Self-motion trajectories can facilitate orientation based figure-ground segregation.

Segregation of objects from the background is a basic and essential property of the visual system. Here we studied the neural detection of objects defined by orientation difference from background in barn owls (Tyto alba). We presented wide-field displays of densely packed stripes with a dominant orientation. Visual objects were created by orienting a circular patch differently from the background. In head fixed conditions, neurons in both tecto- and thalamo- fugal visual pathways (optic tectum and visual Wulst) were weakly responsive to these objects in their receptive fields. However, notably, in free viewing conditions, barn owls occasionally perform peculiar side to side head motions (peering) when scanning the environment. In the second part of the study we thus recorded the neural response from head fixed owls while the visual displays replicated the peering conditions, i.e., the displays (objects and backgrounds) were shifted along trajectories that induced a retinal motion identical to sampled peering motions when viewing a static object. These conditions induced dramatic neural responses to the objects, in the very same neurons that where unresponsive to the objects in static displays. By reverting to circular motions of the display, we show that the pattern of the neural response is mostly shaped by the orientation of the background relative to motion and not the orientation of the object. Thus, our findings provide evidence that peering and/or other self-motions can facilitate orientation-based figure-ground segregation through interaction with inhibition from the surround.