title: Grey matter volume in early human visual cortex predicts proneness to the sound-induced flash illusion.
abstract: Visual perception can be modulated by sounds. A drastic example of this is the sound-induced flash illusion: when a single flash is accompanied by two bleeps, it is sometimes perceived in an illusory fashion as two consecutive flashes. However, there are strong individual differences in proneness to this illusion. Some participants experience the illusion on almost every trial, whereas others almost never do. We investigated whether such individual differences in proneness to the sound-induced flash illusion were reflected in structural differences in brain regions whose activity is modulated by the illusion. We found that individual differences in proneness to the illusion were strongly and significantly correlated with local grey matter volume in early retinotopic visual cortex. Participants with smaller early visual cortices were more prone to the illusion. We propose that strength of auditory influences on visual perception is determined by individual differences in recurrent connections, cross-modal attention and/or optimal weighting of sensory channels.
authors.affiliation: University College London Institute of Cognitive Neuroscience, 17 Queen Square, London WC1N 3BG, UK. benjamin.haas.09@ucl.ac.uk
authors.forename: Benjamin
authors.initials: B
authors.lastname: de Haas
authors.forename: Ryota
authors.initials: R
authors.lastname: Kanai
authors.forename: Lauri
authors.initials: L
authors.lastname: Jalkanen
authors.forename: Geraint
authors.initials: G
authors.lastname: Rees
mesh_terms: D000161:Acoustic Stimulation; D000293:Adolescent; D000328:Adult; D001307:Auditory Perception; D005260:Female; D006801:Humans; D007088:Illusions; D008279:Magnetic Resonance Imaging; D010775:Photic Stimulation; D011897:Random Allocation; D014793:Visual Cortex / Q000033:anatomy & histology*; D014796:Visual Perception; D055815:Young Adult