The importance of the peripheral retina in circular vection

Abstract

Visually induced self-motion (vection) is of theoretical interest in understanding the neural basis of visual-vestibular interaction. Recently, vection is also of practical importance in developing virtual reality systems that provide users with a compelling experience of "presence" in a virtual environment. The purpose of this paper was to investigate the role of the central and peripheral retina in visually induced self-rotation (circular vection, CV). Six patients aged 52-78 years all with pathological peripheral visual defects due to retinitis pigmentosa or glaucoma, and an age-matched control group of eight elderly subjects aged 47-71 years were examined. Monocular visual field defects were verified with the Goldmann perimeter by kinetic perimetry. The device used to induce CV was a random dot pattern projected onto a hemispherical dome with a radius of 75 cm. The pattern was rotated horizontally at a constant acceleration of 1 deg/s2. Monocular stimuli were randomly repeated twice in both the temporal-nasal (T-N) and nasal-temporal (N-T) directions. In the age-matched control group, all subjects experienced CV. There were no significant differences in CV latencies between the right and left eyes in either stimulus direction (p>0.05, Student paired t test). In patients with bilateral deficits of the whole visual periphery and intact central visual fields, CV was absent in both stimulus directions. In patients with bilateral and asymmetric deficits of the visual periphery, CV was either missing or markedly prolonged, depending on the extent of the peripheral visual field defect. In patients with unilateral deficits of about half the visual periphery, CV was missing only for the affected eyes. These findings are compatible with the theory of peripheral dominance and size dependence of CV. In the discussion, our results will be compared to previous experiments with masking in normal subjects and with studies in other kinds of self-motion.