Multisensory integration during self-motion perception

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Overview: As we move through complex environments, our brain must effectively integrate information from vision, muscles and joints (proprioception), and the acceleration detectors in the inner ear (vestibular). An optimal integration of these sensory and motor inputs allows us to estimate movement parameters such as speed, distance, and heading direction with greater certainty. Traditionally, each of these sensory systems has been studied independently of one another, but this research program is aimed at quantifying how these multiple sensory inputs are integrated in the brain during self-motion. The objectives of the proposed research program will be to empirically evaluate established tenets of multisensory integration, as well as to introduce novel experimental manipulations aimed at better characterizing visual, proprioceptive, and vestibular integration during self-motion perception. Specifically it aims to:***Objective 1: In the context of self-motion perception, identify the limits of the multisensory "binding window" (i.e. the range of spatio-temporal disparities over which multiple cues are still integrated), by measuring how the magnitude of a) spatial and b) temporal conflicts between visual and vestibular signals affect optimal cue weighting.***Objective 2: Assess the effects of changing cue reliabilities (e.g. reducing the quality of dynamic visual input) on multisensory self-motion perception during either experimentally introduced a) transient reductions in individual cue reliabilities, or b) prolonged reductions in individual cue reliabilities.***Objective 3: Consider the aging brain as a model for understanding how naturally-occurring, global reductions in cue reliabilities across several sensory systems (e.g. loss of visual acuity and vestibular sensitivity) affect multisensory integration strategies. ***Scientific Approach: This research will be conducted using a state-of-the-art, immersive, Virtual Reality lab combined with a motion platform. These facilities allow us to systematically manipulate the information provided to each sensory channel, as well as to create subtle conflicts between sensory systems. We will use well-established psychophysical paradigms during both passive self-motion tasks (i.e. heading estimation on the motion simulator) and active self-motion tasks (i.e. travelled distance estimation while walking on a treadmill).****Impact: These studies will have significant, global theoretical impacts in the fields of multisensory integration. They will make particularly relevant contributions to the literatures on self-motion perception, spatial updating, locomotion, and aging. Long-term applied impacts of these studies may also be observed in fields including, locomotor rehabilitation, design of simulators, and vehicle design for an aging population.