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The role of sensory experience in developing multisensory integration

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title
The role of sensory experience in developing multisensory integration
author
Smyre, Scott A
abstract
An outstanding issue in sensory neuroscience is how the brain develops its ability to use senses together in synergistic ways to improve perceptual and behavioral decisions. Because each sense transduces a different form of environmental energy, powerful enhancements are obtained by synthesizing signals pertaining to the same event across the sensory modalities. There is an inherent ambiguity, however, in determining which signals belong to the same event, and which to different events. Perhaps because of this ambiguity, multisensory enhancement is not an innate feature of the brain; rather, it must be acquired from experience with cross-modal events in the environment. How the brain uses this experience to solve the causal inference problem in development is not known. To study these questions, the multisensory experience of animals is precisely controlled via special rearing facilities and sensory exposure paradigms, and behavioral methods are leveraged to examine their enhancement capabilities.The initial chapters examine the behavioral correlates of depriving animals of multisensory experience during development. In Chapter I, this deprivation is obtained by raising animals in the dark (‘dark-rearing’), while in Chapter II, by raising animals in a room with constant omnidirectional sound (‘noise-rearing’), effectively masking transient auditory cues. There have been decades of neurophysiological research examining the consequences of dark-rearing and noise-rearing, however, the behavioral impact of depriving these animals of such experience was unknown. These experiments examine this issue by directly comparing the detection/localization performance of dark-reared and noise-reared animals to normally-reared animals in a variety of testing conditions. It is shown that when early visual-auditory experience is prevented, animals fail to show normal multisensory benefits in their detection/localization performance. Following these results, the final chapter examines the developmental principles of multisensory integration and their translation to behavioral outcomes. Prior work has shown that normal multisensory integration principles can be developed in the neurons of the superior colliculus by presenting high-density, regular congruent visual-auditory stimuli and that this experience was not generalized across the topography of the SC. Whether a similar developmental pattern would be seen in associated multisensory behaviors was unknown. The first experiment tests this by exposing animals to repeated cross-modal stimuli at one location in one hemifield and modality-specific stimuli at the homotopic location in the opposite hemifield. Animals are then tested across several locations in a detection/localization paradigm. After exposures, multisensory enhancements were limited to the exposure site (and nearby locations). More distant locations as well as the site of modality-specific exposures did develop multisensory enhancement capabilities. These results show that the developmental patterns seen on the individual neuron level are highly predictive of overt behavior. The second experiment examines whether different principles would simultaneously develop in the two hemifield if they had been repeatedly exposed to different cross-modal cue configurations. Animals were exposed to spatially congruent stimuli in one hemifield and to a spatially discordant configuration in the other. This exposure paradigm resulted in animals developing two conflicting principles in the different hemifields. The results of these experiments reveal that multisensory spatial processing rules flexibly adapt to the specific spatial configurations encountered.
subject
dark-rearing
development
enhancement
multisensory
noise-rearing
contributor
Kishida, Kenneth L (advisor)
Rowland, Benjamin A (committee member)
Stein, Barry E (committee member)
Maier, Joost X (committee member)
Salinas, Emilio (committee member)
Stanford, Terrence R (committee member)
date
2023-07-25T17:48:27Z (accessioned)
2023-07-25T17:48:27Z (available)
2023 (issued)
degree
Neurobiology & Anatomy (discipline)
identifier
http://hdl.handle.net/10339/102217 (uri)
language
en (iso)
publisher
Wake Forest University
type
Dissertation

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