Differential responses in dorsal visual cortex to motion and disparity depth cues

Abstract

We investigated how interactions between monocular motion parallax and binocular cues to depth vary in human motion areas for wide-field visual motion stimuli (110 × 100°). We used fMRI with an extensive 2 × 3 × 2 factorial blocked design in which we combined two types of self-motion (translational motion and translational + rotational motion), with three categories of motion inflicted by the degree of noise (self-motion, distorted self-motion, and multiple object-motion), and two different view modes of the flow patterns (stereo and synoptic viewing). Interactions between disparity and motion category revealed distinct contributions to self- and object-motion processing in 3D. For cortical areas V6 and CSv, but not the anterior part of MT+ with bilateral visual responsiveness (MT+/b), we found a disparity-dependent effect of rotational flow and noise: When self-motion perception was degraded by adding rotational flow and moderate levels of noise, the BOLD responses were reduced compared with translational self-motion alone, but this reduction was cancelled by adding stereo information which also rescued the subject's self-motion percept. At high noise levels, when the self-motion percept gave way to a swarm of moving objects, the BOLD signal strongly increased compared to self-motion in areas MT+/b and V6, but only for stereo in the latter. BOLD response did not increase for either view mode in CSv. These different response patterns indicate different contributions of areas V6, MT+/b, and CSv to the processing of self-motion perception and the processing of multiple independent motions.

Neural bases of self‐ and object‐motion in a naturalistic vision

“…Recent functional magnetic resonance imaging (fMRI) data suggest that some dorsal motion areas (like V3A and V6) likely contribute to perceptual stability during pursuit eye movements (Fischer, Bülthoff, Logothetis, & Bartels, 2012). In particular, V6 could be involved in "subtracting out" self-motion signals across the whole visual field and in providing information about moving objects, as originally suggested by our group (Galletti & Fattori, 2003;Pitzalis et al, 2010Pitzalis et al, , 2015 and later on by others (Arnoldussen, Goossens, & van den Ber, 2013;Cardin, Sherrington, et al, 2012;Fischer et al, 2012). These suggestions remain however at a speculative level and there is not yet a clear and complete picture of the brain regions involved in flow parsing, as well as it is still unclear whether distinct cortical areas are engaged in the detection of objectand self-motion as previously suggested (Previc, 1998;Previc, Liotti, Blakemore, Beer, & Fox, 2000;Rosa & Tweedale, 2001).…”

“…The neural basis of the flow parsing in humans is still a matter of debate (Arnoldussen et al, 2013;Billington & Smith, 2015;Fischer et al, 2012). Rushton (2009a, 2009b) have recently proposed that a flow-parsing mechanism identifies and subtracts the optic flow associated with the observer's movement from the pattern of retinal motion, to estimate the true object-motion.…”

Optic-flow selective cortical sensory regions associated with self-reported states of vection

“…Future studies should aim to validate and strengthen evidence for this multisensory mechanism, possibly by introducing analyses such as multi-voxel pattern analysis (MVPA). Inclusion of MVPA could shed new light to the interpretation of the data by increasing sensitivity to changes in cortical activation between the two perceptual states of vection and no vection ( Arnoldussen et al, 2013 ).…”

Dissociation of retinal and headcentric disparity signals in dorsal human cortex

“…Human V6 shows strong BOLD responses to full field optic flow (Pitzalis et al, 2010 ), specifically patterns that contain depth by motion parallax (Pitzalis et al, 2013 ). Also, V6 integrates depth from motion parallax with depth by binocular disparity (Cardin and Smith, 2011 ), possibly to rescue direction of heading perception from contamination by motion noise, and to distinguish the depth components of multiple moving objects (Arnoldussen et al, 2013a ). These studies did not distinguish between retinal and headcentric disparity.…”