Modulation of motion signals across the visual cortical hierarchy during bistable perception

Abstract

Top-down influences play a central role in perception. In multi-stable sensory phenomena subjective interpretation fluctuates spontaneously over time and the perceptual switches reflect internally driven representations engaging perceptual decision-making. Using functional magnetic resonance imaging (fMRI), we investigated how perceptual states are represented across early visual areas during perception of a bistable moving plaid. While subjects maintained central fixation, perception of the stimulus--two superimposed, obliquely oriented moving gratings--spontaneously alternated between component motion (2 gratings sliding obliquely over each other) and pattern motion (a single coherent pattern moving laterally). Direction-selective clusters were reliably modulated by perceptual state across both early (V1) and higher-order (V2 and the human medial temporal complex (hMT+)) visual regions. Pattern modulation was significantly stronger in primary visual cortex (V1) than in higher-order areas, suggesting that coherent percept formation engages mechanisms beyond simple bottom-up feature integration. Enhanced V1 modulation points to a prominent role for top-down influences from higher-order regions, consistent with predictive coding frameworks in which higher-level areas convey predictions to lower levels to disambiguate sensory input and drive perceptual inference under ambiguous conditions. Eye tracking confirmed that reflexive eye movement direction did not predict perceptual state, excluding an oculomotor confound. Interpretation of the results in light of current knowledge of the physiology of motion integration in early visual areas suggests circuits at which feedback would be predicted to act.