  Our daily perceptual experience is driven by different neural mechanisms that
yield multisensory interaction as the interplay between exogenous stimuli and
endogenous expectations. While the interaction of multisensory cues according
to their spatiotemporal properties and the formation of multisensory
feature-based representations have been widely studied, the interaction of
spatial-associative neural representations has received considerably less
attention. In this paper, we propose a neural network architecture that models
the interaction of spatial-associative representations to perform causal
inference of audiovisual stimuli. We investigate the spatial alignment of
exogenous audiovisual stimuli modulated by associative congruence. In the
spatial layer, topographically arranged networks account for the interaction of
audiovisual input in terms of population codes. In the associative layer,
congruent audiovisual representations are obtained via the experience-driven
development of feature-based associations. Levels of congruency are obtained as
a by-product of the neurodynamics of self-organizing networks, where the amount
of neural activation triggered by the input can be expressed via a nonlinear
distance function. Our novel proposal is that activity-driven levels of
congruency can be used as top-down modulatory projections to spatially
distributed representations of sensory input, e.g. semantically related
audiovisual pairs will yield a higher level of integration than unrelated
pairs. Furthermore, levels of neural response in unimodal layers may be seen as
sensory reliability for the dynamic weighting of crossmodal cues. We describe a
series of planned experiments to validate our model in the tasks of
multisensory interaction on the basis of semantic congruence and unimodal cue
reliability.
