Mapping the Microstructure and Striae of the Human Olfactory Tract with Diffusion MRI

Shiloh L. Echevarria-Cooper, Guangyu Zhou, Christina Zelano, Franco Pestilli, Todd B. Parrish, Thorsten Kahnt*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

16 Scopus citations

Abstract

The human sense of smell plays an important role in appetite and food intake, detecting environmental threats, social interactions, and memory processing. However, little is known about the neural circuity supporting its function. The olfactory tracts project from the olfactory bulb along the base of the frontal cortex, branching into several striae to meet diverse cortical regions. Historically, using diffusion magnetic resonance imaging (dMRI) to reconstruct the human olfactory tracts has been prevented by susceptibility and motion artifacts. Here, we used a dMRI method with readout segmentation of long variable echo-trains (RESOLVE) to minimize image distortions and characterize the human olfactory tracts in vivo. We collected high-resolution dMRI data from 25 healthy human participants (12 male and 13 female) and performed probabilistic tractography using constrained spherical deconvolution (CSD). At the individual subject level, we identified the lateral, medial, and intermediate striae with their respective cortical connections to the piriform cortex and amygdala (AMY), olfactory tubercle (OT), and anterior olfactory nucleus (AON). We combined individual results across subjects to create a normalized, probabilistic atlas of the olfactory tracts. We then investigated the relationship between olfactory perceptual scores and measures of white matter integrity, including mean diffusivity (MD). Importantly, we found that olfactory tract MD negatively correlated with odor discrimination performance. In summary, our results provide a detailed characterization of the connectivity of the human olfactory tracts and demonstrate an association between their structural integrity and olfactory perceptual function.

Original languageEnglish (US)
Pages (from-to)58-68
Number of pages11
JournalJournal of Neuroscience
Volume42
Issue number1
DOIs
StatePublished - Jan 5 2022

Funding

Received July 29, 2021; revised Sep. 30, 2021; accepted Oct. 31, 2021. Author contributions: S.L.E.-C., F.P., T.B.P., and T.K. designed research; S.L.E.-C. performed research; G.Z. and C.Z. contributed unpublished reagents/analytic tools; S.L.E.-C. analyzed data; S.L.E.-C. wrote the first draft of the paper; G.Z., C.Z., F.P., and T.B.P. edited the paper; T.K. wrote the paper. This work was supported by the Northwestern Parkinson’s Disease and Movement Disorders Advisory Council, National Institute on Deafness and Other Communication Disorders Grant R01 DC015426 (to T.K.), and National Institutes on Aging Grants P30 AG013854 (to T.K.) and T32 AG020506 (to S.L.E.-C.). The authors declare no competing financial interests. Correspondence should be addressed to Thorsten Kahnt at [email protected]. https://doi.org/10.1523/JNEUROSCI.1552-21.2021 Copyright © 2022 Echevarria-Cooper et al. This is an open-access article distributed under the terms of the Creative Commons Attribution 4.0 International license, which permits unrestricted use, distribution and reproduction in any medium provided that the original work is properly attributed.

Keywords

  • diffusion MRI
  • human
  • odor perception
  • olfaction
  • olfactory tract
  • tractography

ASJC Scopus subject areas

  • General Neuroscience

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