Dissociating the multiple phases of somatosensory-visual integrations in the human event-related potential: A high-density electrical mapping study.
Poster Presentation

Jeannette Piesco
Nathan Kline Institute

Sophie Molholm
Nathan Kline Institute

Pejman Sehatpour
Nathan Kline Institute

Walter Ritter
Nathan Kline Institute

John Foxe
Nathan Kline Institute

     Abstract ID Number: 146
     Full text: Not available
     Last modified: March 21, 2005

Abstract
Correlated sensory inputs coursing along the individual sensory processing hierarchies arrive at multisensory convergence zones in cortex where research has shown that information is processed in an integrative manner. Here, using high-density electrical mapping (from a 168-channel array), source localization, and complementary psychophysical data, we examined visual and somatosensory interactions. We assessed 1) how early in sensory processing, visual-somatosensory (VS) interactions were seen in the event-related potential (ERP), 2) whether spatial alignment or misalignment had differential effects on these early multisensory interactions. Participants were randomly presented with unisensory-somatosensory, unisensory-visual and multisensory VS stimuli to both the left and right hemifields. Behavioral results indicate that RTs to all multisensory VS conditions were significantly faster than those elicited from the unisensory conditions, regardless of spatial alignment or misalignment. Electrophysiological results yielded significant differences between ‘simultaneous’ and ‘summed’ group-averaged ERPs for all four multisensory conditions at just 125 ms. Considering the nature of the stimuli, the timing and topographies of these early VS interactions is not surprising. Findings are in agreement with those of Murray et al. (2004); the earliest multisensory interactions seen in the ERP occur regardless of spatial register.