Assessing intracortical myelin in the living human brain using myelinated cortical thickness

Rowley, Christopher D.; Bazin, Pierre‐Louis; Tardif, Christine; Sehmbi, Manpreet; Hashim, Eyesha; Zaharieva, Nadejda; Minuzzi, Luciano; Frey, Benício N.; Bock, Nicholas A.

doi:10.3389/fnins.2015.00396

Cited by 57 publications

(67 citation statements)

References 60 publications

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“…Figure 5 maps these values across the cortex both from vertex-wise fits and from fits of signal averaged over the ROIs. The signal maximum plots (k) resemble previously reported myelin maps derived from MRI [Bock et al, 2013;Dinse et al, 2015;Glasser and Van Essen, 2011;Lutti et al, 2014;Rowley et al, 2015;Waehnert et al, 2016], with high signal intensity in primary cortical areas, and lower intensity in association regions. The age where the signal reaches a maximum in the fit shows that the visual regions, cingulate, and left ventromedial prefrontal cortex peak first, and the premotor and primary motor cortices peak last.…”

Section: Estimating Maximum Value From Fitssupporting

confidence: 79%

Age‐related mapping of intracortical myelin from late adolescence to middle adulthood using T₁‐weighted MRI

Rowley

Sehmbi

Bazin

et al. 2017

Human Brain Mapping

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Magnetic resonance imaging (MRI) studies in humans have reported that the T -weighted signal in the cerebral cortex follows an inverted "U" trajectory over the lifespan. Here, we investigated the T -weighted signal trajectory from late adolescence to middle adulthood in humans to characterize the age range when mental illnesses tend to present, and efficacy of treatments are evaluated. We compared linear to quadratic predictors of age on signal in 67 healthy individuals, 17-45 years old. We investigated ¼, ½, and ¾ depths in the cortex representing intracortical myelin (ICM), in the superficial white matter (SWM), and in a reference deep white matter tract. We found that the quadratic fit was superior in all regions of the cortex, while signal in the SWM and deep white matter showed no global dependence on age over this range. The signal trajectory in any region followed a similar shape regardless of cortical depth. The quadratic fit was analyzed in 70 cortical regions to obtain the age of maximum signal intensity. We found that visual, cingulate, and left ventromedial prefrontal cortices peak first around 34 years old, whereas motor and premotor areas peak latest at ∼38 years. Our analysis suggests that ICM trajectories over this range can be modeled well in small cohorts of subjects using quadratic functions, which are amenable to statistical analysis, thus suitable for investigating regional changes in ICM with disease. This study highlights a novel approach to map ICM trajectories using an age range that coincides with the onset of many mental illnesses. Hum Brain Mapp, 2017. © 2017 Wiley Periodicals, Inc.

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Section: Estimating Maximum Value From Fitssupporting

confidence: 79%

Age‐related mapping of intracortical myelin from late adolescence to middle adulthood using T₁‐weighted MRI

Rowley

Sehmbi

Bazin

et al. 2017

Human Brain Mapping

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“…For example, MRI measures that are sensitive to intracortical myelin have revealed a pattern of high myelin content in primary sensorimotor regions, which systematically decreases toward transmodal areas in parietal, temporal, and particularly prefrontal cortex [3,[25][26][27][28] (Figure 1A). A similar spatial distribution has been described for MRI-based measures of cortical thickness [12] and myelinated thickness [29]. Cortical thickness coarsely tracks changes in cytoarchitecture [30] and myelin content [25], and can be viewed as a pragmatic surrogate for cortical microstructure [12].…”

Section: Glossarymentioning

confidence: 77%

Large-Scale Gradients in Human Cortical Organization

Huntenburg

Bazin

Margulies

2018

Trends in Cognitive Sciences

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Recent advances in mapping cortical areas in the human brain provide a basis for investigating the significance of their spatial arrangement. Here we describe a dominant gradient in cortical features that spans between sensorimotor and transmodal areas. We propose that this gradient constitutes a core organizing axis of the human cerebral cortex, and describe an intrinsic coordinate system on its basis. Studying the cortex with respect to these intrinsic dimensions can inform our understanding of how the spectrum of cortical function emerges from structural constraints. The Significance of Cortical LocationFor more than a century, neuroscientists have studied the cerebral cortex by delineating individual cortical areas (see Glossary) and mapping their function [1]. This agenda has substantially advanced in recent years, as automated parcellation methods improve and data sets of unprecedented size and quality become available [2][3][4]. Nevertheless, our understanding of how the complex structure of the cerebral cortex emerges and gives rise to its elaborate functions remains fragmentary. To complement the description of individual cortical areas, we propose an inquiry into the significance of their spatial arrangement, asking the basic question: Why are cortical areas located where they are?Early formulations of this question date to theories from classical neuroanatomy [1,[5][6][7]. They state that the spatial layout of cortical areas is not arbitrary, but a consequence of developmental mechanisms, shaped through evolutionary selection. The location of an area among its neighbors thus provides insight into its microstructural characteristics [6], its connections to other parts of the brain [7], and eventually its position in global processing hierarchies [8]. Consider, for example, the well-researched visual system of the macaque monkey [9,10]. Along the visual hierarchy, low-level visual features are increasingly abstracted and integrated with information from other systems. Traditionally, areas are ordered based on their degree of microstructural differentiation, and the classification of their connections as feedforward or feedback [11]. The framework we advocate emphasizes that an area's position in the visual processing hierarchy -and thus many of its microstructural and connectional features -is strongly related to its distance from the primary visual area [12,13].More generally, we propose that the spatial arrangement of areas along a global gradient between sensorimotor and transmodal regions is a key feature of human cortical organization. A gradient is an axis of variance in cortical features, along which areas fall in a spatially continuous order. Areas that resemble each other with respect to the feature of interest occupy similar positions along the gradient. As we will point out, there is a strong relationship between the similarity of two areas -that is, their relative position along the gradient -and their relative position along the cortical surface. This important role of cortical location pro...

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“…Recent studies in that field have shown a stronger intracortical myelination particularly within primary sensory areas such as PAC (Glasser et al, 2016;Glasser & van Essen, 2011;Shafee et al, 2015;Van Essen, Glasser, Dierker, Harwell, & Coalson, 2012;Wasserthal et al, 2014), and furthermore leftlateralized myelination in HG suggesting a link to language function (Sigalovsky et al, 2006). In fact, the highest proportion of heavily myelinated deeper layers of the cortex has been found in the precentral and postcentral gyrus as well as in the core region of HG (Rowley et al, 2015). Thus, area-specific differences in intracortical myelination should be considered when using novel automated methods for CTH estimation based on T1 images, as the exact GM-WM border of the higher myelinated primary cortex may be difficult to determine within the deeper cortical layers (Glasser & van Essen, 2011).…”

Section: Localization and Lateralization Of Pacmentioning

confidence: 99%

Reduced cortical thickness in Heschl's gyrus as an in vivo marker for human primary auditory cortex

Zoellner

Benner

Zeidler

et al. 2018

Human Brain Mapping

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The primary auditory cortex (PAC) is located in the region of Heschl's gyrus (HG), as confirmed by histological, cytoarchitectonical, and neurofunctional studies. Applying cortical thickness (CTH) analysis based on high‐resolution magnetic resonance imaging (MRI) and magnetoencephalography (MEG) in 60 primary school children and 60 adults, we investigated the CTH distribution of left and right auditory cortex (AC) and primary auditory source activity at the group and individual level. Both groups showed contoured regions of reduced auditory cortex (redAC) along the mediolateral extension of HG, illustrating large inter‐individual variability with respect to shape, localization, and lateralization. In the right hemisphere, redAC localized more within the medial portion of HG, extending typically across HG duplications. In the left hemisphere, redAC was distributed significantly more laterally, reaching toward the anterolateral portion of HG. In both hemispheres, redAC was found to be significantly thinner (mean CTH of 2.34 mm) as compared to surrounding areas (2.99 mm). This effect was more dominant in the right hemisphere rather than in the left one. Moreover, localization of the primary component of auditory evoked activity (P1), as measured by MEG in response to complex harmonic sounds, strictly co‐localized with redAC. This structure–function link was found consistently at the group and individual level, suggesting PAC to be represented by areas of reduced cortex in HG. Thus, we propose reduced CTH as an in vivo marker for identifying shape and localization of PAC in the individual brain.

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Assessing intracortical myelin in the living human brain using myelinated cortical thickness

Cited by 57 publications

References 60 publications

Age‐related mapping of intracortical myelin from late adolescence to middle adulthood using T₁‐weighted MRI

Age‐related mapping of intracortical myelin from late adolescence to middle adulthood using T₁‐weighted MRI

Large-Scale Gradients in Human Cortical Organization

Reduced cortical thickness in Heschl's gyrus as an in vivo marker for human primary auditory cortex

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Assessing intracortical myelin in the living human brain using myelinated cortical thickness

Cited by 57 publications

References 60 publications

Age‐related mapping of intracortical myelin from late adolescence to middle adulthood using T1‐weighted MRI

Age‐related mapping of intracortical myelin from late adolescence to middle adulthood using T1‐weighted MRI

Large-Scale Gradients in Human Cortical Organization

Reduced cortical thickness in Heschl's gyrus as an in vivo marker for human primary auditory cortex

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Product

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Age‐related mapping of intracortical myelin from late adolescence to middle adulthood using T₁‐weighted MRI

Age‐related mapping of intracortical myelin from late adolescence to middle adulthood using T₁‐weighted MRI