Motion processing with two eyes in three dimensions

Abstract

The movement of an object toward or away from the head is perhaps the most critical piece of information an organism can extract from its environment. Such 3D motion produces horizontally opposite motions on the two retinae. Little is known about how or where the visual system combines these two retinal motion signals, relative to the wealth of knowledge about the neural hierarchies involved in 2D motion processing and binocular vision. Canonical conceptions of primate visual processing assert that neurons early in the visual system combine monocular inputs into a single cyclopean stream (lacking eye-of-origin information) and extract 1D ("component") motions; later stages then extract 2D pattern motion from the cyclopean output of the earlier stage. Here, however, we show that 3D motion perception is in fact affected by the comparison of opposite 2D pattern motions between the two eyes. Three-dimensional motion sensitivity depends systematically on pattern motion direction when dichoptically viewing gratings and plaids-and a novel "dichoptic pseudoplaid" stimulus provides strong support for use of interocular pattern motion differences by precluding potential contributions from conventional disparity-based mechanisms. These results imply the existence of eye-of-origin information in later stages of motion processing and therefore motivate the incorporation of such eye-specific pattern-motion signals in models of motion processing and binocular integration.

Binocular Mechanisms of 3D Motion Processing

“…Using a set of binocularly paired or unpaired monocular stimuli comprising many small drifting Gabor patches (termed psuedoplaids), 3D motion percepts have been shown to be consistent with comparisons of pattern motion signals arising from monocular intersection-of-constraints operations (Adelson & Movshon 1982). Crucially, however, the monocular component motion integration can be done over areas much larger than V1 receptive fields (Rokers et al 2011), and component adaptation effects occur even when the local monocular motion signals are in noncorresponding retinal locations between adaptation and test (Greer et al 2016). …”

Determinants of the direction illusion: Motion speed and dichoptic presentation interact to reveal systematic individual differences in sign

“…Since similar dichoptic stimuli presented to human observers in the same study resulted in the perception of coherent pattern motion despite the occurrence of binocular rivalry, the ability of dichoptic presentation to negate pattern responding in single neurons suggests that pattern sensitivity in some MT cells may operate monocularly. Furthermore, research on motion-indepth perception has provided evidence that 2-D plaid motion is extracted at a monocular locus prior to binocular recombination to form a 3-D percept (Rokers, Cormack, & Huk, 2009;Rokers, Czuba, Cormack, & Huk, 2011). This is supported by Guo, Benson, and Blakemore (2004), who found that a significant minority of V1 neurons responded to pattern rather than component motion.…”

“…This is supported by Guo, Benson, and Blakemore (2004), who found that a significant minority of V1 neurons responded to pattern rather than component motion. Although further research is needed to reconcile evidence for early spatial integration with the limited size of receptive fields in V1 (Hubel & Wiesel, 1974;Rokers et al, 2011), the growing research suggesting that global processing is not exclusively binocular may be useful in resolving inconsistencies in the DI literature. Similarly, the divergence of results at the dichoptic level in the current study suggests that the DI is produced by processing at multiple levels of the visual motion hierarchy.…”

Unmixing Binocular Signals

“…There is evidence that area MT can support comparisons between velocities in left and right images for computation of 3D motion (Rokers et al, 2009, 2011), despite being binocularly driven. In this case, MT appears to be performing visual processing as if it had access to the original unmixed images.…”