title: Decoding sound and imagery content in early visual cortex.
abstract: Human early visual cortex was traditionally thought to process simple visual features such as orientation, contrast, and spatial frequency via feedforward input from the lateral geniculate nucleus (e.g., [1]). However, the role of nonretinal influence on early visual cortex is so far insufficiently investigated despite much evidence that feedback connections greatly outnumber feedforward connections [2-5]. Here, we explored in five fMRI experiments how information originating from audition and imagery affects the brain activity patterns in early visual cortex in the absence of any feedforward visual stimulation. We show that category-specific information from both complex natural sounds and imagery can be read out from early visual cortex activity in blindfolded participants. The coding of nonretinal information in the activity patterns of early visual cortex is common across actual auditory perception and imagery and may be mediated by higher-level multisensory areas. Furthermore, this coding is robust to mild manipulations of attention and working memory but affected by orthogonal, cognitively demanding visuospatial processing. Crucially, the information fed down to early visual cortex is category specific and generalizes to sound exemplars of the same category, providing evidence for abstract information feedback rather than precise pictorial feedback. Our results suggest that early visual cortex receives nonretinal input from other brain areas when it is generated by auditory perception and/or imagery, and this input carries common abstract information. Our findings are compatible with feedback of predictive information to the earliest visual input level (e.g., [6]), in line with predictive coding models [7-10].
authors.affiliation: Centre for Cognitive Neuroimaging, Institute of Neuroscience and Psychology, College of Medical, Veterinary and Life Sciences, University of Glasgow, 58 Hillhead Street, Glasgow G12 8QB, UK; Laboratory for Behavioral Neurology and Imaging of Cognition, Department of Neuroscience, Medical School and Swiss Center for Affective Sciences, University of Geneva, Campus Biotech, Case Postale 60, 1211 Geneva, Switzerland. Electronic address: petra.vetter@unige.ch.
authors.forename: Petra
authors.initials: P
authors.lastname: Vetter
authors.affiliation: Centre for Cognitive Neuroimaging, Institute of Neuroscience and Psychology, College of Medical, Veterinary and Life Sciences, University of Glasgow, 58 Hillhead Street, Glasgow G12 8QB, UK.
authors.forename: Fraser W
authors.initials: FW
authors.lastname: Smith
authors.affiliation: Centre for Cognitive Neuroimaging, Institute of Neuroscience and Psychology, College of Medical, Veterinary and Life Sciences, University of Glasgow, 58 Hillhead Street, Glasgow G12 8QB, UK. Electronic address: lars.muckli@glasgow.ac.uk.
authors.forename: Lars
authors.initials: L
authors.lastname: Muckli
mesh_terms: D000161:Acoustic Stimulation; D001307:Auditory Perception; D006801:Humans; D008279:Magnetic Resonance Imaging; D008570:Memory, Short-Term; D010775:Photic Stimulation; D014793:Visual Cortex / Q000502:physiology*; D014796:Visual Perception