References of "Balteau, Evelyne"
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See detailLocal modulation of human brain responses by circadian rhythmicity and sleep debt
Muto, Vincenzo ULg; Jaspar, Mathieu ULg; Meyer, Christelle et al

in Science (2016), 351(6300),

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

Poster (2016, June)

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See detailFeasibility study of repetitive diffusion MRI after Neoadjuvant radiotherapy for following tumor microenvironment.
LALLEMAND, François ULg; Leroi, Natacha ULg; Bahri, Mohamed Ali ULg et al

Conference (2016, March 22)

Purpose/Objective. Neoadjuvant radiotherapy (NeoRT) improves tumor local control and tumor resection in many cancers. The timing between the end of the NeoRT and surgery is mostly driven by the occurrence ... [more ▼]

Purpose/Objective. Neoadjuvant radiotherapy (NeoRT) improves tumor local control and tumor resection in many cancers. The timing between the end of the NeoRT and surgery is mostly driven by the occurrence of side effects or the tumor downsizing. We previously demonstrated in an in vivo model that the timing of surgery and the schedule of NeoRT influenced the tumor dissemination. Here, our aim is to evaluate with functional MRI (fMRI) the impact of the radiation treatment on the tumor microenvironment and subsequently to identify non-invasive markers helping to determine the best timing to perform surgery for avoiding tumor spreading. First, we needed to demonstrate the feasibility of repetitive MRI imaging after NeoRT in mice. Material/methods. We used two models of NeoRT we previously developed in mice: MDA-MB 231 and 4T1 cells implanted in the flank of mice. When tumors reached the planned volume, they are irradiated with 2x5 Gy and then surgically removed at different time points after RT. In the mean time between the end of RT and the surgical procedure, mice were imaged in a 9,4T Agilent® MRI. Diffusion Weighted (DW) -MRI was performed every 2 days between RT and surgery. For each tumors we acquired 8 slices of 1 mm thickness and 0.5 mm gap with an “in plane voxel resolution” of 0.5 mm. For DW-MRI, we performed FSEMS (Fast Spin Echo MultiSlice) sequences, with 9 different B-values (from 40 to 1000) and B0, in the 3 main directions. We also performed IVIM (IntraVoxel Incoherent Motion) analysis, in the aim to obtain information on intravascular diffusion, related to perfusion (F: perfusion factor) and subsequently tumor vessels perfusion. Results. As preliminary results, with the MBA-MB 231 we observed a significant increase of F at day 6 after irradiation than a decrease and stabilization until surgery. No other modifications of the MRI signal, ADC, D or D* were observed. We observed similar results with 4T1 cells, F increased at day 3 than returned to initial signal. The difference in the timing of the peak of F can be related to the difference in tumor growth between MBA-MB 231 and 4T1 (four weeks vs one week). Conclusion. For the first time, we demonstrate the feasibility of repetitive fMRI imaging in mice models after NeoRT. With these models, we show a significant peak of the perfusion factor (F) at day 6 or day 3. This change occurs between the two previous time points of surgery demonstrating a difference in the metastatic spreading. Indeed, after a NeoRT of 2X5Gy we observed more metastases in the lung when MDA-MB 231 tumor bearing mice are operated 4 days after RT compared to 11 days. These preliminary results are very promising for identifying noninvasive markers for determining the best timing for surgery. [less ▲]

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See detailSeasonality in human cognitive brain responses
Meyer, Christelle ULg; Muto, Vincenzo ULg; Jaspar, Mathieu ULg et al

in Proceedings of the National Academy of Sciences of the United States of America (2016)

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See detailDiffusion MRI for following tumor modifications after neoadjuvant radiotherapy.
LALLEMAND, François ULg; Leroi, Natacha ULg; Bahri, Mohamed Ali ULg et al

in Radiotherapy & Oncology (2016), 119

Neoadjuvant radiotherapy (NeoRT) improves tumor local control and tumor resection in many cancers. The timing between the end of the NeoRT and surgery is driven by the occurrence of side effects or the ... [more ▼]

Neoadjuvant radiotherapy (NeoRT) improves tumor local control and tumor resection in many cancers. The timing between the end of the NeoRT and surgery is driven by the occurrence of side effects or the tumor downsizing. Some studies demonstrated that the timing of surgery and the RT schedule could influence tumor dissemination and subsequently patient overall survival. We demonstrated the impact of NeoRT on metastatic spreading in a Scid mice model. After an irradiation of 2x5gy, we show more metastasis in the lung when the mice are operated at day 4 compared to day 11. Here, our aim is to evaluate with functional MRI (fMRI) the impact of the radiation treatment on the tumor microenvironment and subsequently to identify non-invasive markers helping to determine the best timing to perform surgery for avoiding tumor spreading. [less ▲]

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See detailCircadian and homeostatic sleep pressure modulate fMRI correlates of vigilant attention
Muto, Vincenzo ULg; Jaspar, Mathieu ULg; Meyer, C et al

in Journal of Sleep Research (2016), 25(s1),

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See detailSeasonality in human cognitive brain responses.
Meyer, Christelle ULg; Muto, Vincenzo ULg; Jaspar, Mathieu ULg et al

Poster (2015, September 04)

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See detailFunctional MRI for predicting metastatic spreading at the time of surgery after neoadjuvant radiotherapy
LALLEMAND, François ULg; Leroi, Natacha ULg; Bahri, Mohamed Ali ULg et al

Poster (2015, April)

Neoadjuvant radiotherapy (NeoRT) improves tumor local control and tumor resection in many cancers. The timing between the end of the NeoRT and surgery is driven by the occurrence of side effects or the ... [more ▼]

Neoadjuvant radiotherapy (NeoRT) improves tumor local control and tumor resection in many cancers. The timing between the end of the NeoRT and surgery is driven by the occurrence of side effects or the tumor downsizing. Some studies demonstrated that the timing of surgery and the RT schedule could influence tumor dissemination and subsequently patient overall survival. Our aim is to evaluate with functional MRI the impact of the radiation treatment on the tumor microenvironment and subsequently to determine the best timing to perform surgery for avoiding tumor spreading. [less ▲]

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See detailIdentification of predictive markers based on functional imaging of metastatic spreading at the time of surgery after neoadjuvant radiotherapy
LALLEMAND, François ULg; Leroi, Natacha ULg; Bahri, Mohamed Ali ULg et al

Poster (2015, January 27)

Neoadjuvant radiotherapy (NeoRT) improves tumor local control and tumor resection in many cancers. The timing between the end of the NeoRT and surgery are driven by the occurrence of side effects or the ... [more ▼]

Neoadjuvant radiotherapy (NeoRT) improves tumor local control and tumor resection in many cancers. The timing between the end of the NeoRT and surgery are driven by the occurrence of side effects or the tumor downsizing. Some studies demonstrated that the timing of surgery and the RT schedule could influence tumor dissemination. Our aim is to evaluate with functional MRI the impact of the radiation treatment on the tumor microenvironment and subsequently to determine the best timing to perform surgery. We used a model of NeoRT, 4T1 cells were implanted in the flank of BalbC mice. Seven days after, tumors were irradiated with 2x5Gy than we surgically removed this lesion 11 days after RT. Diffusion Weighted (DW) and Dynamic Contrast Enhancement (DCE) -MRI was performed every 2 days during 11 days between RT and surgery. We developed a homemade “portacath” specifically dedicated for mice and for repetitive I.V. contrast agent injection. For DW-MRI, we performed sequences with 10 different B-value to achieve IntraVoxel Incoherent Motion analysis. For DCE-MRI, we used FSEMS sequence for keeping the same slices as with DW-MRI. For both images, we performed analysis on the entire tumor volume. We obtained very promising preliminary results showing good uniformity in the ADC (Attenuation Diffusion Coefficient). We succeeded to follow mice with imaging during the 11 days without major troubles. We observed less variability of the ADC signal during the 11 days in the irradiated tumors compared to the control. The signal to noise ratio was relatively poor for the diffusion sequence and need to be improved. For the first time, we demonstrate the feasibility of repetitive MRI functional imaging in a mice model of NeoRT. These results open perspectives for studying modifications of the tumor microenvironment induced by neoadjuvant RT. The techniques need to be improved and correlated to the tumor dissemination in function of the RT schedule and timing of surgery. [less ▲]

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See detailMapping track density changes in nigrostriatal and extranigral pathways in Parkinson's disease
Ziegler, Erik ULg; Rouillard, Maud; André, Elodie et al

in NeuroImage (2014), 99

Highlights First whole-brain probabilistic tractography study in Parkinson's disease High quality diffusion-weighted images (120 gradient directions, b = 2500 s/mm2) Voxel-based group analysis comparing ... [more ▼]

Highlights First whole-brain probabilistic tractography study in Parkinson's disease High quality diffusion-weighted images (120 gradient directions, b = 2500 s/mm2) Voxel-based group analysis comparing early-stage patients and controls Abnormal reconstructed track density in the nigrostriatal pathway and brainstem Track density also increased in limbic and cognitive circuits. [less ▲]

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See detailPrior light history impacts on higher order cognitive brain function
Chellappa, Sarah Laxhmi ULg; Ly, Julien; Meyer, Christelle ULg et al

Conference (2014, June 17)

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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 detailMemory reactivation during rapid eye movement sleep promotes its generalization and integration in cortical stores.
Sterpenich, Virginie; Schmidt, Christina ULg; Albouy, Genevieve et al

in Sleep (2014), 37(6), 1061-751075-1075

STUDY OBJECTIVES: Memory reactivation appears to be a fundamental process in memory consolidation. In this study we tested the influence of memory reactivation during rapid eye movement (REM) sleep on ... [more ▼]

STUDY OBJECTIVES: Memory reactivation appears to be a fundamental process in memory consolidation. In this study we tested the influence of memory reactivation during rapid eye movement (REM) sleep on memory performance and brain responses at retrieval in healthy human participants. PARTICIPANTS: Fifty-six healthy subjects (28 women and 28 men, age [mean +/- standard deviation]: 21.6 +/- 2.2 y) participated in this functional magnetic resonance imaging (fMRI) study. METHODS AND RESULTS: Auditory cues were associated with pictures of faces during their encoding. These memory cues delivered during REM sleep enhanced subsequent accurate recollections but also false recognitions. These results suggest that reactivated memories interacted with semantically related representations, and induced new creative associations, which subsequently reduced the distinction between new and previously encoded exemplars. Cues had no effect if presented during stage 2 sleep, or if they were not associated with faces during encoding. Functional magnetic resonance imaging revealed that following exposure to conditioned cues during REM sleep, responses to faces during retrieval were enhanced both in a visual area and in a cortical region of multisensory (auditory-visual) convergence. CONCLUSIONS: These results show that reactivating memories during REM sleep enhances cortical responses during retrieval, suggesting the integration of recent memories within cortical circuits, favoring the generalization and schematization of the information. [less ▲]

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See detailEvaluation of segmented 3D acquisition schemes for whole-brain high-resolution arterial spin labeling at 3T
Vidorreta, Marta; Balteau, Evelyne ULg; Wang, Ze et al

in NMR in Biomedicine (2014), 27(11), 1387-1396

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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 detailPrior light history impacts on cognitive brain function
Chellappa, Sarah Laxhmi ULg; Ly, Julien; Meyer, Christelle ULg et al

Conference (2014)

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See detailPrior light history impacts on higher order cognitive brain function
Chellappa, Sarah Laxhmi ULg; Ly, Julien; Meyer, Christelle ULg et al

Conference (2014)

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See detailBrains creating stories of selves: the neural basis of autobiographical reasoning.
D'Argembeau, Arnaud ULg; Cassol, Helena; Phillips, Christophe ULg et al

in Social Cognitive and Affective Neuroscience (2014), 9

Personal identity critically depends on the creation of stories about the self and one's life. The present study investigates the neural substrates of autobiographical reasoning, a process central to the ... [more ▼]

Personal identity critically depends on the creation of stories about the self and one's life. The present study investigates the neural substrates of autobiographical reasoning, a process central to the construction of such narratives. During fMRI scanning, participants approached a set of personally significant memories in two different ways: on some trials, they remembered the concrete content of the events (autobiographical remembering), whereas on other trials they reflected on the broader meaning and implications of their memories (autobiographical reasoning). Relative to remembering, autobiographical reasoning recruited a left-lateralized network involved in conceptual processing (including the dorsal medial prefrontal cortex (MPFC), inferior frontal gyrus, middle temporal gyrus, and angular gyrus). The ventral MPFC-an area that may function to generate personal/affective meaning-was not consistently engaged during autobiographical reasoning across participants but, interestingly, the activity of this region was modulated by individual differences in interest and willingness to engage in self-reflection. These findings support the notion that autobiographical reasoning and the construction of personal narratives go beyond mere remembering in that they require deriving meaning and value from past experiences. [less ▲]

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See detailPhotic memory for executive brain responses
Chellappa*, Sarah Laxhmi ULg; Ly*, Julien ULg; Meyer, Christelle ULg et al

in Proceedings of the National Academy of Sciences of the United States of America (2014), Epub ahead of print

Detailed reference viewed: 124 (20 ULg)