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Journal of Comparative Physiology A

, Volume 181, Issue 4, pp 383–392 | Cite as

Whole-field integration, not detailed analysis, is used by the crab optokinetic system to separate rotation and translation in optic flow

  • H. Blanke
  • H.-O. Nalbach
  • D. Varju
ORIGINAL PAPER

Abstract

For optimal visual control of compensatory eye movements during locomotion it is necessary to distinguish the rotational and translational components of the optic flow field. Optokinetic eye movements can reduce the rotational component only, making the information contained in the translational flow readily available to the animal. We investigated optokinetic eye rotation in the marble rock crab, Pachygrapsus marmoratus, during translational movement, either by displacing the animal or its visual surroundings. Any eye movement in response to such stimuli is taken as an indication that the system is unable to separate the translational and the rotational components in the optic flow in a mathematically perfect way. When the crabs are translated within a pseudo-natural environment, eye movements are negligible, especially during sideways translation. When, however, crabs were placed in a gangway between two elongated rectangular sidewalls carrying dotted patterns which were translated back and forth, marked eye movements were elicited, depending on the translational velocity. To resolve this discrepancy, we tested several hypotheses about mechanisms using detailed analysis of the optic flow or whole-field integration. We found that the latter are sufficient to explain the efficient separation of translation and rotation of crabs in quasi-natural situations.

Key words Crab Optokinetic response Translation Optic flow Motion parallax 

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Copyright information

© Springer-Verlag Berlin Heidelberg 1997

Authors and Affiliations

  • H. Blanke
    • 1
  • H.-O. Nalbach
    • 1
  • D. Varju
    • 1
  1. 1.Lehrstuhl für Biokybernetik, Universität Tübingen, Auf der Morgenstelle 28, D-72076 Tübingen, GermanyDE

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