Aging-Related Differences in Structural and Functional Interhemispheric Connectivity

2021 ◽  
Author(s):  
John D Lewis ◽  
Christian O’Reilly ◽  
Elizabeth Bock ◽  
Rebecca J Theilmann ◽  
Jeanne Townsend
Keyword(s):  
White Matter ◽  
Functional Connectivity ◽  
Imaging Data ◽  
Anatomical Connectivity ◽  
Age Related ◽  
Interhemispheric Connectivity ◽  
Visual Cortices ◽  
The Difference ◽  
And Diffusion ◽  
Insight Into

Abstract There is substantial evidence of age-related declines in anatomical connectivity during adulthood, with associated alterations in functional connectivity. But the relation of those functional alterations to the structural reductions is unclear. The complexities of both the structural and the functional connectomes make it difficult to determine such relationships. We pursue this question with methods, based on animal research, that specifically target the interhemispheric connections between the visual cortices. We collect t1- and diffusion-weighted imaging data from which we assess the integrity of the white matter interconnecting the bilateral visual cortices. Functional connectivity between the visual cortices is measured with electroencephalography during the presentation of drifting sinusoidal gratings that agree or conflict across hemifields. Our results show age-related reductions in the integrity of the white matter interconnecting the visual cortices, and age-related increases in the difference in functional interhemispheric lagged coherence between agreeing versus disagreeing visual stimuli. We show that integrity of the white matter in the splenium of the corpus callosum predicts the differences in lagged coherence for the agreeing versus disagreeing stimuli; and that this relationship is mediated by age. These results give new insight into the causal relationship between age and functional connectivity.

Association of Gyrification Pattern, White Matter Changes, and Phenotypic Profile in Patients With Parkinson Disease

Neurology ◽  
2021 ◽  
pp. 10.1212/WNL.0000000000011894
Author(s):  
Xie Tang ◽  
Yuanchao Zhang ◽  
Daihong Liu ◽  
Yixin Hu ◽  
Lingli Jiang ◽  
...  
Keyword(s):  
White Matter ◽  
Mini Mental State Examination ◽  
Phenotypic Profile ◽  
Diffusion Weighted Images ◽  
Tightly Coupled ◽  
Visual Cortices ◽  
Gyrification Index ◽  
State Examination ◽  
And Diffusion ◽  
Anterior Thalamic Radiation

Objective:To investigate the cortical gyrification changes as well as their relationships with white matter (WM) microstructural abnormalities in the akinetic-rigid (AR) and tremor-dominant (TD) subtypes of Parkinson’s disease (PD).Methods:Sixty-four patients with the AR subtype, 26 patients with the TD subtype and 56 healthy controls (HCs) were included in this study. High-resolution T1-weighted and diffusion-weighted images were acquired for each participant. We computed local gyrification index (LGI) and fractional anisotropy (FA) to identify the cortical gyrification and WM microstructural changes in the AR and TD subtypes.Results:Compared with HCs, patients with the AR subtype showed decreased LGI in the precentral, postcentral, inferior and superior parietal, middle and superior frontal/temporal, anterior and posterior cingulate, orbitofrontal, supramarginal, precuneus, and some visual cortices, and decreased FA in the corticospinal tract, inferior and superior longitudinal fasciculus, inferior fronto-occipital fasciculus, forceps minor/major, and anterior thalamic radiation. Decreases in LGI and FA of the AR subtype were found to be tightly coupled. LGIs of the left inferior and middle frontal gyrus correlated with the mini-mental state examination and the Hoehn and Yahr scores of patients with the AR subtype. Patients with the TD subtype showed no significant change in the LGI and FA compared with patients with the AR subtype and HCs.Conclusions:Our results suggest that cortical gyrification changes in PD are motor phenotype-specific and are possibly mediated by the microstructural abnormalities of the underlying WM tracts.

scholarly journals Brain Substrates of Time-Based Prospective Memory Decline in Aging: A Voxel-Based Morphometry and Diffusion Tensor Imaging Study

2020 ◽  
Vol 31 (1) ◽  
pp. 396-409
Author(s):  
Alexandrine Morand ◽  
Shailendra Segobin ◽  
Grégory Lecouvey ◽  
Julie Gonneaud ◽  
Francis Eustache ◽  
...  
Keyword(s):  
Diffusion Tensor Imaging ◽  
White Matter ◽  
Prospective Memory ◽  
Gray Matter ◽  
Diffusion Tensor ◽  
Imaging Study ◽  
Age Related ◽  
Young Subjects ◽  
Anterior Prefrontal Cortex ◽  
And Diffusion

Abstract Time-based prospective memory (TBPM) allows us to remember to perform intended actions at a specific time in the future. TBPM is sensitive to the effects of age, but the neural substrates of this decline are still poorly understood. The aim of the present study was thus to better characterize the brain substrates of the age-related decline in TBPM, focusing on macrostructural gray matter and microstructural white matter integrity. We administered a TBPM task to 22 healthy young (26 ± 5.2 years) and 23 older (63 ± 5.9 years) participants, who also underwent volumetric magnetic resonance imaging and diffusion tensor imaging scans. Neuroimaging analyses revealed lower gray matter volumes in several brain areas in older participants, but these did not correlate with TBPM performance. By contrast, an age-related decline in fractional anisotropy in several white-matter tracts connecting frontal and occipital regions did correlate with TBPM performance, whereas there was no significant correlation in healthy young subjects. According to the literature, these tracts are connected to the anterior prefrontal cortex and the thalamus, 2 structures involved in TBPM. These results confirm the view that a disconnection process occurs in aging and contributes to cognitive decline.

scholarly journals Altered White Matter Organization in the TUBB3 E410K Syndrome

2018 ◽  
Vol 29 (8) ◽  
pp. 3561-3576 ◽  
Author(s):  
P Ellen Grant ◽  
Kiho Im ◽  
Banu Ahtam ◽  
Cynthia T Laurentys ◽  
Wai-Man Chan ◽  
...  
Keyword(s):  
White Matter ◽  
De Novo ◽  
Neuropsychological Testing ◽  
Network Efficiency ◽  
Age Related ◽  
Bilateral Absence ◽  
Cortical Parcellation ◽  
Social Disabilities ◽  
And Diffusion ◽  
Language Network

Abstract Seven unrelated individuals (four pediatric, three adults) with the TUBB3 E410K syndrome, harboring identical de novo heterozygous TUBB3 c.1228 G>A mutations, underwent neuropsychological testing and neuroimaging. Despite the absence of cortical malformations, they have intellectual and social disabilities. To search for potential etiologies for these deficits, we compared their brain's structural and white matter organization to 22 controls using structural and diffusion magnetic resonance imaging. Diffusion images were processed to calculate fractional anisotropy (FA) and perform tract reconstructions. Cortical parcellation-based network analysis and gyral topology-based FA analyses were performed. Major interhemispheric, projection and intrahemispheric tracts were manually segmented. Subjects had decreased corpus callosum volume and decreased network efficiency. While only pediatric subjects had diffuse decreases in FA predominantly affecting mid- and long-range tracts, only adult subjects had white matter volume loss associated with decreased cortical surface area. All subjects showed aberrant corticospinal tract trajectory and bilateral absence of the dorsal language network long segment. Furthermore, pediatric subjects had more tracts with decreased FA compared with controls than did adult subjects. These findings define a TUBB3 E410K neuroimaging endophenotype and lead to the hypothesis that the age-related changes are due to microscopic intrahemispheric misguided axons that are pruned during maturation.

scholarly journals Disrupted salience network functional connectivity and white-matter microstructure in persons at risk for psychosis: findings from the LYRIKS study

2016 ◽  
Vol 46 (13) ◽  
pp. 2771-2783 ◽  
Author(s):  
C. Wang ◽  
F. Ji ◽  
Z. Hong ◽  
J. S. Poh ◽  
R. Krishnan ◽  
...  
Keyword(s):  
At Risk ◽  
White Matter ◽  
Functional Connectivity ◽  
Symptom Severity ◽  
Diffusion Tensor ◽  
Structural Connectivity ◽  
Salience Network ◽  
White Matter Microstructure ◽  
Close Proximity ◽  
And Diffusion

BackgroundSalience network (SN) dysconnectivity has been hypothesized to contribute to schizophrenia. Nevertheless, little is known about the functional and structural dysconnectivity of SN in subjects at risk for psychosis. We hypothesized that SN functional and structural connectivity would be disrupted in subjects with At-Risk Mental State (ARMS) and would be associated with symptom severity and disease progression.MethodWe examined 87 ARMS and 37 healthy participants using both resting-state functional magnetic resonance imaging and diffusion tensor imaging. Group differences in SN functional and structural connectivity were examined using a seed-based approach and tract-based spatial statistics. Subject-level functional connectivity measures and diffusion indices of disrupted regions were correlated with CAARMS scores and compared between ARMS with and without transition to psychosis.ResultsARMS subjects exhibited reduced functional connectivity between the left ventral anterior insula and other SN regions. Reduced fractional anisotropy (FA) and axial diffusivity were also found along white-matter tracts in close proximity to regions of disrupted functional connectivity, including frontal-striatal-thalamic circuits and the cingulum. FA measures extracted from these disrupted white-matter regions correlated with individual symptom severity in the ARMS group. Furthermore, functional connectivity between the bilateral insula and FA at the forceps minor were further reduced in subjects who transitioned to psychosis after 2 years.ConclusionsOur findings support the insular dysconnectivity of the proximal SN hypothesis in the early stages of psychosis. Further developed, the combined structural and functional SN assays may inform the prognosis of persons at-risk for psychosis.

scholarly journals Differential Patterns of Gyral and Sulcal Morphological Changes During Normal Aging Process

2021 ◽  
Vol 13 ◽  
Author(s):  
Hsin-Yu Lin ◽  
Chu-Chung Huang ◽  
Kun-Hsien Chou ◽  
Albert C. Yang ◽  
Chun-Yi Zac Lo ◽  
...  
Keyword(s):  
White Matter ◽  
Aging Process ◽  
Morphological Changes ◽  
Normal Aging ◽  
Quadratic Model ◽  
Imaging Data ◽  
Cortical Folding ◽  
Brain Functioning ◽  
Age Related ◽  
Morphological Model

The cerebral cortex is a highly convoluted structure with distinct morphologic features, namely the gyri and sulci, which are associated with the functional segregation or integration in the human brain. During the lifespan, the brain atrophy that is accompanied by cognitive decline is a well-accepted aging phenotype. However, the detailed patterns of cortical folding change during aging, especially the changing age-dependencies of gyri and sulci, which is essential to brain functioning, remain unclear. In this study, we investigated the morphology of the gyral and sulcal regions from pial and white matter surfaces using MR imaging data of 417 healthy participants across adulthood to old age (21–92 years). To elucidate the age-related changes in the cortical pattern, we fitted cortical thickness and intrinsic curvature of gyri and sulci using the quadratic model to evaluate their age-dependencies during normal aging. Our findings show that comparing to gyri, the sulcal thinning is the most prominent pattern during the aging process, and the gyrification of pial and white matter surfaces were also affected differently, which implies the vulnerability of functional segregation during aging. Taken together, we propose a morphological model of aging that may provide a framework for understanding the mechanisms underlying gray matter degeneration.

scholarly journals The spatial correspondence and genetic influence of inter-hemispheric connectivity with white matter microstructure

2018 ◽  
Author(s):  
Jeroen Mollink ◽  
Stephen M. Smith ◽  
Lloyd T. Elliott ◽  
Michiel Kleinnijenhuis ◽  
Marlies Hiemstra ◽  
...  
Keyword(s):  
White Matter ◽  
Functional Connectivity ◽  
Neural Development ◽  
Neural Circuit ◽  
Brain Regions ◽  
Nucleotide Polymorphisms ◽  
Imaging Data ◽  
Single Nucleotide ◽  
White Matter Microstructure ◽  
Microscopic Features

AbstractMicroscopic features (i.e., microstructure) of axons affect neural circuit activity through characteristics such as conduction speed. Deeper understanding of structure-function relationships and translating this into human neuroscience has been limited by the paucity of studies relating axonal microstructure in white matter pathways to functional connectivity (synchrony) between macroscopic brain regions. Using magnetic resonance imaging data in 11354 subjects, we constructed multi-variate models that predict the functional connectivity of pairs of brain regions from the microstructural signature of white matter pathways that connect them. Microstructure-derived models provide predictions of functional connectivity that were significant in up to 86% of the brain region pairs considered. These relationships are specific to the relevant white matter pathway and have high reproducibility. The microstructure-function relationships are associated to genetic variants (single-nucleotide polymorphisms), co-located with genes DAAM1 and LPAR1, that have previously been reported to play a role in neural development. Our results demonstrate that variation in white matter microstructure across individuals consistently and specifically predicts functional connectivity, and that this relationship is underpinned by genetic variability.

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