Weighted parallel contributions of binocular correlation and match signals to conscious perception of depth

Abstract

One contribution of 15 to a theme issue 'Vision in our three-dimensional world'. Binocular disparity is detected in the primary visual cortex by a process similar to calculation of local cross-correlation between left and right retinal images. As a consequence, correlation-based neural signals convey information about false disparities as well as the true disparity. The false responses in the initial disparity detectors are eliminated at later stages in order to encode only disparities of the features correctly matched between the two eyes. For a simple stimulus configuration, a feed-forward nonlinear process can transform the correlation signal into the match signal. For human observers, depth judgement is determined by a weighted sum of the correlation and match signals rather than depending solely on the latter. The relative weight changes with spatial and temporal parameters of the stimuli, allowing adaptive recruitment of the two computations under different visual circumstances. A full transformation from correlation-based to match-based representation occurs at the neuronal population level in cortical area V4 and manifests in single-neuron responses of inferior temporal and posterior parietal cortices. Neurons in area V5/MT represent disparity in a manner intermediate between the correlation and match signals. We propose that the correlation and match signals in these areas contribute to depth perception in a weighted, parallel manner.This article is part of the themed issue 'Vision in our three-dimensional world'.

Specialization of mid-tier stages of dorsal and ventral pathways in stereoscopic processing

“…Our above proposal is supported by earlier psychophysical studies with the same graded anticorrelation paradigm (see Fujita and Doi, 2016 for a review). Human depth judgment does indeed exhibit a trace of the correlation-based disparity representation (e.g., reversed depth perception for aRDSs; Aoki et al, 2017;.…”

“…Moreover, MT and V4 share a common link between the disparity-tuning shape and the type of disparity representation. It is possible that the interactions between the dorsal and ventral pathways play several roles in solving the correspondence problem, deriving 3D object representation, making decision about stereoscopic depth, and generating object-oriented motor action (e.g., reaching and grasping), as suggested by a broad range of evidence from neuroanatomy, single-neuron recording, electro-encephalography, psychophysics, and brain imaging (Borra et al, 2008(Borra et al, , 2010Cottereau et al, 2014;Farivar, 2009;Fujita and Doi, 2016;Freud et al, 2016;Janssen et al, 2018;Van Polanen and Davare, 2015).…”

Microstructural properties of the vertical occipital fasciculus explain the variability in human stereoacuity

“…Stereopsis is a fundamental human visual function that has been studied over two centuries (1)(2)(3)(4)(5)(6)(7)(8)(9). Traditional visual neuroscience has focused on the properties of neural response in gray matter towards important cues for the stereopsis, such as binocular disparity, to understand the neural computation achieving the perception of three-dimensional world (10)(11)(12)(13)(14).…”

Vision in our three-dimensional world

“…There are two distinct streams of work represented in this special issue. For the first, stereo has been used as a route to identify which populations of cortical neurons are responsible for driving perceptual decisions about the three-dimensional configuration of objects and which neuronal signals are relevant [25,26]. Krug et al [25] show that neurons in extrastriate cortical area V5/MT maintain high sensitivity to small changes in disparity across significant changes in the firing rate.…”

“…Furthermore, the correlation of the neuron's response with the behavioural decisions of the animal is better predicted by the neuron's sensitivity to disparity rather than the neuron's firing rate. Fujita and Doi [26] also build on neurophysiological data. They suggest that the conscious perception of stereo depth, as reported by human observers, may depend on two separate components of the neuronal response identified in recordings from macaque monkeys.…”