The myeloarchitecture of the corpus callosum (CC) is characterized as a mosaic of distinct differences in fiber density of small- and large-diameter axons along the anterior-posterior axis; however, regional and age differences across the lifespan are not fully understood. Using multiecho T2 magnetic resonance imaging combined with multi-T2 fitting, the myelin water fraction (MWF) and geometric-mean of the intra-/extracellular water T2 (geomT2IEW) in 395 individuals (7-85 years; 41% males) were examined. The approach was validated where regional patterns along the CC closely resembled the histology; MWF matched mean axon diameter and geomT2IEW mirrored the density of large-caliber axons. Across the lifespan, MWF exhibited a quadratic association with age in all 10 CC regions with evidence of a positive linear MWF-age relationship among younger participants and minimal age differences in the remainder of the lifespan. Regarding geomT2IEW, a significant linear age × region interaction reflected positive linear age dependence mostly prominent in the regions with the highest density of small-caliber fibers-genu and splenium. In all, these two indicators characterize distinct attributes that are consistent with histology, which is a first. In addition, these results conform to rapid developmental progression of CC myelination leveling in middle age as well as age-related degradation of axon sheaths in older adults.
Last. Erhan Genç(RUB: Ruhr University Bochum)H-Index: 16
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The corpus callosum serves the functional integration and interaction between the two hemispheres. Many studies investigate callosal microstructure via diffusion tensor imaging (DTI) fractional anisotropy (FA) in geometrically parcellated segments. However, FA is influenced by several different microstructural properties such as myelination and axon density, hindering a neurobiological interpretation. This study explores the relationship between FA and more specific measures of microstructure wi...
Last. Uta Hanning(UHH: University of Hamburg)H-Index: 18
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Quantitative MRI modalities, such as diffusion tensor imaging (DTI) or magnetization transfer imaging (MTI) are sensitive to the neuronal effects of aging of the cerebral white matter (WM), but lack the specificity for myelin content. Myelin Water Imaging (MWI) is highly specific for myelin and may be more sensitive for the detection of changes in myelin content inside the cerebral WM microstructure. In this multiparametric imaging study, we evaluated the performance of Myelin Water Fraction (MW...
Last. Naftali Raz(MPG: Max Planck Society)H-Index: 78
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We investigated test–retest reliability of two MRI-derived indices of white-matter microstructural properties in the human corpus callosum (CC): myelin water fraction (MWF) and geometric mean T2 relaxation time of intra/extracellular water (geomT2IEW), using a 3D gradient and multi spin-echo sequence in 20 healthy adults (aged 24–69 years, 10 men). For each person, we acquired two back-to-back acquisitions in a single session, and the third after a break and repositioning the participant in the ...
Abstract Multicomponent driven equilibrium steady-state observation of T1 and T2 (mcDESPOT) aims to quantify the Myelin Water Fraction (MWF) using a two-pool microstructural model. The MWF has been used to track neurodevelopment and neurodegeneration and has been histologically correlated to myelin content. mcDESPOT has a clinically feasible acquisition time and high signal-to-noise ratio (SNR) relative to other MWF techniques. However, disagreement exists in the literature between experimental ...
Last. Susie Y. Huang(MIT: Massachusetts Institute of Technology)H-Index: 17
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Abstract Cerebral white matter exhibits age-related degenerative changes during the course of normal aging, including decreases in axon density and alterations in axonal structure. Noninvasive approaches to measure these microstructural alterations throughout the lifespan would be invaluable for understanding the substrate and regional variability of age-related white matter degeneration. Recent advances in diffusion magnetic resonance imaging (MRI) have leveraged high gradient strengths to incr...
Abstract MRI relaxometry is sensitive to a variety of tissue characteristics in a complex manner, which makes it both attractive and challenging for characterizing tissue. This article reviews the most common water proton relaxometry measures, T 1 , T 2 , and T 2 * , and reports on their development and current potential to probe the composition and microstructure of brain tissue. The development of these relaxometry measures is challenged by the need for suitably accurate tissue models, as well...
Last. Marc L. Seal(University of Melbourne)H-Index: 41
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The corpus callosum is integral to the central nervous system, and continually develops with age by virtue of increasing axon diameter and ongoing myelination. Magnetic resonance imaging (MRI) techniques offer a means to disentangle these two aspects of white matter development. We investigate the profile of microstructural metrics across the corpus callosum, and assess the impact of age, sex and pubertal development on these processes. This study made use of two independent paediatric populatio...
#1Qijing Yu(WSU: Wayne State University)H-Index: 8
#2Ana M. Daugherty(UIUC: University of Illinois at Urbana–Champaign)H-Index: 23
Last. Noa Ofen(WSU: Wayne State University)H-Index: 18
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An individual's socioeconomic status (SES) is often viewed as a proxy for a host of environmental influences. SES disparities have been linked to variance in brain structures particularly the hippocampus, a neural substrate of learning and memory. However, it is unclear whether the association between SES and hippocampal volume is similar in children and adults. We investigated the relationship between hippocampal volume and SES in a group of children (n = 31, age 8–12 years) and a group of youn...
Knowledge concerning the normal aging of cerebral white matter will improve our understanding of abnormal changes in neurodegenerative diseases. The microstructural basis of white matter maturation and aging can be investigated using diffusion tensor imaging (DTI). Generally, diffusion anisotropy increases during childhood and adolescence followed by a decline in middle age. However, this process is subject to spatial variations between tracts. The aim of this study was to investigate to what ex...
Recent years have seen an increased understanding of the importance of myelination in healthy brain function and neuropsychiatric diseases. Non-invasive microstructural magnetic resonance imaging (MRI) holds the potential to expand and translate these insights to basic and clinical human research, but the sensitivity and specificity of different MR markers to myelination is a subject of debate. To consolidate current knowledge on the topic, we perform a systematic review and meta-analysis of stu...
Abstract The corpus callosum enables integration and coordination of cognitive processing between the cerebral hemispheres. In the aging human brain, these functions are affected by progressive axon and myelin deteriorations, reflected as atrophy of the midsagittal corpus callosum in old age. In non-human primates, these degenerative processes are less pronounced as previous morphometric studies on capuchin monkey, rhesus monkeys, and chimpanzees do not find old-age callosal atrophy. In the pres...