Superadditivity: Putting the Tail in Context
Single Paper Presentation

Terrence Stanford
Neurobiology & Anatomy, Wake Forest U. Sch. of Med.

Barry Stein
Neurobiology & Anatomy, Wake Forest U. Sch. of Med.

     Abstract ID Number: 77
     Full text: Not available
     Last modified: March 16, 2006
     Presentation date: 06/20/2006 11:30 AM in Hamilton Building, McNeil Theatre
     (View Schedule)

Abstract
The behavioral benefits of integrating stimuli from multiple senses (such as decreased reaction time and increased stimulus detection) likely derive from the physiological phenomenon of multisensory enhancement. Whether measured with functional imaging, evoked potentials, or single-neuron recordings, enhancement refers to a relative increase in the level of neural activity for multisensory versus unisensory stimuli. Historically, much emphasis has been placed on “superadditive” enhancements, apparently supralinear interactions wherein the multisensory response exceeds the sum of the responses obtained for the modality-specific component stimuli. Superadditivity is manifest in all recording methods (single neurons, MRI, ERP), has been reported for many neural structures and species, and has had a strong conceptual impact in the multisensory literature. Yet this literature is equivocal, rendering conclusions about the relative incidence of superadditivity ranging from “quite common” to “nonexistent”. This circumstance begs a careful re-examination of how and when superadditivity occurs. Here we show that “superadditivity” cannot be adequately classified as common or rare or anything in between but is only properly considered as context-dependent. Specifically, the mode of integration depends on the efficacy of the modality-specific stimulus components, and when viewed through this prism, even widely disparate findings are unified. (NS36916 and NS22543)