Dynamic modulation of object processing stream during cross-modal integration

Lorina Naci, University of Cambridge

Abstract
It has been suggested that, during object processing, auditory and visual object features are analyzed within hierarchically structured sensory processing streams from sensory-specific cortex to superior/inferior temporal cortex, and are integrated in antero-medial temporal regions (Simmons & Barsalou, 2003; Taylor et al., 2005). This EEG study aimed to investigate the timing of cross-modal effects on auditory/visual sensory processes and on conceptual-semantic processes involved in object processing. High-density (128 channel) ERPs were recorded from fifteen healthy participants while performing a congruency task on auditory, visual, and audio-visual stimuli. The activations’ loci from an erFMRI study using the same stimuli and task [Taylor et al, 2005] were used to constrain the source analysis of the grand averaged ERPs. Cross-modal effects influence sensory processes from 60ms and conceptual-semantic processes between 150ms and 450ms. Auditory and visual sensory ERP components (P1, N1) are enhanced in the cross-modal condition. Cross-modal conceptual-semantic processes start at around 150ms and peak again between 400-450ms, times when the anterior-temporal cortex becomes significantly stronger than the posterior-occipital cortex. The later (400-500ms) effects are right-lateralized, as may be expected for the processing of non-linguistic stimuli. We discuss the implications of these findings with reference to hierarchical models of object processing.

Not available

Back to Abstract