Vertical (Z-axis) acceleration alters the ocular response to linear acceleration in the rabbit

Jun Maruta, Theodore Raphan, John I. Simpson, Bernard Cohen

Research output: Contribution to journalArticlepeer-review

6 Scopus citations


Whether ocular orientation to gravity is produced solely by linear acceleration in the horizontal plane of the head or depends on both horizontal and vertical components of the acceleration of gravity is controversial. Here, we compared orienting eye movements of rabbits during head tilt to those produced by centrifugation that generated centripetal acceleration along the naso-occipital (X-), bitemporal (Y-) and vertical (Z-) axes in a constant gravitational field. Sensitivities of ocular counter-pitch and vergence during pitch tilts were ≈25°/g and ≈26°/g, respectively, and of ocular counter-roll during roll tilts was ≈20°/g. During X-axis centripetal acceleration with 1 g of gravity along the Z-axis, pitch and vergence sensitivities were reduced to ≈13°/g and ≈16°/g. Similarly, Y-axis acceleration with 1g along the Z-axis reduced the roll sensitivity to ≈16°/g. Modulation of Z-axis centripetal acceleration caused sensitivities to drop by ≈6°/g in pitch, ≈2°/g in vergence, and ≈5°/g in roll. Thus, the constant 1g acceleration along the Z-axis reduced the sensitivity of ocular orientation to linear accelerations in the horizontal plane. Orienting responses were also modulated by varying the head Z-axis acceleration; the sensitivity of response to Z-axis acceleration was linearly related to the response to static tilt. Although the sign of the Z-axis modulation is opposite in the lateral-eyed rabbit from that in frontal-eyed species, these data provide evidence that the brain uses both the horizontal and the vertical components of acceleration from the otolith organs to determine the magnitude of ocular orientation in response to linear acceleration.

Original languageEnglish
Pages (from-to)87-99
Number of pages13
JournalExperimental Brain Research
Issue number1
StatePublished - Feb 2008


  • Saccule
  • Shear force
  • Spatial orientation
  • Utricle
  • VOR


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