Perceptual Bias in Motion Discrimination is Related to Asymmetric Interhemispheric Alpha Traveling Waves

Perception relies on hierarchical processes integrating sensory data into higher-order models about the world. In the sensory domain, this hierarchy also involves horizontal pathways aiding interhemispheric interactions. For example, recent focus on the V5-V5 network revealed its role in motion processing. However, despite converging evidence demonstrating the crucial role of oscillatory activity in inter-areas communication, the specific rhythmic code governing V5-V5 interaction is unclear. Through traveling wave analysis, this gap is filled by identifying the alpha/low-beta frequency (9-16 Hz) as crucial for long-range, interhemispheric communication between V5 regions. Notably, a pronounced imbalance is observed: stronger waves travelled in the left-to-right-V5 direction. Crucially, this observation extends to the behavioural level, as Signal Detection Theory analysis uncovered a correlation between the highlighted imbalance and a perceptual bias favouring leftward motion reporting. Our findings underscore asymmetrical projections between V5 regions, highlighting the interplay between inter-hemispheric traveling wave patterns in dictating motion perception.