1
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Champagne AA, Coverdale NS, Allen MD, Tremblay JC, MacPherson REK, Pyke KE, Olver TD, Cook DJ. The physiological basis underlying functional connectivity differences in older adults: A multi-modal analysis of resting-state fMRI. Brain Imaging Behav 2022; 16:1575-1591. [PMID: 35092574 DOI: 10.1007/s11682-021-00570-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2020] [Accepted: 09/27/2021] [Indexed: 11/02/2022]
Abstract
The purpose of this study was to determine if differences in functional connectivity strength (FCS) with age were confounded by vascular parameters including resting cerebral blood flow (CBF0), cerebrovascular reactivity (CVR), and BOLD-CBF coupling. Neuroimaging data were collected from 13 younger adults (24 ± 2 years) and 14 older adults (71 ± 4 years). A dual-echo resting state pseudo-continuous arterial spin labeling sequence was performed, as well as a BOLD breath-hold protocol. A group independent component analysis was used to identify networks, which were amalgamated into a region of interest (ROI). Within the ROI, FC strength (FCS) was computed for all voxels and compared across the groups. CBF0, CVR and BOLD-CBF coupling were examined within voxels where FCS was different between young and older adults. FCS was greater in old compared to young (P = 0.001). When the effect of CBF0, CVR and BOLD-CBF coupling on FCS was examined, BOLD-CBF coupling had a significant effect (P = 0.003) and group differences in FCS were not present once all vascular parameters were considered in the statistical model (P = 0.07). These findings indicate that future studies of FCS should consider vascular physiological markers in order to improve our understanding of aging processes on brain connectivity.
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Affiliation(s)
- Allen A Champagne
- Centre for Neuroscience Studies, Queen's University, Room 260, Kingston, ON, K7L 3N6, Canada
| | - Nicole S Coverdale
- Centre for Neuroscience Studies, Queen's University, Room 260, Kingston, ON, K7L 3N6, Canada
| | - Matti D Allen
- Department of Physical Medicine and Rehabilitation, Queen's University, Kingston, ON, Canada.,School of Kinesiology and Health Studies, Cardiovascular Stress Response Laboratory, Queen's University, Kingston, ON, K7L 3N6, Canada.,Department of Physical Medicine and Rehabilitation, Providence Care Hospital, 752 King St., Ontario, West Kingston, Canada
| | - Joshua C Tremblay
- School of Kinesiology and Health Studies, Cardiovascular Stress Response Laboratory, Queen's University, Kingston, ON, K7L 3N6, Canada
| | - Rebecca E K MacPherson
- Department of Health Sciences, Faculty of Applied Health Sciences, Brock University, 1812 Sir Isaac Brock Way, St Catharines, ON, L2S 3A1, Canada
| | - Kyra E Pyke
- School of Kinesiology and Health Studies, Cardiovascular Stress Response Laboratory, Queen's University, Kingston, ON, K7L 3N6, Canada
| | - T Dylan Olver
- Biomedical Sciences, Western College of Veterinarian Medicine, University of Saskatchewan, 52 Campus Drive, Saskatoon, Saskatchewan, S7N 5B4, Canada
| | - Douglas J Cook
- Centre for Neuroscience Studies, Queen's University, Room 260, Kingston, ON, K7L 3N6, Canada. .,Department of Surgery, Queen's University, Room 232, 18 Stuart St, Kingston, ON, K7L 3N6, Canada.
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2
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Crofts A, Trotman-Lucas M, Janus J, Kelly M, Gibson CL. A longitudinal, multi-parametric functional MRI study to determine age-related changes in the rodent brain. Neuroimage 2020; 218:116976. [PMID: 32464290 PMCID: PMC7422839 DOI: 10.1016/j.neuroimage.2020.116976] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2020] [Revised: 04/24/2020] [Accepted: 05/19/2020] [Indexed: 02/07/2023] Open
Abstract
As the population ages, the incidence of age-related neurological diseases and cognitive decline increases. To further understand disease-related changes in brain function it is advantageous to examine brain activity changes in healthy aging rodent models to permit mechanistic investigation. Here, we examine the suitability, in rodents, of using a novel, minimally invasive anaesthesia protocol in combination with a functional MRI protocol to assess alterations in neuronal activity due to physiological aging. 11 Wistar Han female rats were studied at 7, 9, 12, 15 and 18 months of age. Under an intravenous infusion of propofol, animals underwent functional magnetic resonance imaging (fMRI) and functional magnetic resonance spectroscopy (fMRS) with forepaw stimulation to quantify neurotransmitter activity, and resting cerebral blood flow (CBF) quantification using arterial spin labelling (ASL) to study changes in neurovascular coupling over time. Animals showed a significant decrease in size of the active region with age (P < 0.05). fMRS results showed a significant decrease in glutamate change with stimulation (ΔGlu) with age (P < 0.05), and ΔGlu became negative from 12 months onwards. Global CBF remained constant for the duration of the study. This study shows age related changes in the blood oxygen level dependent (BOLD) response in rodents that correlate with those seen in humans. The results also suggest that a reduction in synaptic glutamate turnover with age may underlie the reduction in the BOLD response, while CBF is preserved. Describe a novel anaesthetic protocol to examine age-related alterations in neuronal activity in rodents. Size of the BOLD signal in the somatosensory cortex decreased with age. Reduction in glutamate turnover with age. No change in resting CBF with age.
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Affiliation(s)
- Andrew Crofts
- Department of Neuroscience, Psychology & Behaviour, University of Leicester, Leicester, UK; Preclinical Imaging Facility, Core Biotechnology Services, University of Leicester, Leicester, UK
| | - Melissa Trotman-Lucas
- Department of Neuroscience, Psychology & Behaviour, University of Leicester, Leicester, UK; School of Psychology, University of Nottingham, Nottingham, UK
| | - Justyna Janus
- Preclinical Imaging Facility, Core Biotechnology Services, University of Leicester, Leicester, UK
| | - Michael Kelly
- Preclinical Imaging Facility, Core Biotechnology Services, University of Leicester, Leicester, UK
| | - Claire L Gibson
- Department of Neuroscience, Psychology & Behaviour, University of Leicester, Leicester, UK; School of Psychology, University of Nottingham, Nottingham, UK.
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3
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Cisneros-Franco JM, Voss P, Kang MS, Thomas ME, Côté J, Ross K, Gaudreau P, Rudko DA, Rosa-Neto P, de-Villers-Sidani É. PET Imaging of Perceptual Learning-Induced Changes in the Aged Rodent Cholinergic System. Front Neurosci 2020; 13:1438. [PMID: 32038142 PMCID: PMC6985428 DOI: 10.3389/fnins.2019.01438] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2019] [Accepted: 12/20/2019] [Indexed: 12/14/2022] Open
Abstract
The cholinergic system enhances attention and gates plasticity, making it a major regulator of adult learning. With aging, however, progressive degeneration of the cholinergic system impairs both the acquisition of new skills and functional recovery following neurological injury. Although cognitive training and perceptual learning have been shown to enhance auditory cortical processing, their specific impact on the cholinergic system remains unknown. Here we used [18F]FEOBV, a positron emission tomography (PET) radioligand that selectively binds to the vesicular acetylcholine transporter (VAChT), as a proxy to assess whether training on a perceptual task results in increased cholinergic neurotransmission. We show for the first time that perceptual learning is associated with region-specific changes in cholinergic neurotransmission, as detected by [18F]FEOBV PET imaging and corroborated with immunohistochemistry.
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Affiliation(s)
- J Miguel Cisneros-Franco
- Montreal Neurological Institute, McGill University, Montreal, QC, Canada.,Centre for Research on Brain, Language and Music, McGill University, Montreal, QC, Canada
| | - Patrice Voss
- Montreal Neurological Institute, McGill University, Montreal, QC, Canada.,Centre for Research on Brain, Language and Music, McGill University, Montreal, QC, Canada
| | - Min Su Kang
- Douglas Mental Health University Institute, McGill University, Montreal, QC, Canada.,Research Centre for Studies in Aging, McGill University, Montreal, QC, Canada
| | - Maryse E Thomas
- Montreal Neurological Institute, McGill University, Montreal, QC, Canada.,Centre for Research on Brain, Language and Music, McGill University, Montreal, QC, Canada
| | - Jonathan Côté
- Montreal Neurological Institute, McGill University, Montreal, QC, Canada.,Centre for Research on Brain, Language and Music, McGill University, Montreal, QC, Canada
| | - Karen Ross
- Montreal Neurological Institute, McGill University, Montreal, QC, Canada
| | - Pierrette Gaudreau
- Réseau Québécois de Recherche sur le Vieillissement, Université de Montréal, Montreal, QC, Canada
| | - David A Rudko
- Department of Biomedical Engineering, McGill University, Montreal, QC, Canada
| | - Pedro Rosa-Neto
- Douglas Mental Health University Institute, McGill University, Montreal, QC, Canada.,Research Centre for Studies in Aging, McGill University, Montreal, QC, Canada
| | - Étienne de-Villers-Sidani
- Montreal Neurological Institute, McGill University, Montreal, QC, Canada.,Centre for Research on Brain, Language and Music, McGill University, Montreal, QC, Canada
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4
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Lu X, Moeini M, Li B, Lu Y, Damseh R, Pouliot P, Thorin É, Lesage F. A Pilot Study Investigating Changes in Capillary Hemodynamics and Its Modulation by Exercise in the APP-PS1 Alzheimer Mouse Model. Front Neurosci 2019; 13:1261. [PMID: 31920472 PMCID: PMC6915102 DOI: 10.3389/fnins.2019.01261] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2019] [Accepted: 11/06/2019] [Indexed: 12/11/2022] Open
Abstract
Dysfunction in neurovascular coupling that results in a mismatch between cerebral blood flow and neuronal activity has been suggested to play a key role in the pathogenesis of Alzheimer's disease (AD). Meanwhile, physical exercise is a powerful approach for maintaining cognitive health and could play a preventive role against the progression of AD. Given the fundamental role of capillaries in oxygen transport to tissue, our pilot study aimed to characterize changes in capillary hemodynamics with AD and AD supplemented by exercise. Exploiting two-photon microscopy, intrinsic signal optical imaging, and magnetic resonance imaging, we found hemodynamic alterations and lower vascular density with AD that were reversed by exercise. We further observed that capillary properties were branch order-dependent and that stimulation-evoked changes were attenuated with AD but increased by exercise. Our study provides novel indications into cerebral microcirculatory disturbances with AD and the modulating role of voluntary exercise on these alterations.
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Affiliation(s)
- Xuecong Lu
- Biomedical Engineering Institute, École Polytechnique de Montréal, Montreal, QC, Canada
- Montreal Heart Institute, Research Center, Montreal, QC, Canada
| | - Mohammad Moeini
- Department of Biomedical Engineering, Amirkabir University of Technology (Tehran Polytechnic), Tehran, Iran
| | - Baoqiang Li
- Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Harvard Medical School, Charlestown, MA, United States
| | - Yuankang Lu
- Biomedical Engineering Institute, École Polytechnique de Montréal, Montreal, QC, Canada
- Montreal Heart Institute, Research Center, Montreal, QC, Canada
| | - Rafat Damseh
- Biomedical Engineering Institute, École Polytechnique de Montréal, Montreal, QC, Canada
- Montreal Heart Institute, Research Center, Montreal, QC, Canada
| | - Philippe Pouliot
- Biomedical Engineering Institute, École Polytechnique de Montréal, Montreal, QC, Canada
- Montreal Heart Institute, Research Center, Montreal, QC, Canada
| | - Éric Thorin
- Montreal Heart Institute, Research Center, Montreal, QC, Canada
- Department of Surgery, Faculty of Medicine, Université de Montréal, Montreal, QC, Canada
| | - Frédéric Lesage
- Biomedical Engineering Institute, École Polytechnique de Montréal, Montreal, QC, Canada
- Montreal Heart Institute, Research Center, Montreal, QC, Canada
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5
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Lu Y, Zhang C, Lu X, Moeini M, Thorin E, Lesage F. Impact of atherosclerotic disease on cerebral microvasculature and tissue oxygenation in awake LDLR-/-hApoB+/+ transgenic mice. NEUROPHOTONICS 2019; 6:045003. [PMID: 31673566 PMCID: PMC6811703 DOI: 10.1117/1.nph.6.4.045003] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/28/2019] [Accepted: 09/17/2019] [Indexed: 05/17/2023]
Abstract
We explore cortical microvasculature changes during the progression of atherosclerosis using young and old transgenic atherosclerotic (ATX) mice with thinned-skull cranial window. In awake animals, exploiting intrinsic signal optical imaging, Doppler optical coherence tomography, and two-photon microscopy, we investigate how the progression of atherosclerotic disease affects the morphology and function of cortical microvasculature as well as baseline cerebral tissue oxygenation. Results show that aged ATX mice exhibited weaker hemodynamic response in the somatosensory cortex to whisker stimulation and that the diameter of their descending arterioles and associated mean blood flow decreased significantly compared with the young ATX group. Data from two-photon phosphorescence lifetime microscopy indicate that old ATX mice had lower and more heterogeneous partial pressure of oxygen ( PO 2 ) in cortical tissue than young ATX mice. In addition, hypoxic micropockets in cortical tissue were found in old, but not young, ATX mice. Capillary red blood cell (RBC) flux, RBC velocity, RBC velocity heterogeneity, hematocrit, and diameter were also measured using line scans with two-photon fluorescence microscopy. When compared with the young group, RBC flux, velocity, and hematocrit decreased and RBC velocity heterogeneity increased in old ATX mice, presumably due to disturbed blood supply from arterioles that were affected by atherosclerosis. Finally, dilation of capillaries in old ATX mice was observed, which suggests that capillaries play an active role in compensating for an oxygen deficit in brain tissue.
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Affiliation(s)
- Yuankang Lu
- École Polytechnique de Montréal, Laboratoire d’Imagerie optique et moléculaire, Montréal, Québec, Canada
| | - Cong Zhang
- Institut de Cardiologie de Montréal, Montréal, Québec, Canada
| | - Xuecong Lu
- École Polytechnique de Montréal, Laboratoire d’Imagerie optique et moléculaire, Montréal, Québec, Canada
| | - Mohammad Moeini
- Amirkabir University of Technology (Tehran Polytechnic), Biomedical Engineering Department, Tehran, Iran
| | - Eric Thorin
- Institut de Cardiologie de Montréal, Montréal, Québec, Canada
- Université de Montréal, Department of Pharmacology and Physiology, Faculty of Medicine, Montréal, Québec, Canada
| | - Frédéric Lesage
- École Polytechnique de Montréal, Laboratoire d’Imagerie optique et moléculaire, Montréal, Québec, Canada
- Institut de Cardiologie de Montréal, Montréal, Québec, Canada
- Address all correspondence to Frédéric Lesage, E-mail:
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6
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Cerebral tissue pO 2 response to stimulation is preserved with age in awake mice. Neurosci Lett 2019; 699:160-166. [PMID: 30738870 DOI: 10.1016/j.neulet.2019.02.007] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2018] [Revised: 01/11/2019] [Accepted: 02/06/2019] [Indexed: 12/15/2022]
Abstract
Compromised oxygen supply to cerebral tissue could be an important mechanism contributing to age-related cognition decline. We recently showed in awake mice that resting cerebral tissue pO2 decreases with age, a phenomenon that manifests mainly after middle-age. To extend these findings, here we aimed to study how tissue pO2 response to neuronal stimulation is affected by aging. We used two-photon phosphorescence lifetime microscopy to directly measure the brain tissue pO2 response to whisker stimulation in healthy awake young, middle-aged and old mice. We show that despite a decrease in baseline tissue pO2, the amplitude of the tissue pO2 response to stimulation is well preserved with age. However, the response dynamics are altered towards a slower response with reduced post-stimulus undershoot in older ages, possibly due to stiffer vessel wall among other factors. An estimation of the net oxygen consumption rate using a modified Krogh model suggests that the O2 overshoot during stimulation may be necessary to secure a higher capillary O2 delivery to the tissue proportional to increased CMRO2 to maintain the capillary tissue pO2. It was observed that the coupling between the CMRO2 and capillary O2 delivery is preserved with age.
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7
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Moeini M, Lu X, Avti PK, Damseh R, Bélanger S, Picard F, Boas D, Kakkar A, Lesage F. Compromised microvascular oxygen delivery increases brain tissue vulnerability with age. Sci Rep 2018; 8:8219. [PMID: 29844478 PMCID: PMC5974237 DOI: 10.1038/s41598-018-26543-w] [Citation(s) in RCA: 54] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2018] [Accepted: 05/16/2018] [Indexed: 11/22/2022] Open
Abstract
Despite the possible role of impaired cerebral tissue oxygenation in age-related cognition decline, much is still unknown about the changes in brain tissue pO2 with age. Using a detailed investigation of the age-related changes in cerebral tissue oxygenation in the barrel cortex of healthy, awake aged mice, we demonstrate decreased arteriolar and tissue pO2 with age. These changes are exacerbated after middle-age. We further uncovered evidence of the presence of hypoxic micro-pockets in the cortex of awake old mice. Our data suggests that from young to middle-age, a well-regulated capillary oxygen supply maintains the oxygen availability in cerebral tissue, despite decreased tissue pO2 next to arterioles. After middle-age, due to decreased hematocrit, reduced capillary density and higher capillary transit time heterogeneity, the capillary network fails to compensate for larger decreases in arterial pO2. The substantial decrease in brain tissue pO2, and the presence of hypoxic micro-pockets after middle-age are of significant importance, as these factors may be related to cognitive decline in elderly people.
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Affiliation(s)
- Mohammad Moeini
- Biomedical Engineering Institute, École Polytechnique de Montréal, Montréal, QC, Canada.,Research Center of Montreal Heart Institute, Montréal, QC, Canada.,Department of Chemistry, McGill University, Montréal, QC, Canada
| | - Xuecong Lu
- Biomedical Engineering Institute, École Polytechnique de Montréal, Montréal, QC, Canada.,Research Center of Montreal Heart Institute, Montréal, QC, Canada
| | - Pramod K Avti
- Biomedical Engineering Institute, École Polytechnique de Montréal, Montréal, QC, Canada.,Research Center of Montreal Heart Institute, Montréal, QC, Canada.,Department of Biophysics, Postgraduate Institute of Medical Education and Research, Chandigarh, India
| | - Rafat Damseh
- Biomedical Engineering Institute, École Polytechnique de Montréal, Montréal, QC, Canada
| | - Samuel Bélanger
- Biomedical Engineering Institute, École Polytechnique de Montréal, Montréal, QC, Canada.,Research Center of Montreal Heart Institute, Montréal, QC, Canada
| | - Frédéric Picard
- Centre de Recherche de l'Institut Universitaire de Cardiologie et Pneumologie de Québec (IUCPQ), Québec, QC, Canada
| | - David Boas
- Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Harvard Medical School, Charlestown, MA, USA.,Biomedical Engineering Department, College of Engineering, Boston University, Boston, MA, USA
| | - Ashok Kakkar
- Department of Chemistry, McGill University, Montréal, QC, Canada
| | - Frédéric Lesage
- Biomedical Engineering Institute, École Polytechnique de Montréal, Montréal, QC, Canada. .,Research Center of Montreal Heart Institute, Montréal, QC, Canada.
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8
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Catchlove SJ, Macpherson H, Hughes ME, Chen Y, Parrish TB, Pipingas A. An investigation of cerebral oxygen utilization, blood flow and cognition in healthy aging. PLoS One 2018; 13:e0197055. [PMID: 29787609 PMCID: PMC5963791 DOI: 10.1371/journal.pone.0197055] [Citation(s) in RCA: 39] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2017] [Accepted: 04/25/2018] [Indexed: 11/26/2022] Open
Abstract
Background Understanding how vascular and metabolic factors impact on cognitive function is essential to develop efficient therapies to prevent and treat cognitive losses in older age. Cerebral metabolic rate of oxygen (CMRO2), cerebral blood flow (CBF) and venous oxygenation (Yv) comprise key physiologic processes that maintain optimum functioning of neural activity. Changes to these parameters across the lifespan may precede neurodegeneration and contribute to age-related cognitive decline. This study examined differences in blood flow and metabolism between 31 healthy younger (<50 years) and 29 healthy older (>50 years) adults; and investigated whether these parameters contribute to cognitive performance. Method Participants underwent a cognitive assessment and MRI scan. Grey matter CMRO2 was calculated from measures of CBF (phase contrast MRI), arterial and venous oxygenation (TRUST MRI) to assess group differences in physiological function and the contribution of these parameters to cognition. Results Performance on memory (p<0.001) and attention tasks (p<0.001) and total CBF were reduced (p<0.05), and Yv trended toward a decrease (p = .06) in the older group, while grey matter CBF and CMRO2 did not differ between the age groups. Attention was negatively associated with CBF when adjusted (p<0.05) in the older adults, but not in the younger group. There was no such relationship with memory. Neither cognitive measure was associated with oxygen metabolism or venous oxygenation in either age group. Conclusion Findings indicated an age-related imbalance between oxygen delivery, consumption and demand, evidenced by a decreased supply of oxygen with unchanged metabolism resulting in increased oxygen extraction. CBF predicted attention when the age-effect was controlled, suggesting a task- specific CBF- cognition relationship.
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Affiliation(s)
- Sarah J. Catchlove
- Centre for Human Psychopharmacology, Swinburne University, Hawthorn Victoria, Australia
- * E-mail:
| | - Helen Macpherson
- Institute for Physical Activity and Nutrition, Deakin University, Geelong, Victoria, Australia
| | - Matthew E. Hughes
- Centre for Mental Health, Swinburne University, Hawthorn, Victoria, Australia
- Australian National Imaging Facility, University of Queensland, St Lucia Queensland, Australia
| | - Yufen Chen
- Feinberg School of Medicine, Northwestern University, Chicago, Illinois, United States of America
| | - Todd B. Parrish
- Feinberg School of Medicine, Northwestern University, Chicago, Illinois, United States of America
| | - Andrew Pipingas
- Centre for Human Psychopharmacology, Swinburne University, Hawthorn Victoria, Australia
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9
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Chiacchiaretta P, Cerritelli F, Bubbico G, Perrucci MG, Ferretti A. Reduced Dynamic Coupling Between Spontaneous BOLD-CBF Fluctuations in Older Adults: A Dual-Echo pCASL Study. Front Aging Neurosci 2018; 10:115. [PMID: 29740310 PMCID: PMC5925323 DOI: 10.3389/fnagi.2018.00115] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2018] [Accepted: 04/03/2018] [Indexed: 11/13/2022] Open
Abstract
Measurement of the dynamic coupling between spontaneous Blood Oxygenation Level Dependent (BOLD) and cerebral blood flow (CBF) fluctuations has been recently proposed as a method to probe resting-state brain physiology. Here we investigated how the dynamic BOLD-CBF coupling during resting-state is affected by aging. Fifteen young subjects and 17 healthy elderlies were studied using a dual-echo pCASL sequence. We found that the dynamic BOLD-CBF coupling was markedly reduced in elderlies, in particular in the left supramarginal gyrus, an area known to be involved in verbal working memory and episodic memory. Moreover, correcting for temporal shift between BOLD and CBF timecourses resulted in an increased correlation of the two signals for both groups, but with a larger increase for elderlies. However, even after temporal shift correction, a significantly decreased correlation was still observed for elderlies in the left supramarginal gyrus, indicating that the age-related dynamic BOLD-CBF uncoupling in this region is more pronounced and can be only partially explained with a simple time-shift between the two signals. Interestingly, these results were observed in a group of elderlies with normal cognitive functions, suggesting that the study of dynamic BOLD-CBF coupling during resting-state is a promising technique, potentially able to provide early biomarkers of functional changes in the aging brain.
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Affiliation(s)
- Piero Chiacchiaretta
- Department of Neuroscience, Imaging and Clinical Sciences, Università degli Studi G. d'Annunzio Chieti e Pescara, Chieti, Italy.,Institute for Advanced Biomedical Technologies (ITAB), Università degli Studi G. d'Annunzio Chieti e Pescara, Chieti, Italy
| | - Francesco Cerritelli
- Department of Neuroscience, Imaging and Clinical Sciences, Università degli Studi G. d'Annunzio Chieti e Pescara, Chieti, Italy.,Institute for Advanced Biomedical Technologies (ITAB), Università degli Studi G. d'Annunzio Chieti e Pescara, Chieti, Italy.,Clinical-Based Human Research Department-C.O.M.E. Collaboration ONLUS, Pescara, Italy
| | - Giovanna Bubbico
- Department of Neuroscience, Imaging and Clinical Sciences, Università degli Studi G. d'Annunzio Chieti e Pescara, Chieti, Italy.,Institute for Advanced Biomedical Technologies (ITAB), Università degli Studi G. d'Annunzio Chieti e Pescara, Chieti, Italy
| | - Mauro Gianni Perrucci
- Department of Neuroscience, Imaging and Clinical Sciences, Università degli Studi G. d'Annunzio Chieti e Pescara, Chieti, Italy.,Institute for Advanced Biomedical Technologies (ITAB), Università degli Studi G. d'Annunzio Chieti e Pescara, Chieti, Italy
| | - Antonio Ferretti
- Department of Neuroscience, Imaging and Clinical Sciences, Università degli Studi G. d'Annunzio Chieti e Pescara, Chieti, Italy.,Institute for Advanced Biomedical Technologies (ITAB), Università degli Studi G. d'Annunzio Chieti e Pescara, Chieti, Italy
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10
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Longitudinal imaging of the ageing mouse. Mech Ageing Dev 2016; 160:93-116. [PMID: 27530773 DOI: 10.1016/j.mad.2016.08.001] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2016] [Revised: 07/30/2016] [Accepted: 08/04/2016] [Indexed: 12/13/2022]
Abstract
Several non-invasive imaging techniques are used to investigate the effect of pathologies and treatments over time in mouse models. Each preclinical in vivo technique provides longitudinal and quantitative measurements of changes in tissues and organs, which are fundamental for the evaluation of alterations in phenotype due to pathologies, interventions and treatments. However, it is still unclear how these imaging modalities can be used to study ageing with mice models. Almost all age related pathologies in mice such as osteoporosis, arthritis, diabetes, cancer, thrombi, dementia, to name a few, can be imaged in vivo by at least one longitudinal imaging modality. These measurements are the basis for quantification of treatment effects in the development phase of a novel treatment prior to its clinical testing. Furthermore, the non-invasive nature of such investigations allows the assessment of different tissue and organ phenotypes in the same animal and over time, providing the opportunity to study the dysfunction of multiple tissues associated with the ageing process. This review paper aims to provide an overview of the applications of the most commonly used in vivo imaging modalities used in mouse studies: micro-computed-tomography, preclinical magnetic-resonance-imaging, preclinical positron-emission-tomography, preclinical single photon emission computed tomography, ultrasound, intravital microscopy, and whole body optical imaging.
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11
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Desjardins M, Sylvestre JP, Jafari R, Kulasekara S, Rose K, Trussart R, Arbour JD, Hudson C, Lesage F. Preliminary investigation of multispectral retinal tissue oximetry mapping using a hyperspectral retinal camera. Exp Eye Res 2016; 146:330-340. [PMID: 27060375 DOI: 10.1016/j.exer.2016.04.001] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2015] [Revised: 03/31/2016] [Accepted: 04/01/2016] [Indexed: 10/22/2022]
Abstract
Oximetry measurement of principal retinal vessels represents a first step towards understanding retinal metabolism, but the technique could be significantly enhanced by spectral imaging of the fundus outside of main vessels. In this study, a recently developed Hyperspectral Retinal Camera was used to measure relative oximetric (SatO2) and total hemoglobin (HbT) maps of the retina, outside of large vessels, in healthy volunteers at baseline (N = 7) and during systemic hypoxia (N = 11), as well as in patients with glaucoma (N = 2). Images of the retina, on a field of view of ∼30°, were acquired between 500 and 600 nm with 2 and 5 nm steps, in under 3 s. The reflectance spectrum from each pixel was fitted to a model having oxy- and deoxyhemoglobin as the main absorbers and scattering modeled by a power law, yielding estimates of relative SatO2 and HbT over the fundus. Average optic nerve head (ONH) saturation over 8 eyes was 68 ± 5%. During systemic hypoxia, mean ONH saturation decreased by 12.5% on average. Upon further development and validation, the relative SatO2 and HbT maps of microvasculature obtained with this imaging system could ultimately contribute to the diagnostic and management of diseases affecting the ONH and retina.
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Affiliation(s)
- Michèle Desjardins
- École Polytechnique de Montréal, Institut de génie biomédical, Département de Génie électrique, 2900, boul. Édouard-Montpetit, Montréal, Qc, H3T 1J4, Canada.
| | | | - Reza Jafari
- Optina Diagnostics, 3900 boul. Cote-Vertu, Suite #220, St-Laurent, Qc, H4R 1V4, Canada
| | - Susith Kulasekara
- University of Toronto, Department of Ophthalmology and Vision Sciences, Toronto Western Hospital, 399 Bathurst Street, Toronto, On, M5T 2S8, Canada
| | - Kalpana Rose
- University of Toronto, Department of Ophthalmology and Vision Sciences, Toronto Western Hospital, 399 Bathurst Street, Toronto, On, M5T 2S8, Canada
| | - Rachel Trussart
- Université de Montréal, Département d'ophtalmologie, 2900 Boulevard Édouard-Montpetit, Montréal, Qc, H3T 1J4, Canada
| | - Jean Daniel Arbour
- Université de Montréal, Département d'ophtalmologie, 2900 Boulevard Édouard-Montpetit, Montréal, Qc, H3T 1J4, Canada
| | - Chris Hudson
- University of Toronto, Department of Ophthalmology and Vision Sciences, Toronto Western Hospital, 399 Bathurst Street, Toronto, On, M5T 2S8, Canada; University of Waterloo, School of Optometry and Vision Science, 200 University Ave W, Waterloo, On, N2L 3G1, Canada
| | - Frédéric Lesage
- École Polytechnique de Montréal, Institut de génie biomédical, Département de Génie électrique, 2900, boul. Édouard-Montpetit, Montréal, Qc, H3T 1J4, Canada.
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12
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Quantifying the microvascular origin of BOLD-fMRI from first principles with two-photon microscopy and an oxygen-sensitive nanoprobe. J Neurosci 2015; 35:3663-75. [PMID: 25716864 DOI: 10.1523/jneurosci.3555-14.2015] [Citation(s) in RCA: 156] [Impact Index Per Article: 17.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023] Open
Abstract
The blood oxygenation level-dependent (BOLD) contrast is widely used in functional magnetic resonance imaging (fMRI) studies aimed at investigating neuronal activity. However, the BOLD signal reflects changes in blood volume and oxygenation rather than neuronal activity per se. Therefore, understanding the transformation of microscopic vascular behavior into macroscopic BOLD signals is at the foundation of physiologically informed noninvasive neuroimaging. Here, we use oxygen-sensitive two-photon microscopy to measure the BOLD-relevant microvascular physiology occurring within a typical rodent fMRI voxel and predict the BOLD signal from first principles using those measurements. The predictive power of the approach is illustrated by quantifying variations in the BOLD signal induced by the morphological folding of the human cortex. This framework is then used to quantify the contribution of individual vascular compartments and other factors to the BOLD signal for different magnet strengths and pulse sequences.
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13
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Belanger-Nelson E, Freyburger M, Pouliot P, Beaumont E, Lesage F, Mongrain V. Brain hemodynamic response to somatosensory stimulation in Neuroligin-1 knockout mice. Neuroscience 2015; 289:242-50. [DOI: 10.1016/j.neuroscience.2014.12.069] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2014] [Revised: 11/25/2014] [Accepted: 12/24/2014] [Indexed: 10/24/2022]
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14
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Billard JM. D-Serine in the aging hippocampus. J Pharm Biomed Anal 2015; 116:18-24. [PMID: 25740810 DOI: 10.1016/j.jpba.2015.02.013] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2014] [Revised: 02/03/2015] [Accepted: 02/07/2015] [Indexed: 01/06/2023]
Abstract
Experimental evidences now indicate that memory formation relies on the capacity of neuronal networks to manage long-term changes in synaptic communication. This property is driven by N-methyl-D-aspartate receptors (NMDAR), which requires the binding of glutamate but also the presence of the co-agonist D-serine at the glycine site. Defective memory function and impaired brain synaptic plasticity observed in aging are rescued by partial agonist acting at this site suggesting that this gating process is targeted to induce age-related cognitive defects. This review aims at compelling recent studies characterizing the role of D-serine in changes in functional plasticity that occur in the aging hippocampus since deficits are rescued by D-serine supplementation. The impaired efficacy of endogenous D-serine is not due to changes in the affinity to glycine-binding site but to a decrease in tissue levels of the amino acid resulting from a weaker expression of the producing enzyme serine racemase (SR). Interestingly, neither SR expression, D-serine levels, nor NMDAR activation is affected in aged LOU/C rats, a model of healthy aging in which memory deficits do not occur. These old animals do not develop oxidative stress suggesting that the D-serine-related pathway could be targeted by the age-related accumulation of reactive oxygen species. Accordingly, senescent rats chronically treated with the reducing agent N-acetyl-cysteine to prevent oxidative damage, show intact NMDAR activation linked to preserved D-serine levels and SR expression. These results point to a significant role of D-serine in age-related functional alterations underlying hippocampus-dependent memory deficits, at least within the CA1 area since the amino acid does not appear as critical in changes affecting the dentate gyrus.
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Affiliation(s)
- Jean-Marie Billard
- Center of Psychiatry and Neurosciences, Paris Descartes University, Sorbonne Paris City, UMR U894, Paris 75014 France.
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15
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Desjardins M, Berti R, Pouliot P, Dubeau S, Lesage F. Multimodal study of the hemodynamic response to hypercapnia in anesthetized aged rats. Neurosci Lett 2014; 563:33-7. [PMID: 24480251 DOI: 10.1016/j.neulet.2014.01.027] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2013] [Revised: 01/13/2014] [Accepted: 01/17/2014] [Indexed: 10/25/2022]
Abstract
With aging, the brain undergoes changes in metabolism and perfusion, both of which influence the widely used blood-oxygenation-level-dependent (BOLD) MRI signal. To isolate the vascular effects associated with age, this study measured the response to a hypercapnic challenge using different imaging modalities in 19 young (3 months-old) and 13 old (24 months-old) Long-Evans rats. Intrinsic optical imaging was used to measure oxy (HbO), deoxy (HbR) and total (HbT) hemoglobin concentration changes, laser speckle for cerebral blood flow (CBF) changes, and MRI for the BOLD signal. Older rats had smaller HbO (41% smaller), HbT (50%) and CBF (34%) responses, but the temporal dynamics did not exhibit significant age differences. The ratio of CBV to CBF responses was also smaller in older adults, potentially indicating a change in the compliance of vessels.
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Affiliation(s)
- Michèle Desjardins
- Institut de Génie Biomédical, Dpt. de Génie Électrique, École Polytechnique de Montréal, C.P. 6079, succ. Centre-ville, Montréal, QC, H3C 3A7, Canada; Montreal Heart Institute, 5000 rue Bélanger, Montréal, QC, H1T 1C8, Canada.
| | - Romain Berti
- Institut de Génie Biomédical, Dpt. de Génie Électrique, École Polytechnique de Montréal, C.P. 6079, succ. Centre-ville, Montréal, QC, H3C 3A7, Canada; Montreal Heart Institute, 5000 rue Bélanger, Montréal, QC, H1T 1C8, Canada
| | - Philippe Pouliot
- Institut de Génie Biomédical, Dpt. de Génie Électrique, École Polytechnique de Montréal, C.P. 6079, succ. Centre-ville, Montréal, QC, H3C 3A7, Canada; Montreal Heart Institute, 5000 rue Bélanger, Montréal, QC, H1T 1C8, Canada
| | - Simon Dubeau
- Institut de Génie Biomédical, Dpt. de Génie Électrique, École Polytechnique de Montréal, C.P. 6079, succ. Centre-ville, Montréal, QC, H3C 3A7, Canada; Montreal Heart Institute, 5000 rue Bélanger, Montréal, QC, H1T 1C8, Canada
| | - Frédéric Lesage
- Institut de Génie Biomédical, Dpt. de Génie Électrique, École Polytechnique de Montréal, C.P. 6079, succ. Centre-ville, Montréal, QC, H3C 3A7, Canada; Montreal Heart Institute, 5000 rue Bélanger, Montréal, QC, H1T 1C8, Canada
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16
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Calcinaghi N, Wyss MT, Jolivet R, Singh A, Keller AL, Winnik S, Fritschy JM, Buck A, Matter CM, Weber B. Multimodal imaging in rats reveals impaired neurovascular coupling in sustained hypertension. Stroke 2013; 44:1957-64. [PMID: 23735955 DOI: 10.1161/strokeaha.111.000185] [Citation(s) in RCA: 46] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
BACKGROUND AND PURPOSE Arterial hypertension is an important risk factor for cerebrovascular diseases, such as transient ischemic attacks or stroke, and represents a major global health issue. The effects of hypertension on cerebral blood flow, particularly at the microvascular level, remain unknown. METHODS Using the spontaneously hypertensive rat (SHR) model, we examined cortical hemodynamic responses on whisker stimulation applying a multimodal imaging approach (multiwavelength spectroscopy, laser speckle imaging, and 2-photon microscopy). We assessed the effects of hypertension in 10-, 20-, and 40-week-old male SHRs and age-matched male Wistar Kyoto rats (CTRL) on hemodynamic responses, histology, and biochemical parameters. In 40-week-old animals, losartan or verapamil was administered for 10 weeks to test the reversibility of hypertension-induced impairments. RESULTS Increased arterial blood pressure was associated with a progressive impairment in functional hyperemia in 20- and 40-week-old SHRs; baseline capillary red blood cell velocity was increased in 40-week-old SHRs compared with age-matched CTRLs. Antihypertensive treatment reduced baseline capillary cerebral blood flow almost to CTRL values, whereas functional hyperemic signals did not improve after 10 weeks of drug therapy. Structural analyses of the microvascular network revealed no differences between normo- and hypertensive animals, whereas expression analyses of cerebral lysates showed signs of increased oxidative stress and signs of impaired endothelial homeostasis upon early hypertension. CONCLUSIONS Impaired neurovascular coupling in the SHR evolves upon sustained hypertension. Antihypertensive monotherapy using verapamil or losartan is not sufficient to abolish this functional impairment. These deficits in neurovascular coupling in response to sustained hypertension might contribute to accelerate progression of neurodegenerative diseases in chronic hypertension.
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Affiliation(s)
- Novella Calcinaghi
- Institute of Pharmacology and Toxicology, University of Zurich, Zurich, Switzerland
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17
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Guevara E, Sadekova N, Girouard H, Lesage F. Optical imaging of resting-state functional connectivity in a novel arterial stiffness model. BIOMEDICAL OPTICS EXPRESS 2013; 4:2332-46. [PMID: 24298398 PMCID: PMC3829531 DOI: 10.1364/boe.4.002332] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/03/2013] [Revised: 09/04/2013] [Accepted: 09/05/2013] [Indexed: 05/12/2023]
Abstract
This study aims to assess the impact of unilateral increases in carotid stiffness on cortical functional connectivity measures in the resting state. Using a novel animal model of induced arterial stiffness combined with optical intrinsic signals and laser speckle imaging, resting state functional networks derived from hemodynamic signals are investigated for their modulation by isolated changes in stiffness of the right common carotid artery. By means of seed-based analysis, results showed a decreasing trend of homologous correlation in the motor and cingulate cortices. Furthermore, a graph analysis indicated a randomization of the cortex functional networks, suggesting a loss of connectivity, more specifically in the motor cortex lateral to the treated carotid, which however did not translate in differentiated metabolic activity.
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Affiliation(s)
- Edgar Guevara
- Department of Electrical Engineering, École Polytechnique de Montréal, 2500 Chemin de Polytechnique, Montréal, Qc, H3C 3A7 Canada
- Research Center, Montreal Heart Institute, 5000 Bélanger Est, Montréal, Qc, H3T 1J4, Canada
| | - Nataliya Sadekova
- Department of Pharmacology, Faculty of Medicine, Université de Montréal, 2900 Édouard-Montpetit Montréal, Qc, H3T 1J4 Canada
| | - Hélène Girouard
- Department of Pharmacology, Faculty of Medicine, Université de Montréal, 2900 Édouard-Montpetit Montréal, Qc, H3T 1J4 Canada
| | - Frédéric Lesage
- Department of Electrical Engineering, École Polytechnique de Montréal, 2500 Chemin de Polytechnique, Montréal, Qc, H3C 3A7 Canada
- Research Center, Montreal Heart Institute, 5000 Bélanger Est, Montréal, Qc, H3T 1J4, Canada
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Paban V, Billard JM, Bouet V, Freret T, Boulouard M, Chambon C, Loriod B, Alescio-Lautier B. Genomic transcriptional profiling in LOU/C/Jall rats identifies genes for successful aging. Brain Struct Funct 2012; 218:1501-12. [DOI: 10.1007/s00429-012-0472-8] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2012] [Accepted: 10/25/2012] [Indexed: 02/04/2023]
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19
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Dubeau S, Desjardins M, Pouliot P, Beaumont E, Gaudreau P, Ferland G, Lesage F. Biophysical model estimation of neurovascular parameters in a rat model of healthy aging. Neuroimage 2011; 57:1480-91. [PMID: 21549843 DOI: 10.1016/j.neuroimage.2011.04.030] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2011] [Revised: 04/11/2011] [Accepted: 04/14/2011] [Indexed: 11/27/2022] Open
Abstract
Neuronal, vascular and metabolic factors result in a deterioration of the cerebral hemodynamic response with age. The interpretation of neuroimaging studies in the context of aging is rendered difficult due to the challenge in untangling the composite effect of these modifications. In this work we integrate multimodal optical imaging in biophysical models to investigate vascular and metabolic changes occurring in aging. Multispectral intrinsic optical imaging of an animal model of healthy aging, the LOU/c rat, is used in combination with somatosensory stimulation to study the modifications of the hemodynamic response with increasing age. Results are fitted with three macroscopic biophysical models to extract parameters, providing a phenomenological description of vascular and metabolic changes. Our results show that 1) biophysical parameters are estimable from multimodal data and 2) parameter estimates in this population change with aging.
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Affiliation(s)
- S Dubeau
- Department of Electrical Engineering, École Polytechnique de Montréal, Montréal, QC, Canada
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