Histological Basis of Laminar MRI Patterns in High Resolution Images of Fixed Human Auditory Cortex.

Wallace, Mark N ORCID: 0000-0001-6894-4903, Cronin, Matthew J ORCID: 0000-0002-3474-6949, Bowtell, Richard W, Scott, Ian S ORCID: 0000-0003-1266-9521, Palmer, Alan R and Gowland, Penny A ORCID: 0000-0002-4900-4817 (2016) Histological Basis of Laminar MRI Patterns in High Resolution Images of Fixed Human Auditory Cortex. Frontiers in neuroscience, 10. 455-.

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Official URL: http://dx.doi.org/10.3389/fnins.2016.00455

Abstract

Functional magnetic resonance imaging (fMRI) studies of the auditory region of the temporal lobe would benefit from the availability of image contrast that allowed direct identification of the primary auditory cortex, as this region cannot be accurately located using gyral landmarks alone. Previous work has suggested that the primary area can be identified in magnetic resonance (MR) images because of its relatively high myelin content. However, MR images are also affected by the iron content of the tissue and in this study we sought to confirm that different MR image contrasts did correlate with the myelin content in the gray matter and were not primarily affected by iron content as is the case in the primary visual and somatosensory areas. By imaging blocks of fixed post-mortem cortex in a 7 T scanner and then sectioning them for histological staining we sought to assess the relative contribution of myelin and iron to the gray matter contrast in the auditory region. Evaluating the image contrast in [Formula: see text]-weighted images and quantitative [Formula: see text] maps showed a reasonably high correlation between the myelin density of the gray matter and the intensity of the MR images. The correlation with T<sub>1</sub>-weighted phase sensitive inversion recovery (PSIR) images was better than with the previous two image types, and there were clearly differentiated borders between adjacent cortical areas in these images. A significant amount of iron was present in the auditory region, but did not seem to contribute to the laminar pattern of the cortical gray matter in MR images. Similar levels of iron were present in the gray and white matter and although iron was present in fibers within the gray matter, these fibers were fairly uniformly distributed across the cortex. Thus, we conclude that T<sub>1</sub>- and [Formula: see text]-weighted imaging sequences do demonstrate the relatively high myelin levels that are characteristic of the deep layers in primary auditory cortex and allow it and some of the surrounding areas to be reliably distinguished.

Item Type:	Article
Uncontrolled Keywords:	auditory cortex, iron, magnetic resonance imaging, myelin, myeloarchitectonics
Divisions:	Faculty of Health and Life Sciences Faculty of Health and Life Sciences > Institute of Systems, Molecular and Integrative Biology
Depositing User:	Symplectic Admin
Date Deposited:	18 Dec 2023 08:55
Last Modified:	18 Mar 2024 04:10
DOI:	10.3389/fnins.2016.00455
Related URLs:	Author Publisher
URI:	https://livrepository.liverpool.ac.uk/id/eprint/3177457