References of "Collette, Fabienne"
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See detailNeural substrates of phonological and lexicosemantic representations in Alzheimer's disease.
Peters, Frederic; Majerus, Steve ULg; Collette, Fabienne ULg et al

in Human Brain Mapping (2009), 30(1), 185-99

The language profile of patients suffering from Alzheimer's disease (AD) is characterized not only by lexicosemantic impairments but also by phonological deficits, as shown by an increasing number of ... [more ▼]

The language profile of patients suffering from Alzheimer's disease (AD) is characterized not only by lexicosemantic impairments but also by phonological deficits, as shown by an increasing number of neuropsychological studies. This study explored the functional neural correlates underlying phonological and lexicosemantic processing in AD. Using H(215)O PET functional brain imaging, a group of mild to moderate AD patients and a group of age-matched controls were asked to repeat four types of verbal stimuli: words, wordlike nonwords (WL+), non-wordlike nonwords (WL-) and simple vowels. The comparison between the different conditions allowed us to determine brain activation preferentially associated with lexicosemantic or phonological levels of language representations. When repeating words, AD patients showed decreased activity in the left temporo-parietal and inferior frontal regions relative to controls, consistent with distorted lexicosemantic representations. Brain activity was abnormally increased in the right superior temporal area during word repetition, a region more commonly associated with perceptual-phonological processing. During repetition of WL+ and WL- nonwords, AD patients showed decreased activity in the middle part of the superior temporal gyrus, presumably associated with sublexical phonological information; at the same time, AD patients showed larger activation than controls in the inferior temporal gyrus, typically associated with lexicosemantic levels of representation. Overall, the results suggest that AD patients use altered pathways to process phonological and lexicosemantic information, possibly related to a progressive loss of specialization of phonological and lexicosemantic neural networks. [less ▲]

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See detailOn the multivariate nature of brain metabolic impairment in Alzheimer’s disease
Salmon, Eric ULg; Kerrouche, Nacer; Perani, Daniela et al

in Neurobiology of Aging (2009), 30

We used principal component analysis to decompose functional images of patients with AD in orthogonal ensembles of brain regions with maximal metabolic covariance. Three principal components explained 38 ... [more ▼]

We used principal component analysis to decompose functional images of patients with AD in orthogonal ensembles of brain regions with maximal metabolic covariance. Three principal components explained 38% of the total variance in a large sample of FDG-PET images obtained in 225 AD patients. One functional ensemble (PC2) included limbic structures from Papez's circuit (medial temporal regions, posterior and anterior cingulate cortex, thalamus); its disruption in AD patients was related to episodic memory impairment. Another principal component (PC1) illustrated major metabolic variance in posterior cerebral cortices, and patients' scores were correlated to instrumental functions (language and visuospatial abilities). PC3 comprised frontal, parietal, temporal and posteromedial (posterior cingulate and precuneus) cortices, and patients' scores were related to executive dysfunction and global cognitive impairment. The three main metabolic covariance networks converged in the posterior cingulate area that showed complex relationships with medial temporal structures within each PC. Individual AD scores were distributed as a continuum along PC axes: an individual combination of scores would determine specific clinical symptoms in each patient. [less ▲]

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See detailHomeostatic sleep pressure and responses to sustained attention in the suprachiasmatic area.
Schmidt, Christina ULg; Collette, Fabienne ULg; Leclercq, Yves ULg et al

in Science (2009), 324(5926), 516-9

Throughout the day, cognitive performance is under the combined influence of circadian processes and homeostatic sleep pressure. Some people perform best in the morning, whereas others are more alert in ... [more ▼]

Throughout the day, cognitive performance is under the combined influence of circadian processes and homeostatic sleep pressure. Some people perform best in the morning, whereas others are more alert in the evening. These chronotypes provide a unique way to study the effects of sleep-wake regulation on the cerebral mechanisms supporting cognition. Using functional magnetic resonance imaging in extreme chronotypes, we found that maintaining attention in the evening was associated with higher activity in evening than morning chronotypes in a region of the locus coeruleus and in a suprachiasmatic area (SCA) including the circadian master clock. Activity in the SCA decreased with increasing homeostatic sleep pressure. This result shows the direct influence of the homeostatic and circadian interaction on the neural activity underpinning human behavior. [less ▲]

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See detailPerspective taking to assess self-personality: What's modified in Alzheimer's disease?
Ruby, Perrine; Collette, Fabienne ULg; D'Argembeau, Arnaud ULg et al

in Neurobiology of Aging (2009), 30(10), 1637-1651

Personality changes are frequently described by caregivers of patients with Alzheimer's disease, while they are less often reported by the patients. This relative anosognosia of Alzheimer disease (AD ... [more ▼]

Personality changes are frequently described by caregivers of patients with Alzheimer's disease, while they are less often reported by the patients. This relative anosognosia of Alzheimer disease (AD) patients for personality changes might be related to impaired self-judgment and to decreased ability to understand their caregiver's perspective. To investigate this issue, we explored the cerebral correlates of self-assessment and perspective taking in patients with mild AD, elderly and young volunteers. All subjects assessed relevance of personality traits adjectives for self and a relative, taking either their own or their relative's perspective, during a functional imaging experiment. The comparison of subject's and relative's answers provided congruency scores used to assess self-judgment and perspective taking performance. The self-judgment "accuracy" score was diminished in AD, and when patients assessed adjectives for self-relevance, they predominantly activated bilateral intraparietal sulci (IPS). Previous studies associated IPS activation with familiarity judgment, which AD patients would use more than recollection when retrieving information to assess self-personality. When taking a third-person perspective, patients activated prefrontal regions (similarly to young volunteers), while elderly controls recruited visual associative areas (also activated by young volunteers). This suggests that mild AD patients relied more on reasoning processes than on visual imagery of autobiographical memories to take their relative's perspective. This strategy may help AD patients to cope with episodic memory impairment even if it does not prevent them from making some mind-reading errors. [less ▲]

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See detailInhibitory control of memory in normal ageing: Dissociation between impaired intentional and preserved unintentional processes.
Collette, Fabienne ULg; Germain, Sophie ULg; Hogge, Michaël et al

in Memory (2009), 17(1), 104-122

The aim of this study was to compare the performance of elderly and young participants on a series of memory tasks involving either intentional or unintentional inhibitory control of memory content ... [more ▼]

The aim of this study was to compare the performance of elderly and young participants on a series of memory tasks involving either intentional or unintentional inhibitory control of memory content. Intentional inhibition processes in working and episodic memory were explored with directed forgetting tasks and in semantic memory with the Hayling task. Unintentional inhibitory processes in working memory, long-term memory, and semantic memory were explored with an interference resolution task, the retrieval practice paradigm, and the flanker task, respectively. The results indicate that elderly participants' performance on the two directed forgetting tasks and the Hayling task is lower than that of young ones, and that this impairment is not related to their initial memory capacity. This suggests that there is a specific dysfunction affecting intentional inhibitory control of memory contents in normal ageing. [less ▲]

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See detailLes déficits d’inhibition : vieillissement normal et pathologique
Collette, Fabienne ULg

Scientific conference (2008, October 24)

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See detailInfluence des processus attentionnels sur le fonctionnement exécutif lors du vieillissement normal
Collette, Fabienne ULg; Hogge, Michaël

Conference (2008, September 04)

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See detailExploration du réseau cérébral impliqué dans des jugements sur soi chez les personnes jeunes et âgées
Feyers, Dorothée ULg; Collette, Fabienne ULg; D'Argembeau, Arnaud ULg et al

Poster (2008, September 04)

Nous avons récemment observé que le cortex préfrontal ventro-médial (CPFVM) est activé à la fois chez des sujets jeunes et âgés dans une tâche de jugement d’adjectifs nécessitant d’évaluer sa propre ... [more ▼]

Nous avons récemment observé que le cortex préfrontal ventro-médial (CPFVM) est activé à la fois chez des sujets jeunes et âgés dans une tâche de jugement d’adjectifs nécessitant d’évaluer sa propre personnalité par rapport à celle d’un autre dans le contexte d’un prise de perspective à la première (1PP) et à la troisième (3PP) personne (Ruby et al., submitted). Nous avons poursuivi l’analyse de ces données par des analyses de connectivité fonctionnelle afin de déterminer le réseau des régions cérébrales associées à la performance des sujets jeunes et âgés. Les résultats montrent qu’en 1PP, l’activité du CPFVM est associée à celle du gyrus frontal inférieur et du gyrus parahippocampique chez les sujet âgés, mais uniquement à celle du cortex occipital chez les sujets jeunes. En 3PP, une connectivité fonctionnelle existe entre le CPFVM et le gyrus frontal médial, le gyrus frontal inférieur et les régions temporales supérieures chez les sujets âgées ; mais uniquement avec les régions occipitale et pariétale chez les sujets jeunes. Les régions cérébrales associées à l’activité du CPFVM chez les sujets jeunes ont été décrites comme impliquées dans la récupération en mémoire autobiographique ainsi que dans les processus de « mentalizing ». En ce qui concerne les personne âgées, le réseau cérébral découvert est relié à la récupération de souvenirs sémantique et épisodique (gyrus parahippocampique et temporal supérieur) mais aussi à l’attribution d’une valence émotionnelle à l’adjectif (gyrus frontal inférieur) et à la prise de perspective (gyrus frontal médial). Ces résultats indiquent (1) que le CPFVM est connecté à un réseau cérébral plus important chez les personnes âgées que chez les jeunes lors de jugement sur soi ; (2) que les sujets jeunes réalisent la tâche sur base d’informations autobiographiques seulement alors que les personnes âgées recrutent en plus des processus cognitifs de nature plus réflexive. [less ▲]

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See detailNeural network involved in self-judgment in young and elderly adults
Feyers, Dorothée ULg; Collette, Fabienne ULg; D'Argembeau, Arnaud ULg et al

Poster (2008, May 29)

In agreement with the literature, we have recently observed that the ventro-medial prefrontal cortex (VMPFC) is activated both in young and elderly subjects during a adjective judgment task requiring ... [more ▼]

In agreement with the literature, we have recently observed that the ventro-medial prefrontal cortex (VMPFC) is activated both in young and elderly subjects during a adjective judgment task requiring judgment about self vs. other in the context of a first (1PP) or third (3PP) perspective-taking (Ruby et al., submitted). Here, we have performed functional connectivity analyses to determine the network of cerebral areas associated to the performance of young and elderly subjects. <br />Results indicate that, in the 1PP condition, activity of the VMPFC is related to the inferior frontal gyrus, parahippocampal gyrus in elderly but to the occipital cortex only in young subjects. In the 3PP condition, functional connectivity exist between the VMPFC and medial frontal gyrus, inferior frontal gyrus and superior temporal areas in elderly, but with occipital and parietal areas only in young subjects. <br />The cerebral areas associated to VMPFC activity in young subjects were previously described as involved both in autobiographical memory retrieval and mentalizing processes. With regard to elderly, the cerebral network evidenced is related to retrieval of semantic and episodic memories (parahippocampal and superior temporal) but also to the attribution of emotional valence to the adjectives (inferior frontal) and perspective taking (medial frontal gyrus). <br />These results indicate (1) that the VMPFC is connected to a larger cerebral network in elderly than in young subjects during self judgements; (2) that young subjects perform the task on the basis of autobiographical information retrieval only, while elderly subjects use supplementary, more reflexive, cognitive processes. [less ▲]

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See detailModifications cognitives liées au vieillissement normal
Collette, Fabienne ULg

Scientific conference (2008, May 27)

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See detailFunctional imaging of cognition in Alzheimer's disease using positron emission tomography
Salmon, Eric ULg; Lekeu, Françoise ULg; Garraux, Gaëtan ULg et al

in Neuropsychologia (2008), 46(6), 1613-1623

Positron emission tomography in Alzheimer's disease (AD) demonstrates a metabolic decrease, predominantly in associative posterior cortices (comprising the posterior cingulate cortex), and also involving ... [more ▼]

Positron emission tomography in Alzheimer's disease (AD) demonstrates a metabolic decrease, predominantly in associative posterior cortices (comprising the posterior cingulate cortex), and also involving medial temporal structures and frontal regions at a lesser degree. The level of activity in this wide network is roughly correlated with dementia severity, but several confounds (such as age, education or subcortical ischemic lesions) may influence the brain-behaviour relationship. Univariate analyses allow one to segregate brain regions that are particularly closely related to specific neuropsychological performances. For example, a relationship was established between the activity in lateral associative cortices and semantic performance in AD. The role of semantic capacities (subserved by temporal or parietal regions) in episodic memory tasks was also emphasized. The residual activity in medial temporal structures was related to episodic memory abilities, as measured by free recall performance, cued recall ability and recognition accuracy. More generally, AD patients' performance on episodic memory tasks was correlated with the metabolism in several structures of Papez's circuit (including the medial temporal and posterior cingulate regions). Multivariate analyses should provide complementary information on impaired metabolic covariance in functional networks of brain regions and the consequences for AD patients' cognitive performance. More longitudinal studies are being conducted that should tell us more about the prognostic value of initial metabolic impairment and the neural correlates of progressive deterioration of cognitive performance in AD. [less ▲]

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See detailFonctions exécutives et vieillissement
Collette, Fabienne ULg

Scientific conference (2008, April 24)

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See detailNeural network involved in young and elderly adults
Feyers, Dorothée ULg; Collette, Fabienne ULg; D'Argembeau, Arnaud ULg et al

in Proceedings of the Cognitive Aging Conference (2008, April 11)

In agreement with the literature, we have recently observed that the ventro-medial prefrontal cortex (VMPFC) is activated both in young and elderly subjects during a adjective judgment task requiring ... [more ▼]

In agreement with the literature, we have recently observed that the ventro-medial prefrontal cortex (VMPFC) is activated both in young and elderly subjects during a adjective judgment task requiring judgment about self vs. other in the context of a first (1PP) or third (3PP) perspective-taking (Ruby et al., submitted). Here, we have performed functional connectivity analyses to determine the network of cerebral areas associated to the performance of young and elderly subjects. Results indicate that, in the 1PP condition, activity of the VMPFC is related to the medial orbito-frontal, posterior and inferior temporal and parietal areas in elderly, but to the occipital cortex only in young subjects. In the 3PP condition, functional connectivity exist between the VMPFC and posterior temporal and lateral orbito-frontal areas in elderly, but with occipital and parietal areas only in young subjects. The cerebral areas associated to VMPFC activity in young subjects were previously described as involved both in autobiographic memory retrieval and mentalizing processes. With regard to elderly, the cerebral network evidenced is related to autobiographic memory retrieval (parietal and temporal areas) but also to the attribution of emotional valence to the adjectives (medial orbito-frontal) and perspective taking both in 1PP and 3PP conditions (lateral orbito-frontal). These results indicate (1) that the VMPFC is connected to a larger cerebral network in elderly than in young subjects during self judgements; (2) that young subjects perform the task on the basis of autobiographical information retrieval only, while elderly subjects use supplementary, more reflexive, cognitive processes. [less ▲]

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See detailInteractions entre la mémoire de travail et les autres domaines de la cognition
Collette, Fabienne ULg

Scientific conference (2008, March 19)

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See detailChronotype-dependent performance modulation according to time of day : a functional neuroimaging approach
Schmidt, Christina; Collette, Fabienne ULg; Sterpenich, Virginie et al

in NeuroImage (2008), 41(Suppl. 1),

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See detailOwl or lark? Stroop-related cerebral activity is modulated by time of day and chronotype
Schmidt, Christina; Collette, Fabienne ULg; Sterpenich, Virginie et al

in Journal of Sleep Research (2008), 17(Suppl. 1),

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See detailLes troubles cognitifs associés au vieillissement normal
Collette, Fabienne ULg

in Proceedings du congrès "L'homme au coeur des dynamiques sociales, territoriales et culturelles" (2008)

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See detailImagerie cérébrale de la réflexion sur soi
Salmon, Eric ULg; D'Argembeau, Arnaud ULg; Bastin, Christine ULg et al

in Revue Médicale de Liège (2008), 63

Precise brain regions are activated when a subject gives a judgment on himself. Those are the medial parietal cortex, essentially related to episodic memory processing, and the ventromedial prefrontal ... [more ▼]

Precise brain regions are activated when a subject gives a judgment on himself. Those are the medial parietal cortex, essentially related to episodic memory processing, and the ventromedial prefrontal cortex, recruited for evaluating the personal valence of an information. These regions are not activated in Alzheimer's disease. The decrease of awareness for own deficits in a patient with Alzheimer's disease would depend on a reduction of episodic memory capacities and a worsening of judgment for self significance. [less ▲]

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