Alpha fluctuations regulate the accrual of visual information to awareness

AbstractEndogenous brain processes play a paramount role in shaping up perceptual phenomenology, as illustrated by the alternations experienced by humans (and other animals) when watching perceptually ambiguous, static images. Here, we hypothesised that endogenous alpha fluctuations in the visual cortex pace the accumulation of sensory information leading to perceptual outcomes. We addressed this hypothesis using binocular rivalry combined with visual entrainment and electroencephalography in humans (42 female, 40 male). The results revealed a correlation between the individual frequency of alpha oscillations in the occipital cortex and perceptual alternation rates experienced during binocular rivalry. In subsequent experiments we show that regulating endogenous brain activity via entrainment produced corresponding changes in perceptual alternation rate, which were observed only in the alpha range but not at lower entrainment frequencies. Overall, rhythmic alpha stimulation resulted in faster perceptual alternation rates, compared to arrhythmic or no stimulation. These findings support the notion that visual information is accumulated via alpha cycles to promote the emergence of conscious perceptual representations. We suggest that models of binocular rivalry incorporating posterior alpha as a pacemaker can provide an important advance in the comprehension of the dynamics of visual awareness.Significance statementMainstream theories in cognitive neuroscience agree that endogenous brain processes play a paramount role in shaping our perceptual experience of sensory inputs. In vision, endogenous fluctuations in the alpha rhythm have been pointed out to regulate visual inputs to perception. In support of this hypothesis, here we used EEG recordings and visual entrainment to demonstrate that inter-individual differences in the speed of endogenous alpha fluctuations in the brain are causally related to the accrual of visual information to awareness. These findings provide, for the first time, evidence for alpha-gated regulation of the dynamics of alternations in conscious visual perception.

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Cortico-motor control dynamics orchestrates visual sampling

10.1101/2020.03.23.003228 ◽

2020 ◽

Author(s):

Alice Tomassini ◽

Eric Maris ◽

Pauline Hilt ◽

Luciano Fadiga ◽

Alessandro D’Ausilio

Keyword(s):

Motor Control ◽

Visual Information ◽

Brain Activity ◽

Sensory Information ◽

Motor Task ◽

Phase Relationship ◽

Stimulus Onset ◽

Motor Output ◽

Beta Band ◽

Visual Inputs

AbstractMovements overtly sample sensory information, making sensory analysis an active-sensing process. In this study, we show that visual information sampling is not just locked to the (overt) movement dynamics, but it is structured by the internal (covert) dynamics of cortico-motor control. We asked human participants to perform an isometric motor task – based on proprioceptive feedback – while detecting unrelated near-threshold visual stimuli. The motor output (Force) shows zero-lag coherence with brain activity (recorded via electroencephalography) in the beta-band, as previously reported. In contrast, cortical rhythms in the alpha-band systematically forerun the motor output by 200ms. Importantly, visual detection is facilitated when cortico-motor alpha (not beta) synchronization is enhanced immediately before stimulus onset, namely at the optimal phase relationship for sensorimotor communication. These findings demonstrate an automatic gating of visual inputs by the ongoing motor control processes, providing evidence of an internal and alpha-cycling visuomotor loop.

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Right parietal brain activity precedes perceptual alternation during binocular rivalry

Human Brain Mapping ◽

10.1002/hbm.21117 ◽

2010 ◽

Vol 32 (9) ◽

pp. 1432-1442 ◽

Cited By ~ 42

Author(s):

Juliane Britz ◽

Michael A. Pitts ◽

Christoph M. Michel

Keyword(s):

Binocular Rivalry ◽

Brain Activity ◽

Perceptual Alternation

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Regulating the Access to Awareness: Brain Activity Related to Probe-related and Spontaneous Reversals in Binocular Rivalry

Journal of Cognitive Neuroscience ◽

10.1162/jocn_a_01104 ◽

2017 ◽

Vol 29 (6) ◽

pp. 1089-1102 ◽

Cited By ~ 3

Author(s):

Brian A. Metzger ◽

Kyle E. Mathewson ◽

Evelina Tapia ◽

Monica Fabiani ◽

Gabriele Gratton ◽

...

Keyword(s):

Binocular Rivalry ◽

Stimulus Change ◽

Brain Activity ◽

Visual Awareness ◽

Intermediate Stage ◽

Neural Correlates ◽

Brain Regions ◽

Conscious Awareness ◽

Network Properties ◽

Per Se

Research on the neural correlates of consciousness (NCC) has implicated an assortment of brain regions, ERP components, and network properties associated with visual awareness. Recently, the P3b ERP component has emerged as a leading NCC candidate. However, typical P3b paradigms depend on the detection of some stimulus change, making it difficult to separate brain processes elicited by the stimulus itself from those associated with updates or changes in visual awareness. Here we used binocular rivalry to ask whether the P3b is associated with changes in awareness even in the absence of changes in the object of awareness. We recorded ERPs during a probe-mediated binocular rivalry paradigm in which brief probes were presented over the image in either the suppressed or dominant eye to determine whether the elicited P3b activity is probe or reversal related. We found that the timing of P3b (but not its amplitude) was closely related to the timing of the report of a perceptual change rather than to the onset of the probe. This is consistent with the proposal that P3b indexes updates in conscious awareness, rather than being related to stimulus processing per se. Conversely, the probe-related P1 amplitude (but not its latency) was associated with reversal latency, suggesting that the degree to which the probe is processed increases the likelihood of a fast perceptual reversal. Finally, the response-locked P3b amplitude (but not its latency) was associated with the duration of an intermediate stage between reversals in which parts of both percepts coexist (piecemeal period). Together, the data suggest that the P3b reflects an update in consciousness and that the intensity of that process (as indexed by P3b amplitude) predicts how immediate that update is.

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Conflicting Bottom-up and Top-down Signals during Misrecognition of Visual Objects

10.1101/521252 ◽

2019 ◽

Author(s):

Mohamed Abdelhack ◽

Yukiyasu Kamitani

Keyword(s):

Visual Information ◽

Visual Recognition ◽

Brain Activity ◽

Sensory Information ◽

Visual Input ◽

Neural Representation ◽

Perceptual Decision Making ◽

Inference Process ◽

Top Down ◽

Bottom Up

AbstractVisual recognition involves integrating visual information with other sensory information and prior knowledge. In accord with Bayesian inference under conditions of unreliable visual input, the brain relies on the prior as a source of information to achieve the inference process. This drives a top-down process to improve the neural representation of visual input. However, the extent to which non-stimulus-driven top-down information affects processing in the ventral stream is still unclear. We conducted a perceptual decision-making task using blurred images, while conducting functional magnetic resonance imaging. We then transformed brain activity into deep neural network features to distinguish bottom-up and top-down signals. We found that top-down information unrelated to the stimulus had a minimal effect on lower-level visual processes. The neural representations of degraded stimuli that were misrecognized were still correlated with the correct object category in the lower levels of processing. In contrast, activity in the higher cognitive areas was more strongly correlated with recognition reported by the subjects. The results indicated a discrepancy between the results of processing at the lower and higher levels, indicating the existence of a stimulus-independent top-down signal flowing back down the hierarchy. These findings suggest that integration between bottom-up and top-down information takes the form of competing evidence in higher visual areas between prior-driven top-down and stimulus-driven bottom-up signals. These findings could provide important insight into the different modes of integration of neural signals in the visual cortex that contribute to the visual inference process.

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Modality Dependent Cross-Modal Functional Reorganization Following Congenital Visual Deprivation within Occipital Areas: A Meta-Analysis of Tactile and Auditory Studies

Multisensory Research ◽

10.1163/22134808-00002454 ◽

2014 ◽

Vol 27 (3-4) ◽

pp. 247-262 ◽

Cited By ~ 9

Author(s):

Emiliano Ricciardi ◽

Leonardo Tozzi ◽

Andrea Leo ◽

Pietro Pietrini

Keyword(s):

Visual Information ◽

Meta Analysis ◽

Sensory Modality ◽

Temporal Cortex ◽

Sensory Information ◽

Occipital Cortex ◽

Inferior Temporal Cortex ◽

Functional Studies ◽

Superior Parietal Cortex ◽

Blind Individuals

Cross-modal responses in occipital areas appear to be essential for sensory processing in visually deprived subjects. However, it is yet unclear whether this functional recruitment might be dependent on the sensory channel conveying the information. In order to characterize brain areas showing task-independent, but sensory specific, cross-modal responses in blind individuals, we pooled together distinct brain functional studies in a single based meta-analysis according only to the modality conveying experimental stimuli (auditory or tactile). Our approach revealed a specific functional cortical segregation according to the sensory modality conveying the non-visual information, irrespectively from the cognitive features of the tasks. In particular, dorsal and posterior subregions of occipital and superior parietal cortex showed a higher cross-modal recruitment across tactile tasks in blind as compared to sighted individuals. On the other hand, auditory stimuli activated more medial and ventral clusters within early visual areas, the lingual and inferior temporal cortex. These findings suggest a modality-specific functional modification of cross-modal responses within different portions of the occipital cortex of blind individuals. Cross-modal recruitment can thus be specifically influenced by the intrinsic features of sensory information.

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Activity in early visual areas predicts interindividual differences in binocular rivalry dynamics

Journal of Neurophysiology ◽

10.1152/jn.00509.2013 ◽

2014 ◽

Vol 111 (6) ◽

pp. 1190-1202 ◽

Cited By ~ 21

Author(s):

Hiroyuki Yamashiro ◽

Hiroki Yamamoto ◽

Hiroaki Mano ◽

Masahiro Umeda ◽

Toshihiro Higuchi ◽

...

Keyword(s):

Binocular Rivalry ◽

Brain Activity ◽

Potential Contribution ◽

Continuous Flash Suppression ◽

Visual Areas ◽

Potential Link ◽

The Individual ◽

High Level ◽

Parietal Cortices ◽

The Invisible

When dissimilar images are presented to the two eyes, binocular rivalry (BR) occurs, and perception alternates spontaneously between the images. Although neural correlates of the oscillating perception during BR have been found in multiple sites along the visual pathway, the source of BR dynamics is unclear. Psychophysical and modeling studies suggest that both low- and high-level cortical processes underlie BR dynamics. Previous neuroimaging studies have demonstrated the involvement of high-level regions by showing that frontal and parietal cortices responded time locked to spontaneous perceptual alternation in BR. However, a potential contribution of early visual areas to BR dynamics has been overlooked, because these areas also responded to the physical stimulus alternation mimicking BR. In the present study, instead of focusing on activity during perceptual switches, we highlighted brain activity during suppression periods to investigate a potential link between activity in human early visual areas and BR dynamics. We used a strong interocular suppression paradigm called continuous flash suppression to suppress and fluctuate the visibility of a probe stimulus and measured retinotopic responses to the onset of the invisible probe using functional MRI. There were ∼130-fold differences in the median suppression durations across 12 subjects. The individual differences in suppression durations could be predicted by the amplitudes of the retinotopic activity in extrastriate visual areas (V3 and V4v) evoked by the invisible probe. Weaker responses were associated with longer suppression durations. These results demonstrate that retinotopic representations in early visual areas play a role in the dynamics of perceptual alternations during BR.

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Reduced alpha amplitudes predict perceptual suppression

10.1101/2020.11.15.383562 ◽

2020 ◽

Author(s):

Eva Poland ◽

Aishwarya Bhonsle ◽

Iris Steinmann ◽

Melanie Wilke

Keyword(s):

Visual Awareness ◽

Occipital Cortex ◽

Threshold Level ◽

Stimulus Onset ◽

Alpha Activity ◽

Motion Onset ◽

Full Field ◽

Motion Stimulus ◽

The Individual ◽

Target Visibility

ABSTRACTThe amplitude of prestimulus alpha oscillations over parieto-occipital cortex has been shown to predict visual detection of masked and threshold-level stimuli. Whether alpha activity similarly predicts target visibility in perceptual suppression paradigms, another type of illusion commonly used to investigate visual awareness, is presently unclear. Here, we examined prestimulus alpha activity in the electroencephalogram (EEG) of healthy participants in the context of a generalized flash suppression (GFS) task during which salient target stimuli are rendered subjectively invisible in a subset of trials following the onset of a full-field motion stimulus. Unlike for masking or threshold paradigms, alpha (8-12 Hz) amplitude prior to motion onset was significantly higher when targets remained subjectively visible compared to trials during which the targets became perceptually suppressed. Furthermore, individual prestimulus alpha amplitudes strongly correlated with the individual trial-to-trial variability quenching following motion stimulus onset, indicating that variability quenching in visual cortex is closely linked to prestimulus alpha activity. We conclude that predictive correlates of conscious perception derived from perceptual suppression paradigms differ substantially from those of obtained with “near threshold paradigms”, possibly reflecting the effectiveness of the suppressor stimulus.

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Alpha oscillations in the human brain implement distractor suppression independent of target selection

10.1101/721019 ◽

2019 ◽

Cited By ~ 1

Author(s):

Malte Wöstmann ◽

Mohsen Alavash ◽

Jonas Obleser

Keyword(s):

Target Selection ◽

Sensory Information ◽

Stimulus Onset ◽

Alpha Power ◽

Single Trial ◽

Attention Task ◽

Alpha Oscillations ◽

Eeg Recordings ◽

Cortical Regions ◽

The Individual

AbstractIn principle, selective attention is the net result of target selection and distractor suppression. The way in which both mechanisms are implemented neurally has remained contested. Neural oscillatory power in the alpha frequency band (~10 Hz) has been implicated in the selection of to-be-attended targets, but there is lack of empirical evidence for its involvement in the suppression of to-be-ignored distractors. Here, we use electroencephalography (EEG) recordings of N = 33 human participants (males and females) to test the pre-registered hypothesis that alpha power directly relates to distractor suppression and thus operates independently from target selection. In an auditory spatial pitch discrimination task, we modulated the location (left vs right) of either a target or a distractor tone sequence, while fixing the other in the front. When the distractor was fixed in the front, alpha power relatively decreased contralaterally to the target and increased ipsilaterally. Most importantly, when the target was fixed in the front, alpha lateralization reversed in direction for the suppression of distractors on the left versus right. These data show that target-selection–independent alpha power modulation is involved in distractor suppression. While both lateralized alpha responses for selection and for suppression proved reliable, they were uncorrelated and distractor-related alpha power emerged from more anterior, frontal cortical regions. Lending functional significance to suppression-related alpha oscillations, alpha lateralization at the individual, single-trial level was predictive of behavioral accuracy. These results fuel a renewed look at neurobiological accounts of selection-independent suppressive filtering in attention.Significance statementAlthough well-established models of attention rest on the assumption that irrelevant sensory information is filtered out, the neural implementation of such a filter mechanism is unclear. Using an auditory attention task that decouples target selection from distractor suppression, we demonstrate that two sign-reversed lateralized alpha responses reflect target selection versus distractor suppression. Critically, these alpha responses are reliable, independent of each other, and generated in more anterior, frontal regions for suppression versus selection. Prediction of single-trial task performance from alpha modulation after stimulus onset agrees with the view that alpha modulation bears direct functional relevance as a neural implementation of attention. Results demonstrate that the neurobiological foundation of attention implies a selection-independent alpha oscillatory mechanism to suppress distraction.

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When You Do Not Get the Whole Picture: Scene Perception After Occipital Cortex Lesions

Frontiers in Neuroscience ◽

10.3389/fnins.2021.716273 ◽

2021 ◽

Vol 15 ◽

Author(s):

Anna C. Geuzebroek ◽

Karlijn Woutersen ◽

Albert V. van den Berg

Keyword(s):

Everyday Life ◽

Visual Processing ◽

Visual Information ◽

Scene Perception ◽

Occipital Cortex ◽

Scene Recognition ◽

Visual Field Defects ◽

Humphrey Perimetry ◽

Neuroimaging Data ◽

The Individual

Background: Occipital cortex lesions (OCLs) typically result in visual field defects (VFDs) contralateral to the damage. VFDs are usually mapped with perimetry involving the detection of point targets. This, however, ignores the important role of integration of visual information across locations in many tasks of everyday life. Here, we ask whether standard perimetry can fully characterize the consequences of OCLs. We compare performance on a rapid scene discrimination task of OCL participants and healthy observers with simulated VFDs. While the healthy observers will only suffer the loss of part of the visual scene, the damage in the OCL participants may further compromise global visual processing.Methods: VFDs were mapped with Humphrey perimetry, and participants performed two rapid scene discrimination tasks. In healthy participants, the VFDs were simulated with hemi- and quadrant occlusions. Additionally, the GIST model, a computational model of scene recognition, was used to make individual predictions based on the VFDs.Results: The GIST model was able to predict the performance of controls regarding the effects of the local occlusion. Using the individual predictions of the GIST model, we can determine that the variability between the OCL participants is much larger than the extent of the VFD could account for. The OCL participants can further be categorized as performing worse, the same, or better as their VFD would predict.Conclusions: While in healthy observers the extent of the simulated occlusion accounts for their performance loss, the OCL participants’ performance is not fully determined by the extent or shape of their VFD as measured with Humphrey perimetry. While some OCL participants are indeed only limited by the local occlusion of the scene, for others, the lesions compromised the visual network in a more global and disruptive way. Yet one outperformed a healthy observer, suggesting a possible adaptation to the VFD. Preliminary analysis of neuroimaging data suggests that damage to the lateral geniculate nucleus and corpus callosum might be associated with the larger disruption of rapid scene discrimination. We believe our approach offers a useful behavioral tool for investigating why similar VFDs can produce widely differing limitations in everyday life.

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Reduced alpha amplitudes predict perceptual suppression

Scientific Reports ◽

10.1038/s41598-021-92404-8 ◽

2021 ◽

Vol 11 (1) ◽

Author(s):

Eva Poland ◽

Aishwarya Bhonsle ◽

Iris Steinmann ◽

Melanie Wilke

Keyword(s):

Visual Awareness ◽

Occipital Cortex ◽

Threshold Level ◽

Stimulus Onset ◽

Alpha Activity ◽

Motion Onset ◽

Full Field ◽

Motion Stimulus ◽

The Individual ◽

Target Visibility

AbstractThe amplitude of prestimulus alpha oscillations over parieto-occipital cortex has been shown to predict visual detection of masked and threshold-level stimuli. Whether alpha activity similarly predicts target visibility in perceptual suppression paradigms, another type of illusion commonly used to investigate visual awareness, is presently unclear. Here, we examined prestimulus alpha activity in the electroencephalogram (EEG) of healthy participants in the context of a generalized flash suppression (GFS) task during which salient target stimuli are rendered subjectively invisible in a subset of trials following the onset of a full-field motion stimulus. Unlike for masking or threshold paradigms, alpha (8–12 Hz) amplitude prior to motion onset was significantly higher when targets remained subjectively visible compared to trials during which the targets became perceptually suppressed. Furthermore, individual prestimulus alpha amplitudes strongly correlated with the individual trial-to-trial variability quenching following motion stimulus onset, indicating that variability quenching in visual cortex is closely linked to prestimulus alpha activity. We conclude that predictive correlates of conscious perception derived from perceptual suppression paradigms differ substantially from those obtained with “near threshold paradigms”, possibly reflecting the effectiveness of the suppressor stimulus.

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