title: The dynamics of contour integration: A simultaneous EEG-fMRI study.
abstract: To study the dynamics of contour integration in the human brain, we simultaneously acquired EEG and fMRI data while participants were engaged in a passive viewing task. The stimuli were Gabor arrays with some Gabor elements positioned on the contour of an embedded shape, in three conditions: with local and global structure (perfect contour alignment), with global structure only (orthogonal orientations interrupting the alignment), or without contour. By applying JointICA to the EEG and fMRI responses of the subjects, new insights could be obtained that cannot be derived from unimodal recordings. In particular, only in the global structure condition, an ERP peak around 300ms was identified that involved a loop from LOC to the early visual areas. This component can be interpreted as being related to the verification of the consistency of the different local elements with the globally defined shape, which is necessary when perfect local-to-global alignment is absent. By modifying JointICA, a quantitative comparison of brain regions and the time-course of their interplay were obtained between different conditions. More generally, we provide additional support for the presence of feedback loops from higher areas to lower level sensory regions.
authors.affiliation: KU Leuven, Department of Electrical Engineering, STADIUS, Leuven, Belgium; KU Leuven, iMinds Future Health Department, Leuven, Belgium. Electronic address: bogdan.mijovic@esat.kuleuven.be.
authors.forename: Bogdan
authors.initials: B
authors.lastname: Mijović
authors.affiliation: KU Leuven, Department of Electrical Engineering, STADIUS, Leuven, Belgium; Oldenburg University, Department of Psychology, Neuropsychology Lab, Oldenburg, Germany.
authors.forename: Maarten
authors.initials: M
authors.lastname: De Vos
authors.affiliation: KU Leuven, Department of Electrical Engineering, STADIUS, Leuven, Belgium; KU Leuven, iMinds Future Health Department, Leuven, Belgium.
authors.forename: Katrien
authors.initials: K
authors.lastname: Vanderperren
authors.affiliation: KU Leuven, Laboratory of Experimental Psychology, Leuven, Belgium.
authors.forename: Bart
authors.initials: B
authors.lastname: Machilsen
authors.affiliation: KU Leuven, Department of Radiology, Leuven, Belgium.
authors.forename: Stefan
authors.initials: S
authors.lastname: Sunaert
authors.affiliation: KU Leuven, Department of Electrical Engineering, STADIUS, Leuven, Belgium; KU Leuven, iMinds Future Health Department, Leuven, Belgium.
authors.forename: Sabine
authors.initials: S
authors.lastname: Van Huffel
authors.affiliation: KU Leuven, Laboratory of Experimental Psychology, Leuven, Belgium.
authors.forename: Johan
authors.initials: J
authors.lastname: Wagemans
mesh_terms: D000328:Adult; D002540:Cerebral Cortex / Q000000981:diagnostic imaging / Q000502:physiology*; D004569:Electroencephalography / Q000379:methods*; D005071:Evoked Potentials / Q000502:physiology*; D005260:Female; D005556:Form Perception / Q000502:physiology*; D059907:Functional Neuroimaging / Q000379:methods*; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D010364:Pattern Recognition, Visual / Q000502:physiology*
keywords: Contour integration; Data driven methods; EEG–fMRI integration; Shape detection; Vision