Visuo-vestibular interaction in the reconstruction of travelled trajectories

Abstract

We recently published a study of the reconstruction of passively travelled trajectories from optic flow. Perception was prone to illusions in a number of conditions, and not always veridical in the others. Part of the illusionary reconstructed trajectories could be explained by assuming that subjects base their reconstruction on the ego-motion percept built during the stimulus' initial moments. In the current paper, we test this hypothesis using a novel paradigm: if the final reconstruction is governed by the initial percept, providing additional, extra-retinal information that modifies the initial percept should predictably alter the final reconstruction. The extra-retinal stimulus was tuned to supplement the information that was under-represented or ambiguous in the optic flow: the subjects were physically displaced or rotated at the onset of the visual stimulus. A highly asymmetric velocity profile (high acceleration, very low deceleration) was used.Subjects were required to guide an input device (in the form of a model vehicle; we measured position and orientation) along the perceived trajectory. We show for the first time that a vestibular stimulus of short duration can influence the perception of a much longer lasting visual stimulus. Perception of the ego-motion translation component in the visual stimulus was improved by a linear physical displacement: perception of the ego-motion rotation component by a physical rotation. This led to a more veridical reconstruction in some conditions, but to a less veridical reconstruction in other conditions.

Stabilization and mobility of the head and trunk in vervet monkeys(Cercopithecus aethiops) during treadmill walks and gallops

“…Whereas balance must be maintained during both overground and treadmill locomotion, the tasks of integrating visual information with vestibular and proprioceptive inputs to propel the body and maintain a desired trajectory (Bertin and Berthoz, 2004;Dietz, 1992;Grillner, 1981;Schubert et al, 2003) are minimized. The need to inspect the surface for obstacles and proper hand and foot placement, which are primarily visual tasks (Patla and Vickers, 1997;Patla et al, 1991;Sherk and Fowler, 2001), is reduced because the unnatural smoothness and regularity of the treadmill belt surface exceeds that of flat surfaces available for overground locomotion, such as the ground and wall-tops used by the bonnet macaques and hanuman langurs (Dunbar et al, 2004).…”

Visual and Nonvisual Contributions to Three-Dimensional Heading Selectivity in the Medial Superior Temporal Area

“…Vestibular signals regarding translation are encoded by the otolith organs, which sense linear accelerations of the head through space (Fernandez and Goldberg, 1976a,b). Vestibular contributions to heading perception have not been studied extensively, but there is evidence that humans integrate visual and vestibular signals to estimate heading more robustly (Telford et al, 1995;Ohmi, 1996;Harris et al, 2000;Bertin and Berthoz, 2004). Little is known, however, about how or where this sensory integration takes place in the brain.…”

Spatial Reference Frames of Visual, Vestibular, and Multimodal Heading Signals in the Dorsal Subdivision of the Medial Superior Temporal Area

“…A possible solution may be to combine visual information with inertial signals that specify the motion of the head in space, such as from the vestibular otolith organs (Fernandez and Goldberg, 1976). Indeed, behavioral evidence suggests that humans and monkeys can combine visual and vestibular cues to improve self-motion perception (Telford et al, 1995;Ohmi, 1996;Harris et al, 2000;Bertin and Berthoz, 2004;Gu et al, 2006b), but it remains unclear exactly where and how the brain carries out this sensory integration.…”