Summary: LETTER Communicated by B. E. Stein
Using Bayes' Rule to Model Multisensory Enhancement in the
Thomas J. Anastasio
Beckman InstituteandDepartment ofMolecular andIntegrative Physiology, University
of Illinois at Urbana/Champaign, Urbana, IL 61801, U.S.A.
Paul E. Patton
Beckman Institute, University of Illinois at Urbana/Champaign, Urbana, IL 61801,
The deep layers of the superior colliculus (SC) integrate multisensory
inputs and initiate an orienting response toward the source of stimula-
tion (target). Multisensory enhancement, which occurs in the deep SC, is
the augmentation of a neural response to sensory input of one modality
by input of another modality. Multisensory enhancement appears to un-
derlie the behavioral observation that an animal is more likely to orient
toward weak stimuli if a stimulus of one modality is paired with a stim-
ulus of another modality. Yet not all deep SC neurons are multisensory.
Those that are exhibit the property of inverse effectiveness: combinations
of weaker unimodal responses produce larger amounts of enhancement.