References of "Collette, Fabienne"
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See detailEXploration des processus inhibiteurs dans le vieillissement normal et la maladie d'Alzheimer
Collette, Fabienne ULg; Adam, Stéphane ULg; Hogge, Michaël et al

Conference (2005, November)

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See detailExploring the unity and diversity of the neural substrates of executive functioning
Collette, Fabienne ULg; Van der Linden, Martial ULg; Laureys, Steven ULg et al

in Human Brain Mapping (2005), 25(4), 409-423

Previous studies exploring the neural substrates of executive functioning used task-specific analyses, which might not be the most appropriate approach due to the difficulty of precisely isolating ... [more ▼]

Previous studies exploring the neural substrates of executive functioning used task-specific analyses, which might not be the most appropriate approach due to the difficulty of precisely isolating executive functions. Consequently, the aim of this study was to use positron emission tomography (PET) to reexamine by conjunction and interaction paradigms the cerebral areas associated with three executive processes (updating, shifting, and inhibition). Three conjunction analyses allowed us to isolate the cerebral areas common to tasks selected to tap into the same executive process. A global conjunction analysis demonstrated that foci of activation common to all tasks were observed in the right intraparietal sulcus, the left superior parietal gyrus, and at a lower statistical threshold, the left lateral prefrontal cortex. These regions thus seem to play a general role in executive functioning. The right intraparietal sulcus seems to play a role in selective attention to relevant stimuli and in suppression of irrelevant information. The left superior parietal region is involved in amodal switching/integration processes. One hypothesis regarding the functional role of the lateral prefrontal cortex is that monitoring and temporal organization of cognitive processes are necessary to carry out ongoing tasks. Finally, interaction analyses showed that specific prefrontal cerebral areas were associated with each executive process. The results of this neuro-imaging study are in agreement with cognitive studies demonstrating that executive functioning is characterized by both unity and diversity of processes. [less ▲]

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See detailInvolvement of both prefrontal and inferior parietal cortex in dual-task performance
Collette, Fabienne ULg; Olivier, L.; Van der Linden, Martial ULg et al

in Cognitive Brain Research (2005), 24(2), 237-251

This PET study explored the neural substrate of both dual-task management and integration task using single tasks that are known not to evoke any prefrontal activation. The paradigm included two simple ... [more ▼]

This PET study explored the neural substrate of both dual-task management and integration task using single tasks that are known not to evoke any prefrontal activation. The paradigm included two simple (visual and auditory) discrimination tasks, a dual task and an integration task (requiring simultaneous visual and auditory discrimination), and baseline tasks (passive viewing and hearing). Data were analyzed using SPM99. As predicted, the comparison of each single task to the baseline task showed no activity in prefrontal areas. The comparison of the dual task to the single tasks demonstrated left-sided foci of activity in the frontal gyrus (BA 9/46, BA 10/47 and BA 6), inferior parietal gyrus (BA 40), and cerebellum. By reference to previous neuroimaging studies, BA 9/46 was associated with the coordinated manipulation of simultaneously presented information, BA 10/47 with selection processes, BA 6 with articulatory rehearsal, and BA 40 with attentional shifting. Globally similar regions were found for the integration task, except that the inferior parietal gyrus was not recruited. These results confirm the hypothesis that the left prefrontal cortex is implicated in dual-task performance. Moreover, the involvement of a parietal area in the dual task is in keeping with the hypothesis that a parieto-frontal network sustains executive functioning. [less ▲]

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See detailFurther exploration of controlled and automatic memory processes in early Alzheimer's disease
Adam, Stéphane ULg; Van der Linden, Martial ULg; Collette, Fabienne ULg et al

in Neuropsychology (2005), 19(4), 420-427

The authors' aim in this study was to explore automatic and controlled processes in Alzheimer's disease (AD) by using a variant of the word-stem completion task that applies the process-dissociation ... [more ▼]

The authors' aim in this study was to explore automatic and controlled processes in Alzheimer's disease (AD) by using a variant of the word-stem completion task that applies the process-dissociation procedure. Several methodological precautions were taken in order to limit problems observed in previous studies (e.g., poor task sensitivity, ceiling and/or floor effects, no control over comprehension of instructions). Our results (a) confirmed the marked deterioration in controlled processes and (b) showed that when psychometric constraints were limited, automatic memory processes were preserved in AD. These data are in line with those from more global studies in suggesting that AD is characterized by an early deterioration in controlled processes and an initial preservation of automatic processes. [less ▲]

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See detailSelf-referential reflective activity and its relationship with rest : a PET study
D'Argembeau, Arnaud ULg; Collette, Fabienne ULg; Van der Linden, Martial ULg et al

in NeuroImage (2005), 25(2), 616-624

This study used positron emission tomography (PET) to identify the brain substrate of self-referential reflective activity and to investigate its relationship with brain areas that are active during the ... [more ▼]

This study used positron emission tomography (PET) to identify the brain substrate of self-referential reflective activity and to investigate its relationship with brain areas that are active during the resting state. Thirteen healthy volunteers performed reflective tasks pertaining to three different matters (the self, another person, and social issues) while they were scanned. Rest scans were also acquired, in which subjects were asked to simply relax and not think in a systematic way. The mental activity experienced during each scan was assessed with rating scales. The results showed that, although self-referential thoughts were most frequent during the self-referential task, some self-referential reflective activity also occurred during rest. Compared to rest, performing the reflective tasks was associated with increased blood flow in the dorsomedial prefrontal cortex, the left anterior middle temporal gyros, the temporal pole bilaterally, and the right cerebellum; there was a decrease of blood flow in right prefrontal regions,and in medial and right lateral parietal regions. In addition, the ventromedial prefrontal cortex (VMPFC) (1) was more active during the self-referential reflective task than during the other two reflective tasks, (2) showed common activation during rest and the self-referential task, and (3) showed a correlation between cerebral metabolism and the amount of self-referential processing. It is suggested that the VMPFC is crucial for representing knowledge pertaining to the self and that this is an important function of the resting state. [less ▲]

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See detailModulation of brain activity during phonological familiarization
Majerus, Steve ULg; Van der Linden, Martial ULg; Collette, Fabienne ULg et al

in Brain & Language (2005), 92(3), 320-331

We measured brain activity in 12 adults for the repetition of auditorily presented words and nonwords, before and after repeated exposure to their phonological form. The nonword phoneme combinations were ... [more ▼]

We measured brain activity in 12 adults for the repetition of auditorily presented words and nonwords, before and after repeated exposure to their phonological form. The nonword phoneme combinations were either of high (HF) or low (LF) phonotactic frequency. After familiarization, we observed, for both word and nonword conditions, decreased activation in the left posterior superior temporal gyrus, in the bilateral temporal pole and middle temporal gyri. At the same time, interaction analysis showed that the magnitude of decrease of activity in bilateral posterior temporal lobe was significantly smaller for LF nonwords, relative to words and HF nonwords. Decrease of activity in this area also correlated with the size of behavioral familiarization effects for LF nonwords. The results show that the posterior superior temporal gyrus plays a fundamental role during phonological learning. Its relationship to sublexical and lexical phonological processing as well as to phonological short-term memory is discussed. (c) 2004 Elsevier Inc. All rights reserved. [less ▲]

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See detailCerebral metabolic correlates of four dementia scales in Alzheimer's disease
Salmon, Eric ULg; Lespagnard, Solange ULg; Marique, Patricia et al

in Journal of Neurology (2005), 252(3), 283-290

Different scales can be used to evaluate dementia severity in Alzheimers disease (AD). They do assess different cognitive or functional abilities, but their global scores are frequently in mutual ... [more ▼]

Different scales can be used to evaluate dementia severity in Alzheimers disease (AD). They do assess different cognitive or functional abilities, but their global scores are frequently in mutual correlation. Functional imaging provides an objective method for the staging of dementia severity. Positron emission tomography was used to assess the relationship between brain metabolism and four dementia scales that reflect a patients global cognitive abilities (mini mental state), caregivers evaluation of cognitive impairment (newly designed scale), daily living functioning (instrumental activities of daily living) and global dementia (clinical dementia rating). We wondered whether different clinical dementia scales would be related to severity of metabolic impairment in the same brain regions, and might reflect impairment of common cognitive processes. 225 patients with probable AD were recruited in a prospective multicentre European study. All clinical scales were related to brain metabolism in associative temporal, parietal or frontal areas. A factorial analysis demonstrated that all scales could be classified in a single factor. That factor was highly correlated to decrease of cerebral activity in bilateral parietal and temporal cortices, precuneus, and left middle frontal gyrus. This finding suggests that global scores for all scales provided similar information on the neural substrate of dementia severity. Capitalizing on the neuroimaging literature, dementia severity reflected by reduced metabolism in posterior and frontal associative areas in AD might be related to a decrease of controlled processes. [less ▲]

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See detailTime-of-day modulations of rCBF response in functional brain imaging studies: a meta-analysis
Schmidt, Christina; Dang Vu, Thanh; Orban, Pierre et al

in NeuroImage (2005), 26(Suppl. 1),

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See detailEXploration des processus inhibiteurs dans le vieillissement normal et la maladie d'Alzheimer
Collette, Fabienne ULg; Adam, Stéphane ULg; Hogge, Michaël et al

in Revue Neurologique (2005), 161(12), 467

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See detailTwo Aspects of Impaired Consciousness in Alzheimer's Disease
Salmon, Eric ULg; Ruby, Perrine; Perani, Daniela et al

in Progress in Brain Research (2005), 150(Boundaries of Consciousness: Neurobiology and Neuropathology), 287-98

Alzheimer's disease (AD) is a degenerative dementia characterized by different aspects of impaired consciousness. For example, there is a deficit of controlled processes that require conscious processing ... [more ▼]

Alzheimer's disease (AD) is a degenerative dementia characterized by different aspects of impaired consciousness. For example, there is a deficit of controlled processes that require conscious processing of information. Such an impairment is indexed by decreased performances at controlled cognitive tasks, and it is related to reduced brain metabolic activity in a network of frontal, posterior associative, and limbic regions. Another aspect of impaired consciousness is that AD patients show variable levels of anosognosia concerning their cognitive deficits. A discrepancy score between patient's and caregiver's assessment of cognitive functions is one of the most frequently used measures of anosognosia. A high discrepancy score has been related to impaired activity in the superior frontal sulcus and the parietal cortex in AD. Anosognosia for cognitive deficits in AD could be partly explained by impaired metabolism in parts of networks subserving self-referential processes (e.g., the superior frontal sulcus) and perspective-taking (e.g., the temporoparietal junction). We hypothesize that these patients are impaired in the ability to see themselves with a third-person perspective (i.e., being able to see themselves as other people see them). [less ▲]

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See detailLa mémoire de travail
Collette, Fabienne ULg; Van der Linden, Martial ULg

in Gély-Nargeot, Marie-Christine; Ergis, Anne-Marie; Van der Linden, Martial (Eds.) Les troubles de la mémoire dans la maladie d'Alzheimer (2005)

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See detailExploration de l'administrateur central de la mémoire de travail au moyen de la tomographie par émission de positons (TEP)
Collette, Fabienne ULg

in Gueguen, B.; Chauvel, P.; Touchon, J. (Eds.) Neurophysiologie des mémoires (2005)

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See detailEvaluation de l’effet d’oubli induit à la récupération dans le vieillissement normal
Hogge, Michaël; Adam, Stéphane ULg; Collette, Fabienne ULg

Poster (2004, December 04)

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See detailStroop interference and negative priming in normal aging
Hogge, Michaël; Adam, Stéphane ULg; Collette, Fabienne ULg

Poster (2004, December 02)

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See detailAre spatial memories strengthened in the human hippocampus during slow wave sleep?
Peigneux, Philippe ULg; Laureys, Steven ULg; Fuchs, Sonia et al

in Neuron (2004), 44(3), 535-545

In rats, the firing sequences observed in hippocampal ensembles during spatial learning are replayed during subsequent sleep, suggesting a role for posttraining sleep periods in the offline processing of ... [more ▼]

In rats, the firing sequences observed in hippocampal ensembles during spatial learning are replayed during subsequent sleep, suggesting a role for posttraining sleep periods in the offline processing of spatial memories. Here, using regional cerebral blood flow measurements, we show that, in humans, hippocampal areas that are activated during route learning in a virtual town are likewise activated during subsequent slow wave sleep. Most importantly, we found that the amount of hippocampal activity expressed during slow wave sleep positively correlates with the improvement of performance in route retrieval on the next day. These findings suggest that learning-dependent modulation in hippocampal activity during human sleep reflects the offline processing of recent episodic and spatial memory traces, which eventually leads to the plastic changes underlying the subsequent improvement in performance. [less ▲]

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