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Randolph Blake - One of the best experts on this subject based on the ideXlab platform.

  • Modulation of spatiotemporal dynamics of Binocular Rivalry by collinear facilitation and pattern-dependent adaptation
    2020
    Co-Authors: Minsuk Kang, Sanghun Lee, June Kim, David Heeger, Randolph Blake
    Abstract:

    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

  • individual differences in sensory eye dominance reflected in the dynamics of Binocular Rivalry
    Vision Research, 2017
    Co-Authors: Kevin C Dieter, Randolph Blake
    Abstract:

    Normal Binocular vision emerges from the combination of neural signals arising within separate monocular pathways. It is natural to wonder whether both eyes contribute equally to the unified cyclopean impression we ordinarily experience. Binocular Rivalry, which occurs when the inputs to the two eyes are markedly different, affords a useful means for quantifying the balance of influence exerted by the eyes (called sensory eye dominance, SED) and for relating that degree of balance to other aspects of Binocular visual function. However, the precise ways in which Binocular Rivalry dynamics change when the eyes are unbalanced remain uncharted. Relying on widespread individual variability in the relative predominance of the two eyes as demonstrated in previous studies, we found that an observer's overall tendency to see one eye more than the other was driven both by differences in the relative duration and frequency of instances of that eye's perceptual dominance. Specifically, larger imbalances between the eyes were associated with longer and more frequent periods of exclusive dominance for the stronger eye. Increases in occurrences of dominant eye percepts were mediated in part by a tendency to experience "return transitions" to the predominant eye - that is, observers often experienced sequential exclusive percepts of the dominant eye's image with an intervening mixed percept. Together, these results indicate that the often-observed imbalances between the eyes during Binocular Rivalry reflect true differences in sensory processing, a finding that has implications for our understanding of the mechanisms underlying Binocular vision in general.

  • can Binocular Rivalry reveal neural correlates of consciousness
    Philosophical Transactions of the Royal Society B, 2014
    Co-Authors: Randolph Blake, Jan W Brascamp, David J Heeger
    Abstract:

    This essay critically examines the extent to which Binocular Rivalry can provide important clues about the neural correlates of conscious visual perception. Our ideas are presented within the framework of four questions about the use of Rivalry for this purpose: (i) what constitutes an adequate comparison condition for gauging Rivalry's impact on awareness, (ii) how can one distinguish abolished awareness from inattention, (iii) when one obtains unequivocal evidence for a causal link between a fluctuating measure of neural activity and fluctuating perceptual states during Rivalry, will it generalize to other stimulus conditions and perceptual phenomena and (iv) does such evidence necessarily indicate that this neural activity constitutes a neural correlate of consciousness? While arriving at sceptical answers to these four questions, the essay nonetheless offers some ideas about how a more nuanced utilization of Binocular Rivalry may still provide fundamental insights about neural dynamics, and glimpses of at least some of the ingredients comprising neural correlates of consciousness, including those involved in perceptual decision-making.

  • inattention abolishes Binocular Rivalry perceptual evidence
    Psychological Science, 2012
    Co-Authors: Randolph Blake, Jan W Brascamp
    Abstract:

    Binocular Rivalry refers to the unstable perceptual experience that arises when an observer views a different image with each eye: Each image reaches awareness in turn as the other becomes temporarily invisible. Using a novel experimental paradigm, we provide the first direct, perceptual evidence that Binocular Rivalry occurs only in the presence of attention. Observers in our experiment withdrew attention from a Binocular Rivalry stimulus shortly after one of the eyes' images was forced to visibility. Seconds later, they shifted attention back to the stimulus to report their perception. For all observers, reported perception strongly and significantly deviated from the results that would be expected if Binocular Rivalry continued during inattention. Strikingly, reports instead exactly matched those obtained when the stimulus was physically removed for seconds rather than left unattended. These results show that disregarding a Binocular Rivalry stimulus is equivalent to having it removed from view. Thus, inattention abolishes Binocular Rivalry.

  • suppression during Binocular Rivalry broadens orientation tuning
    Journal of Vision, 2010
    Co-Authors: Sam Ling, Randolph Blake
    Abstract:

    During Binocular-Rivalry suppression, an ordinarily visible stimulus is erased from awareness, but how is the sensory representation of that stimulus affected? Although it is established that Rivalry suppression attenuates signal strength, the influence of suppression on signal fidelity remains unknown. Here, we show that noise plays a hitherto undiscovered role in the degradation of the percept under suppression. In Experiment 1, we measured psychometric functions for a stimulus presented under dominance and suppression, and found that the slope of these functions was shallower under suppression—a result suggesting that the signal representation was rendered noisier. Experiment 2 then revealed the source of this noise: An examination of the influence of suppression on the orientation bandwidth of noise masking showed that tuning bandwidth is significantly broadened under suppression. Thus, the discriminability of a suppressed stimulus is weakened not only by a general decrease in signal strength, but als...

David J Heeger - One of the best experts on this subject based on the ideXlab platform.

  • attention model of Binocular Rivalry
    Proceedings of the National Academy of Sciences of the United States of America, 2017
    Co-Authors: John Rinzel, James Rankin, Marisa Carrasco, David J Heeger
    Abstract:

    When the corresponding retinal locations in the two eyes are presented with incompatible images, a stable percept gives way to perceptual alternations in which the two images compete for perceptual dominance. As perceptual experience evolves dynamically under constant external inputs, Binocular Rivalry has been used for studying intrinsic cortical computations and for understanding how the brain regulates competing inputs. Converging behavioral and EEG results have shown that Binocular Rivalry and attention are intertwined: Binocular Rivalry ceases when attention is diverted away from the Rivalry stimuli. In addition, the competing image in one eye suppresses the target in the other eye through a pattern of gain changes similar to those induced by attention. These results require a revision of the current computational theories of Binocular Rivalry, in which the role of attention is ignored. Here, we provide a computational model of Binocular Rivalry. In the model, competition between two images in Rivalry is driven by both attentional modulation and mutual inhibition, which have distinct selectivity (feature vs. eye of origin) and dynamics (relatively slow vs. relatively fast). The proposed model explains a wide range of phenomena reported in Rivalry, including the three hallmarks: (i) Binocular Rivalry requires attention; (ii) various perceptual states emerge when the two images are swapped between the eyes multiple times per second; (iii) the dominance duration as a function of input strength follows Levelt's propositions. With a bifurcation analysis, we identified the parameter space in which the model's behavior was consistent with experimental results.

  • can Binocular Rivalry reveal neural correlates of consciousness
    Philosophical Transactions of the Royal Society B, 2014
    Co-Authors: Randolph Blake, Jan W Brascamp, David J Heeger
    Abstract:

    This essay critically examines the extent to which Binocular Rivalry can provide important clues about the neural correlates of conscious visual perception. Our ideas are presented within the framework of four questions about the use of Rivalry for this purpose: (i) what constitutes an adequate comparison condition for gauging Rivalry's impact on awareness, (ii) how can one distinguish abolished awareness from inattention, (iii) when one obtains unequivocal evidence for a causal link between a fluctuating measure of neural activity and fluctuating perceptual states during Rivalry, will it generalize to other stimulus conditions and perceptual phenomena and (iv) does such evidence necessarily indicate that this neural activity constitutes a neural correlate of consciousness? While arriving at sceptical answers to these four questions, the essay nonetheless offers some ideas about how a more nuanced utilization of Binocular Rivalry may still provide fundamental insights about neural dynamics, and glimpses of at least some of the ingredients comprising neural correlates of consciousness, including those involved in perceptual decision-making.

  • a model of Binocular Rivalry and cross orientation suppression
    PLOS Computational Biology, 2013
    Co-Authors: Christopher P Said, David J Heeger
    Abstract:

    Binocular Rivalry and cross-orientation suppression are well-studied forms of competition in visual cortex, but models of these two types of competition are in tension with one another. Binocular Rivalry occurs during the presentation of dichoptic grating stimuli, where two orthogonal gratings presented separately to the two eyes evoke strong alternations in perceptual dominance. Cross-orientation suppression occurs during the presentation of plaid stimuli, where the responses to a component grating presented to both eyes is weakened by the presence of a superimposed orthogonal grating. Conventional models of Rivalry that rely on strong competition between orientation-selective neurons incorrectly predict Rivalry between the components of plaids. Lowering the inhibitory weights in such models reduces Rivalry for plaids, but also reduces it for dichoptic gratings. Using an exhaustive grid search, we show that this problem cannot be solved simply by adjusting the parameters of the model. Instead, we propose a robust class of models that rely on ocular opponency neurons, previously proposed as a mechanism for efficient stereo coding, to yield Rivalry only for dichoptic gratings, not for plaids. This class of models reconciles models of Binocular Rivalry with the divisive normalization framework that has been used to explain cross-orientation. Our model makes novel predictions that we confirmed with psychophysical tests.

  • normal Binocular Rivalry in autism implications for the excitation inhibition imbalance hypothesis
    Vision Research, 2013
    Co-Authors: Christopher P Said, David J Heeger, Ryan Egan, Nancy J Minshew, Marlene Behrmann
    Abstract:

    Autism is characterized by disruption in multiple dimensions of perception, emotion, language and social cognition. Many hypotheses for the underlying neurophysiological basis have been proposed. Among these is the excitation/inhibition (E/I) imbalance hypothesis, which states that levels of cortical excitation and inhibition are disrupted in autism. We tested this theory in the visual system, because vision is one of the better understood systems in neuroscience, and because the E/I imbalance theory has been proposed to explain hypersensitivity to sensory stimuli in autism. We conducted two experiments on Binocular Rivalry, a well-studied psychophysical phenomenon that depends critically on excitation and inhibition levels in cortex. Using a computational model, we made specific predictions about how imbalances in excitation and inhibition levels would affect perception during two aspects of Binocular Rivalry: mixed perception (Experiment 1) and traveling waves (Experiment 2). We found no significant differences in either of these phenomena between high-functioning adults with autism and controls, and no evidence for a relationship between these measurements and the severity of autism. These results do not conclusively rule out an excitation/inhibition imbalance in the visual system of those with autism, but they suggest that such an imbalance, if it exists, is likely to be small in magnitude.

  • hierarchy of cortical responses underlying Binocular Rivalry
    Nature Neuroscience, 2007
    Co-Authors: Sanghun Lee, Randolph Blake, David J Heeger
    Abstract:

    During Binocular Rivalry, physical stimulation is dissociated from conscious visual awareness. Human brain imaging reveals a tight linkage between the neural events in human primary visual cortex (V1) and the dynamics of perceptual waves during transitions in dominance during Binocular Rivalry. Here, we report results from experiments in which observers' attention was diverted from the rival stimuli, implying that: competition between two rival stimuli involves neural circuits in V1, and attention is crucial for the consequences of this neural competition to advance to higher visual areas and promote perceptual waves.

Geraint Rees - One of the best experts on this subject based on the ideXlab platform.

  • right parietal tms shortens dominance durations in Binocular Rivalry
    Current Biology, 2010
    Co-Authors: Geraint Rees, David Carmel, Vincent Walsh, Nilli Lavie
    Abstract:

    Binocular Rivalry occurs when dissimilar images are presented to each eye. Rather than a combined picture being perceived, each monocular image competes for perceptual dominance, becoming visible for a few seconds while the other is suppressed. Stable visual input thus leads to alternations in conscious perception, dissociating stimulation from awareness. This makes Rivalry particularly useful for elucidating the neural processes underlying consciousness [1]. Retinotopic visual cortex [2] and lateral geniculate nucleus [3] activity are modulated by such alternating perception, implying an early locus for rivaling neural representations. However, higher cortical regions, including right superior parietal cortex, exhibit activity that is time-locked to perceptual transitions [4]. Though this implies the involvement of top-down processes in Rivalry, the correlational nature of neuroimaging precludes the attribution of a causal role to such activity, which may instead simply reflect orientating attention to the transition. Here we distinguish these two hypotheses by showing that repetitive transcranial magnetic stimulation (rTMS) over right superior parietal cortex shortened Binocular Rivalry dominance durations. This suggests that right parietal cortex maintains the current perceptual state during Rivalry.

  • A neural basis for percept stabilization Binocular Rivalry
    J COGNITIVE NEUROSCI, 2008
    Co-Authors: Geraint Rees
    Abstract:

    When the same visual input has conflicting interpretations, conscious perception can alternate spontaneously between each competing percept. Surprisingly, such bistable perception can be stabilized by intermittent stimulus removal, suggesting the existence of perceptual "memory" across interruptions in stimulation. The neural basis of such a process remains Unknown. Here, we studied Binocular Rivalry, one type of bistable perception, in two linked experiments in human participants. First, we showed, in a behavioral experiment using Binocular Rivalry between face and grating stimuli, that the stabilizing effect of stimulus removal was specific to perceptual alternations evoked by Rivalry, and did not occur following physical alternations in the absence of Rivalry. We then used functional magnetic resonance imaging to measure brain activity in a variable delay period Of Stimulus removal. Activity in the fusiform face area during the delay period following removal of rivalrous Stimuli was greater following face than grating perception, whereas such a difference was absent during removal of non-rivalrous Stimuli. Moreover, activity in areas of fronto-parietal regions during the delay period correlated with the degree to which individual participants tended to experience percept stabilization. Our findings Suggest that percept-related activity in specialized extrastriate visual areas help to stabilize perception during perceptual conflict, and that high-level mechanisms may determine the influence of such signals on conscious perception.

  • eye specific effects of Binocular Rivalry in the human lateral geniculate nucleus
    Nature, 2005
    Co-Authors: Johndylan Haynes, Ralf Deichmann, Geraint Rees
    Abstract:

    When our eyes are presented with incompatible images, our conscious perception fluctuates spontaneously between each monocular view. The nature of the resulting ‘Binocular Rivalry’, and how the brain resolves it, is the subject of a long-standing debate that touches on fundamental aspects of human cognition such as attention and selection. Now a neural signature characteristic for Binocular Rivalry has been identified, at the very earliest stages of visual processing, in the human lateral geniculate nucleus (LGN). This region of the brain contains cells that respond only to stimulation of one or other eye, and the signals in the LGN closely reflect the perceptual dominance seen during Binocular Rivalry. When dissimilar images are presented to the two eyes, they compete for perceptual dominance so that each image is visible in turn for a few seconds while the other is suppressed. Such Binocular Rivalry is associated with relative suppression of local, eye-based representations1,2,3,4 that can also be modulated by high-level influences such as perceptual grouping3,5,6. However, it is currently unclear how early in visual processing the suppression of eye-based signals can occur. Here we use high-resolution functional magnetic resonance imaging (fMRI) in conjunction with a new Binocular Rivalry stimulus to show that signals recorded from the human lateral geniculate nucleus (LGN) exhibit eye-specific suppression during Rivalry. Regions of the LGN that show strong eye-preference independently show strongly reduced activity during Binocular Rivalry when the stimulus presented in their preferred eye is perceptually suppressed. The human LGN is thus the earliest stage of visual processing that reflects eye-specific dominance and suppression.

Bruno Richard - One of the best experts on this subject based on the ideXlab platform.

  • dynamic properties of internal noise probed by modulating Binocular Rivalry
    PLOS Computational Biology, 2019
    Co-Authors: Daniel H Baker, Bruno Richard
    Abstract:

    Neural systems are inherently noisy, and this noise can affect our perception from moment to moment. This is particularly apparent in Binocular Rivalry, where perception of competing stimuli shown to the left and right eyes alternates over time. We modulated rivalling stimuli using dynamic sequences of external noise of various rates and amplitudes. We repeated each external noise sequence twice, and assessed the consistency of percepts across repetitions. External noise modulations of sufficiently high contrast increased consistency scores above baseline, and were most effective at 1/8Hz. A computational model of Rivalry in which internal noise has a 1/f (pink) temporal amplitude spectrum, and a standard deviation of 16% contrast, provided the best account of our data. Our novel technique provides detailed estimates of the dynamic properties of internal noise during Binocular Rivalry, and by extension the stochastic processes that drive our perception and other types of spontaneous brain activity.

  • dynamic properties of internal noise probed by modulating Binocular Rivalry
    bioRxiv, 2018
    Co-Authors: Daniel H Baker, Bruno Richard
    Abstract:

    Abstract Neural systems are inherently noisy, and this noise can affect our perception from moment to moment. This is particularly apparent in Binocular Rivalry, where our perception of competing stimuli shown to the left and right eyes alternates over time in a seemingly random fashion. We investigated internal noise using Binocular Rivalry by modulating rivalling stimuli using dynamic sequences of external noise of various rates and amplitudes. As well as measuring the effect on dominance durations, we repeated each external noise sequence twice, and assessed the consistency of percepts across repetitions. External noise modulations with standard deviations above 4% contrast increased consistency scores above baseline, and were most effective at 1/8Hz. A computational model of Rivalry in which internal noise has a 1/f (pink) temporal amplitude spectrum, and a standard deviation of 16%, provided the best account of our data, and was able to correctly predict perception in additional conditions. Our novel technique provides detailed estimates of the dynamic properties of internal noise during Binocular Rivalry, and by extension the stochastic processes that drive our perception and other types of spontaneous brain activity. Significance statement Although our perception of the world appears constant, sensory representations are variable because of the ‘noisy’ nature of biological neurons. Here we used a Binocular Rivalry paradigm, in which conflicting images are shown to the two eyes, to probe the properties of this internal variability. Using a novel paradigm in which the contrasts of rivalling stimuli are modulated by two independent external noise streams, we infer the amplitude and character of this internal noise. The temporal amplitude spectrum of the noise has a 1/f spectrum, similar to that of natural visual input, and consistent with the idea that the visual system evolved to match its environment.

Stephen A Engel - One of the best experts on this subject based on the ideXlab platform.

  • stimulus Rivalry and Binocular Rivalry share a common neural substrate
    Journal of Vision, 2018
    Co-Authors: Vadim Petruk, Stephen A Engel
    Abstract:

    When two incompatible images are shown separately to each eye, a perceptual process known as Binocular Rivalry occurs by which the two images compete for awareness. The site of competition for Binocular Rivalry has been a topic of debate, and recent theories are that it may occur either at low levels of the visual system where the inputs from the two eyes are combined or at high levels of the visual system where the two images are processed. One of the major pieces of evidence for a high-level image account of Rivalry is a phenomenon known as stimulus Rivalry, in which two competing stimuli are swapped between the eyes at 3 Hz. However, there is little available neurophysiological evidence for a neural substrate for this high-level competition. Here, we used frequency tagging of two competing stimuli in Binocular Rivalry and stimulus Rivalry in humans to evaluate whether the steady-state visually evoked potentials (SSVEPs) show similar signatures of neural competition for both conditions. We found that flickering the stimuli generates spectral power at the tagged frequencies in both types of Rivalry in the early visual cortex. We then quantified dynamic signatures of competition by tracking amplitude changes in the frequency tags, which showed that both types of Rivalry colocalized in occipital regions of the cortex. Thus, contrary to our hypothesis that stimulus Rivalry was being mediated by high-level competition between the images, we find that neural competition measured by the SSVEP instead suggests that the sites of competition for stimulus Rivalry and Binocular Rivalry may similarly include the occipital pole and middle temporal gyrus (hMT+/V5) of the visual system, consistent with a low-level, Binocular interpretation.

  • deactivation in the posterior mid cingulate cortex reflects perceptual transitions during Binocular Rivalry evidence from simultaneous eeg fmri
    NeuroImage, 2017
    Co-Authors: Abhrajeet V Roy, Keith Jamison, Stephen A Engel
    Abstract:

    Binocular Rivalry is a phenomenon in which perception spontaneously shifts between two different images that are dichoptically presented to the viewer. By elucidating the cortical networks responsible for these stochastic fluctuations in perception, we can potentially learn much about the neural correlates of visual awareness. We obtained concurrent EEG-fMRI data for a group of 20 healthy human subjects during the continuous presentation of dichoptic visual stimuli. The two eyes' images were tagged with different temporal frequencies so that eye specific steady-state visual evoked potential (SSVEP) signals could be extracted from the EEG data for direct comparison with changes in fMRI BOLD activity associated with Binocular Rivalry. We additionally included a smooth replay condition that emulated the perceptual transitions experienced during Binocular Rivalry as a control stimulus. We evaluated a novel SSVEP-informed fMRI analysis in this study in order to delineate the temporal dynamics of Rivalry-related BOLD activity from both an electrophysiological and behavioral perspective. In this manner, we assessed BOLD activity during Rivalry that was directly correlated with peaks and crosses of the two rivaling, frequency-tagged SSVEP signals, for comparison with BOLD activity associated with subject reported perceptual transitions. Our findings point to a critical role of a right lateralized fronto-parietal network in the processing of bistable stimuli, given that BOLD activity in the right superior/inferior parietal lobules was significantly elevated throughout Binocular Rivalry and in particular during perceptual transitions, compared with the replay condition. Based on the SSVEP-informed analysis, Rivalry was further associated with significantly enhanced BOLD suppression in the posterior mid-cingulate cortex during perceptual transitions, compared with SSVEP crosses. Overall, this work points to a careful interplay between early visual areas, the right posterior parietal cortex and the mid-cingulate cortex in mediating the spontaneous perceptual changes associated with Binocular Rivalry and has significant implications for future multimodal imaging studies of perception and awareness.

  • neurons that detect interocular conflict during Binocular Rivalry revealed with eeg
    Journal of Vision, 2016
    Co-Authors: Sucharit Katyal, Stephen A Engel
    Abstract:

    When the two eyes view incompatible images, perception alternates between them. What neural computations underlie this Binocular Rivalry? Perceptual alternations may simply reflect competition between the sets of monocular neurons that respond to each image, with the stronger driving perception. Here, we test an alternative hypothesis, that the computations that resolve Rivalry make use of an active signal that reflects interocular conflict. Images presented to each eye were flickered at different frequencies while we measured steady-state visually evoked potentials (SSVEP). Signals at frequencies that are combinations of the two input frequencies can arise only from Binocular neurons. In a first experiment, we measured energy at these "intermodulation" frequencies during Binocular Rivalry and found it to be highest immediately before Rivalry restarted following a period of incomplete resolution of Rivalry (a "mixed" percept). This suggests that the intermodulation signals may arise from neurons important for resolving the conflict between the two eyes' inputs. In a second experiment, we tested whether the intermodulation signal arose from neurons that measure interocular conflict by parametrically increasing conflict while simultaneously reducing image contrast. The activity of neurons that receive input from both eyes but are not sensitive to conflict should reduce monotonically as contrast decreases. The intermodulation response, however, peaked at intermediate levels of conflict, suggesting that it arises in part from neurons that respond to interocular conflict. Binocular Rivalry appears to depend on an active mechanism that detects interocular conflict, whose levels of activity can be measured by the intermodulation frequencies of the SSVEP.

  • Binocular Rivalry requires visual attention
    Neuron, 2011
    Co-Authors: Peng Zhang, Keith Jamison, Stephen A Engel
    Abstract:

    An interocular conflict arises when different images are presented to each eye at the same spatial location. The visual system resolves this conflict through Binocular Rivalry: observers consciously perceive spontaneous alternations between the two images. Visual attention is generally important for resolving competition between neural representations. However, given the seemingly spontaneous and automatic nature of Binocular Rivalry, the role of attention in resolving interocular competition remains unclear. Here we test whether visual attention is necessary to produce Rivalry. Using an EEG frequency-tagging method to track cortical representations of the conflicting images, we show that when attention was diverted away, Rivalry stopped. The EEG data further suggested that the neural representations of the dichoptic images combined without attention. Thus, attention is necessary for dichoptic images to be engaged in sustained Rivalry and may be generally required for resolving conflicting, potentially ambiguous input and giving a single interpretation access to consciousness.