Affiliations: [a] Jenks Vestibular Physiology Laboratory, Massachusetts Eye and Ear Infirmary, Boston, MA, USA | [b] Department of Otology and Laryngology, Harvard Medical School, Boston, MA, USA
Correspondence:
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Corresponding author: Dr. Lionel H. Zupan, Jenks Vestibular Physiology Laboratory, Suite 421, Massachusetts Eye and Ear Infirmary, Boston MA 02114, USA. Tel.: +1 617 573 5522; Fax: +1 617 573 5596; E-mail: lionel_zupan@meei.harvard.edu
Abstract: We investigated if human ocular torsion (OT) and perceived roll (PR) are elicited in response to either dynamic interaural linear acceleration or dynamic roll tilt of the gravito-inertial force (GIF). We expanded a previous study [26] that measured only OT across a limited frequency-range (from 0.35 Hz to 1 Hz) by simultaneously measuring OT and PR at three very low (0.01, 0.02 and 0.05 Hz) and one high (1 Hz) frequencies. Three experimental conditions were investigated: (1) Y-Upright with acceleration along the interaural (Y) axis while upright, (2) Y-Supine with acceleration along the Y-axis while supine, and (3) Z-RED with acceleration along the rostro-caudal (Z) axis with right-ear-down (RED). OT was measured by video-oculography, while PR was measured by use of a somatosensory bar. OT and PR were qualitatively different. Large OT responses were measured for Y-Upright and Y-Supine, while large perceived roll responses were observed for Y-Upright and Z-RED. OT for Z-RED was small, and PR for Y-Supine was absent. In conclusion, OT and PR appear governed by qualitatively different neural mechanisms. OT appears mostly influenced by central low-pass filtering of interaural graviceptor cues, while PR appears mostly influenced by roll tilt of the GIF.
