Multisensory integration in the human brain is parametrized by frequency and time delays.
Poster

Collins G. Assisi
Center for Complex Systems and Brain Sciences, Florida Atlantic University

Mukeshwar Dhamala
Center for Complex Systems and Brain Sciences, Florida Atlantic University

Viktor K. Jirsa
Center for Complex Systems and Brain Sciences, Florida Atlantic University

J. A. Scott Kelso
Center for Complex Systems and Brain Sciences, Florida Atlantic University

     Abstract ID Number: 106
     Full text: Not available
     Last modified: June 8, 2003

Abstract
We present an experimental and theoretical parametric study of multisensory perceptual phenomena. In our experiments the presentation frequency and the time between the onsets of pairs of rhythmic multisensory stimuli (auditory-visual, auditory-haptic and haptic-visual) were used as control parameters.
As the parameters were varied, subjects reported one of three percepts.
a) The stimuli appeared simultaneous
b) The stimuli appeared in sequential order
c) The relative phase between the two stimuli drifted
To identify the neural correlates, similar experiments were conducted using fMRI. The different percepts reported by the subjects correlate with the activity of the superior colliculus, a region implicated in the integration of multisensory stimuli. Based on these results we propose a dynamic model that characterizes the structure of the parameter space. The model consists of three mutually coupled, excitable units, representing the primary sensory areas and an integrative area of the brain. The coupling includes a time delay in the information transfer across the different functional units. Numerical and mathematical studies of our model reproduce the experimentally observed results. We hypothesize that the differences in the time delay between sensory and integrative areas are the basis of the formation of different percepts as a function of timing.