The Extraction of 3D Shape in the Visual System of Human and Nonhuman Primates

Abstract

Depth structure, the third dimension of object shape, is extracted from disparity, motion, texture, and shading in the optic array. Gradient-selective neurons play a key role in this process. Such neurons occur in CIP, AIP, TEs, and F5 (for first- or second-order disparity gradients), in MT/V5, in FST (for speed gradients), and in CIP and TEs (for texture gradients). Most of these regions are activated during magnetic resonance scanning in alert monkeys by comparing 3D conditions with the 2D controls for the different cues. Similarities in activation patterns of monkeys and humans tested with identical paradigms suggest that like gradient-selective neurons are found in corresponding human cortical areas. This view gains credence as the homologies between such areas become more evident. Furthermore, 3D shape-processing networks are similar in the two species, with the exception of the greater involvement of human posterior parietal cortex in the extraction of 3D shape from motion. Thus we can begin to understand how depth structure is extracted from motion, disparity, and texture in the primate brain, but the extraction of depth structure from shading and that of wire-like objects requires further scrutiny.

Effective Connectivity of the Human Cerebellum during Visual Attention

“…These regions showing this enhanced connectivity with the cerebellum where almost exclusively located in the dorsal visual stream (including V5 and PPC), which is associated with spatial localization of objects (PPC: Corradi-Dell' Acqua et al, 2008;Lane et al, 2011), motion perception (V5: Wilms et al, 2005;Orban, 2011) and spatial attention (PPC: Fan et al, 2005;Malhotra et al, 2009;Rawley and Constantinidis, 2010;Kellermann et al, 2011;Lane et al, 2012). Before we turn to the discussion of the consequential analyses of dynamic causal modeling, we briefly review some theoretical considerations regarding the functionality of the cerebellum.…”

Organization and evolution of parieto-frontal processing streams in macaque monkeys and humans

“…Concerning visual analysis, LIP neurons encode the 3D structure and properties of visual objects (Gnadt and Mays, 1995;Sereno et al, 2002;Shikata et al, 1996;Vanduffel et al, 2002; for a review, see Orban, 2011). Area LIP is a central node of the decision-making network of PPC (for reviews, see Gold and Shadlen, 2007;Gottlieb et al, 2014;Kable and Glimcher, 2009).…”

Sensory memory of structure-from-motion is shape-specific

“…The sensory memory for apparent rotation of SFM displays can be disrupted by TMS of cortical area hMT/V5 (Brascamp et al, 2010), which is known to play a prominent role in processing visual motion (Born & Bradley, 2005;Campana et al, 2002;Orban, 2011;Rokers, Cormack, & Huk, 2009;Tootell et al, 1995). In the context of binocular rivalry, a sensory memory for faces appears to engage the fusiform face area (FFA), as well as several fronto-parietal regions (Sterzer & Rees, 2008).…”