Action-associated modulation of visual event-related potentials evoked by abstract and ecological stimuli
This study investigated the influence of action-associated predictive processes on visual event-related potentials (ERPs). In two experiments (N=17 and N=19), we sought evidence for sensory attenuation (SA) indexed by ERP amplitude reductions for self-induced stimuli when compared to passive viewing of the same images. We assessed if SA (1) is stronger for ecologically valid versus abstract stimuli (by comparing ERPs to pictures depicting hands versus checkerboards), (2) is specific to stimulus identity (certain versus uncertain action-effect contingencies), and (3) is sensitive to laterality of hand movements (dominant versus subdominant hand actions). We found reduced occipital responses for self-triggered hand stimuli very early, between 80-90 ms (C1 component), but this effect was absent for checkerboards. On the contrary, the P1 component (100-140 ms) was enhanced for all action-associated stimuli, and this effect proved to be sensitive to stimulus predictability for hands only. The parietal N1 component (170-190 ms) showed amplitude enhancement after right-hand movements for checkerboards only. Overall, our findings indicate that action-associated predictive processes attenuate early cortical responses to ecologically valid visual stimuli. Moreover, we propose that subsequent ERPs show amplitude enhancement that might result from the interaction between expectation-based SA and attention. Movement-initiated modulation of visual ERPs does not appear to show strong lateralization in healthy individuals, although the absence of lateralized effects cannot be excluded. These results can have implications for assessing the influence of action-associated predictions on visual processing in psychiatric disorders characterized by aberrant sensory predictions and alterations in hemispheric asymmetry, such as schizophrenia.