Talk mit Jenny Read 18.11.2015: What neural signal underlies human stereoscopic depth perception?
Talk 18.11.2015: What neural signal underlies human stereoscopic depth perception? 10 Uhr, Raum F5, Otto-Behaghel-Straße 10F, 35394 Gießen
Title: What neural signal underlies human stereoscopic depth perception?
Authors: Jenny Read (presenting), Sid Henriksen, Bruce Cumming
Human stereopsis can operate in dense "cyclopean" images containing no monocular objects. This ability is believed to depend on the activity of disparity-tuned neurons in primary visual cortex (V1). The behaviour of these neurons is qualitatively well captured by the stereo energy model of Ohzawa, DeAngelis & Freeman (Science, 1990). In essence, this model computes the binocular correlation between the two eyes. Accordingly, it inverts its disparity tuning to anti-correlated stereograms, and shows no disparity tuning for stimuli which have no net binocular correlation. Recently Ichiro Fujita's lab has shown that humans perceive depth in one particular form of stimuli with no net binocular correlation, so-called "half-matched random dot stereograms". This led them to propose that human depth perception in these stimuli occurs without an explicit signal in V1. Consequently, a "matching" computation in extrastriate cortex has been proposed - the first pathway supporting stereo depth perception that is not derived from disparity selectivity in V1. However, recording from disparity-selective neurons in V1 of fixating monkeys, we found that they are in fact able to signal disparity in half-matched stimuli. We present a simple model that explains these results. This reinstates the view that disparity-selective neurons in V1 provide the initial substrate for perception in dense cyclopean stimuli.