The sound & the memory: Rapid, incidental brain discrimination of visual and multisensory memories
Single Paper Presentation

Micah M Murray
Functional Brain Mapping Laboratory & Neurorehabilitation Clinic, University of Geneva

Christoph M. Michel
Functional Brain Mapping Laboratory, University of Geneva

Rolando Grave de Peralta
Functional Brain Mapping Laboratory, University of Geneva

Stephanie Ortigue
Functional Brain Mapping Laboratory, University of Geneva

Denis Brunet
Functional Brain Mapping Laboratory, University of Geneva

Sara Gonzalez Andino
Functional Brain Mapping Laboratory, University of Geneva

Armin Schnider
Neurorehabilitation Clinic, University of Geneva

     Abstract ID Number: 59
     Full text: Not available
     Last modified: May 22, 2003

Abstract
Everyday experiences indicate that memories influence ongoing sensory processes. Yet, their neural mechanisms remain unresolved. Here, electrical neuroimaging revealed that visual stimuli are rapidly and incidentally differentiated according to their multisensory or unisensory memories at ~60-136ms post-stimulus onset in the right lateral-occipital complex (rLOC). Subjects discriminated repeated versus initial image presentations. Corresponding, but task-irrelevant, sounds accompanied half of initial image presentations. Only images were used for repeated presentations, yielding two situations ? images having initially appeared only visually or with sounds (i.e. with multisensory pasts). Subjects better discriminated repetitions of images with multisensory pasts, though no faster, than images without them. Analyses were restricted to repeated presentations and statistically tested (1) visual evoked potential morphology/amplitude, (2) global electric field power, (3) the electric field?s topographic stability, and (4) intracranial distributed linear source estimations (LAURA; Grave de Peralta et al., 2001). Electrophysiological responses to images with multisensory pasts first differed at ~60-136ms and had a distinct scalp topography, indicating changes in the underlying generator configuration, localized to the (rLOC). Observation of multisensory memory representations within regions considered unisensory extends evidence for multisensory interactions in sensory processes to memory functions. We conclude that multisensory memories first alter sensory responses at early processing stages.