, 2003) and ventral (via thin and pale stripes, DeYoe and Van Essen, 1985, Nakamura et al., 1993 and Nascimento-Silva et al., 2003) pathways, it raises the issue of how these disparity are differentially used in the two pathways. Role of Disparity Selective Responses in V4 in Fine Depth Perception. Although binocular disparity has traditionally been considered a dorsal pathway function (e.g., Livingstone and Hubel, 1988, Sakata et al., 1997 and Gonzalez and Perez, 1998), recent physiological studies are overturning this long-standing belief. Indeed, V4 cells http://www.selleckchem.com/products/hydroxychloroquine-sulfate.html exhibit selectivity for

binocular disparity ( Hinkle and Connor, 2001, Hinkle and Connor, 2005, Watanabe et al., 2002, Tanabe et al., 2004, Tanabe et al., 2005 and Hegdé and Van Essen, 2005a), disparity-defined shape in random-dot stereograms ( Hegdé and Van Essen, 2005b), and 3-D orientation of bars ( Hinkle and Connor, 2002). As shown by studies in both monkeys and humans, these response characteristics are consistent with the use of disparity cues in the

ventral pathway for object recognition (fine stereopsis involving higher spatial frequencies, retinal disparities < 0.5 deg, stationary or slowly moving objects), and are distinct from this website those in the dorsal pathway for vision related to motion, self-motion, and visually guided behavior (coarse steropsis involving lower spatial frequencies, larger retinal disparities between 0.5–10 deg, and moving targets) ( Neri et al., 2004, Parker, 2007 and Preston et al., 2008). Further confirming V4′s role in fine depth perception, microstimulation in V4 biases behavioral judgment of fine depth ( Shiozaki et al., 2012), whereas microstimulation of MT biases behavioral judgment of coarse but not fine depth ( Uka and DeAngelis, 2006). Consistent with these results, V4 and IT neurons show trial-by-trial response variation correlated with fine depth judgment ( Uka et al., 2005 and Shiozaki et al., 2012), while MT neuron responses correlate with coarse

depth judgment ( Uka and DeAngelis, 2004). Binocular Matching. To calculate binocular disparity, how does from the visual system find the appropriate matching between left and right eye images? A very useful tool for investigating this “binocular correspondence problem” is the random dot stereogram (RDS, Figure 5C, left), a stimulus in which 3D structure is perceived only with appropriate matching of dots in left and right eyes ( Julesz, 1972). The degree of spatial shift of dots between the left and right eyes determines the depth plane perceived. To probe what stage in the visual system binocular correspondence is computed, a control (anticorrelated RDS, aRDS) was designed in which the matching dots were reversed in contrast (e.g.