Audio-visual Interaction in P300

Abstract

The present study investigated the interaction in the processing of auditory and visual stimuli in the generation of P300 and the effect of electrode site on P300. P300 was obtained for auditory alone condition, audio-visual congruent and audio-visual incongruent conditions, which in turn were between two electrode sites ( Cz & Pz) for latency and amplitude. The experimental data was obtained from 20 normal hearing adults. The results showed that the mean latencies were shorter in audio-visual congruent condition compared to that in auditory mode and audio-visual incongruent conditions. The mean amplitude was higher in the audio-visual congruent condition compared to auditory and audio-visual incongruent conditions in both the electrode sites. The mean latency was shorter and amplitude was higher in Pz than that in Cz in all the three stimulus conditions suggesting that distribution of the electrical field and the dipole of the potential can be better recorded from the regions closer to the parietal lobe compared to mid and frontal regions of the brain. The P300 recordings supported earlier perceptual processing and better speech perception in auditory-visual mode compared to that in audito1y mode suggesting that bimodal condition facilitates the detection of the stimulus.