Interocular Grouping in Perceptual Rivalry Localized with fMRI

Abstract

Bistable perception refers to a broad class of dynamically alternating visual illusions that result from ambiguous images. These illusions provide a powerful method to study the mechanisms that determine how visual input is integrated over space and time. Binocular rivalry occurs when subjects view different images in each eye, and a similar experience called stimulus rivalry occurs even when the left and right images are exchanged at a fast rate. Many previous studies have identified with fMRI a network of cortical regions that are recruited during binocular rivalry, relative to non-rivalrous control conditions (termed replay) that use physically changing stimuli to mimic rivalry. However, we show here for the first time that additional cortical areas are activated when subjects experience rivalry with interocular grouping. When interocular grouping occurs, activation levels broadly increase, with a slight shift towards right hemisphere lateralization. Moreover, direct comparison of binocular rivalry with and without grouping highlights strong focused activity in the intraparietal sulcus and lateral occipital areas, such as right-sided retinotopic visual areas LO1 and IP2, as well as activity in left-sided visual areas LO1, and IP0-IP2. The equivalent analyses for comparable stimulus (eye-swap) rivalry showed very similar results; the main difference is greater recruitment of the right superior parietal cortex for binocular rivalry, as previously reported. Thus, we found minimal interaction between the novel networks isolated here for interocular grouping, and those previously attributed to stimulus and binocular rivalry. We conclude that spatial integration (i.e,. image grouping/segmentation) is a key function of lateral occipital/intraparietal cortex that acts similarly on competing binocular stimulus representations, regardless of fast monocular changes.

Slow–Fast Dynamics Behaviors under the Comprehensive Effect of Rest Spike Bistability and Timescale Difference in a Filippov Slow–Fast Modified Chua’s Circuit Model

“…where the two coefficients µ 1,2 can be calculated by submitting the corresponding initial conditions of a sliding trajectory Φ S into (18). It is not difficult to verify that the two cusp points on sliding boundaries ∂Σ S± both are visible, computed as VC ± (0, − 0.445±0.…”

“…As shown in Figure 9b,where trajectories starting from visible points between VC + and P B+ converge to PE to behave in sticking motions after a minimal oscillation in R + , while trajectories starting from visible points between P B+ and P S+ oscillate to spike attractor LC SA+ . Similarly, another special sliding orbit, denoted as Φ + sep , can be obtained numerically by taking P B+ as the initial condition of (18). It can be regarded as an attractor basin boundary of the rest spike bistability II in sliding region.…”

“…Bistability, referring to two coexisting attractors in a fixed parameter range, represents a common dynamics structure in nonlinear dynamical systems, and mounting evidence suggests that this geometric structure is a key factor (but not necessary) in the presence of bursting oscillations [2,[14][15][16]. Two coexisting stable equilibria have been analytically investigated to be the principal reason of winner-take-all behavior in competition models [2,17], or the binocular rivalry in the so-called Levelt's propositions [18]. Another bistability structure, namely rest spike bistability consisting of a stable limit cycle and a stable equilibrium separated by a saddle, has been studied as the core structure for slow spiking and bursting phenomena in the family of Morris-Lecar models [19].…”

Effects of interocular grouping demands on binocular rivalry

“…In their view, coordinated dominance between difference regions of the retinotopic representation (local zones that correspond to local patches of the stimulus) as opposed to dominance based on the representation of the entire stimulus could explain IOG. However, recent functional magnetic resonance imaging (fMRI) findings support the idea that IOG rivalry primarily occurs between binocular neurons with larger receptive fields in higher level areas ( Buckthought, Kirsch, Fesi, & Mendola, 2021 ). In sum, the observation that individuals experience coherent percepts when viewing intermingled patchwork of rivalrous images highlights the importance of spatial integration mechanisms for the experience of BR.…”

Perceptual Resolution of Ambiguity: Can Tuned, Divisive Normalization Account for both Interocular Similarity Grouping and Difference Enhancement

“…It occurs with multiple, steadily presented rivalrous stimuli and even when the rivalrous images are swapped between the two eyes several times each second. The prevalence of this perceptual similarity bias has prompted theories proposing a grouping process driven by a posited mechanism for spatially integrated ‘filling-in’ that is regulated by attention (Brascamp et al, 2019; Buckthought, Kirsch, Fesi, & Mendola, 2021; Lee & Blake, 1999; Lee & Blake, 2004). Emerging evidence, however, adds nuance to this view.…”