References of "Jaspar, Mathieu"
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See detailModulating effect of COMT Val158Met polymorphism on interference resolution during a working memory task
Jaspar, Mathieu ULg; DIDEBERG, Vinciane ULg; Bours, Vincent ULg et al

in Brain & Cognition (in press)

Genetic variability related to the catechol-O-methyltransferase (COMT) gene has received increasing attention in the last 15 years, in particular as a potential modulator of the neural substrates ... [more ▼]

Genetic variability related to the catechol-O-methyltransferase (COMT) gene has received increasing attention in the last 15 years, in particular as a potential modulator of the neural substrates underlying inhibitory processes and updating in working memory (WM). In an event-related functional magnetic resonance imaging (fMRI) study, we administered a modified version of the Sternberg probe recency task (Sternberg, 1966) to 43 young healthy volunteers, varying the level of interference across successive items. The task was divided into two parts (high vs. low interference) to induce either proactive or reactive control processes. The participants were separated into three groups according to their COMT Val158Met genotype [Val/Val (VV); Val/Met (VM); Met/Met (MM)]. The general aim of the study was to determine whether COMT polymorphism has a modulating effect on the neural substrates of interference resolution during WM processing. Results indicate that interfering trials were associated with greater involvement of frontal cortices (bilateral medial frontal gyrus, left precentral and superior frontal gyri, right inferior frontal gyrus) in VV homozygous subjects (by comparison to Met allele carriers) only in the proactive condition of the task. In addition, analysis of peristimulus haemodynamic responses (PSTH) revealed that the genotype-related difference observed in the left SFG was specifically driven by a larger increase in activity from the storage to the recognition phase of the interfering trials in VV homozygous subjects. These results confirm the impact of COMT genotype on inhibitory processes during a WM task, with an advantage for Met allele carriers. Interestingly, this impact on frontal areas is present only when the level of interference is high, and especially during the transition from storage to recognition in the left superior frontal gyrus. [less ▲]

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See detailAutomatic artifact detection for whole-night polysomnographic sleep recordings
Coppieters't Wallant, Dorothée ULg; Chellappa, Sarah Laxhmi ULg; Gaggioni, Giulia ULg et al

Poster (2014, September 17)

Detecting of bad channels and artifacts for whole-night polysomnographic recordings is very time consuming and tedious. We therefore developed an automatic procedure to automatize this job.

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See detailAutomatic biorythms description from actigraphic data
González y Viagas, Miguel ULg; Ly, Julien ULg; Gaggioni, Giulia ULg et al

Poster (2014, September)

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See detailInfluence of noise correction on intra- and inter-subject variability of quantitative metrics in diffusion kurtosis imaging
André, Elodie ULg; Grinberg, Farida; Farrher, Ezequiel et al

in PLoS ONE (2014)

Diffusion kurtosis imaging (DKI) is a promising extension of diffusion tensor imaging, giving new insights into the white matter microstructure and providing new biomarkers. Given the rapidly increasing ... [more ▼]

Diffusion kurtosis imaging (DKI) is a promising extension of diffusion tensor imaging, giving new insights into the white matter microstructure and providing new biomarkers. Given the rapidly increasing number of studies, DKI has a potential to establish itself as a valuable tool in brain diagnostics. However, to become a routine procedure, DKI still needs to be improved in terms of robustness, reliability, and reproducibility. As it requires acquisitions at higher diffusion31 weightings, results are more affected by noise than in diffusion tensor imaging. The lack of standard procedures for post-processing, especially for noise correction, might become a significant obstacle for the use of DKI in clinical routine limiting its application. We considered two noise correction schemes accounting for the noise properties of multichannel phased-array coils, in order to improve the data quality at signal-to-noise ratio (SNR) typical for DKI. The SNR dependence of estimated DKI metrics such as mean kurtosis (MK), mean diffusivity (MD) and fractional anisotropy (FA) is investigated for these noise correction approaches in Monte Carlo simulations and in in vivo human studies. The intra-subject reproducibility is investigated in a single subject study by varying the SNR level and SNR spatial distribution. Then the impact of the noise correction on inter-subject variability is evaluated in a homogeneous sample of 25 healthy volunteers. Results show a strong impact of noise correction on the MK estimate, while the estimation of FA and MD was affected to a lesser extent. Both intra- and inter-subject SNR related variability of the MK estimate is considerably reduced after correction for the noise bias, providing more accurate and reproducible measures. In this work, we have proposed a straightforward method that improves accuracy of DKI metrics. This should contribute to standardization of DKI applications in clinical studies and making valuable inferences in group analysis and longitudinal studies. [less ▲]

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See detailSleep loss changes executive brain responses in the wake maintenance zone
Jaspar, Mathieu ULg; Meyer, Christelle ULg; Muto, Vincenzo ULg et al

Conference (2014)

Objectives:Brain mechanisms underlying executive processes are regulated by circadian and sleep homeostatic processes. Furthermore, during sleep deprivation (SD), cognitive performance and neural ... [more ▼]

Objectives:Brain mechanisms underlying executive processes are regulated by circadian and sleep homeostatic processes. Furthermore, during sleep deprivation (SD), cognitive performance and neural responses are differentially modulated by a clock gene PERIOD3 polymorphism. Here, we investigated interindividual differences on executive brain responses under SD. Critically, we focused on the circadian evening wake maintenance zone (WMZ), a key time-point for sleep-wake regulation. Methods:Thirty healthy young volunteers, genotyped for the PER3 polymorphism (10 PER3 5/5;20 PER3 4/4 homozygotes), underwent42-h SD under constant routine conditions. They performed a 3-back working memorytask in 13successivefMRI sessions. To compare neural activity in the WMZ before and during SD, sessions were realigned according to individual dim light melatonin onset. Results:We tested for a group (PER3 5/5>PER3 4/4) by session effect (WMZ before vs. during SD). From the first evening WMZ(i.e. during a normal waking day) to the second (i.e. following 40h of continuous waking), PER3 5/5 individuals relative toPER3 4/4 showed significantly larger increase in responsesin the left mid-cingulate, bilateral precuneus and thalamus. Interestingly, these regions are involved in executive processes and arousal regulation (thalamus). Conclusions:These results show that the strong circadian wake-maintenance signal depends on sleep pressure, in a PER3-genotype dependent manner. Interestingly, pronounced genotype differences wereobserved in the thalamus, an area that compensates potential lower cortical activity under SD. [less ▲]

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See detailSleep loss changes executive brain responses in the wake maintenance zone
Jaspar, Mathieu ULg; Meyer, Christelle ULg; Muto, Vincenzo ULg et al

in Journal of Sleep Research (2014), 23(1), 61

Objectives: Brain mechanisms underlying executive processes are regulated by circadian and sleep homeostatic processes. Furthermore, during sleep deprivation (SD), cognitive performance and neural ... [more ▼]

Objectives: Brain mechanisms underlying executive processes are regulated by circadian and sleep homeostatic processes. Furthermore, during sleep deprivation (SD), cognitive performance and neural responses are differentially modulated by a clock gene PERIOD3 polymorphism. Here, we investigated interindividual differences on executive brain responses under SD. Critically, we focused on the circadian evening wake maintenance zone (WMZ), a key time-point for sleep-wake regulation. Methods: Thirty healthy young volunteers, genotyped for the PER3 polymorphism (10 PER3 5/5; 20 PER3 4/4 homozygotes), underwent 42-h SD under constant routine conditions. They performed a 3-back working memory task in 13 successive fMRI sessions. To compare neural activity in the WMZ before and during SD, sessions were realigned according to individual dim light melatonin onset. Results: We tested for a group (PER3 5/5 > PER3 4/4) by session effect (WMZ before vs. during SD). From the fi rst evening WMZ (i.e. during a normal waking day) to the second (i.e. following 40 h of continuous waking), PER3 5/5 individuals relative to PER3 4/4 showed significantly larger increase in responses in the left mid-cingulate, bilateral precuneus and thalamus. Interestingly, these regions are involved in executive processes and arousal regulation (thalamus). Conclusions: These results show that the strong circadian wake-maintenance signal depends on sleep pressure, in a PER3-genotype dependent manner. Interestingly, pronounced genotype differences were observed in the thalamus, an area that compensates potential lower cortical activity under SD. [less ▲]

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See detailInfluence of COMT Genotype on Antero-Posterior Cortical Functional Connectivity Underlying Interference Resolution
Jaspar, Mathieu ULg; Manard, Marine ULg; DIDEBERG, Vinciane ULg et al

in Cerebral Cortex (2014)

Genetic variability related to the catechol-O-methyltransferase (COMT) gene (Val158Met) has received increasing attention as a possible modulator of executive functioning and its neural correlates ... [more ▼]

Genetic variability related to the catechol-O-methyltransferase (COMT) gene (Val158Met) has received increasing attention as a possible modulator of executive functioning and its neural correlates. However, this attention has generally centred on the prefrontal cortices because of the well-known direct impact of COMT enzyme on these cerebral regions. In this study, we were interested in the modulating effect of COMT genotype on anterior and posterior brain areas underlying interference resolution during a Stroop task. More specifically, we were interested in the functional connectivity between the right inferior frontal operculum (IFop), an area frequently associated with inhibitory efficiency, and posterior brain regions involved in reading/naming processes (the two main non-executive determinants of the Stroop effect). The Stroop task was administered during fMRI scanning to three groups of 15 young adults divided according to their COMT Val158Met genotype [Val/Val (VV), Val/Met (VM) and Met/Met (MM)]. Results indicate greater activity in the right IFop and the left middle temporal gyrus (MTG) in homozygous VV individuals than in Met allele carriers. In addition, the VV group exhibited stronger positive functional connectivity between these two brain regions and stronger negative connectivity between the right IFop and left lingual gyrus. These results confirm the impact of COMT genotype on frontal function. They also strongly suggest that differences in frontal activity influence posterior brain regions related to a non-executive component of the task. Especially, changes in functional connectivity between anterior and posterior brain areas might correspond to compensatory processes for performing the task efficiently when the available dopamine level is low. [less ▲]

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See detailSeasonal variation in human executive brain responses
Meyer, Christelle ULg; Jaspar, Mathieu ULg; Muto, Vincenzo ULg et al

Poster (2014)

It is well established that cognition shows daily fluctuations with changes in circadian phase and sleep pressure. The physiological impact of season changes, which is well characterized in animals ... [more ▼]

It is well established that cognition shows daily fluctuations with changes in circadian phase and sleep pressure. The physiological impact of season changes, which is well characterized in animals, remains largely unexplored in human. Here we investigated the impact of seasonal variation on human cognitive brain function. This cross-sectional study,conducted in Liège (Belgium),spanned from May 2010 to October 2011. Following 8h in-lab baseline night of sleep, 30 volunteers (age 20.9+1.5; 15F)spent 42h awake under constant routine conditions(<5lux, semi-recumbent position, no time-cues). After12h recovery night, they underwent15minfMRI recording while performing a working memory 3-back task (3b) and a letter detection 0-back task (0b). Thus, fMRI data were acquired when volunteers had been in isolation under controlled conditionsfor 63h. Executive brain responses were isolated by subtracting 0b activity from 3b responses (3b>0b).Analysis tested seasonal influence on executive brain responses at the random effects level, using a phasoranalysis across the year.Inferences were conducted at p<0.05, after correction for multiple comparisons over a priori small volume of interest. Significanteffects of season on executive responses were detected inmiddle frontal and frontopolarregions, insula, and thalamus, with a maximum response at the end of summer and a minimum response at the end of winter.These brain areas are key regions for executive control and alertness. These results constitute the first demonstration that seasonality directly impacts on human cognitive brain functions. [less ▲]

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See detailAge-related decline in cognitive control: the role of fluid intelligence and processing speed
Manard, Marine ULg; Carabin, Delphine; Jaspar, Mathieu ULg et al

in BMC Neuroscience (2014), 15(7),

Background Research on cognitive control suggests an age-related decline in proactive control abilities whereas reactive control seems to remain intact. However, the reason of the differential age effect ... [more ▼]

Background Research on cognitive control suggests an age-related decline in proactive control abilities whereas reactive control seems to remain intact. However, the reason of the differential age effect on cognitive control efficiency is still unclear. This study investigated the potential influence of fluid intelligence and processing speed on the selective age-related decline in proactive control. Eighty young and 80 healthy older adults were included in this study. The participants were submitted to a working memory recognition paradigm, assessing proactive and reactive cognitive control by manipulating the interference level across items. Results Repeated measures ANOVAs and hierarchical linear regressions indicated that the ability to appropriately use cognitive control processes during aging seems to be at least partially affected by the amount of available cognitive resources (assessed by fluid intelligence and processing speed abilities). Conclusions This study highlights the potential role of cognitive resources on the selective age-related decline in proactive control, suggesting the importance of a more exhaustive approach considering the confounding variables during cognitive control assessment. [less ▲]

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See detailModulating effect of COMT genotype on the brain regions underlying proactive control process during inhibition
Jaspar, Mathieu ULg; Genon, Sarah ULg; Muto, Vincenzo ULg et al

in Cortex : A Journal Devoted to the Study of the Nervous System & Behavior (2014), 50

Introduction. Genetic variability related to the catechol-O-methyltransferase (COMT) gene (Val158Met polymorphism) has received increasing attention as a possible modulator of cognitive control functions ... [more ▼]

Introduction. Genetic variability related to the catechol-O-methyltransferase (COMT) gene (Val158Met polymorphism) has received increasing attention as a possible modulator of cognitive control functions. Methods. In an event-related fMRI study, a modified version of the Stroop task was administered to three groups of 15 young adults according to their COMT Val158Met genotype [Val/Val (VV), Val/Met (VM) and Met/Met (MM)]. Based on the theory of dual mechanisms of control (Braver, et al., 2007), the Stroop task has been built to induce proactive or reactive control processes according to the task context. Results. Behavioral results did not show any significant group differences for reaction times but Val allele carriers individuals are less accurate in the processing of incongruent items. fMRI results revealed that proactive control is specifically associated with increased activity in the anterior cingulate cortex (ACC) in carriers of the Met allele, while increased activity is observed in the middle frontal gyrus (MFG) in carriers of the Val allele. Conclusion. These observations, in keeping with a higher cortical dopamine level in MM individuals, support the hypothesis of a COMT Val158Met genotype modulation of the brain regions underlying proactive control, especially in frontal areas as suggested by Braver et al. [less ▲]

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See detailDorsomedial prefrontal metabolism and unawareness of current characteristics of personality traits in Alzheimer’s disease
Jedidi, Haroun ULg; Feyers, Dorothée ULg; Collette, Fabienne ULg et al

in Social Cognitive and Affective Neuroscience (2014)

Anosognosia is a complex symptom corresponding to a lack of awareness of one’s current clinical status. Anosognosia for cognitive deficits has frequently been described in Alzheimer’s disease (AD), while ... [more ▼]

Anosognosia is a complex symptom corresponding to a lack of awareness of one’s current clinical status. Anosognosia for cognitive deficits has frequently been described in Alzheimer’s disease (AD), while unawareness of current characteristics of personality traits has rarely been considered. We used a well-established questionnaire-based method in a group of 37 AD patients and in healthy controls to probe self- and hetero-evaluation of patients’ personality and we calculated differential scores between each participant’s and his/her relative’s judgments. A brain-behavior correlation was performed using FDG-PET images. The behavioral data showed that AD patients presented with anosognosia for current characteristics of their personality and their anosognosia was primarily explained by impaired third perspective taking. The brain-behavior correlation analysis revealed a negative relationship between anosognosia for current characteristics of personality and dorsomedial prefrontal cortex (dMPFC) activity. Behavioral and neuroimaging data are consistent with the view that impairment of different functions subserved by the dMPFC (self-evaluation, inferences regarding complex enduring dispositions of self and others, confrontation of perspectives in interpersonal scripts) plays a role in anosognosia for current characteristics of personality in AD patients. [less ▲]

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See detailInfluence of circadian rhythm and PER3 genotype on executive discriminative ability under sleep deprivation during a constant routine
Jaspar, Mathieu ULg; Meyer, Christelle ULg; Muto, Vincenzo ULg et al

Conference (2013, August 12)

Maintaining optimal performance during a working memory task requires not only to detect target items but also to discard fillers. Following signal detection theory, the ability to discriminate target ... [more ▼]

Maintaining optimal performance during a working memory task requires not only to detect target items but also to discard fillers. Following signal detection theory, the ability to discriminate target from non-target stimuli is estimated by d prime (d'). Here we assessed whether d' was modulated by the oscillating circadian signal during a 42-hour constant routine while participants performed 13 sessions of auditory 3-back task. We also tested whether the individual vulnerability to sleep loss predicted by the PERIOD3 gene polymorphism would influence this cognitive modulation imposed by sleep/wake regulation. From a sample of about 400 screened volunteers, thirty-five healthy young volunteers (age 19-26; 17 females) were recruited based on the PER3 polymorphism (twelve 5/5 and twenty-three 4/4 homozygotes). A linear mixed model tested on d’ the effect of circadian rhythmicity (based on melatonin level) and PER3 polymorphism. Given that 3back sessions were not administered at equidistant points, we used ranges to center each individual performance on dim light melatonin onset (DLMO). Analyses on d’ showed an effect of circadian oscillation (F(12,302) = 16.05, p< 0.0001), but also an interaction between gene and circadian oscillation (F(12,302)=1,88, p = 0.0362). This interaction was mainly characterized by a worst d’ in PER35/5subjects in the range covering a period between 21 and 23 hours after the DLMO (W=47; p = 0.0426). These results showed that circadian rhythm influence the discriminative ability under constant routine condition. Interestingly, we observed a better performance in PER34/4in the phase preceding the DLMO, but only in situation of high sleep pressure. Those results show that discriminative ability is differently affect by sleep homeostasis in PER3 polymorphism at the same circadian phase. We interpret this as a bigger vulnerability to sleep loss in PER35/5individuals in the period just before the wake maintenance zone. [less ▲]

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See detailFunctional neuroimaging of human REM sleep
Meyer, Christelle ULg; Jedidi, Zayd ULg; Muto, Vincenzo ULg et al

in Nofzinger, Eric; Maquet, Pierre; Thorpy, Michael J. (Eds.) Neuroimaging of sleep and sleep disorders (2013)

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