Please use this identifier to cite or link to this item: http://hdl.handle.net/1959.3/3728

Title

Integration of audiovisual information with relevant bimodal stimuli: an event related potential study

Author(s)

Barutchu, Ayla;  Crewther, David P.;  Crewther, Sheila

Abstract

Introduction: Recent behavioral and electrophysiological studies have shown that the nature of cross-modal integration or the merging of spatially and temporally coincident sensory stimuli is partially dependent on the characteristics of both the stimuli and the tasks employed. Thus, the goal of this study was to investigate further the role ‘modality relevance’ plays in auditory and visual integration at both, a behavioral and neural level. Method: Event Related Potentials (ERPs) were recorded from 32 scalp electrodes while performing a simple discrimination task. Participants were presented with unimodal and bimodal auditory and visual stimuli. Each modality was allocated a target stimulus: visual target [Vt] = red flash and auditory target [At] = 1000 Hz tone, and an invalid stimulus: visual invalid [Vi] = green flash and auditory invalid [Ai] = 500 Hz tone. In total, participants were presented with 8 stimulus types: two unimodal and three bimodal target stimuli that required motor responses upon detection (At, Vt, AiVt, AtVi, and AtVt), and three invalid stimuli (Ai, Vi and AiVi) which participants were instructed to ignore. Results: Motor reaction times were fastest (by ~ 50 ms) for bimodal stimuli with both auditory and visual stimuli as targets (AtVt). In contrast, single target stimuli whether bimodal or unimodal had slower reaction times, with the coincident invalid stimuli in AiVt and AtVi having little effect in both cases. Calculating the difference between the bimodal waves and their unimodal subcomponent waves isolated the cross-modal activity within the ERPs. Audiovisual integration for AtVt was first observed approximately 120 ms post stimulus onset with the greatest amplitude modulation at N2. In contrast, minimal neural integrative activity was observed for AiVt and AtVi bimodal stimuli. Conclusion: Cross-modal integration processes are dependent on the characteristics of the bimodal stimuli, where maximum facilitation at both a behavioral and neural level is observed when both modalities are relevant to the task at hand.

Publication type

Conference poster

Research centre

Swinburne University of Technology. Faculty of Life and Social Sciences

Source

Paper presented at the 10th Annual Meeting of the Organization for Human Brain Mapping (HBM 2004), Budapest, Hungary, 13-17 June 2004

Publication year

2004

Publisher

Academic Press

Publisher URL

http://www.conferences.hu/hbm2004/