Contextual influences on oculomotor reflexes: an internal-model perspective

Gaze-stablizing eye movements, such as the visual-motion-driven optokinetic reflex (OKR) serve to maintain stable eye orientation during active or passive self-motion and thereby stabilize the retinal image. Therefore, they require an explicit or implicit internal estimate of an organism's relative motion with respect to its surroundings. This thesis examines the hypothesis that contextual cues from the visual scene (such as contrast intensity, polarity and color) influence the OKR in Xenopus tadpoles. The studies reported herein found that these contextual clues have a distinct influence on gaze stabilization performance. This gives rise to the interpretation that Xenopus tadpoles exploit information contained in the spatial properties of the moving visual scene to form an internal self-motion estimate and distinguish self-motion through the environment from moving external objects. Finally, I will argue that the observed context-specific performance differences can be interpreted as an implementation of an internal model of the world.