Conflicting Motor Plans and Sensory Attenuation: Evidence From Event-Related Potentials for Sounds Generated by Pro- and Antisaccades.

Abstract

The reduction of neural responses to self- versus externally generated stimuli has been ascribed to predictions based on an efference copy of motor commands. However, general predictive mechanisms not specific to movements may also play a role. For antisaccades, that is, eye movements in the opposite direction of a target stimulus, an automated prosaccade has to be suppressed, which may lead to conflicting efference copy signals, as an efference copy is likely created also for the prosaccade. If efference copies for the suppressed and executed saccade are in conflict with each other, prediction mechanisms based on their information are potentially disturbed, which may affect the processing of saccade-generated stimuli. We compared the N1 and P2 components for pro- and antisaccade-generated sounds with those for visually cued external sounds and found differing temporal dynamics of both components during the course of the experiment, depending on the saccade type. The N1 amplitude for pro- but not antisaccade-generated sounds changed over the course of the experiment, with evidence of an attenuation relative to visually cued sounds at the end. The P2 for prosaccade-generated sounds decreased already earlier than that for antisaccade-generated sounds, which only decreased toward the end of the experiment. These findings suggest that both early (N1) and late (P2) processing of saccade-generated sounds is affected by conflicting efference copies, with the early effect probably reflecting forward model predictions and the later effect indicating agency perception based on these predictions.