Characterization of the hemodynamic response function in white matter tracts for event-related fMRI.

Li M, Newton AT, Anderson AW, Ding Z, Gore JC
Nat Commun. 2019 10 (1): 1140

PMID: 30850610 · PMCID: PMC6408456 · DOI:10.1038/s41467-019-09076-2

Accurate estimates of the BOLD hemodynamic response function (HRF) are crucial for the interpretation and analysis of event-related functional MRI data. To date, however, there have been no comprehensive measurements of the HRF in white matter (WM) despite increasing evidence that BOLD signals in WM change after a stimulus. We performed an event-related cognitive task (Stroop color-word interference) to measure the HRF in selected human WM pathways. The task was chosen in order to produce robust, distributed centers of activity throughout the cortex. To measure the HRF in WM, fiber tracts were reconstructed between each pair of activated cortical areas. We observed clear task-specific HRFs with reduced magnitudes, delayed onsets and prolonged initial dips in WM tracts compared with activated grey matter, thus calling for significant changes to current standard models for accurately characterizing the HRFs in WM and for modifications of standard methods of analysis of functional imaging data.

MeSH Terms (16)

Adult Cerebral Cortex Cerebrovascular Circulation Female Gray Matter Healthy Volunteers Hemodynamics Hemoglobins Humans Magnetic Resonance Imaging Male Nerve Net Oxygen Pattern Recognition, Visual Stroop Test White Matter

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