title: Visual representations are dominated by intrinsic fluctuations correlated between areas.
abstract: Intrinsic cortical dynamics are thought to underlie trial-to-trial variability of visually evoked responses in animal models. Understanding their function in the context of sensory processing and representation is a major current challenge. Here we report that intrinsic cortical dynamics strongly affect the representational geometry of a brain region, as reflected in response-pattern dissimilarities, and exaggerate the similarity of representations between brain regions. We characterized the representations in several human visual areas by representational dissimilarity matrices (RDMs) constructed from fMRI response-patterns for natural image stimuli. The RDMs of different visual areas were highly similar when the response-patterns were estimated on the basis of the same trials (sharing intrinsic cortical dynamics), and quite distinct when patterns were estimated on the basis of separate trials (sharing only the stimulus-driven component). We show that the greater similarity of the representational geometries can be explained by coherent fluctuations of regional-mean activation within visual cortex, reflecting intrinsic dynamics. Using separate trials to study stimulus-driven representations revealed clearer distinctions between the representational geometries: a Gabor wavelet pyramid model explained representational geometry in visual areas V1-3 and a categorical animate-inanimate model in the object-responsive lateral occipital cortex.
authors.affiliation: MRC Cognition and Brain Sciences Unit, Cambridge CB2 7EF, UK; Brain Research Unit, Department of Neuroscience and Biomedical Engineering, Aalto University, 02150 Espoo, Finland. Electronic address: linda.henriksson@aalto.fi.
authors.forename: Linda
authors.initials: L
authors.lastname: Henriksson
authors.affiliation: MRC Cognition and Brain Sciences Unit, Cambridge CB2 7EF, UK; Computer Science & Artificial Intelligence Laboratory, Massachusetts Institute of Technology, Cambridge, MA 02139, USA.
authors.forename: Seyed-Mahdi
authors.initials: SM
authors.lastname: Khaligh-Razavi
authors.affiliation: Department of Psychology, Washington University in St. Louis, St. Louis, MO 63130, USA.
authors.forename: Kendrick
authors.initials: K
authors.lastname: Kay
authors.affiliation: MRC Cognition and Brain Sciences Unit, Cambridge CB2 7EF, UK.
authors.forename: Nikolaus
authors.initials: N
authors.lastname: Kriegeskorte
mesh_terms: D001931:Brain Mapping / Q000379:methods*; D006801:Humans; D007091:Image Processing, Computer-Assisted; D008279:Magnetic Resonance Imaging / Q000379:methods*; D010775:Photic Stimulation; D014793:Visual Cortex / Q000502:physiology*; D014796:Visual Perception / Q000502:physiology*
keywords: Functional MRI; Intrinsic dynamics; Natural images; Pattern information; Representational similarity; Visual cortex