Faculty Collaboration Database

An investigation of positive and inverted hemodynamic response functions across multiple visual areas. Hum Brain Mapp 2014 Nov;35(11):5550-64

Date

07/22/2014

Pubmed ID

25044672

Pubmed Central ID

PMC4254893

DOI

10.1002/hbm.22569

Scopus ID

2-s2.0-84919578721 (requires institutional sign-in at Scopus site)   25 Citations

Abstract

Recent studies have demonstrated significant regional variability in the hemodynamic response function (HRF), highlighting the difficulty of correctly interpreting functional MRI (fMRI) data without proper modeling of the HRF. The focus of this study was to investigate the HRF variability within visual cortex. The HRF was estimated for a number of cortical visual areas by deconvolution of fMRI blood oxygenation level dependent (BOLD) responses to brief, large-field visual stimulation. Significant HRF variation was found across visual areas V1, V2, V3, V4, VO-1,2, V3AB, IPS-0,1,2,3, LO-1,2, and TO-1,2. Additionally, a subpopulation of voxels was identified that exhibited an impulse response waveform that was similar, but not identical, to an inverted version of the commonly described and modeled positive HRF. These voxels were found within the retinotopic confines of the stimulus and were intermixed with those showing positive responses. The spatial distribution and variability of these HRFs suggest a vascular origin for the inverted waveforms. We suggest that the polarity of the HRF is a separate factor that is independent of the suppressive or activating nature of the underlying neuronal activity. Correctly modeling the polarity of the HRF allows one to recover an estimate of the underlying neuronal activity rather than discard the responses from these voxels on the assumption that they are artifactual. We demonstrate this approach on phase-encoded retinotopic mapping data as an example of the benefits of accurately modeling the HRF during the analysis of fMRI data.

Author List

Puckett AM, Mathis JR, DeYoe EA

Author

Edgar A. DeYoe PhD Adjunct Professor in the Radiology department at Medical College of Wisconsin

MESH terms used to index this publication - Major topics in bold

Adult
Brain Mapping
Cerebrovascular Circulation
Functional Laterality
Hemodynamics
Humans
Image Interpretation, Computer-Assisted
Magnetic Resonance Imaging
Male
Middle Aged
Oxygen
Photic Stimulation
Reaction Time
Visual Cortex
Visual Pathways