Linear systems analysis for laminar fMRI: evaluating BOLD amplitude scaling for luminance contrast manipulations

van Dijk, J. A., Fracasso, A. , Petridou, N. and Dumoulin, S. O. (2020) Linear systems analysis for laminar fMRI: evaluating BOLD amplitude scaling for luminance contrast manipulations. Scientific Reports, 10, 5462. (doi: 10.1038/s41598-020-62165-x) (PMID:32214136) (PMCID:PMC7096513)

Abstract

A fundamental assumption of nearly all functional magnetic resonance imaging (fMRI) analyses is that the relationship between local neuronal activity and the blood oxygenation level dependent (BOLD) signal can be described as following linear systems theory. With the advent of ultra-high field (7T and higher) MRI scanners, it has become possible to perform sub-millimeter resolution fMRI in humans. A novel and promising application of sub-millimeter fMRI is measuring responses across cortical depth, i.e. laminar imaging. However, the cortical vasculature and associated directional blood pooling towards the pial surface strongly influence the cortical depth-dependent BOLD signal, particularly for gradient-echo BOLD. This directional pooling may potentially affect BOLD linearity across cortical depth. Here we assess whether the amplitude scaling assumption for linear systems theory holds across cortical depth. For this, we use stimuli with different luminance contrasts to elicit different BOLD response amplitudes. We find that BOLD amplitude across cortical depth scales with luminance contrast, and that this scaling is identical across cortical depth. Although nonlinearities may be present for different stimulus configurations and acquisition protocols, our results suggest that the amplitude scaling assumption for linear systems theory across cortical depth holds for luminance contrast manipulations in sub-millimeter laminar BOLD fMRI.

• Item Type: Articles
• Additional Information: This work was supported by the European Union’s Horizon 2020 research and innovation programme under the Marie Sklodowska-Curie grant agreement No. 641805 (S.O.D.), Ammodo KNAW Award (S.O.D.), and a Netherlands Organization for Scientific Research (NWO) Vidi Grant 13339 (N.P.). A.F. is supported by a grant from the Biotechnology and Biology research council (BBSRC, grant number: BB/S006605/1).
• Status: Published
• Refereed: Yes
• Glasgow Author(s) Enlighten ID: Fracasso, Dr Alessio
• Authors: van Dijk, J. A., Fracasso, A., Petridou, N., and Dumoulin, S. O.
• College/School: College of Medical Veterinary and Life Sciences > School of Psychology & Neuroscience
• Journal Name: Scientific Reports
• Publisher: Nature Research
• ISSN: 2045-2322
• ISSN (Online): 2045-2322
• Copyright Holders: Copyright © 2020 The Authors
• First Published: First published in Scientific Reports 10: 5462
• Publisher Policy: Reproduced under a Creative Commons License

Project Code	Award No	Project Name	Principal Investigator	Funder's Name	Funder Ref	Lead Dept
303685		Stable perception of external stimuli over time: oculo-motor and visual processing mechanisms	Alessio Fracasso	Biotechnology and Biological Sciences Research Council (BBSRC)	BB/S006605/1	NP - Centre for Cognitive Neuroimaging (CCNi)