Presentation Information
[P3-07]Top-Down Control of Alpha-Band Phase as a Mechanism of Interval Temporal Prediction: Direct Test and Preliminary Evidence
*Christina Bruckmann1,2, Assaf Breska1 (1. Max Planck Institute for Biological Cybernetics (Germany), 2. University of Tübingen (Germany))
Keywords:
temporal attention,alpha phase,interval timing,EEG,visual perception
The brain is able to use cue-interval associations to increase perceptual sensitivity at a specific moment in time, yet the underlying neural mechanisms are still being unraveled. Previous studies on visual perception in non-timing contexts have reported perceptual benefits at specific phases of occipital alpha-band activity. Moreover, exposure to 10 Hz sensory rhythms entrains alpha oscillations to phase-align to on-beat times. However, whether the alpha phase can be adjusted to align with the interval-based predicted target moment, without preceding entrainment, is highly debated. Here, we investigate this by presenting challenging visual discrimination targets at fully predictable intervals that differ in length by half an alpha cycle (800 or 850ms). Top-down control over the alpha-band phase should manifest in phase opposition between the two conditions in a pre-target time window. To examine whether phase inversion depends on temporal sensitivity, we assessed participants’ Just-Noticable-Difference (JND) in a temporal discrimination task.In our preliminary data (N=14), alpha phase appears to be correlated with visual discrimination performance, replicating previous results from non-timing paradigms. This suggests a perceptual benefit could be gained by consistent alignment of phase. However, the preliminary data provides only partial evidence of phase inversion. We observe a substantial shift in the distribution of phase differences across participants relative to a uniform chance model towards a phase opposition model, but only a trend for increase in group-averaged mean phase difference relative to chance level. Surprisingly, we found no correlation between the degree of phase opposition and the JND or alpha amplitude. Additionally, in contrast to previous studies, pre-target intertrial phase concentration is low, calling into question the robustness of this mechanism. Future work should study the modulating factors within and across participants