Eye orientation during static tilts and its relationship to spontaneous head pitch in the laboratory mouse

BS Oommen, JS Stahl - Brain research, 2008 - Elsevier
BS Oommen, JS Stahl
Brain research, 2008Elsevier
Both eye position and head orientation are influenced by the macular (otolith) organs, via
the tilt maculo-ocular reflex (tiltMOR) and the vestibulo-collic reflexes, respectively. The
mechanisms that control head position also influence the rest position of the eye because
head orientation influences eye position through the tiltMOR. Despite the increasing
popularity of mice for studies of vestibular and ocular motor functions, relatively little is
known in this species about tiltMOR, spontaneous orientation of the head, and their …
Both eye position and head orientation are influenced by the macular (otolith) organs, via the tilt maculo-ocular reflex (tiltMOR) and the vestibulo-collic reflexes, respectively. The mechanisms that control head position also influence the rest position of the eye because head orientation influences eye position through the tiltMOR. Despite the increasing popularity of mice for studies of vestibular and ocular motor functions, relatively little is known in this species about tiltMOR, spontaneous orientation of the head, and their interrelationship. We used 2D video oculography to determine in C57BL/6 mice the absolute horizontal and vertical positions of the eyes over body orientations spanning 360° about the pitch and roll axes. We also determined head pitch during ambulation in the same animals. Eye elevation varied approximately sinusoidally as functions of pitch or roll angle. Over the central ±30° of pitch, sensitivity and gain in the light were 31.7°/g and 0.53, respectively. The corresponding values for roll were 31.5°/g and 0.52. Absolute positions adopted in light and darkness differed only slightly. During ambulation, mice carried the lambda–bregma plane at a downward pitch of 29°, corresponding to a horizontal eye position of 64° and a vertical eye position of 22°. The vertical position is near the center of the range of eye movements produced by the pitch tiltMOR. The results indicate that the tiltMOR is robust in this species and favor standardizing pitch orientation across laboratories. The robust tiltMOR also has significant methodological implications for the practice of pupil-tracking video oculography in this species.
Elsevier