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Behavioral/Systems/Cognitive Translation Speed Compensation in the Dorsal Aspect of the
 

Summary: Behavioral/Systems/Cognitive
Translation Speed Compensation in the Dorsal Aspect of the
Medial Superior Temporal Area
Brian Lee, Bijan Pesaran, and Richard A. Andersen
Division of Biology, California Institute of Technology, Pasadena, California 91125
The dorsal aspect of the medial superior temporal area (MSTd) is involved in the computation of heading direction from the focus of
expansion(FOE)ofthevisualimage.OurlaboratorypreviouslyfoundthatMSTdneuronsadjusttheirfocustuningcurvestocompensate
for shifts in the FOE produced by eye rotation (Bradley et al., 1996) as well as for changes in pursuit speed (Shenoy et al., 2002). The
translation speed of an observer also affects the shift of the FOE. To investigate whether MSTd neurons can adjust their focus tuning
curves to compensate for varying translation speeds, we recorded extracellular responses from 93 focus-tuned MSTd neurons in two
rhesus monkeys (Macaca mulatta) performing pursuit eye movements across displays of varying translation speeds. We found that
MSTd neurons had larger shifts in their tuning curves for slow translation speeds and smaller shifts for fast translation speeds. These
shifts aligned the focus tuning curves with the true heading direction and not with the retinal position of the FOE. Because the eye was
pursuing at the same rate for varying translation speeds, these results indicate that retinal cues related both to translation speed and
extraretinal signals from pursuit eye movements are used by MSTd neurons to compute heading direction.
Key words: MSTd; optic flow; self-motion; heading perception; compensation; translation
Introduction
It has been proposed that, for an individual in motion, the focus
of expansion (FOE) of the retinal image could be used to deter-
mine the direction of heading (Gibson, 1950). However, when

  

Source: Andersen, Richard - Division of Biology, California Institute of Technology

 

Collections: Biology and Medicine