Visually Induced Plasticity of Auditory Spatial Perception in Macaques

Abstract

When experiencing spatially disparate visual and auditory stimuli, a common percept is that the sound originates from the location of the visual stimulus, an illusion known as the ventriloquism effect. This illusion can persist for tens of minutes, a phenomenon termed the ventriloquism aftereffect. The underlying neuronal mechanisms of this rapidly induced plasticity remain unclear; indeed, it remains untested whether similar multimodal interactions occur in other species. We therefore tested whether macaque monkeys experience the ventriloquism aftereffect similar to the way humans do. The ability of two monkeys to determine which side of the midline a sound was presented from was tested before and after a period of 20-60 min in which the monkeys experienced either spatially identical or spatially disparate auditory and visual stimuli. In agreement with human studies, the monkeys did experience a shift in their auditory spatial perception in the direction of the spatially disparate visual stimulus, and the aftereffect did not transfer across sounds that differed in frequency by two octaves. These results show that macaque monkeys experience the ventriloquism aftereffect similar to the way humans do in all tested respects, indicating that these multimodal interactions are a basic phenomenon of the central nervous system.

Distribution of eye position information in the monkey inferior colliculus

“…One modality can dramatically influence the other. Estimates of the location of sound sources are reliably biased in the direction of a task-irrelevant displaced visual cue in humans and in monkeys Knudsen 1985, 1989;Kopco et al 2009;Recanzone 1998Recanzone , 2009Woods and Recanzone 2004). Participants in such ventriloquism experiments are subject to a direct effect of visual information on auditory percepts.…”

Relearning Auditory Spectral Cues for Locations Inside and Outside the Visual Field

“…Perturbing the visual input during development has been shown to produce compensatory changes in the auditory map of space so as to maintain topographic alignment between the two. More recent studies have shown that, under certain conditions, such effects can also be demonstrated in the mature animal (Brainard and Knudsen 1998;Zwiers et al 2003;Bergan et al 2005;Linkenhoker and Knudsen 2002;Woods and Recanzone 2004) indicating that this influence is not fundamentally restricted to some limited sensitive period of development.…”

Cross-Modal Correspondences in Non-human Mammal Communication

“…Spatial ventriloquism not only occurs in humans (e.g., Bertelson and Radeau, 1981), but can also lead to the mislocalisation of auditory cues in rhesus macaques Macaca mulatta (Woods and Recanzone, 2004). Because vocal production mechanisms in vertebrates usually result in the co-occurrence of visual and auditory signals, processing spatial and temporal information can support the receiver's ability to combine the sensory percepts together.…”