Muller, K. S. | Search bioRxiv

bioRxiv2022

Behavior shapes retinal motion statistics during natural locomotion

AO_SCPLOWBSTRACTC_SCPLOWWalking through an environment generates retinal motion, which humans rely on to perform a variety of visual tasks. Retinal motion patterns are determined by an interconnected set of factors, including gaze location, gaze stabilization, the structure of the environment, and the walkers goals. The characteristics of these motion signals have important consequences for neural organization and behavior. However, to date, there are no empirical in situ measurements of how combined eye and body movements interact with real 3D environments to shape the statistics of retinal motion signals. Here, we collect measurements of the eyes, the body, and the 3D environment during locomotion. We describe properties of the resulting retinal motion patterns. We explain how these patterns are shaped by gaze location in the world, as well as by behavior, and how they may provide a template for the way motion sensitivity and receptive field properties vary across the visual field.

neuroscience↗

bioRxiv2020

Retinal optic flow during natural locomotion

We examine the structure of visual motion on the retina during natural locomotion in real world environments. Natural locomotion generates a rhythmic translation and rotation profile of the head in space, which means that visually specified heading varies throughout the gait cycle. This presents a challenge if optic flow is to be used to control heading towards a goal. The complex, phasic head movements that occur through the gait cycle create a highly unstable pattern of flow relative to the head. In contrast, vestibular-ocular-reflex mediated fixation simplifies patterns of optic flow on the retinae, resulting in regular features that may be valuable for the control of locomotion. In particular, the sign and magnitude of foveal curl in retinal flow fields specifies the bodys trajectory relative to the fixation point. In addition, the peak in the divergence of the retinal flow field specifies the walkers instantaneous overground velocity/momentum vector in retinotopic coordinates. Assuming that walkers can determine the body position relative to fixation, this time-varying retinotopic cue for the bodys momentum could provide a visual control signal for foot placement over complex terrain. In contrast, the temporal variation of heading is large enough to be problematic for use in steering towards a goal. Consideration of optic flow in the context of natural locomotion therefore suggests a re-evaluation of the role of optic flow in the visual control of locomotion.

neuroscience↗