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Kavroulakis E, Simos NJ, Maris TG, Zaganas I, Panagiotakis S, Papadaki E. Evidence of Age-Related Hemodynamic and Functional Connectivity Impairment: A Resting State fMRI Study. Front Neurol 2021; 12:633500. [PMID: 33833727 PMCID: PMC8021915 DOI: 10.3389/fneur.2021.633500] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2020] [Accepted: 03/01/2021] [Indexed: 11/13/2022] Open
Abstract
Purpose: To assess age-related changes in intrinsic functional brain connectivity and hemodynamics during adulthood in the context of the retrogenesis hypothesis, which states that the rate of age-related changes is higher in late-myelinating (prefrontal, lateral-posterior temporal) cerebrocortical areas as compared to early myelinating (parietal, occipital) regions. In addition, to examine the dependence of age-related changes upon concurrent subclinical depression symptoms which are common even in healthy aging. Methods: Sixty-four healthy adults (28 men) aged 23-79 years (mean 45.0, SD = 18.8 years) were examined. Resting-state functional MRI (rs-fMRI) time series were used to compute voxel-wise intrinsic connectivity contrast (ICC) maps reflecting the strength of functional connectivity between each voxel and the rest of the brain. We further used Time Shift Analysis (TSA) to estimate voxel-wise hemodynamic lead or lag for each of 22 ROIs from the automated anatomical atlas (AAL). Results: Adjusted for depression symptoms, gender and education level, reduced ICC with age was found primarily in frontal, temporal regions, and putamen, whereas the opposite trend was noted in inferior occipital cortices (p < 0.002). With the same covariates, increased hemodynamic lead with advancing age was found in superior frontal cortex and thalamus, with the opposite trend in inferior occipital cortex (p < 0.002). There was also evidence of reduced coupling between voxel-wise intrinsic connectivity and hemodynamics in the inferior parietal cortex. Conclusion: Age-related intrinsic connectivity reductions and hemodynamic changes were demonstrated in several regions-most of them part of DMN and salience networks-while impaired neurovascular coupling was, also, found in parietal regions. Age-related reductions in intrinsic connectivity were greater in anterior as compared to posterior cortices, in line with implications derived from the retrogenesis hypothesis. These effects were affected by self-reported depression symptoms, which also increased with age.
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Affiliation(s)
- Eleftherios Kavroulakis
- Department of Radiology, School of Medicine, University of Crete, University Hospital of Heraklion, Heraklion, Greece
| | - Nicholas J Simos
- Department of Electrical and Computer Engineering, Technical University of Crete, Chania, Greece.,Computational Bio-Medicine Laboratory, Institute of Computer Science, Foundation for Research and Technology - Hellas, Heraklion, Greece
| | - Thomas G Maris
- Department of Medical Physics, School of Medicine, University of Crete, University Hospital of Heraklion, Heraklion, Greece
| | - Ioannis Zaganas
- Department of Neurology, School of Medicine, University of Crete, University Hospital of Heraklion, Heraklion, Greece
| | - Simeon Panagiotakis
- Department of Internal Medicine, University Hospital of Heraklion, Heraklion, Greece
| | - Efrosini Papadaki
- Department of Radiology, School of Medicine, University of Crete, University Hospital of Heraklion, Heraklion, Greece.,Computational Bio-Medicine Laboratory, Institute of Computer Science, Foundation for Research and Technology - Hellas, Heraklion, Greece
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2
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Cox SR, Harris MA, Ritchie SJ, Buchanan CR, Valdés Hernández MC, Corley J, Taylor AM, Madole JW, Harris SE, Whalley HC, McIntosh AM, Russ TC, Bastin ME, Wardlaw JM, Deary IJ, Tucker-Drob EM. Three major dimensions of human brain cortical ageing in relation to cognitive decline across the eighth decade of life. Mol Psychiatry 2021; 26:2651-2662. [PMID: 33398085 PMCID: PMC8254824 DOI: 10.1038/s41380-020-00975-1] [Citation(s) in RCA: 27] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/14/2020] [Revised: 11/17/2020] [Accepted: 11/30/2020] [Indexed: 12/28/2022]
Abstract
Different brain regions can be grouped together, based on cross-sectional correlations among their cortical characteristics; this patterning has been used to make inferences about ageing processes. However, cross-sectional brain data conflate information on ageing with patterns that are present throughout life. We characterised brain cortical ageing across the eighth decade of life in a longitudinal ageing cohort, at ages ~73, ~76, and ~79 years, with a total of 1376 MRI scans. Volumetric changes among cortical regions of interest (ROIs) were more strongly correlated (average r = 0.805, SD = 0.252) than were cross-sectional volumes of the same ROIs (average r = 0.350, SD = 0.178). We identified a broad, cortex-wide, dimension of atrophy that explained 66% of the variance in longitudinal changes across the cortex. Our modelling also discovered more specific fronto-temporal and occipito-parietal dimensions that were orthogonal to the general factor and together explained an additional 20% of the variance. The general factor was associated with declines in general cognitive ability (r = 0.431, p < 0.001) and in the domains of visuospatial ability (r = 0.415, p = 0.002), processing speed (r = 0.383, p < 0.001) and memory (r = 0.372, p < 0.001). Individual differences in brain cortical atrophy with ageing are manifest across three broad dimensions of the cerebral cortex, the most general of which is linked with cognitive declines across domains. Longitudinal approaches are invaluable for distinguishing lifelong patterns of brain-behaviour associations from patterns that are specific to aging.
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Affiliation(s)
- S. R. Cox
- grid.4305.20000 0004 1936 7988Lothian Birth Cohorts Group, The University of Edinburgh, Edinburgh, UK ,grid.4305.20000 0004 1936 7988Department of Psychology, The University of Edinburgh, Edinburgh, UK ,Scottish Imaging Network, A Platform for Scientific Excellence (SINAPSE) Collaboration, Edinburgh, UK
| | - M. A. Harris
- grid.4305.20000 0004 1936 7988Division of Psychiatry, The University of Edinburgh, Edinburgh, UK
| | - S. J. Ritchie
- grid.13097.3c0000 0001 2322 6764Social, Genetic and Developmental Psychiatry Centre, King’s College London, London, UK
| | - C. R. Buchanan
- grid.4305.20000 0004 1936 7988Lothian Birth Cohorts Group, The University of Edinburgh, Edinburgh, UK ,grid.4305.20000 0004 1936 7988Department of Psychology, The University of Edinburgh, Edinburgh, UK ,Scottish Imaging Network, A Platform for Scientific Excellence (SINAPSE) Collaboration, Edinburgh, UK
| | - M. C. Valdés Hernández
- grid.4305.20000 0004 1936 7988Lothian Birth Cohorts Group, The University of Edinburgh, Edinburgh, UK ,Scottish Imaging Network, A Platform for Scientific Excellence (SINAPSE) Collaboration, Edinburgh, UK ,grid.4305.20000 0004 1936 7988Centre for Clinical Brain Sciences, The University of Edinburgh, Edinburgh, UK
| | - J. Corley
- grid.4305.20000 0004 1936 7988Lothian Birth Cohorts Group, The University of Edinburgh, Edinburgh, UK ,grid.4305.20000 0004 1936 7988Department of Psychology, The University of Edinburgh, Edinburgh, UK
| | - A. M. Taylor
- grid.4305.20000 0004 1936 7988Lothian Birth Cohorts Group, The University of Edinburgh, Edinburgh, UK ,grid.4305.20000 0004 1936 7988Department of Psychology, The University of Edinburgh, Edinburgh, UK
| | - J. W. Madole
- grid.55460.320000000121548364Department of Psychology, University of Texas, Austin, TX USA
| | - S. E. Harris
- grid.4305.20000 0004 1936 7988Lothian Birth Cohorts Group, The University of Edinburgh, Edinburgh, UK ,grid.4305.20000 0004 1936 7988Department of Psychology, The University of Edinburgh, Edinburgh, UK
| | - H. C. Whalley
- grid.4305.20000 0004 1936 7988Division of Psychiatry, The University of Edinburgh, Edinburgh, UK
| | - A. M. McIntosh
- grid.4305.20000 0004 1936 7988Division of Psychiatry, The University of Edinburgh, Edinburgh, UK
| | - T. C. Russ
- grid.4305.20000 0004 1936 7988Lothian Birth Cohorts Group, The University of Edinburgh, Edinburgh, UK ,grid.4305.20000 0004 1936 7988Division of Psychiatry, The University of Edinburgh, Edinburgh, UK ,grid.4305.20000 0004 1936 7988Centre for Clinical Brain Sciences, The University of Edinburgh, Edinburgh, UK ,grid.4305.20000 0004 1936 7988Alzheimer Scotland Dementia Research Centre, The University of Edinburgh, Edinburgh, UK
| | - M. E. Bastin
- grid.4305.20000 0004 1936 7988Lothian Birth Cohorts Group, The University of Edinburgh, Edinburgh, UK ,Scottish Imaging Network, A Platform for Scientific Excellence (SINAPSE) Collaboration, Edinburgh, UK ,grid.4305.20000 0004 1936 7988Centre for Clinical Brain Sciences, The University of Edinburgh, Edinburgh, UK
| | - J. M. Wardlaw
- grid.4305.20000 0004 1936 7988Lothian Birth Cohorts Group, The University of Edinburgh, Edinburgh, UK ,Scottish Imaging Network, A Platform for Scientific Excellence (SINAPSE) Collaboration, Edinburgh, UK ,grid.4305.20000 0004 1936 7988Centre for Clinical Brain Sciences, The University of Edinburgh, Edinburgh, UK ,grid.4305.20000 0004 1936 7988UK Dementia Research Institute at The University of Edinburgh, Edinburgh, UK
| | - I. J. Deary
- grid.4305.20000 0004 1936 7988Lothian Birth Cohorts Group, The University of Edinburgh, Edinburgh, UK ,grid.4305.20000 0004 1936 7988Department of Psychology, The University of Edinburgh, Edinburgh, UK
| | - E. M. Tucker-Drob
- grid.55460.320000000121548364Department of Psychology, University of Texas, Austin, TX USA
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Papadaki E, Kavroulakis E, Kalaitzakis G, Karageorgou D, Makrakis D, Maris TG, Simos PG. Age‐related deep white matter changes in myelin and water content: A T
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relaxometry study. J Magn Reson Imaging 2019; 50:1393-1404. [DOI: 10.1002/jmri.26707] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2018] [Revised: 02/16/2019] [Accepted: 02/19/2019] [Indexed: 11/11/2022] Open
Affiliation(s)
- Efrosini Papadaki
- Department of RadiologySchool of Medicine, University of Crete Heraklion, Crete Greece
- Institute of Computer ScienceFoundation of Research and Technology Heraklion Greece
| | | | - Georgios Kalaitzakis
- Department of Medical PhysicsSchool of Medicine, University of Crete Heraklion, Crete Greece
| | - Dimitra Karageorgou
- Department of RadiologySchool of Medicine, University of Crete Heraklion, Crete Greece
| | - Dimitrios Makrakis
- Department of RadiologySchool of Medicine, University of Crete Heraklion, Crete Greece
| | - Thomas G. Maris
- Institute of Computer ScienceFoundation of Research and Technology Heraklion Greece
- Department of Medical PhysicsSchool of Medicine, University of Crete Heraklion, Crete Greece
| | - Panagiotis G. Simos
- Institute of Computer ScienceFoundation of Research and Technology Heraklion Greece
- Department of PsychiatrySchool of Medicine, University of Crete Heraklion, Crete Greece
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Pareek V, Rallabandi VS, Roy PK. A Correlational Study between Microstructural White Matter Properties and Macrostructural Gray Matter Volume Across Normal Ageing: Conjoint DTI and VBM Analysis. MAGNETIC RESONANCE INSIGHTS 2018; 11:1178623X18799926. [PMID: 30349289 PMCID: PMC6194920 DOI: 10.1177/1178623x18799926] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/30/2017] [Accepted: 07/08/2018] [Indexed: 11/17/2022]
Abstract
We investigate the relationship between Gray matter’s volume vis-a-vis White matter’s integrity indices, such Axial diffusivity, Radial diffusivity, Mean diffusivity, and Fractional anisotropy, in individuals undergoing healthy aging. We investigated MRI scans of 177 adults across 20 to 85 years. We used Voxel-based morphometry, and FDT-FSL analysis for estimation of Gray matter volume and White matter’s diffusion indices respectively. Across the life span, we observed an inter-relationship between the Gray matter and White matter, namely that both Axial diffusivity and Mean Diffusivity show strong correlation with Gray matter volume, along the aging process. Furthermore, across all ages the Fractional anisotropy and Mean diffusivity are found to be significantly reduced in females when compared to males, but there are no significant gender differences in Axial Diffusivity and Radial diffusivity. We conclude that for both genders across all ages, the Gray matter’s Volume is strongly correlated with White matter’s Axial Diffusivity and Mean Diffusivity, while being weakly correlated with Fractional Anisotropy. Our study clarifies the multi-scale relationship in brain tissue, by elucidating how the White matter’s micro-structural parameters influences the Gray matter’s macro-structural characteristics, during healthy aging across the life-span.
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Affiliation(s)
- Vikas Pareek
- National Neuroimaging Facility, National Brain Research Centre, Manesar, India
| | | | - Prasun K Roy
- Computational Neuroscience & Neuro-Imaging Laboratory, School of Biomedical Engineering, Indian Institute of Technology (BHU), Varanasi, India
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5
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Fernandes SM, Araújo AM, Vázquez-Justo E, Pereira C, Silva A, Paul N, Yubero R, Maestú F. Effects of aging on memory strategies: a validation of the Portuguese version of the Test of Memory Strategies. Clin Neuropsychol 2018; 32:133-151. [PMID: 29954246 DOI: 10.1080/13854046.2018.1490456] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2022]
Abstract
OBJECTIVE Previous literature has shown that executive functions (EF) are related to performance in memory tasks. The fact that there are no psychometric tests that evaluate these two constructs simultaneously led a group of researchers to develop the Test of Memory Strategies (TSM). Given the potential importance of this instrument for neuropsychological evaluation, in this study, we aimed to evaluate the psychometric properties of the TMS in Portuguese sample. We also examined the effect of aging by exploring profiles of performance on the TMS, comparing young and elderly healthy subjects. METHOD Total of 135 healthy participants were submitted to a neuropsychological assessment and were divided into four age groups: a group of young adults (25-35 years) and three groups of older individuals (aged 60-69 years, 70-79 years, and 80 or more years). RESULTS Findings supported the reliability of the TMS scores, based on analyses of internal consistency. As expected, factor analysis of the TMS scores revealed that the test yielded two factors, one capturing EF and the other memory. Correlations with classic neuropsychological tests supported convergent and discriminant validity of the TMS scores. The elderly groups presented more difficulties in creating and mobilizing memory strategies when compared with a younger group, after controlling for the influence of education, although both groups presented increases in performance throughout the five TMS subscales. CONCLUSIONS The findings suggest that the TMS is an adequate measure to assess memory and EF, simultaneously, presenting adequate psychometric properties for a Portuguese sample.
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Affiliation(s)
- Sara M Fernandes
- a INPP - Portucalense Institute for Human Development , Portucalense University , Porto , Portugal.,b IJP - Portucalense Institute for Legal Research , Portucalense University , Porto , Portugal
| | - Alexandra M Araújo
- a INPP - Portucalense Institute for Human Development , Portucalense University , Porto , Portugal
| | - Enrique Vázquez-Justo
- a INPP - Portucalense Institute for Human Development , Portucalense University , Porto , Portugal.,b IJP - Portucalense Institute for Legal Research , Portucalense University , Porto , Portugal
| | - Carolina Pereira
- a INPP - Portucalense Institute for Human Development , Portucalense University , Porto , Portugal
| | - Ana Silva
- a INPP - Portucalense Institute for Human Development , Portucalense University , Porto , Portugal
| | - Nuria Paul
- c Faculty of Psychology, Department of Experimental Psychology , Complutense University of Madrid , Madrid , Spain
| | - Raquel Yubero
- c Faculty of Psychology, Department of Experimental Psychology , Complutense University of Madrid , Madrid , Spain
| | - Fernando Maestú
- d Laboratory of Cognitive and Computational Neuroscience , Center for Biomedical Technology (Complutense University of Madrid and Technical University of Madrid) , Madrid , Spain.,e CIBER-BBN , Instituto de Salud Carlos III , Madrid , Spain
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6
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Wright AK, Theilmann RJ, Ridgway SH, Scadeng M. Diffusion tractography reveals pervasive asymmetry of cerebral white matter tracts in the bottlenose dolphin (Tursiops truncatus). Brain Struct Funct 2017; 223:1697-1711. [PMID: 29189908 PMCID: PMC5884918 DOI: 10.1007/s00429-017-1525-9] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2016] [Accepted: 07/06/2017] [Indexed: 12/18/2022]
Abstract
Brain enlargement is associated with concomitant growth of interneuronal distance, increased conduction time, and reduced neuronal interconnectivity. Recognition of these functional constraints led to the hypothesis that large-brained mammals should exhibit greater structural and functional brain lateralization. As a taxon with the largest brains in the animal kingdom, Cetacea provides a unique opportunity to examine asymmetries of brain structure and function. In the present study, diffusion tensor imaging and tractography were used to investigate cerebral white matter asymmetry in the bottlenose dolphin (Tursiops truncatus). Widespread white matter asymmetries were observed with the preponderance of tracts exhibiting leftward structural asymmetries. Leftward lateralization may reflect differential processing and execution of behaviorally variant sensory and motor functions by the cerebral hemispheres. The arcuate fasciculus, an association tract linked to human language evolution, was isolated and exhibited rightward asymmetry suggesting a right hemisphere bias for conspecific communication unlike that of most mammals. This study represents the first examination of cetacean white matter asymmetry and constitutes an important step toward understanding potential drivers of structural asymmetry and its role in underpinning functional and behavioral lateralization in cetaceans.
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Affiliation(s)
- Alexandra K Wright
- Center for Marine Biotechnology and Biomedicine, Scripps Institution of Oceanography, University of California-San Diego, La Jolla, CA, 92093, USA.
| | - Rebecca J Theilmann
- Department of Radiology, University of California-San Diego, La Jolla, CA, 92093, USA
| | - Sam H Ridgway
- National Marine Mammal Foundation, San Diego, CA, 92106, USA
| | - Miriam Scadeng
- Center for Functional MRI, Department of Radiology, University of California-San Diego, La Jolla, CA, 92093, USA
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7
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Ruigrok ANV, Salimi-Khorshidi G, Lai MC, Baron-Cohen S, Lombardo MV, Tait RJ, Suckling J. A meta-analysis of sex differences in human brain structure. Neurosci Biobehav Rev 2013; 39:34-50. [PMID: 24374381 PMCID: PMC3969295 DOI: 10.1016/j.neubiorev.2013.12.004] [Citation(s) in RCA: 650] [Impact Index Per Article: 59.1] [Reference Citation Analysis] [Abstract] [Key Words] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2013] [Revised: 12/13/2013] [Accepted: 12/17/2013] [Indexed: 02/02/2023]
Abstract
This is the first meta-analysis of sex differences in the typical human brain. Regional sex differences overlap with areas implicated in psychiatric conditions. The amygdala, hippocampus, planum temporale and insula display sex differences. On average, males have larger brain volumes than females. Most articles providing sex differences in volume are in the ‘mature’ category.
The prevalence, age of onset, and symptomatology of many neuropsychiatric conditions differ between males and females. To understand the causes and consequences of sex differences it is important to establish where they occur in the human brain. We report the first meta-analysis of typical sex differences on global brain volume, a descriptive account of the breakdown of studies of each compartmental volume by six age categories, and whole-brain voxel-wise meta-analyses on brain volume and density. Gaussian-process regression coordinate-based meta-analysis was used to examine sex differences in voxel-based regional volume and density. On average, males have larger total brain volumes than females. Examination of the breakdown of studies providing total volumes by age categories indicated a bias towards the 18–59 year-old category. Regional sex differences in volume and tissue density include the amygdala, hippocampus and insula, areas known to be implicated in sex-biased neuropsychiatric conditions. Together, these results suggest candidate regions for investigating the asymmetric effect that sex has on the developing brain, and for understanding sex-biased neurological and psychiatric conditions.
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Affiliation(s)
- Amber N V Ruigrok
- Autism Research Centre, Department of Psychiatry, University of Cambridge, Douglas House, 18B Trumpington Road, Cambridge CB2 8AH, United Kingdom.
| | - Gholamreza Salimi-Khorshidi
- Centre for Functional MRI of the Brain (FMRIB), Nuffield Department of Clinical Neurosciences, University of Oxford, John Radcliffe Hospital, Oxford OX3 9DU, United Kingdom
| | - Meng-Chuan Lai
- Autism Research Centre, Department of Psychiatry, University of Cambridge, Douglas House, 18B Trumpington Road, Cambridge CB2 8AH, United Kingdom; Department of Psychiatry, College of Medicine, National Taiwan University, No. 1 Jen-Ai Road Section 1, Taipei 10051, Taiwan
| | - Simon Baron-Cohen
- Autism Research Centre, Department of Psychiatry, University of Cambridge, Douglas House, 18B Trumpington Road, Cambridge CB2 8AH, United Kingdom; Cambridgeshire and Peterborough NHS Foundation Trust, Elizabeth House, Fulbourn Hospital, Cambridge CB21 5EF, United Kingdom
| | - Michael V Lombardo
- Autism Research Centre, Department of Psychiatry, University of Cambridge, Douglas House, 18B Trumpington Road, Cambridge CB2 8AH, United Kingdom; Department of Psychology, University of Cyprus, P.O. Box 20537, CY 1678 Nicosia, Cyprus
| | - Roger J Tait
- Brain Mapping Unit, School of Clinical Medicine, University of Cambridge, Herchel Smith Building, Robinson Way, Cambridge CB2 0SP, United Kingdom; Behavioural and Clinical Neuroscience Institute, Department of Psychology, University of Cambridge, Downing Street, Cambridge CB2 3EB, United Kingdom
| | - John Suckling
- Cambridgeshire and Peterborough NHS Foundation Trust, Elizabeth House, Fulbourn Hospital, Cambridge CB21 5EF, United Kingdom; Brain Mapping Unit, School of Clinical Medicine, University of Cambridge, Herchel Smith Building, Robinson Way, Cambridge CB2 0SP, United Kingdom; Behavioural and Clinical Neuroscience Institute, Department of Psychology, University of Cambridge, Downing Street, Cambridge CB2 3EB, United Kingdom
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8
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Phillips OR, Clark KA, Luders E, Azhir R, Joshi SH, Woods RP, Mazziotta JC, Toga AW, Narr KL. Superficial white matter: effects of age, sex, and hemisphere. Brain Connect 2013; 3:146-59. [PMID: 23461767 DOI: 10.1089/brain.2012.0111] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022] Open
Abstract
Structural and diffusion imaging studies demonstrate effects of age, sex, and asymmetry in many brain structures. However, few studies have addressed how individual differences might influence the structural integrity of the superficial white matter (SWM), comprised of short-range association (U-fibers), and intracortical axons. This study thus applied a sophisticated computational analysis approach to structural and diffusion imaging data obtained from healthy individuals selected from the International Consortium for Brain Mapping (ICBM) database across a wide adult age range (n=65, age: 18-74 years, all Caucasian). Fractional anisotropy (FA), radial diffusivity (RD), and axial diffusivity (AD) were sampled and compared at thousands of spatially matched SWM locations and within regions-of-interest to examine global and local variations in SWM integrity across age, sex, and hemisphere. Results showed age-related reductions in FA that were more pronounced in the frontal SWM than in the posterior and ventral brain regions, whereas increases in RD and AD were observed across large areas of the SWM. FA was significantly greater in left temporoparietal regions in men and in the posterior callosum in women. Prominent leftward FA and rightward AD and RD asymmetries were observed in the temporal, parietal, and frontal regions. Results extend previous findings restricted to the deep white matter pathways to demonstrate regional changes in the SWM microstructure relating to processes of demyelination and/or to the number, coherence, or integrity of axons with increasing age. SWM fiber organization/coherence appears greater in the left hemisphere regions spanning language and other networks, while more localized sex effects could possibly reflect sex-specific advantages in information strategies.
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Affiliation(s)
- Owen R Phillips
- Laboratory of Neuro Imaging, Department of Neurology, Geffen School of Medicine at UCLA, Los Angeles, California 90095-7334, USA
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Takao H, Hayashi N, Ohtomo K. White matter microstructure asymmetry: effects of volume asymmetry on fractional anisotropy asymmetry. Neuroscience 2012; 231:1-12. [PMID: 23219841 DOI: 10.1016/j.neuroscience.2012.11.038] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2012] [Revised: 11/20/2012] [Accepted: 11/21/2012] [Indexed: 12/13/2022]
Abstract
Diffusion tensor imaging (DTI) provides information regarding white matter microstructure; however, macroscopic fiber architectures can affect DTI measures. A larger brain (fiber tract) has a 'relatively' smaller voxel size, and the voxels are less likely to contain more than one fiber orientation and more likely to have higher fractional anisotropy (FA). Previous DTI studies report left-to-right differences in the white matter; however, these may reflect true microscopic differences or be caused purely by volume differences. Using tract-based spatial statistics, we investigated left-to-right differences in white matter microstructure across the whole brain. Voxel-wise analysis revealed a large number of white matter volume asymmetries, including leftward asymmetry of the arcuate fasciculus and cingulum. In many white matter regions, FA asymmetry was positively correlated with volume asymmetry. Voxel-wise analysis with adjustment for volume asymmetry revealed many white matter FA asymmetries, including leftward asymmetry of the arcuate fasciculus and cingulum. The voxel-wise analysis showed a reduced number of regions with significant FA asymmetry compared with analysis performed without adjustment for volume asymmetry; however, the overall trend of the results was unchanged. The results of the present study suggest that these FA asymmetries are not caused by volume differences and reflect microscopic differences in the white matter.
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Affiliation(s)
- H Takao
- Department of Radiology, Graduate School of Medicine, University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8655, Japan.
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10
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Yin X, Han Y, Ge H, Xu W, Huang R, Zhang D, Xu J, Fan L, Pang Z, Liu S. Inferior frontal white matter asymmetry correlates with executive control of attention. Hum Brain Mapp 2011; 34:796-813. [PMID: 22110013 DOI: 10.1002/hbm.21477] [Citation(s) in RCA: 62] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2011] [Revised: 08/11/2011] [Accepted: 09/02/2011] [Indexed: 11/08/2022] Open
Abstract
White matter (WM) asymmetries of the human brain have been well documented using diffusion tensor imaging (DTI). However, the relationship between WM asymmetry pattern and cognitive performance is poorly understood. By means of tract-based spatial statistics (TBSS) and voxel-based analyses of whole brain, this study examined the WM asymmetries and the correlations between WM integrity/asymmetries and three distinct components of attention, namely alerting, orienting, and executive control (EC), which were assessed by attention network test (ANT). We revealed a number of WM anisotropy asymmetries, including leftward asymmetry of cingulum, corticospinal tract and cerebral peduncle, rightward asymmetry of internal capsule, superior longitudinal fasciculus and posterior corona radiata, as well as heterogeneous asymmetries in anterior corpus callosum and anterior corona radiata (ACR). Moreover, specific correlation was found between asymmetric pattern of inferior frontal ACR and EC performance. Additionally, this study also proposed that there were no significant relationships of WM anisotropy asymmetries to alerting and orienting functions. Further clusters of interest analyses and probabilistic fiber tracking validated our findings. In conclusion, there are a number of differences in WM integrity between human brain hemispheres. Specially, the anisotropy asymmetry in inferior frontal ACR plays a crucial role in EC function. Our finding is supportive of the functional studies of inferior frontal regions and in keeping with the theory of the brain lateralization on human ventral attention system.
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Affiliation(s)
- Xuntao Yin
- Research Center for Sectional and Imaging Anatomy, Shandong University School of Medicine, Jinan, Shandong, China
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Frontotemporal connections in episodic memory and aging: a diffusion MRI tractography study. J Neurosci 2011; 31:13236-45. [PMID: 21917806 DOI: 10.1523/jneurosci.2317-11.2011] [Citation(s) in RCA: 178] [Impact Index Per Article: 13.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Human episodic memory is supported by networks of white matter tracts that connect frontal, temporal, and parietal regions. Degradation of white matter microstructure is increasingly recognized as a general mechanism of cognitive deterioration with aging. However, atrophy of gray matter regions also occurs and, to date, the potential role of specific white matter connections has been largely ignored. Changes to frontotemporal tracts may be important for the decline of episodic memory; while frontotemporal cooperation is known to be critical, the precise pathways of interaction are unknown. Diffusion-weighted MRI tractography was used to reconstruct three candidate fasciculi known to link components of memory networks: the fornix, the parahippocampal cingulum, and the uncinate fasciculus. Age-related changes in the microstructure of these tracts were investigated in 40 healthy older adults between the ages of 53 and 93 years. The relationships between aging, microstructure, and episodic memory were assessed for each individual tract. Age-related reductions of mean fractional anisotropy and/or increased mean diffusivity were found in all three tracts. However, age-related decline in recall was specifically associated with degradation of fornix microstructure, consistent with the view that this tract is important for episodic memory. In contrast, a decline in uncinate fasciculus microstructure was linked to impaired error monitoring in a visual object-location association task, echoing the effects of uncinate transection in monkeys. These results suggest that degradation of microstructure in the fornix and the uncinate fasciculus make critical but differential contributions to the mechanisms underlying age-related cognitive decline and subserve distinct components of memory.
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A framework for voxel-based morphometric analysis of the optic radiation using diffusion tensor imaging in glaucoma. Magn Reson Imaging 2011; 29:1076-87. [DOI: 10.1016/j.mri.2011.02.034] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2010] [Revised: 02/09/2011] [Accepted: 02/20/2011] [Indexed: 11/22/2022]
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Takao H, Hayashi N, Ohtomo K. White matter asymmetry in healthy individuals: a diffusion tensor imaging study using tract-based spatial statistics. Neuroscience 2011; 193:291-9. [PMID: 21824507 DOI: 10.1016/j.neuroscience.2011.07.041] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2011] [Revised: 07/21/2011] [Accepted: 07/21/2011] [Indexed: 12/13/2022]
Affiliation(s)
- H Takao
- Department of Radiology, Graduate School of Medicine, University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8655, Japan.
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Stamatakis EA, Shafto MA, Williams G, Tam P, Tyler LK. White matter changes and word finding failures with increasing age. PLoS One 2011; 6:e14496. [PMID: 21249127 PMCID: PMC3017545 DOI: 10.1371/journal.pone.0014496] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2010] [Accepted: 12/06/2010] [Indexed: 11/18/2022] Open
Abstract
BACKGROUND Increasing life expectancy necessitates the better understanding of the neurophysiological underpinnings of age-related cognitive changes. The majority of research examining structural-cognitive relationships in aging focuses on the role of age-related changes to grey matter integrity. In the current study, we examined the relationship between age-related changes in white matter and language production. More specifically, we concentrated on word-finding failures, which increase with age. METHODOLOGY/PRINCIPAL FINDINGS We used Diffusion tensor MRI (a technique used to image, in vivo, the diffusion of water molecules in brain tissue) to relate white matter integrity to measures of successful and unsuccessful picture naming. Diffusion tensor images were used to calculate Fractional Anisotropy (FA) images. FA is considered to be a measure of white matter organization/integrity. FA images were related to measures of successful picture naming and to word finding failures using voxel-based linear regression analyses. Successful naming rates correlated positively with white matter integrity across a broad range of regions implicated in language production. However, word finding failure rates correlated negatively with a more restricted region in the posterior aspect of superior longitudinal fasciculus. CONCLUSIONS/SIGNIFICANCE The use of DTI-MRI provides evidence for the relationship between age-related white matter changes in specific language regions and word finding failures in old age.
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Affiliation(s)
- Emmanuel A Stamatakis
- Division of Anaesthesia, School of Clinical Medicine, University of Cambridge, Cambridge, United Kingdom.
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Takao H, Hayashi N, Ohtomo K. Effect of scanner in asymmetry studies using diffusion tensor imaging. Neuroimage 2010; 54:1053-62. [PMID: 20850553 DOI: 10.1016/j.neuroimage.2010.09.023] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2010] [Revised: 09/02/2010] [Accepted: 09/08/2010] [Indexed: 10/19/2022] Open
Abstract
The purpose of this study was to evaluate the effects of longitudinal drift in scanner hardware, inter-scanner variability (bias) and scanner upgrade on asymmetries of diffusion properties using longitudinal data obtained on two scanners of the exact same model at one institution. A total of 224 normal subjects (63 females and 161 males) were included in this study. Each subject was scanned twice, at an interval of about 1 year (mean interval=1.0±0.11 years, range=0.6-1.3 years), using two 3.0-T scanners of the exact same model. Both scanners were simultaneously upgraded during the study period (159 subjects underwent a follow-up scan before upgrade, and the remaining 65 subjects underwent a follow-up scan after upgrade). The subjects were divided into 4 groups according to the combination of scanners used. With the use of tract-based spatial statistics (TBSS), we investigated the effects of scanner drift and inter-scanner variability (bias) on asymmetries of fractional anisotropy (FA) and mean diffusivity (MD). We also investigated the effect of scanner upgrade on FA and MD asymmetries. The voxel-wise analyses revealed a number of regions with significant longitudinal changes in FA and MD asymmetries in the groups where baseline and follow-up images were obtained on different scanners. Even with scanners of the exact same model, inter-scanner variability (bias) significantly affected FA and MD asymmetries, which were relatively stable within the same scanner. Scanner upgrade had a small effect on FA and MD asymmetries. The results indicate that the use of multiple scanners increases variability of DTI asymmetry measurements, and can affect the results of cross-sectional and especially longitudinal DTI asymmetry studies.
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Affiliation(s)
- Hidemasa Takao
- Department of Radiology, Graduate School of Medicine, University of Tokyo, Tokyo, Japan.
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Computational analysis of cerebral cortex. Neuroradiology 2010; 52:691-8. [DOI: 10.1007/s00234-010-0715-4] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2010] [Accepted: 04/30/2010] [Indexed: 10/19/2022]
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