Why aren't all deep superior colliculus neurons multisensory?
Single Paper Presentation

Hans Colonius
Department of Psychology, Oldenburg University

Diederich Adele
School of Humanities and Social Sciences, International University Bremen

     Abstract ID Number: 67
     Full text: Not available
     Last modified: May 20, 2003

Abstract
Multisensory neurons in the deep layers of superior colliculus (DSC) show response enhancement to cross-modal stimuli that are spatially coincident, whereas spatially disparate cross-modal cues either fail to produce multisensory interaction or lead to response depression. However, for unimodal inputs – or when certain cortical influences are eliminated – the response of multisensory DSC neurons parallels that of modality-specific neurons. Given that multisensory neurons can do everything unimodal neurons can, it is legitimate to ask why not all DSC neurons are multisensory or – at least – develop multisensory behavior during an organism’s maturation. The novel answer given here derives from an elaboration of the maximum likelihood model of multisensory enhancement by Colonius & Diederich (NIPS, 2002). Within a signal-detection theory framework, the model basically postulates that the response of a DSC neuron to a given (cross-modal or unimodal) target realizes optimal performance by maximizing the probability of correct target detection. Assuming multisensory neurons pick up the contingencies between, e.g., visual and auditory events, a total absence of modality-specific neurons would prevent optimal performance with unimodal targets. The model may also account for the differing proportions of multisensory neurons in different species in terms of their environmental conditions.