title: Sounds reset rhythms of visual cortex and corresponding human visual perception.
abstract: An event in one sensory modality can phase reset brain oscillations concerning another modality. In principle, this may result in stimulus-locked periodicity in behavioral performance. Here we considered this possible cross-modal impact of a sound for one of the best-characterized rhythms arising from the visual system, namely occipital alpha-oscillations (8-14 Hz). We presented brief sounds and concurrently recorded electroencephalography (EEG) and/or probed visual cortex excitability (phosphene perception) through occipital transcranial magnetic stimulation (TMS). In a first, TMS-only experiment, phosphene perception rate against time postsound showed a periodic pattern cycling at ~10 Hz phase-aligned to the sound. In a second, combined TMS-EEG experiment, TMS-trials reproduced the cyclical phosphene pattern and revealed a ~10 Hz pattern also for EEG-derived measures of occipital cortex reactivity to the TMS pulses. Crucially, EEG-data from intermingled trials without TMS established cross-modal phase-locking of occipitoparietal alpha oscillations. These independently recorded variables, i.e., occipital cortex excitability and reactivity and EEG phase dynamics, were significantly correlated. This shows that cross-modal phase locking of oscillatory visual cortex activity can arise in the human brain to affect perceptual and EEG measures of visual processing in a cyclical manner, consistent with occipital alpha oscillations underlying a rapid cycling of neural excitability in visual areas.
authors.affiliation: Institute of Neuroscience and Psychology, University of Glasgow, 58 Hillhead Street, Glasgow G12 8QB, UK. v.romei@ucl.ac.uk
authors.forename: Vincenzo
authors.initials: V
authors.lastname: Romei
authors.forename: Joachim
authors.initials: J
authors.lastname: Gross
authors.forename: Gregor
authors.initials: G
authors.lastname: Thut
mesh_terms: D004569:Electroencephalography; D006801:Humans; D014793:Visual Cortex / Q000502:physiology*; D014796:Visual Perception