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Stanislas Dehaene - One of the best experts on this subject based on the ideXlab platform.
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A theory of working memory without Consciousness or sustained activity
eLife, 2017Co-Authors: Darinka Trübutschek, Jean-rémi King, Sébastien Marti, Andrés Ojeda, Misha Tsodyks, Stanislas DehaeneAbstract:Working memory and Conscious Perception are thought to share similar brain mechanisms, yet recent reports of non-Conscious working memory challenge this view. Combining visual masking with magnetoencephalography, we investigate the reality of non-Conscious working memory and dissect its neural mechanisms. In a spatial delayed-response task, participants reported the location of a subjectively unseen target above chance-level after several seconds. Conscious Perception and Conscious working memory were characterized by similar signatures: a sustained desynchronization in the alpha/beta band over frontal cortex, and a decodable representation of target location in posterior sensors. During non-Conscious working memory, such activity vanished. Our findings contradict models that identify working memory with sustained neural firing, but are compatible with recent proposals of 'activity-silent' working memory. We present a theoretical framework and simulations showing how slowly decaying synaptic changes allow cell assemblies to go dormant during the delay, yet be retrieved above chance-level after several seconds.
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decoding the dynamics of Conscious Perception the temporal generalization method
2016Co-Authors: Stanislas Dehaene, Jean-rémi KingAbstract:Parsing a cognitive task into a sequence of successive operations is a central problem in cognitive neuroscience. A major advance is now possible thanks to the application of pattern classifiers to time-resolved recordings of brain activity [electro-encephalography (EEG), magneto-encephalography (MEG), or intracranial recordings]. The method determines precisely when a specific mental content becomes explicitly represented in brain activity. Most importantly, the ability of these pattern classifiers to generalize across time and experimental conditions sheds light on the temporal organization of information-processing stages. To illustrate these ideas, we show how the decoding of MEG and EEG recordings can be used to track the fate of Conscious and unConscious brain processes during simple masking and auditory novelty tasks. The experimental results yield converging results, suggesting that Conscious Perception is associated with the late formation of a distributed and stable neural assembly that encodes the content of subjective Perception.
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levels of processing during non Conscious Perception a critical review of visual masking
Philosophical Transactions of the Royal Society B, 2007Co-Authors: Sid Kouider, Stanislas DehaeneAbstract:Understanding the extent and limits of non-Conscious processing is an important step on the road to a thorough understanding of the cognitive and cerebral correlates of Conscious Perception. In thi...
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levels of processing during non Conscious Perception a critical review of visual masking
Philosophical Transactions of the Royal Society B, 2007Co-Authors: Sid Kouider, Stanislas DehaeneAbstract:Understanding the extent and limits of non-Conscious processing is an important step on the road to a thorough understanding of the cognitive and cerebral correlates of Conscious Perception. In this article, we present a critical review of research on subliminal Perception during masking and other related experimental conditions. Although initially controversial, the possibility that a broad variety of processes can be activated by a non-reportable stimulus is now well established. Behavioural findings of subliminal priming indicate that a masked word or digit can have an influence on perceptual, lexical and semantic levels, while neuroimaging directly visualizes the brain activation that it evokes in several cortical areas. This activation is often attenuated under subliminal presentation conditions compared to Consciously reportable conditions, but there are sufficiently many exceptions, in paradigms such as the attentional blink, to indicate that high activation, per se, is not a sufficient condition for Conscious access to occur. We conclude by arguing that for a stimulus to reach Consciousness, two factors are jointly needed: (i) the input stimulus must have enough strength (which can be prevented by masking) and (ii) it must receive top-down attention (which can be prevented by drawing attention to another stimulus or task). This view leads to a distinction between two types of non-Conscious processes, which we call subliminal and preConscious. According to us, maintaining this distinction is essential in order to make sense of the growing neuroimaging data on the neural correlates of Consciousness.
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nonConscious semantic processing of emotional words modulates Conscious access
Proceedings of the National Academy of Sciences of the United States of America, 2006Co-Authors: Raphaa L Gaillard, Fabien Vinckier, Lionel Naccache, Laurent D. Cohen, Stanislas DehaeneAbstract:Whether masked words can be processed at a semantic level remains a controversial issue in cognitive psychology. Although recent behavioral studies have demonstrated masked semantic priming for number words, attempts to generalize this finding to other categories of words have failed. Here, as an alternative to subliminal priming, we introduce a sensitive behavioral method to detect nonConscious semantic processing of words. The logic of this method consists of presenting words close to the threshold for Conscious Perception and examining whether their semantic content modulates performance in objective and subjective tasks. Our results disclose two independent sources of modulation of the threshold for access to Consciousness. First, prior Conscious Perception of words increases the detection rate of the same words when they are subsequently presented with stronger masking. Second, the threshold for Conscious access is lower for emotional words than for neutral ones, even for words that have not been previously Consciously perceived, thus implying that written words can receive nonConscious semantic processing.
Brian Maniscalco - One of the best experts on this subject based on the ideXlab platform.
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initial state dependent robust transient neural dynamics encode Conscious visual Perception
PLOS Computational Biology, 2017Co-Authors: Alexis T Baria, Brian ManiscalcoAbstract:Recent research has identified late-latency, long-lasting neural activity as a robust correlate of Conscious Perception. Yet, the dynamical nature of this activity is poorly understood, and the mechanisms governing its presence or absence and the associated Conscious Perception remain elusive. We applied dynamic-pattern analysis to whole-brain slow (< 5 Hz) cortical dynamics recorded by magnetoencephalography (MEG) in human subjects performing a threshold-level visual Perception task. Up to 1 second before stimulus onset, brain activity pattern across widespread cortices significantly predicted whether a threshold-level visual stimulus was later Consciously perceived. This initial state of brain activity interacts nonlinearly with stimulus input to shape the evolving cortical activity trajectory, with seen and unseen trials following well separated trajectories. We observed that cortical activity trajectories during Conscious Perception are fast evolving and robust to small variations in the initial state. In addition, spontaneous brain activity pattern prior to stimulus onset also influences unConscious perceptual making in unseen trials. Together, these results suggest that brain dynamics underlying Conscious visual Perception belongs to the class of initial-state-dependent, robust, transient neural dynamics.
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on a failed attempt to manipulate Conscious Perception with transcranial magnetic stimulation to prefrontal cortex
bioRxiv, 2017Co-Authors: Eugene Ruby, Hakwan Lau, Brian Maniscalco, Megan A K PetersAbstract:It has been reported that continuous theta burst transcranial magnetic stimulation (TMS) to the dorsolateral prefrontal cortex (DLPFC) impairs metacognitive awareness in visual Perception (Rounis et al., 2010). Bor et al. (2017) recently attempted to replicate this result. However, the authors modified the experimental design of the original study considerably, meaning that this was not strictly a replication. In some cases, the changes are a priori expected to lower the chance of obtaining positive findings. Despite these changes, the researchers in fact still found an effect similar to Rounis et al.9s, but they claimed that it was necessary to adopt certain criteria to discard ~30% of their subjects, after which a null result was reported. Using computer simulations, we evaluated whether the subject exclusion criteria Bor et al. adopted was appropriate or beneficial. We found that, contrary to their intended purpose, excluding subjects by their criteria does not actually reduce false positive rates. Taking into account both their positive result (without subject exclusion) and negative result (after exclusion) in a Bayesian framework, we further found that their results suggest a 75% or greater likelihood that TMS to DLPFC does in fact impair metacognition, directly contradicting their claim of replication failure. That lesion and chemical inactivation studies are known to demonstrate positive effects in similar paradigms further suggests that Bor et al.9s alleged negative finding cannot be taken as evidence against the role of the prefrontal cortex in Conscious Perception in general.
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initial state dependent robust transient neural dynamics encode Conscious visual Perception
bioRxiv, 2017Co-Authors: Alexis T Baria, Brian ManiscalcoAbstract:Recent research has identified late-latency, long-lasting neural activity as a robust correlate of Conscious Perception. Yet, the dynamical nature of this activity is poorly understood, and the mechanisms governing its presence or absence and the associated Conscious Perception remain elusive. We applied dynamic-pattern analysis to whole-brain slow cortical dynamics recorded by magnetoencephalography (MEG) in human subjects performing a threshold-level visual Perception task. Up to 1 second before stimulus onset, brain activity pattern across widespread cortices significantly predicted whether a threshold-level visual stimulus was later Consciously perceived. This initial state of brain activity interacts nonlinearly with stimulus input to shape the evolving cortical activity trajectory, with seen and unseen trials following well separated trajectories. Furthermore, cortical activity trajectories during Conscious Perception are fast evolving and robust to small variations in the initial state. These results suggest that brain dynamics underlying Conscious visual Perception belongs to the class of initial-state-dependent, robust, transient neural dynamics.
Naotsugu Tsuchiya - One of the best experts on this subject based on the ideXlab platform.
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Conscious Perception of flickering stimuli in binocular rivalry and continuous flash suppression is not affected by tacs induced ssr modulation
Consciousness and Cognition, 2020Co-Authors: Naotsugu Tsuchiya, Georg Schauer, Carolina Yuri Ogawa, A BartelsAbstract:Abstract The content of Conscious Perception is known to correlate with steady-state responses (SSRs), yet their causal relationship remains unclear. Can we manipulate Conscious Perception by directly interfering with SSRs through transcranial alternating current stimulation (tACS)? Here, we directly addressed this question in three experiments involving binocular rivalry and continuous flash suppression (CFS). Specifically, while participants (N = 24) viewed either binocular rivalry or tried to detect stimuli masked by CFS, we applied sham or real tACS across parieto-occipital cortex at either the same or a different frequency and phase as an SSR eliciting flicker stimulus. We found that tACS did not differentially affect Conscious Perception in the forms of predominance, CFS detection accuracy, reaction time, or metacognitive sensitivity, confirmed by Bayesian statistics. We conclude that tACS application at frequencies of stimulus-induced SSRs does not have perceptual effects and that SSRs may be epiphenomenal to Conscious Perception.
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Conscious access in the near absence of attention critical extensions on the dual task paradigm
Philosophical Transactions of the Royal Society B, 2018Co-Authors: Julian Matthews, Pia Schröder, Lisandro Kaunitz, Jeroen Van Boxtel, Naotsugu TsuchiyaAbstract:Whether Conscious Perception requires attention remains a topic of intense debate. While certain complex stimuli such as faces and animals can be discriminated outside the focus of spatial attentio...
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attention periodically samples competing stimuli during binocular rivalry
bioRxiv, 2018Co-Authors: Matthew J Davidson, Jeroen J A Van Boxtel, David Alais, Naotsugu TsuchiyaAbstract:The attentional sampling hypothesis suggests attention periodically enhances sensory processing. We investigated whether periodic sampling also acts as a gateway for attended stimuli competing for perceptual dominance. Here we report that during binocular rivalry crossmodal cues directed towards perceptually dominant stimuli resulted in an ~8 Hz attentional sampling rate, consistent with undivided attention. Conversely, crossmodal cues directed towards perceptually suppressed visual images resulted in an ~3.5 Hz attentional sampling rate, indicating that attentional sampling can be divided away from a Conscious visual image. At these attentional sampling frequencies, the strength of inter-trial phase coherence over lateral-occipital and fronto-temporal cortex correlated with behavioral measures of changes in Conscious Perception, suggesting this mechanism acted to bind crossmodal stimuli into a single perceptual object. When crossmodal cues were not task-relevant, these effects disappeared, confirming that changes in Conscious Perception were dependent upon the allocation of attention, which flexibly samples stimuli in a task-dependent manner.
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Conscious Perception as Integrated Information Patterns in Human Electrocorticography
eNeuro, 2017Co-Authors: Andrew M Haun, Masafumi Oizumi, Christopher K Kovach, Hiroto Kawasaki, Matthew A Howard, Ralph Adolphs, Hiroyuki Oya, Naotsugu TsuchiyaAbstract:A significant problem in neuroscience concerns the distinction between neural processing that is correlated with Conscious percepts from processing that is not. Here, we tested if a hierarchical structure of causal interactions between neuronal populations correlates with Conscious Perception. We derived the hierarchical causal structure as a pattern of integrated information, inspired by the integrated information theory (IIT) of Consciousness. We computed integrated information patterns from intracranial electrocorticography (ECoG) from six human neurosurgical patients with electrodes implanted over lateral and ventral cortices. During recording, subjects viewed continuous flash suppression (CFS) and backward masking (BM) stimuli intended to dissociate Conscious percept from stimulus, and unmasked suprathreshold stimuli. Object-sensitive areas revealed correspondence between Conscious percepts and integrated information patterns. We quantified this correspondence using unsupervised classification methods that revealed clustering of visual experiences with integrated information, but not with broader information measures including mutual information and entropy. Our findings point to a significant role of locally integrated information for understanding the neural substrate of Conscious object Perception.
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Conscious Perception as integrated information patterns in human electrocorticography
eNeuro, 2017Co-Authors: Andrew M Haun, Masafumi Oizumi, Christopher K Kovach, Hiroto Kawasaki, Matthew A Howard, Ralph Adolphs, Naotsugu TsuchiyaAbstract:A significant problem in neuroscience concerns the distinction between neural processing that is correlated with Conscious percepts from processing that is not. Here, we tested if a hierarchical structure of causal interactions between neuronal populations correlates with Conscious Perception. We derived the hierarchical causal structure as a pattern of integrated information, inspired by the integrated information theory (IIT) of Consciousness. We computed integrated information patterns from intracranial electrocorticography (ECoG) from six human neurosurgical patients with electrodes implanted over lateral and ventral cortices. During recording, subjects viewed continuous flash suppression (CFS) and backward masking (BM) stimuli intended to dissociate Conscious percept from stimulus, and unmasked suprathreshold stimuli. Object-sensitive areas revealed correspondence between Conscious percepts and integrated information patterns. We quantified this correspondence using unsupervised classification methods that revealed clustering of visual experiences with integrated information, but not with broader information measures including mutual information and entropy. Our findings point to a significant role of locally integrated information for understanding the neural substrate of Conscious object Perception.
Heleen A. Slagter - One of the best experts on this subject based on the ideXlab platform.
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Conscious Perception and the modulatory role of dopamine no effect of the dopamine d2 agonist cabergoline on visual masking the attentional blink and probabilistic discrimination
Psychopharmacology, 2020Co-Authors: E A Boonstra, M R Van Schouwenburg, Anil K Seth, Markus Bauer, J B Zantvoord, E M Kemper, C S Lansink, Heleen A. SlagterAbstract:Conscious Perception is thought to depend on global amplification of sensory input. In recent years, striatal dopamine has been proposed to be involved in gating information and Conscious access, due to its modulatory influence on thalamocortical connectivity. Since much of the evidence that implicates striatal dopamine is correlational, we conducted a double-blind crossover pharmacological study in which we administered cabergoline—a dopamine D2 agonist—and placebo to 30 healthy participants. Under both conditions, we subjected participants to several well-established experimental Conscious-Perception paradigms, such as backward masking and the attentional blink task. We found no evidence in support of an effect of cabergoline on Conscious Perception: key behavioral and event-related potential (ERP) findings associated with each of these tasks were unaffected by cabergoline. Our results cast doubt on a causal role for dopamine in visual Perception. It remains an open possibility that dopamine has causal effects in other tasks, perhaps where perceptual uncertainty is more prominent.
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Contributions of the ventral striatum to Conscious Perception : An intracranial EEG study of the attentional blink
The Journal of Neuroscience, 2016Co-Authors: Heleen A. Slagter, Ali Mazaheri, Leon C. Reteig, Ruud Smolders, P. Richard Schuurman, Mariska Mantione, Martijn Figee, Damiaan DenysAbstract:The brain is limited in its capacity to Consciously process information, necessitating gating of information. While Conscious Perception is robustly associated with sustained, recurrent interactions between widespread cortical regions, subcortical regions, including the striatum, influence cortical activity. Here, we examined if the ventral striatum, given its ability to modulate cortical information flow, contributes to Conscious Perception. Using intracranial EEG, we recorded ventral striatum activity while 7 patients performed an attentional blink task in which they had to detect two targets (T1 and T2) in a stream of distractors. Typically, when T2 follows T1 within 100-500ms, it is often not perceived (i.e., the attentional blink). We found that Conscious T2 Perception was influenced and signaled by ventral striatal activity. Specifically, the failure to perceive T2 was foreshadowed by a T1-induced increase in alpha and low beta oscillatory activity as early as 80ms post-T1, indicating that the attentional blink to T2 may be due to very early T1-driven attentional capture. Moreover, only Consciously perceived targets were associated with an increase in theta activity between 200-400ms. These unique findings shed new light on the mechanisms that give rise to the attentional blink by revealing that Conscious target Perception may be determined by T1 processing at a much earlier processing stage than traditionally believed. More generally, they indicate that ventral striatum activity may contribute to Conscious Perception, presumably by gating cortical information flow. SIGNIFICANCE STATEMENT: What determines whether we become aware of a piece of information or not? Conscious access has been robustly associated with activity within a distributed network of cortical regions. Using intracranial electrophysiological recordings during an attentional blink task, we tested the idea that the ventral striatum, because of its ability to modulate cortical information flow, may contribute to Conscious Perception. We find that Conscious Perception is influenced, and signaled by ventral striatal activity; Short-latency (80-140ms) striatal responses to a first target determined Conscious Perception of a second target. Moreover, Conscious Perception of the second target was signaled by longer-latency (200-400ms) striatal activity. These results suggest that the ventral striatum may be part of a subcortical network that influences Conscious experience.
E A Boonstra - One of the best experts on this subject based on the ideXlab platform.
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Conscious Perception and the modulatory role of dopamine no effect of the dopamine d2 agonist cabergoline on visual masking the attentional blink and probabilistic discrimination
Psychopharmacology, 2020Co-Authors: E A Boonstra, M R Van Schouwenburg, Anil K Seth, Markus Bauer, J B Zantvoord, E M Kemper, C S Lansink, Heleen A. SlagterAbstract:Conscious Perception is thought to depend on global amplification of sensory input. In recent years, striatal dopamine has been proposed to be involved in gating information and Conscious access, due to its modulatory influence on thalamocortical connectivity. Since much of the evidence that implicates striatal dopamine is correlational, we conducted a double-blind crossover pharmacological study in which we administered cabergoline—a dopamine D2 agonist—and placebo to 30 healthy participants. Under both conditions, we subjected participants to several well-established experimental Conscious-Perception paradigms, such as backward masking and the attentional blink task. We found no evidence in support of an effect of cabergoline on Conscious Perception: key behavioral and event-related potential (ERP) findings associated with each of these tasks were unaffected by cabergoline. Our results cast doubt on a causal role for dopamine in visual Perception. It remains an open possibility that dopamine has causal effects in other tasks, perhaps where perceptual uncertainty is more prominent.