Shared physiological correlates of multisensory and expectation-based facilitation

Abstract

Perceptual performance in a visual task can be enhanced by simultaneous multisensory information, but can also be enhanced by a symbolic or amodal cue inducing a specific expectation. That similar benefits can arise from multisensory information and within-modality expectation raises the question of whether the underlying neurophysiological processes are the same or distinct. We investigated this by comparing the influence of three types of auxiliary probabilistic cues on visual motion discrimination in humans: i) acoustic motion, ii) a pre-motion visual symbolic cue, iii) a post-motion symbolic cue. Using multivariate analysis of the EEG data we show that both the multisensory and preceding visual symbolic cue enhance the encoding of visual motion direction as reflected by cerebral activity arising from occipital regions around 200-400ms post-stimulus onset. This suggests a common or overlapping physiological correlate of crossmodal and intramodal auxiliary information, pointing to neural mechanism susceptive to both multisensory and more abstract probabilistic cues. We also asked how pre-stimulus activity shapes the cue-stimulus combination and found a differential influence on crossmodal and intramodal combination: while alpha power modulated the relative weight of visual motion and the acoustic cue, it did not modulate the behavioural influence of a visual symbolic cue, pointing to differences in how pre-stimulus activity shapes the combination of multisensory and abstract cues with task-relevant information

Significance Statement Perception can be enhanced by the combination of multisensory information and by the exploitation of amodal or symbolic cues presented within the same modality as the task-relevant information. We here asked whether the physiological correlates reflecting the behavioural benefits induced by each type of cue are similar or not. Using multivariate analysis of EEG data we show that the perceptual enhancement induced by an acoustic cue and a visual-symbolic cue for the discrimination of visual motion arise from the same physiological source. This suggests that the impact of multisensory information and more abstract sensory expectations on perception arise from shared mechanisms.