Depth of interocular suppression associated with continuous flash suppression, flash suppression, and binocular rivalry

When conflicting images are presented to the corresponding regions of the two eyes, only one image may be consciously perceived. In binocular rivalry (BR), two images alternate in phenomenal visibility; even a salient image is eventually suppressed by an image of low saliency. Recently, N. Tsuchiya and C. Koch (2005) reported a technique called continuous flash suppression (CFS), extending the suppression duration more than 10-fold. Here, we investigated the depth of this prolonged form of interocular suppression as well as conventional BR and flash suppression (FS) using a probe detection task. Compared to monocular viewing condition, CFS elevated detection thresholds more than 20-fold, whereas BR did so by 3-fold. In subsequent experiments, we dissected CFS into several components. By manipulating the number and timing of flashes with respect to the probe, we found that the stronger suppression in CFS is not due to summation between BR and FS but is caused by the summation of the suppression due to multiple flashes. Our results support the view that CFS is not a stronger version of BR but is due to the accumulated suppressive effects of multiple flashes

Brain Areas Active during Visual Perception of Biological Motion

AbstractTheories of vision posit that form and motion are represented by neural mechanisms segregated into functionally and anatomically distinct pathways. Using point-light animations of biological motion, we examine the extent to which form and motion pathways are mutually involved in perceiving figures depicted by the spatio-temporal integration of local motion components. Previous work discloses that viewing biological motion selectively activates a region on the posterior superior temporal sulcus (STSp). Here we report that the occipital and fusiform face areas (OFA and FFA) also contain neural signals capable of differentiating biological from nonbiological motion. EBA and LOC, although involved in perception of human form, do not contain neural signals selective for biological motion. Our results suggest that a network of distributed neural areas in the form and motion pathways underlie the perception of biological motion

A Dissociation of Attention and Awareness in Phase-sensitive but Not Phase-insensitive Visual Channels

The elements most vivid in our conscious awareness are the ones to which we direct our attention. Scientific study confirms the impression of a close bond between selective attention and visual awareness, yet the nature of this association remains elusive. Using visual afterimages as an index, we investigate neural processing of stimuli as they enter awareness and as they become the object of attention. We find evidence of response enhancement accompanying both attention and awareness, both in the phase-sensitive neural channels characteristic of early processing stages and in the phase-insensitive channels typical of higher cortical areas. The effects of attention and awareness on phase-insensitive responses are positively correlated, but in the same experiments, we observe no correlation between the effects on phase-sensitive responses. This indicates independent signatures of attention and awareness in early visual areas yet a convergence of their effects at more advanced processing stages

Stimulus Fractionation by Interocular Suppression

Can human observers distinguish physical removal of a visible stimulus from phenomenal suppression of that stimulus during binocular rivalry? As so often happens, simple questions produce complex answers, and that is the case in the study reported here. Using continuous flash suppression to produce binocular rivalry, we were able to identify stimulus conditions where most – but not all – people utterly fail to distinguish physical from phenomenal stimulus removal, although we can be certain that those two equivalent perceptual states are accompanied by distinct neural events. More interestingly, we find subtle variants of the task where distinguishing the two states is trivially easy, even for people who utterly fail under the original conditions. We found that stimulus features are differentially vulnerable to suppression. Observers are able to be aware of existence/removal of some stimulus attributes (flicker) but not others (orientation), implying that interocular suppression breaks down the unitary awareness of integrated features belonging to a visual object. These findings raise questions about the unitary nature of awareness and, also, place qualifications on the utility of binocular rivalry as a tool for studying the neural concomitants of conscious visual awareness

Наближення мультифрактальних процесів і полів абсолютно неперервними процесами

Визначено абсолютно неперервні процеси, які збігаються до мультифрактального броунівського руху за ймовірністю в просторах типу Бєсова. Одержано результат про збіжність розв'язків стохастичних диференціальних рівнянь з такими процесами до розв'язку рівняння з мультифрактальним броунівським рухом. Аналогічні наближення побудовано для випадку двопараметричних процесів.We define absolute continuous stochastic processes that converge to a multifractal Brownian motion in Besov-type spaces. The convergence of solutions of stochastic differential equations with such processes to a solution of the equation with multifractal Brownian motion is proved. Similar approximations are constructed in the case of two-parameter processes

Mixed messengers, unified message: spatial grouping from temporal structure

AbstractIn dynamic visual environments, objects can differ from their backgrounds in terms of their associated temporal structure—the time course of changes in some stimulus property defining object and background. In a series of experiments, we investigated whether different “messengers” of temporal structure group into coherent spatial forms. Observers viewed arrays of Gabor patches in which different temporal structures designated figure and ground regions; extracting the figure required grouping across synchronized orientation, spatial frequency, phase, and/or contrast changes. Observers were able to extract spatial form from temporal structure even when information had to be combined across different messengers. Further, mixing messengers of temporal structure proved cost-free: task performance when grouping across messengers approximated performance when all information resided within a single messenger. Thus, the visual system can abstract temporal structure regardless of the messenger of the dynamic event; a coherent spatial structure emerges from this abstracted temporal structure

Making Electrospun Spider Silk Fibers Stronger

Spider silk is one of the most robust and versatile fibers making it a topic of interest in the scientific community. Possessing strength and elasticity many have sought to create fibers comparable to natural spider silk. Up until recently many scientists have fallen short of creating said fibers. With the use of a technique called electrospinning, comparable spider silk fibers have been created. Electrospinning is the process of creating fibers from a polymer solution using an electrical field. This method leads to the formation of nanofibers. These Fibers can then be further modified by crosslinking, a technique traditionally used to analyze protein-protein interactions

Modulation of spatiotemporal dynamics of binocular rivalry by collinear facilitation and pattern-dependent adaptation

The role of collinear facilitation was investigated to test predictions of a model for traveling waves of dominance during binocular rivalry (H. Wilson, R. Blake, & S

Land cover classification and change during mine reclamation in Northeast Florida using multispectral imagery

Titanium is commonly used in the aerospace industry because it is lightweight and durable in extreme temperatures. The Green Cove Springs Mine, near Green Cove Springs, Florida, was used for mining and processing titanium and other minerals from 1972 until 2009. Since then, the mine area is being reclaimed, or rehabilitated and restored to its natural state, as required by Florida Department of Environmental Protection regulations. In this study, we use high-resolution multispectral satellite and aerial imagery obtained from 2016 to 2022 to examine land cover (LC) changes at the Green Cove Springs Mine during this reclamation period. We use the National Land Cover Database (NLCD; 30-m resolution) to identify regions of no LC change and train a support vector machine classification of LC across the entire mine area at a much finer scale

Stimulus Motion Propels Traveling Waves in Binocular Rivalry

State transitions in the nervous system often take shape as traveling waves, whereby one neural state is replaced by another across space in a wave-like manner. In visual perception, transitions between the two mutually exclusive percepts that alternate when the two eyes view conflicting stimuli (binocular rivalry) may also take shape as traveling waves. The properties of these waves point to a neural substrate of binocular rivalry alternations that have the hallmark signs of lower cortical areas. In a series of experiments, we show a potent interaction between traveling waves in binocular rivalry and stimulus motion. The course of the traveling wave is biased in the motion direction of the suppressed stimulus that gains dominance by means of the wave-like transition. Thus, stimulus motion may propel the traveling wave across the stimulus to the extent that the stimulus motion dictates the traveling wave's direction completely. Using a computational model, we show that a speed-dependent asymmetry in lateral inhibitory connections between retinotopically organized and motion-sensitive neurons can explain our results. We argue that such a change in suppressive connections may play a vital role in the resolution of dynamic occlusion situations