Participation du CR CERVO à la première Q2 Summer School
2025 08 15
Ce fut un grand plaisir et un immense honneur de participer à la toute première Q2 Summer School, organisée conjointement avec nos collègues de l’Instituto…
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Centre de recherche CERVO
Contact et liens
Michele.Desjardins@crchudequebec.ulaval.ca
Adresse postale
2301 Avenue d’Estimauville Québec (Québec) G1E 0N5 Canada
Michèle Desjardins
Ph. D.
Professeure agrégée
Chercheuse, CERVO
Axe de recherche:
Neurosciences cliniques et cognitives
Les projets de recherche de la professeure Desjardins se déploient selon trois thèmes principaux : le développement de méthodes d’imagerie et de modèles numériques, ainsi que leur application à l’étude de l’activité cérébrale et du couplage neuro-vasculaire.
Les méthodes utilisées par la professeure Desjardins pour imager le cerveau des souris à différentes échelles spatiales comprennent la microscopie biphotonique, l’imagerie à champ large (fluorescence et signaux intrinsèques), la tomographie par cohérence optique et l’imagerie par résonance magnétique. Ses méthodes d’analyse de données et de modélisation incluent des modèles biophysiques du transport d’oxygène, des simulations Monte-Carlo de la résonance magnétique et des réseaux de neurones artificiels.
Ces méthodes d’imagerie et de modélisation permettent d’explorer diverses questions en neurosciences dans le modèle de la souris. Ses projets récents, certains menés en collaboration avec plusieurs collègues, s’intéressent ainsi à l’évolution des réseaux neuronaux et vasculaires au fil du vieillissement, à la distribution de l’oxygène et à la radiosensibilité dans les tumeurs, à la modulation du couplage neuro-vasculaire par la noradrénaline, ainsi qu’au lien entre la structure et la fonction dans le cerveau.
Biographie courte
Après avoir obtenu un baccalauréat en physique, la professeure Desjardins a poursuivi ses études avec un doctorat en génie biomédical en cotutelle entre l’Université Pierre et Marie Curie Paris 6 et l’École Polytechnique de Montréal, complété par un stage post-doctoral à l’Université de Californie à San Diego
Publications
Jonathan Bouchard; Béatrice Daigle; Adeline Collignon; Vincent St-Arnault; Luisa Bandeira Binder; Laura Menegatti Bevilacqua; Véronique Rioux; Laurence Dion-Albert; Manon Lebel; Martin Lévesque; Michèle Desjardins; Caroline Ménard
Investigation of Poststroke Depression Following a Nucleus Accumbens Infarct in Mice Article de journal
Dans: Stroke, vol. 56, no 9, p. 2772–2781, 2025, ISSN: 1524-4628.
@article{pmid40534558,
title = {Investigation of Poststroke Depression Following a Nucleus Accumbens Infarct in Mice},
author = {Jonathan Bouchard and Béatrice Daigle and Adeline Collignon and Vincent St-Arnault and Luisa Bandeira Binder and Laura Menegatti Bevilacqua and Véronique Rioux and Laurence Dion-Albert and Manon Lebel and Martin Lévesque and Michèle Desjardins and Caroline Ménard},
doi = {10.1161/STROKEAHA.125.050839},
issn = {1524-4628},
year = {2025},
date = {2025-09-01},
journal = {Stroke},
volume = {56},
number = {9},
pages = {2772--2781},
abstract = {BACKGROUND: Poststroke depression (PSD) affects ≈33% of individuals 1 year after a stroke. Blood-brain barrier (BBB) dysfunction in the nucleus accumbens (NAc), a hub for emotional processing, reward, and mood regulation, has been linked to stress-induced depressive-like behaviors in male mice. Neurovascular alterations were also observed in postmortem tissue samples from men with a diagnosis of major depression. Thus, we aimed to investigate if BBB changes in the NAc could contribute to PSD pathophysiology.nnMETHODS: Stereotaxic injection of ET-1 (endothelin-1), a potent vasoconstrictor, was performed in the NAc of male mice to create a focal brain stroke, and then, infarct size and localization were assessed and quantified. We subsequently evaluated transcriptomic and morphological effects of the infarct on BBB-related genes and cells in the NAc, particularly those known to be altered after stress exposure in mice or human depression. BBB integrity was assessed with a dextran dye, and magnetic resonance imaging scans were conducted before versus after the injection of Gadovist, a contrast agent. Last, a battery of behavioral tests related to depressive- and anxiety-like behaviors was performed to determine if an infarct in the NAc is sufficient to induce a PSD-like phenotype.nnRESULTS: Following ET-1 injection, ≈50% of the total lesion was observed in the NAc leading to BBB hyperpermeability in this brain area. BBB gene expression was impacted by ET-1, and also surgery alone and profiles were differentially regulated throughout time up to 14 days. Gliosis in the NAc was observed with increased reactivity of astrocytes and microglia. The effect of ET-1 on PSD-like symptoms was limited. However, body weight, sociability, and activity were affected by surgery with a more pronounced impact of ET-1 on social interactions compared with naive animals.nnCONCLUSIONS: While no clear PSD phenotype was observed following an ET-1-induced stroke in the NAc of male mice, our study shed light on the technical complexity of focal lesions in deep brain structures, an understudied phenomenon occurring in humans. We provide technical insights for the development of a mouse model of deep brain lesions, characterize its impact at molecular, cellular, and behavioral levels, and highlight the need to control for vascular alterations when performing stroke surgeries.},
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Jordan Charest; Mathieu Walsh; Élie Genois; Emmanuelle Sévigny; Pierre-Olivier Schwarz; Louis Gagnon; Michèle Desjardins
Dans: NMR Biomed, vol. 37, no 12, p. e5252, 2024, ISSN: 1099-1492.
@article{pmid39245649,
title = {Comparison of compartmental analytical Blood-Oxygen-Level-Dependent functional Magnetic Resonance Imaging models against Monte Carlo simulations performed over cortical micro-angiograms},
author = {Jordan Charest and Mathieu Walsh and Élie Genois and Emmanuelle Sévigny and Pierre-Olivier Schwarz and Louis Gagnon and Michèle Desjardins},
doi = {10.1002/nbm.5252},
issn = {1099-1492},
year = {2024},
date = {2024-12-01},
journal = {NMR Biomed},
volume = {37},
number = {12},
pages = {e5252},
abstract = {Blood oxygen level-dependent functional magnetic resonance imaging (BOLD fMRI) arises from a physiological and physical cascade of events taking place at the level of the cortical microvasculature which constitutes a medium with complex geometry. Several analytical models of the BOLD contrast have been developed, but these have not been compared directly against detailed bottom-up modeling methods. Using a 3D modeling method based on experimentally measured images of mice microvasculature and Monte Carlo simulations, we quantified the accuracy of two analytical models to predict the amplitude of the BOLD response from 1.5 to 7 T, for different echo time (TE) and for both gradient echo and spin echo acquisition protocols. We also showed that accounting for the tridimensional structure of the microvasculature results in more accurate prediction of the BOLD amplitude, even if the values for SO were averaged across individual vascular compartments. A secondary finding is that modeling the venous compartment as two individual compartments results in more accurate prediction of the BOLD amplitude compared with standard homogenous venous modeling, arising from the bimodal distribution of venous SO across the microvasculature in our data.},
keywords = {},
pubstate = {published},
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Jérémie Guilbert; Antoine Légaré; Paul De Koninck; Patrick Desrosiers; Michèle Desjardins
Toward an integrative neurovascular framework for studying brain networks Article de journal
Dans: Neurophotonics, vol. 9, no 3, p. 032211, 2022, ISSN: 2329-423X.
@article{pmid35434179,
title = {Toward an integrative neurovascular framework for studying brain networks},
author = {Jérémie Guilbert and Antoine Légaré and Paul De Koninck and Patrick Desrosiers and Michèle Desjardins},
doi = {10.1117/1.NPh.9.3.032211},
issn = {2329-423X},
year = {2022},
date = {2022-07-01},
journal = {Neurophotonics},
volume = {9},
number = {3},
pages = {032211},
abstract = {Brain functional connectivity based on the measure of blood oxygen level-dependent (BOLD) functional magnetic resonance imaging (fMRI) signals has become one of the most widely used measurements in human neuroimaging. However, the nature of the functional networks revealed by BOLD fMRI can be ambiguous, as highlighted by a recent series of experiments that have suggested that typical resting-state networks can be replicated from purely vascular or physiologically driven BOLD signals. After going through a brief review of the key concepts of brain network analysis, we explore how the vascular and neuronal systems interact to give rise to the brain functional networks measured with BOLD fMRI. This leads us to emphasize a view of the vascular network not only as a confounding element in fMRI but also as a functionally relevant system that is entangled with the neuronal network. To study the vascular and neuronal underpinnings of BOLD functional connectivity, we consider a combination of methodological avenues based on multiscale and multimodal optical imaging in mice, used in combination with computational models that allow the integration of vascular information to explain functional connectivity.},
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pubstate = {published},
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}
Élie Genois; Louis Gagnon; Michèle Desjardins
Modeling of vascular space occupancy and BOLD functional MRI from first principles using real microvascular angiograms Article de journal
Dans: Magn Reson Med, vol. 85, no 1, p. 456–468, 2021, ISSN: 1522-2594.
@article{pmid32726489,
title = {Modeling of vascular space occupancy and BOLD functional MRI from first principles using real microvascular angiograms},
author = {Élie Genois and Louis Gagnon and Michèle Desjardins},
doi = {10.1002/mrm.28429},
issn = {1522-2594},
year = {2021},
date = {2021-01-01},
journal = {Magn Reson Med},
volume = {85},
number = {1},
pages = {456--468},
abstract = {PURPOSE: The vascular space occupancy (VASO) is a functional MRI technique for probing cerebral blood volume changes noninvasively, including during neuronal activation in humans. An important consideration when implementing VASO is the BOLD effect in the signal. Assessing the physical origin of this BOLD contamination and the capabilities of correction methods could improve the quantification of cerebral blood volume changes with VASO.nnMETHODS: Given the heterogeneity of cerebral microvascular architecture, the vascular geometry within an MRI voxel can influence both BOLD and VASO signals. To investigate this effect, 3D high-resolution images of mouse cerebral vasculature measured with two-photon microscopy were used to model BOLD and VASO signals from first principles using Monte Carlo diffusion of water protons. Quantitative plots of VASO together with intravascular and extravascular BOLD signals as a function of TE at B fields 1.5 T to 14 T were obtained.nnRESULTS: The BOLD contamination of the VASO response was on the order of 50% for gradient echo and 5% for spin echo at 7 T and TE = 6 ms and significantly increased with TE and B . Two currently used correction schemes were shown to account for most of this contamination and recover accurate relative signal changes, with optimal correction obtained using TEs as short as possible.nnCONCLUSION: These results may provide useful information for optimizing sequence parameters in VASO and BOLD functional MRI, leading the way to a wider application of these techniques in healthy and diseased brain.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}