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Behavioral/Systems/Cognitive Vestibular Heading Discrimination and Sensitivity to Linear
 

Summary: Behavioral/Systems/Cognitive
Vestibular Heading Discrimination and Sensitivity to Linear
Acceleration in Head and World Coordinates
Paul R. MacNeilage,1 Martin S. Banks,2 Gregory C. DeAngelis,3 and Dora E. Angelaki1
1Department of Anatomy and Neurobiology, Washington University School of Medicine, St. Louis, Missouri 63110, 2Vision Science Program, University
of California, Berkeley, Berkeley, California 94720, and 3Department of Brain and Cognitive Sciences, University of Rochester, Rochester,
New York 14642
Effective navigation and locomotion depend critically on an observer's ability to judge direction of linear self-motion, i.e., heading. The
vestibular cue to heading is the direction of inertial acceleration that accompanies transient linear movements. This cue is transduced by
the otolith organs. The otoliths also respond to gravitational acceleration, so vestibular heading discrimination could depend on (1) the
directionofmovementinheadcoordinates(i.e.,relativetotheotoliths),(2)thedirectionofmovementinworldcoordinates(i.e.,relative
to gravity), or (3) body orientation (i.e., the direction of gravity relative to the otoliths). To quantify these effects, we measured vestibular
and visual discrimination of heading along azimuth and elevation dimensions with observers oriented both upright and side-down
relative to gravity. We compared vestibular heading thresholds with corresponding measurements of sensitivity to linear motion along
lateralandverticalaxesofthehead(coarsedirectiondiscriminationandamplitudediscrimination).Neitherheadingnorcoarsedirection
thresholds depended on movement direction in world coordinates, demonstrating that the nervous system compensates for gravity.
Instead, they depended similarly on movement direction in head coordinates (better performance in the horizontal plane) and on body
orientation (better performance in the upright orientation). Heading thresholds were correlated with, but significantly larger than,
predictionsbasedonsensitivityinthecoarsediscriminationtask.Simulationsofaneuron/anti-neuronpairwithidealizedcosine-tuning
properties show that heading thresholds larger than those predicted from coarse direction discrimination could be accounted for by an

  

Source: Angelaki, Dora - Department of Anatomy and Neurobiology, Washington University in St. Louis
DeAngelis, Gregory - Department of Brain and Cognitive Sciences, University of Rochester

 

Collections: Biology and Medicine