Function and connectivity in human primary auditory cortex: a combined fMRI and DTI study at 3 Tesla.

Jaymin Upadhyay, Mathieu Ducros, Tracey A. Knaus, Kristen A. Lindgren, Andrew Silver, Helen Tager-Flusberg, Dae-Shik Kim
Cerebral Cortex. 2006-12-26; 17(10): 2420-2432
DOI: 10.1093/cercor/bhl150

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1. Cereb Cortex. 2007 Oct;17(10):2420-32. Epub 2006 Dec 26.

Function and connectivity in human primary auditory cortex: a combined fMRI and
DTI study at 3 Tesla.

Upadhyay J(1), Ducros M, Knaus TA, Lindgren KA, Silver A, Tager-Flusberg H, Kim

Author information:
(1)Center for Biomedical Imaging, Department of Anatomy and Neurobiology, Boston
University School of Medicine, 715 Albany Street, Boston, MA 02118, USA.

Human primary auditory cortex (PAC) is functionally organized in a tonotopic
manner. Past studies have used neuroimaging to characterize tonotopic
organization in PAC and found similar organization as that described in mammals.
In contrast to what is known about PAC in primates and nonprimates, in humans,
the structural connectivity within PAC has not been defined. In this study,
stroboscopic event-related functional magnetic resonance imaging (fMRI) was
utilized to reveal mirror symmetric tonotopic organization consisting of a
high-low-high frequency gradient in PAC. Furthermore, diffusion tensor
tractography and probabilistic mapping was used to study projection patterns
within tonotopic areas. Based on earlier physiological and histological work in
nonhuman PAC, we hypothesized the existence of cross-field isofrequency
(homotopic) and within-field non-isofrequency (heterotopic)-specific axonal
projections in human PAC. The presence of both projections types was found in all
subjects. Specifically, the number of diffusion tensor imaging (DTI)
reconstructed fibers projecting between high- and low-frequency regions was
greater than those fibers projecting between 2 high-frequency areas, the latter
of which are located in distinct auditory fields. The fMRI and DTI results
indicate that functional and structural properties within early stages of the
auditory processing stream are preserved across multiple mammalian species at
distinct evolutionary levels.

DOI: 10.1093/cercor/bhl150
PMID: 17190967 [Indexed for MEDLINE]

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