References of "Degueldre, Christian"
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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 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 detailThe neural correlates of implicit and explicit sequence learning : Interacting networks revealed by the process dissociation procedure
Destrebecqz, Arnaud; Peigneux, Philippe ULg; Laureys, Steven ULg et al

in Learning & Memory (Cold Spring Harbor, N.Y.) (2005), 12(5), 480-490

In two (H15O)-O-2 PET scan experiments, we investigated the cerebral correlates of explicit and implicit knowledge in a serial reaction time (SRT) task. To do so, we used a novel application of the ... [more ▼]

In two (H15O)-O-2 PET scan experiments, we investigated the cerebral correlates of explicit and implicit knowledge in a serial reaction time (SRT) task. To do so, we used a novel application of the Process Dissociation Procedure, a behavioral paradigm that makes it possible to separately assess conscious and unconscious contributions to performance during a subsequent sequence generation task. To manipulate the extent to which the repeating sequential pattern was learned explicitly, we varied the pace of the choice reaction time task-a variable that is known to have differential effects on the extent to which sensitivity to sequence structure involves implicit or explicit knowledge. Results showed that activity in the striatum subtends the implicit component of performance during recollection of a learned sequence, whereas the anterior cingulate/mesial prefrontal cortex (ACC/MPFC) supports the explicit component. Most importantly, we found that the ACC/MPFC exerts control on the activity of the striatum during retrieval of the sequence after explicit learning, whereas the activity of these regions is uncoupled when learning had been essentially implicit. These data suggest that implicit learning processes can be successfully controlled by conscious knowledge when learning is essentially explicit. They also supply further evidence for a partial dissociation between the neural substrates supporting conscious and nonconscious components of performance during recollection of a learned sequence. [less ▲]

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See detailNeural Correlates of a Non-Image-Forming Response to Light Exposure During the Daytime: a fMRI Study
Vandewalle, Gilles ULg; Balteau, Evelyne ULg; Moreau, V et al

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

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See detailA Prominent Role for Amygdaloïd Complexes in the Variability of Heart Rate during Rapid Eye Movement (REM) Sleep
Desseilles, Martin ULg; Dang Vu, Thanh; Laureys, Steven ULg et al

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

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See detailNeural correlates of fast and slow ocular sequence learning
Albouy, Geneviève ULg; Ruby, Perrine; Balteau, Evelyne ULg et al

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

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See detailNeural mechanisms involved in the detection of our first name : A combined ERPs and PET study
Perrin, Fabien; Maquet, Pierre ULg; Peigneux, Philippe ULg et al

in Neuropsychologia (2005), 43(1), 12-19

In everyday social interactions, hearing our own first name captures our attention and gives rise to a sense of self-awareness, since it is one of the most socially self related stimulus. In the present ... [more ▼]

In everyday social interactions, hearing our own first name captures our attention and gives rise to a sense of self-awareness, since it is one of the most socially self related stimulus. In the present study, we combined ERPs and PET scan methods to explore the cerebral mechanisms underlying the detection of our own name. While categorical analyses of PET data failed to reveal significant results, we found that the amplitude of the P3 component, elicited when hearing one's own name, correlates with regional cerebral blood changes in right superior temporal sulcus, precuneus and medial prefrontal cortex. Additionally, the latter was more correlated to the P3 obtained for the subject's name compared to that obtained for other first names. These results suggest that the medial prefrontal cortex plays the most prominent role in self-processing. (C) 2004 Elsevier Ltd. All rights reserved. [less ▲]

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See detailCerebral correlates of delta waves during non-REM sleep revisited.
Dang Vu, Thien Thanh ULg; Desseilles, Martin ULg; Laureys, Steven ULg et al

in NeuroImage (2005), 28(1), 14-21

We aimed at characterizing the neural correlates of delta activity during Non Rapid Eye Movement (NREM) sleep in non-sleep-deprived normal young adults, based on the statistical analysis of a positron ... [more ▼]

We aimed at characterizing the neural correlates of delta activity during Non Rapid Eye Movement (NREM) sleep in non-sleep-deprived normal young adults, based on the statistical analysis of a positron emission tomography (PET) sleep data set. One hundred fifteen PET scans were obtained using H(2)(15)O under continuous polygraphic monitoring during stages 2-4 of NREM sleep. Correlations between regional cerebral blood flow (rCBF) and delta power (1.5-4 Hz) spectral density were analyzed using statistical parametric mapping (SPM2). Delta power values obtained at central scalp locations negatively correlated during NREM sleep with rCBF in the ventromedial prefrontal cortex, the basal forebrain, the striatum, the anterior insula, and the precuneus. These regions embrace the set of brain areas in which rCBF decreases during slow wave sleep (SWS) as compared to Rapid Eye Movement (REM) sleep and wakefulness (Maquet, P., Degueldre, C., Delfiore, G., Aerts, J., Peters, J.M., Luxen, A., Franck, G., 1997. Functional neuroanatomy of human slow wave sleep. J. Neurosci. 17, 2807-S2812), supporting the notion that delta activity is a valuable prominent feature of NREM sleep. A strong association was observed between rCBF in the ventromedial prefrontal regions and delta power, in agreement with electrophysiological studies. In contrast to the results of a previous PET study investigating the brain correlates of delta activity (Hofle, N., Paus, T., Reutens, D., Fiset, P., Gotman, J., Evans, A.C., Jones, B.E., 1997. Regional cerebral blood flow changes as a function of delta and spindle activity during slow wave sleep in humans. J. Neurosci. 17, 4800-4808), in which waking scans were mixed with NREM sleep scans, no correlation was found with thalamus activity. This latter result stresses the importance of an extra-thalamic delta rhythm among the synchronous NREM sleep oscillations. Consequently, this rCBF distribution might preferentially reflect a particular modulation of the cellular processes involved in the generation of cortical delta waves during NREM sleep. [less ▲]

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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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See detailImaging a cognitive model of apraxia: The neural substrate of gesture-specific cognitive processes
Peigneux, Philippe ULg; Van der Linden, Martial ULg; Garraux, Gaëtan ULg et al

in Human Brain Mapping (2004), 21(3), 119-142

The present study aimed to ascertain the neuroanatomical basis of an influential neuropsychological model for upper limb apraxia [Rothi LJ, et al. The Neuropsychology of Action. 1997. Hove, UK: Psychology ... [more ▼]

The present study aimed to ascertain the neuroanatomical basis of an influential neuropsychological model for upper limb apraxia [Rothi LJ, et al. The Neuropsychology of Action. 1997. Hove, UK: Psychology Press]. Regional cerebral blood flow was measured in healthy volunteers using (H2O)-O-15 PET during performance of four tasks commonly used for testing upper limb apraxia, i.e., pantomime of familiar gestures on verbal command, imitation of familiar gestures, imitation of novel gestures, and an action-semantic task that consisted in matching objects for functional use. We also re-analysed data from a previous PET study in which we investigated the neural basis. of the visual analysis of gestures. First; we found that two sets of discrete brain areas are predominantly engaged in the imitation of familiar and novel gestures, respectively. Segregated brain activation for novel gesture mutation concur with neuropsychological reports to support the hypothesis that knowledge about the organization of the human body mediates the transition from visual perception to motor execution when imitating novel gestures [Goldenberg Neuropsychologia 1995;35.63-72]. Second, conjunction analyses revealed distinctive neural bases for most of the gesture-specific cognitive processes proposed in this cognitive model of upper limb apraxia. However, a functional analysis of brain imaging data suggested that one single memory store may be used for "to be-perceived" and "to-be-produced" gestural representations, departing from Rothi et al.'s proposal. Based on the above considerations, we suggest and discuss a revised model for upper limb apraxia that might best account for both brain imaging findings and neuropsychological dissociations reported in the apraxia literature. (C) 2004 Wiley-Liss, Inc. [less ▲]

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See detailCerebral correlates of delta waves during human sleep-wake cycle
Dang-Vu, T.T.; Maquet, Pierre ULg; Desseilles, Martin ULg et al

Conference (2004)

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