given that these dementias are progressive in onset, many clinicians and researchers have proposed criteria that allow for the identification of older subjects manifesting cognitive impairment, but not responding to the criteria for dementia. Our knowledge of subjects with mild cognitive impairment is limited; it is, however, established that they present a high risk of developing dementia in the future. Although it is essential to increase our comprehension of their cognitive and functional decline, the study of subjects presenting mild cognitive impairment is compromised due to the existence of numerous non-converging classifications. The goal of the present article is to conduct a critical review of the different classifications of mild cognitive impairment in the elderly in order to attempt to identify the optimal criteria, allowing for a distinction to be made between subjects with mild cognitive impairment, who remain in a stable state and those whose condition evolves to a dementia. These criteria may enable us to describe a homogenuous group of individuals presenting with different rates of dementia risk factors. We present the classifications most frequently used in clinical and research settings. After listing them according to categorial, clinical or dimensional approaches, we performed a critical analysis for each one. Depending on the diagnostic criteria applied, major variations are revealed for the prevalence of cognitive impairment and the incidence of dementia. They are explained by methodological and theoretical shortcomings that we point out and discuss (e.g., reference group, lack of diagnostic criteria or exclusion criteria, high level of subjectivity). Beyond these criticisms, we discuss the challenges to be met in order to reach the optimal identification criteria. Notably, the impact of mild cognitive impairment on daily living activities should be tested with the use of more specific questionnaires/tasks. The goal of the objective definition of cognitive impairment should be to minimize subjectivity in the diagnosis. It is also suggested that sensitive cognitive measures would be used on all aspects of cognition, while recognizing and taking into account all confounding factors (e.g., age, education level). Given the nature and consequences of mild cognitive impairment, an inter-disciplinary approach is suggested (e.g., neurobiological, psychiatric, and genetic cues). A consensus on optimal diagnostic criteria is essential to propose cognitive and pharmacological treatments for the effective prevention of ementia.

Age Factors↗
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↗
PubMed2000

Conceptual apraxia and semantic memory deficit in Alzheimer's disease: two sides of the same coin?

This study was designed to examine the patterns of apraxic disturbances and the relationships between action knowledge and other measures of semantic knowledge about objects in 10 well-characterized Alzheimer's disease (AD) patients. Five tasks were used to assess components of action knowledge (action-tool relationships, pantomime recognition, and sequential organization of action) and praxis execution (actual use, pantomiming) according to the cognitive model of praxis. Three tasks (verbal comprehension, naming, and a visual semantic matching task) were used to assess verbal-visual semantics. Considering patterns of apraxia first, conceptual apraxia was found in 9 out of the 10 AD patients, suggesting that it is a common feature even in the early stages of AD. Second, we found partly parallel deficits in tests of action-semantic and verbal-visual semantic knowledge in 9 AD patients. Impaired action knowledge was found only in patients with a semantic language deficit. These findings provide no evidence that "action semantics" may be separated from other semantic information. Our results support the view of a unitary semantic system, given that the representations of action-semantic and other semantic knowledge of objects are often simultaneously disrupted in AD.

Aged↗
PubMed2000

[Plurality of patterns of cognitive impairment in normal aging and in dementia].

Normal aging, as well as most of the degenerative diseases of the central nervous system characterizing old age, have an impact on cognitive abilities which are obvious as well as increasingly understood. Cognitive changes in normal ageing realize a plurality of possible patterns of cognitive disabilities. Dementias are also well known to be characterized by a plurality of cognitive impairments patterns. The different cognitive patterns are likely to be due to distinct levels of impairments of different domains of cognition, or of different components within one given domain of cognition. These differences are such that in some cases they can even realize double dissociations. The plurality of cognitive impairments patterns in normal aging and in dementia will be discussed as well as the different factors that could contribute to such a plurality. Some of these factors relate to pre-morbid characteristics of the individuals known to influence the functional organization of the brain for cognition. Others--of major importance--are related to the nature and the distribution of the pathophysiological processes underlying normal ageing or a given degenerative disease. It is also reminded that some or many of these factors can interact with more general cognitive factors, such as speed of execution. It is however suggested that, despite of their presence, these general factors partly contribute to the cognitive impairments in neurodegenerative dementia. In this case, the impact of different disease-related factors over a general cognitive factor is probably much greater than in the case of normal aging.

Aged↗
PubMed1999

Clinical note: acquired pragmatic impairments and aphasia.

Recent advances in the field of communication sciences have led to the description of acquired communication disorders affecting pragmatic skills in patients with brain damage. The present article discusses the impact of such findings on the clinical concept of aphasia. Through reference to a number of articles contained in this Special Issue, it must be reiterated that pragmatic and other linguistic components of communication abilites are two sides of a same coin-that of language-and intimately interrelated. It is also argued that the difference between traditional (e.g., syntax) and pragmatic components of language cannot be explained in simple terms such as the former being subserved only by linguistic processes and the latter by other cognitive processes. Pragmatic components are thus to be considered as part of language. The evolution of the concept of language has a direct impact on the clinical concept of aphasia. Indeed, if aphasia corresponds to an acquired impairment of language, then pragmatic impairments must be considered part of aphasia. The inclusion of pragmatic impairments in the concept of aphasia does not hold only when they occur within the frame of classic types of aphasia, but also when they occur in isolation. Consequently, a new type of aphasia-pragmatic aphasia-should be considered and defined in order to describe the clinical condition of those individuals suffering from acquired pragmatic disorders as those reported among right-hemisphere-damaged right-handers. It is concluded that the recent evolution around the concept of language should be followed by an evolution of the concept of aphasia per se.

Aphasia↗
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↗
PubMed1998

Postcomatose unawareness in a brain-injured population.

Different states of unawareness are present following a coma in the brain-injured population. An attempt to answer three questions is made based on a review of the literature and multiple case studies: Which type of sensory and motor stimulation can be suggested? Which instruments can be used to measure behaviors and what are their benefits and limitation? Does learning theory help explain the postcomatose unawareness experience? The theoretical paradigm strongly suggests employing learning theory to target a precise behavior to unmask learning potential and to use known remediation mechanisms such as errorless learning or implicit learning. Speculations in the area of unmasking potential are available; these require intervention to target specific function that could be lost with nonuse.

Adolescent↗
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

Analysis of conversational topic shifts: a multiple case study.

Investigation into the natural conversational discourse of patients with Dementia of the Alzheimer Type has received minimal attention, in part due to the inherent methodological problems. There are no satisfactory theoretical models of conversation; existing global checklists give minimal information on meaning relationships and analysis of conversation does not lend itself to group studies. The present study offered an initial example of how meaning relationships, expressed through topic shifting behavior, can be described in DAT and normal elderly subjects in natural conversational discourse. Categorization of topic units was done in an attempt to describe general phenomena, type of shift, reason for shift, and contextual relationship. Although very little differences were visually observed in the general categories, some convergence of data were observed in other topic shift categories. Discussion of the results in relation to a discourse processing model is presented.

Aged↗
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↗
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↗
PubMed1996

The effects of age-induced changes in communicative abilities on the type of aphasia.

The purpose of this study was to explore the possibility that some normal age-related changes in aspects of conversational discourse could account for the recurrent finding in aphasiology that fluent aphasics are approximately a decade older than their nonfluent counterparts. Normal subjects taken from two age groups representative of the mean age of fluent and nonfluent aphasics were submitted to an interview similar to the one used with aphasic patients in order to evaluate fluency. Results showed that, in answer to both closed and open questions, older subjects' discourse was made up of more than three times as many morphemes as younger subjects' discourse. The increase in fluency was more marked for men than it was for women. Thus, discourse-expressed changes in communicative strategies among the elderly could contribute to the semiology of language impairments in such a way that nonfluent aphasias would be more frequent. The reasons for this change in normal controls are still unknown but have been proposed to range from biological to sociological age-related characteristics of the individual.

Age Factors↗