Computational evidence for a rivalry hierarchy in vision

Abstract

Cortical-form vision comprises multiple, hierarchically arranged areas with feedforward and feedback interconnections. This complex architecture poses difficulties for attempts to link perceptual phenomena to activity at a particular level of the system. This difficulty has been especially salient in studies of binocular rivalry alternations, where there is seemingly conflicting evidence for a locus in primary visual cortex or alternatively in higher cortical areas devoted to object perception. Here, I use a competitive neural model to demonstrate that the data require at least two hierarchic rivalry stages for their explanation. This model demonstrates that competitive inhibition in the first rivalry stage can be eliminated by using suitable stimulus dynamics, thereby revealing properties of a later stage, a result obtained with both spike-rate and conductance-based model neurons. This result provides a synthesis of competing rivalry theories and suggests that neural competition may be a general characteristic throughout the form-vision hierarchy.W hen an observer views orthogonal gratings, e.g., vertical and horizontal, one in each eye, the percept is not stable but rather fluctuates among horizontal, vertical, and patchwork mixtures of the two. The traditional interpretation of this rivalry is that it reflects competition between monocularly driven neurons in primary visual cortex (V1), termed interocular rivalry here (1). Two functional MRI studies have tested this idea and provided evidence for the presence of rivalry-correlated alternations in the activation of human V1 (2, 3). Furthermore, recent psychophysical evidence has shown that rivalry transitions generally occur as waves that propagate at constant speed when mapped onto V1 (4). However, primate physiological evidence has suggested that rivalry is more prominent in higher cortical areas such as V4 than in V1 (5). In addition, recent psychophysics has shown that 18.0-Hz on-off flicker of orthogonal monocular gratings coupled with swapping gratings between eyes at 1.5 Hz (3 swaps per sec) leads to perceptual dominance durations of Ϸ2.0 sec (6). This indicates that observers perceive a single pattern while it switches back and forth between eyes several times, a result clearly incompatible with a monocular basis for rivalry under these conditions. Finally, experiments in which the rivaling patterns are objects such as faces and houses are compatible with a higher cortical locus for rivalry (7,8).How can these prima facie conflicting experimental results be reconciled? Certainly one of the most definitive arguments against interocular rivalry is the 18.0-Hz flicker combined with 1.5-Hz eye-switching (F&S) procedure described above (6). The persistence of dominance across several eye swaps, however, has been shown to depend critically on the temporal parameters of the F&S procedure (9), which suggests the hypothesis that F&S stimulus dynamics might bypass or defeat an early interocular stage of rivalry competition, thereby revealing higher levels of bin...

Predictive coding explains binocular rivalry: An epistemological review

“…Perceptual inference about different hierarchically organised attributes of the visual scene are made at different levels (Friston, 2005). It is not unusual for theories of visual processing and of binocular rivalry in particular (e.g., Freeman, 2005;Wilson, 2003) to be hierarchical, the crucial point here concerns the computational implications of hierarchical levels and the fact that these provide formal constraints on the generative models that make them empirical Bayes models.…”

“…This has been modelled successfully in a hierarchical neural model (Wilson, 2003). In short, it may be that the hyperprior for a variable environment favours slow change over rapid change (cf.…”

“…A number of formal models have been developed which are able to reproduce aspects of binocular rivalry (Dayan, 1998;Grossberg & Mingolla, 1985;Kalarickal, 2000;Kawamoto & Anderson, 1985;Koene, 2006;Laing & Chow, 2002;Lehky, 1988;Lumer, 1998;Matsuoka, 1984;Noest et al, 2007;Wilson, 2003;Wilson, 2007;Zhou, Gao, White, Merk, & Yao, 2004). The majority of these models analyse binocular rivalry a priori as a phenomenon driven by adaptation of the winning neural population, and lateral and/or top down inhibition of the competing population.…”

A low-dimensional model of binocular rivalry using winnerless competition

“…To account for the empirical data on the role of stimulus properties in binocular rivalry [19,4,5], as well as on its neurophysiological correlates [9,11,18,29], a number of models have been put forward, most of which have been based on a reciprocal inhibition architecture, whereby the parts of the system that code for the two competing percepts suppress each other [3,10,14,15,16,20,30]. Dominance switching is typically instantiated via slow negative feedback (e.g.…”

“…In particular, [26] set out to examine the models' behaviour in relation to proposition IV (see above). Four models were subjected to scrutiny: the Laing and Chow model [15], two modified versions of this model (one without population adaptation and one without synaptic depression), and the model by Wilson [30]. Although the latter is mathematically different from the Laing and Chow model, the two share some important qualitative features: mutual inhibition between the model components representing the competing stimuli and the presence of a slow population adaptation process that is essential for the switching of dominance.…”