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Yong Gu, Dora E. Angelaki, Gregory C. DeAngelis; Visual and Vestibular Contributions to 3D Heading Selectivity in Area MSTd. Journal of Vision 2004;4(8):708. doi: https://doi.org/10.1167/4.8.708.
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© ARVO (1962-2015); The Authors (2016-present)
Perception of self-motion is a multi-modal process involving integration of visual and non-visual (vestibular, proprioceptive) cues. Area MSTd has been implicated in self-motion perception, as neurons in this area are sensitive to global patterns of optic flow that mimic those experienced during self-motion. More recently, neurons in MSTd have also been shown to be selective for the direction of translation in darkness, suggesting that they may integrate visual and vestibular signals to compute the direction of heading. To characterize the contributions of visual and vestibular signals to heading selectivity, we developed a virtual reality system that can move animals along arbitrary paths through a 3D virtual environment. In this study, neurons were tested with translational motion defined by: optic flow alone, vestibular stimulation alone (real motion without optic flow), or congruent and synchronous combinations of optic flow and real motion. In all three cases, which were randomly interleaved, stimuli were smooth motion trajectories (with a Gaussian velocity profile) directed along one of 26 directions (45 deg apart in azimuth and elevation) emanating from the center of a sphere. Among 99 neurons recorded from one hemisphere, 96 neurons (97%) exhibit significant heading selectivity based on optic flow alone, and nearly half of these units (47 neurons) show significant tuning for heading defined by vestibular stimulation alone. Surprisingly, however, the preferred heading in response to vestibular stimulation was typically 90–180 deg away from the preferred heading defined by optic flow. As a result, heading selectivity in response to combined visual/vestibular stimulation was typically weaker than that obtained using optic flow alone. Although MSTd is involved in the analysis of optic flow, our findings are not consistent with the idea that MSTd neurons integrate visual and vestibular signals to provide more robust estimates of the direction of heading.
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