The spatiotemporal hemodynamic response function for depth-dependent functional imaging of human cortex

Alexander M Puckett; Kevin M Aquino; P A Robinson; Michael Breakspear; Mark M Schira

doi:10.1016/j.neuroimage.2016.06.019

The spatiotemporal hemodynamic response function for depth-dependent functional imaging of human cortex

Neuroimage. 2016 Oct 1:139:240-248. doi: 10.1016/j.neuroimage.2016.06.019. Epub 2016 Jun 15.

Authors

Alexander M Puckett¹, Kevin M Aquino², P A Robinson³, Michael Breakspear⁴, Mark M Schira⁵

Affiliations

¹ School of Psychology, University of Wollongong, Wollongong, NSW 2522, Australia. Electronic address: [email protected].
² School of Physics, University of Sydney, Sydney, NSW 2006, Australia; Center for Integrative Brain Function, QIMR Berghofer Medical Research Institute, Herston, QLD 4006, Australia; Center for Integrative Brain Function, University of Sydney, Sydney, NSW 2006, Australia; Sir Peter Mansfield Imaging Centre, School of Physics and Astronomy, University of Nottingham, Nottingham, Nottinghamshire NG7 2RD, United Kingdom.
³ School of Physics, University of Sydney, Sydney, NSW 2006, Australia; Center for Integrative Brain Function, University of Sydney, Sydney, NSW 2006, Australia.
⁴ Center for Integrative Brain Function, QIMR Berghofer Medical Research Institute, Herston, QLD 4006, Australia; Metro North Mental Health Service, Royal Brisbane and Women's Hospital, Herston, QLD 4029, Australia.
⁵ School of Psychology, University of Wollongong, Wollongong, NSW 2522, Australia; Neuroscience Research Australia, Randwick, NSW 2031, Australia.

PMID: 27321045
DOI: 10.1016/j.neuroimage.2016.06.019

Abstract

The gray matter of human cortex is characterized by depth-dependent differences in neuronal activity and connections (Shipp, 2007) as well as in the associated vasculature (Duvernoy et al., 1981). The resolution limit of functional magnetic resonance imaging (fMRI) measurements is now below a millimeter, promising the non-invasive measurement of these properties in awake and behaving humans (Muckli et al., 2015; Olman et al., 2012; Ress et al., 2007). To advance this endeavor, we present a detailed spatiotemporal hemodynamic response function (HRF) reconstructed through the use of high-resolution, submillimeter fMRI. We decomposed the HRF into directions tangential and perpendicular to the cortical surface and found that key spatial properties of the HRF change significantly with depth from the cortical surface. Notably, we found that the spatial spread of the HRF increases linearly from 4.8mm at the gray/white matter boundary to 6.6mm near the cortical surface. Using a hemodynamic model, we posit that this effect can be explained by the depth profile of the cortical vasculature, and as such, must be taken into account to properly estimate the underlying neuronal responses at different cortical depths.

Keywords: Hemodynamic response; High-resolution; Human; Layers; Visual cortex; fMRI.

MeSH terms

Adult
Brain Mapping / methods*
Cerebral Cortex / blood supply*
Cerebral Cortex / physiology*
Female
Humans
Image Processing, Computer-Assisted
Magnetic Resonance Imaging*
Male
Neurovascular Coupling
Signal Processing, Computer-Assisted
Young Adult