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Behavioral/Systems/Cognitive Resolution of Sensory Ambiguities for Gaze Stabilization
 

Summary: Behavioral/Systems/Cognitive
Resolution of Sensory Ambiguities for Gaze Stabilization
Requires a Second Neural Integrator
Andrea M. Green and Dora E. Angelaki
Department of Anatomy and Neurobiology, Washington University School of Medicine, St. Louis, Missouri 63110
Theabilitytosimultaneouslymoveintheworldandmaintainstablevisualperceptiondependscriticallyonthecontributionofvestibulo-
ocular reflexes (VORs) to gaze stabilization. It is traditionally believed that semicircular canal signals drive compensatory responses to
rotational head disturbances (rotational VOR), whereas otolith signals compensate for translational movements [translational VOR
(TVOR)]. However, a sensory ambiguity exists because otolith afferents are activated similarly during head translations and reorienta-
tions relative to gravity (i.e., tilts). Extra-otolith cues are, therefore, necessary to ensure that dynamic head tilts do not elicit a TVOR. To
investigate how extra-otolith signals contribute, we characterized the temporal and viewing distance-dependent properties of a TVOR
elicitedintheabsenceofalateralaccelerationstimulustotheotolithsduringcombinedtranslational/rotationalmotion.Weshowthat,in
addition to otolith signals, angular head position signals derived by integrating sensory canal information drive the TVOR. A physiolog-
ical basis for these results is proposed in a model with two distinct integration steps. Upstream of the well known oculomotor velocity-
to-position neural integrator, the model incorporates a separate integration element that could represent the "velocity storage integra-
tor," whose functional role in the oculomotor system has so far remained controversial. We propose that a key functional purpose of the
velocitystoragenetworkistotemporallyintegratesemicircularcanalsignals,sothattheymaybeusedtoextracttranslationinformation
from ambiguous otolith afferent signals in the natural and functionally relevant bandwidth of head movements.
Key words: eye movement; vestibular; oculomotor; sensorimotor; model; otolith; VOR; velocity storage
Introduction

  

Source: Angelaki, Dora - Department of Anatomy and Neurobiology, Washington University in St. Louis

 

Collections: Biology and Medicine