Change detection in audio-visual space: neural evidence for age effects.

Introduction: The ability to perceive spatial changes is crucial for everyday life. However, the effects of age on multisensory integration in spatial change detection are still less researched. Here, we investigated whether audio-visual stimulation enhances spatial change detection compared to auditory-only processing, and whether older adults benefit more from multisensory stimulation than younger adults. Methods: In an active oddball task, younger and older participants had to detect spatial changes in azimuth (in the horizontal plane) or distance (in the depth dimension). Stimuli were presented as auditory-only or audio-visual (spatially congruent). Behavioral performance and event-related potentials indexing sensory processing (P1, N1, P2), automatic change detection (mismatch negativity), attention orienting (P3a), and evaluation (P3b) were measured. Results: Detection accuracy was higher for azimuth than distance changes in auditory-only conditions, but this difference was reduced with audio-visual stimulation. Older adults showed comparable behavioral performance to younger adults across both conditions, with no additional benefit from multisensory input. However, older adults exhibited enhanced early sensory processing (larger N1, P2 amplitudes), reduced MMN differentiation between azimuth and distance deviations, and later evaluative processing that was primarily modulated by spatial dimension and stimulation modality. Thus, age-related neural differences were component-specific and depended on spatial dimension and stimulation modality. Discussion: Taken together, audio-visual integration facilitated spatial change detection, particularly in the depth dimension. While older adults maintained behavioral performance possibly through compensatory neural mechanisms involving enhanced attentional allocation, the use of multisensory stimuli for spatial change detection appears to be largely preserved in aging.