Abstract
Sometimes one person can miss a brief visual event that others may readily detect. This variability in visual awareness may be a consequence of different processing times in visual cortex for different individuals. We and others have previously shown that specific temporal processing windows, namely later feedback activity to primary visual cortex (V1) (Supèr et al., 2001; Ro et al., 2003) and the phase of alpha (8-12 Hz) oscillations (Mathewson et al., 2009; Jaegle & Ro, 2014), are important for visual awareness. Recent evidence also suggests that alpha oscillations arise from feedback activity to V1 (van Kerkoerle et al., 2014). In the current study, we assessed whether alpha oscillations reflect feedback/reentrant activity by testing the relationship between peak alpha oscillation frequency and signatures of feedback processing in V1 for conscious visual perception. Using scalp electroencephalography (EEG) recordings, single-pulse transcranial magnetic stimulation (TMS), and metacontrast masking, we show that individual peak alpha oscillation frequencies are highly correlated with optimal TMS visual suppression times and metacontrast masking latencies, both of which have been suggested to index feedback processing in V1. These findings suggest that alpha oscillations reflect waves of feedback activity to V1 for visual awareness and that the time to visual awareness varies across individuals.
Meeting abstract presented at VSS 2017