Inhibition of Return Decreases Early Audiovisual Integration: An Event-Related Potential Study

Abstract

Previous behavioral studies have found that inhibition of return decreases the audiovisual integration, while the underlying neural mechanisms are unknown. The current work utilized the high temporal resolution of event-related potentials (ERPs) to investigate how audiovisual integration would be modulated by inhibition of return. We employed the cue-target paradigm and manipulated the target type and cue validity. Participants were required to perform the task of detection of visual (V), auditory (A), or audiovisual (AV) targets shown in the identical (valid cue) or opposed (invalid cue) side to be the preceding exogenous cue. The neural activities between AV targets and the sum of the A and V targets were compared, and their differences were calculated to present the audiovisual integration effect in different cue validity conditions (valid, invalid). The ERPs results showed that a significant super-additive audiovisual integration effect was observed on the P70 (60∼90 ms, frontal-central) only under the invalid cue condition. The significant audiovisual integration effects were observed on the N1 or P2 components (N1, 120∼180 ms, frontal-central-parietal; P2, 200∼260 ms, frontal-central-parietal) in both valid cue as well as invalid cue condition. And there were no significant differences on the later components between invalid cue and valid cue. The result offers the first neural demonstration that inhibition of return modulates the early audiovisual integration process.

Keywords: audiovisual integration; cue-target paradigm; event-related potentials; exogenous spatial attention; inhibition of return.

FIGURE 1

Illustration for the stimuli and experiment. (A) Size and position. (B) Sequence of event and duration under the valid cue condition.

FIGURE 2

Grand average ERPs from audiovisual stimuli in valid cue (red dotted line) and invalid cue (black solid line) conditions on the analyzed electrodes.

FIGURE 3

Audiovisual integration by IOR interactions on the fronto-central P70 components. The P70 components for the audiovisual stimuli were noticeably greater under the invalid cue condition as compared with that for the total unisensory response, whereas this study did not find such an effect in the valid cue. (A) Grand average ERPs of differences between AV (red dotted line) and A + V (black solid line) conditions. (B) The scalp topographies of the P70 components of AV minus A + V condition.

FIGURE 4

ERP waveform for the unisensory and multisensory (AV) late processing. (A) Grand average ERPs of differences between AV (red dotted line) and A + V (black solid line) conditions for valid and invalid cue stimuli. (B) Scalp topographies from 120 to 260 ms after the onset of the stimulus for the different waves of the multisensory (AV) and the summed (A + V) ERP responses, indicating multisensory integration effect for valid and invalid cue.