title: The effect of acquisition resolution on orientation decoding from V1 BOLD fMRI at 7T.
abstract: A decade after it was shown that the orientation of visual grating stimuli can be decoded from human visual cortex activity by means of multivariate pattern classification of BOLD fMRI data, numerous studies have investigated which aspects of neuronal activity are reflected in BOLD response patterns and are accessible for decoding. However, it remains inconclusive what the effect of acquisition resolution on BOLD fMRI decoding analyses is. The present study is the first to provide empirical ultra high-field fMRI data recorded at four spatial resolutions (0.8mm, 1.4mm, 2mm, and 3mm isotropic voxel size) on this topic - in order to test hypotheses on the strength and spatial scale of orientation discriminating signals. We present detailed analysis, in line with predictions from previous simulation studies, about how the performance of orientation decoding varies with different acquisition resolutions. Moreover, we also examine different spatial filtering procedures and its effects on orientation decoding. Here we show that higher-resolution scans with subsequent down-sampling or low-pass filtering yield no benefit over scans natively recorded in the corresponding lower resolution regarding decoding accuracy. The orientation-related signal in the BOLD fMRI data is spatially broadband in nature, includes both high spatial frequency components, as well as large-scale biases previously proposed in the literature. Moreover, we found above chance-level contribution from large draining veins to orientation decoding. Acquired raw data were publicly released to facilitate further investigation.
authors.affiliation: Department of Experimental Psychology, Institute of Psychology II, Otto-von-Guericke University, Universitätsplatz 2, 39016 Magdeburg, Germany. Electronic address: ayan.sengupta@ovgu.de.
authors.forename: Ayan
authors.initials: A
authors.lastname: Sengupta
authors.affiliation: Department of Biomedical Magnetic Resonance, Institute for Experimental Physics, Otto-von-Guericke University, Leipziger Str. 44, 39120 Magdeburg, Germany.
authors.forename: Renat
authors.initials: R
authors.lastname: Yakupov
authors.affiliation: Department of Biomedical Magnetic Resonance, Institute for Experimental Physics, Otto-von-Guericke University, Leipziger Str. 44, 39120 Magdeburg, Germany; Center for Behavioral Brain Sciences, Universitätsplatz 2, 39016 Magdeburg, Germany; Leibniz Institute for Neurobiology, Brenneckestr. 6, 39118 Magdeburg, Germany; German Center for Neurodegenerative Disease (DZNE), Site Magdeburg, Leipziger Straße 44, Germany.
authors.forename: Oliver
authors.initials: O
authors.lastname: Speck
authors.affiliation: Department of Experimental Psychology, Institute of Psychology II, Otto-von-Guericke University, Universitätsplatz 2, 39016 Magdeburg, Germany; Center for Behavioral Brain Sciences, Universitätsplatz 2, 39016 Magdeburg, Germany.
authors.forename: Stefan
authors.initials: S
authors.lastname: Pollmann
authors.affiliation: Center for Behavioral Brain Sciences, Universitätsplatz 2, 39016 Magdeburg, Germany; Psychoinformatics Lab, Institute of Psychology II, Otto-von-Guericke University, Universitätsplatz 2, 39016 Magdeburg, Germany.
authors.forename: Michael
authors.initials: M
authors.lastname: Hanke
mesh_terms: D000328:Adult; D000465:Algorithms; D001931:Brain Mapping; D002560:Cerebrovascular Circulation / Q000502:physiology; D003198:Computer Simulation; D004574:Electromagnetic Fields; D005260:Female; D006801:Humans; D007091:Image Processing, Computer-Assisted / Q000379:methods*; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D016011:Normal Distribution; D009949:Orientation / Q000502:physiology*; D010100:Oxygen / Q000097:blood*; D010775:Photic Stimulation; D011597:Psychomotor Performance / Q000502:physiology; D014793:Visual Cortex / Q000502:physiology; D014796:Visual Perception / Q000502:physiology*; D055815:Young Adult
chemical_list: D010100:Oxygen
keywords: Acquisition resolution; Decoding; Functional magnetic resonance imaging