Fast Backprojections from the Motion to the Primary Visual Area Necessary for Visual Awareness

Pascual‐Leone, Álvaro; Walsh, Vincent

doi:10.1126/science.1057099

Cited by 703 publications

(478 citation statements)

References 35 publications

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“…with latencies in the magnocellular pathway being less than those in the parvocellular pathway) (Lamme & Roelfsema, 2000). Recurrent interactions between feedforward and feedback activity also occur on the timescale of a few 10s of ms (Bullier, 2001;Hupe et al, 2001;Pascual-Leone & Walsh, 2001). As all of these activities need to be processed as a whole, this suggests that activities occurring within a few 10s of ms are grouped.…”

Section: Discussionmentioning

confidence: 99%

Pop-out from abrupt visual onsets

Hancock

Phillips

2004

Vision Research

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We report a novel psychophysical paradigm that distinguishes the information present in abrupt stimulus onset from that in the following display. The task is to pick the one odd item from a set added to a pre-existing background of similar items. When all new items are added simultaneously, observers are impaired even at distinguishing one red item amongst several green ones. An asynchrony of about 40ms between target and distracter items restores performance, with evidence that it is cortical, rather than stimulus timing difference that is significant. The results are consistent with a role for neural synchrony in dynamic grouping.

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Section: Discussionmentioning

confidence: 99%

Pop-out from abrupt visual onsets

Hancock

Phillips

2004

Vision Research

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“…Importantly, there is substantial evidence to suggest that top-down processes not only play an important role in sensory processing in general but also are crucial for conscious perception, in particular [75][76][77][78][79][80][81][82] (see also the review articles by Pollen, 83 Lamme and Roelfsema, 84 Bullier, 85 Hochstein and Ahissar, 86 and Meyer 87 ). For example, when subjects perceive apparent motion (as is the case when two dots in different locations are seen in rapid alteration, creating the impression that a single dot is moving from one location to the other), there is V1 activity along the apparent motion trace (where there is no actual visual stimulus), and this activity is induced by top-down signals.…”

Section: Top-down Signals and Conscious Perception: What We Already Knowmentioning

confidence: 99%

The Role of Dendritic Signaling in the Anesthetic Suppression of Consciousness

Meyer

2015

Anesthesiology

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Despite considerable progress in the identification of the molecular targets of general anesthetics, it remains unclear how these drugs affect the brain at the systems level to suppress consciousness. According to recent proposals, anesthetics may achieve this feat by interfering with corticocortical topdown processes, that is, by interrupting information flow from association to early sensory cortices. Such a view entails two immediate questions. First, at which anatomical site, and by virtue of which physiological mechanism, do anesthetics interfere with top-down signals? Second, why does a breakdown of top-down signaling cause unconsciousness? While an answer to the first question can be gleaned from emerging neurophysiological evidence on dendritic signaling in cortical pyramidal neurons, a response to the second is offered by increasingly popular theoretical frameworks that place the element of prediction at the heart of conscious perception. Science magazine posed this question in a special section titled "What don't we know?," dedicated to the greatest challenges of contemporary science. 1 "Scientists are chipping away at the drugs' effects on individual neurons," the article reads, "but understanding how they render us unconscious will be a tougher nut to crack." This prediction proved correct: a decade later, we have expanded considerably our knowledge of the molecular targets of general anesthetics, but it remains enigmatic how these drugs affect the brain at the systems level. Why does the potentiation of γ-aminobutyric acid (GABA) receptors caused by propofol or desflurane cause unconsciousness? How are the brain's computational processes affected by this and other molecular mechanisms of anesthetics, so that patients undergoing surgery cease to experience their surrounds in terms of sight, sound, and touch? Anesthesiologists and cognitive neuroscientists alike have been captivated by these questions and have proposed a number of models in an attempt to answer them, such as Flohr's "information processing theory of anesthesia," 2 Alkire's "thalamic consciousness switch hypothesis," 3-6 Mashour's "cognitive unbinding paradigm," 7,8 John and Prichep's "anesthetic cascade," 9 or Hudetz's "forgotten present." 10,11 We shall return to some of these frameworks in a later section of the article.One recent development is particularly intriguing. Given that the most striking feature of general anesthesia is an interruption of the patient's ability to perceive the environment, it would appear intuitive for anesthetics to interfere primarily with bottom-up information flow along the sensory pathways, that is, with the signals that carry perceptual information from the thalamus to the primary sensory cortices and on to unimodal and multimodal association cortices. However, the very opposite appears to be the case. Several recent studies-carried out in both humans and animals, and using a variety of different anesthetic agents-have investigated differences in directional corticocortical connectivity bet...

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“…Each time information reaches a successive stage in this hierarchy, this higher level area also starts to sent information back to lower level areas through feedback connections. Single-cell recordings in monkeys (Super, Spekreijse, & Lamme, 2001) and TMS (Pascual-Leone & Walsh, 2001), fMRI (Haynes, Driver, & Rees, 2005), and EEG (Fahrenfort, Scholte, & Lamme, 2007) experiments in humans have revealed that the feedforward sweep probably remains unconscious, whereas recurrent interactions trigger awareness of a stimulus (for reviews, see Dehaene et al, 2006;Lamme, 2006). Interestingly, masking probably disrupts feedback activations but leaves feedforward activations relatively intact (Del Cul, Baillet, & Dehaene, 2007;Fahrenfort et al, 2007;Lamme, Zipser, & Spekreijse, 2002).…”

Section: Underlying Neural Mechanisms Of Conscious Versus Unconsciousmentioning

confidence: 99%

Dissociable Brain Mechanisms Underlying the Conscious and Unconscious Control of Behavior

Gaal¹,

Lamme²,

Fahrenfort³

et al. 2011

Journal of Cognitive Neuroscience

107

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General rightsIt is not permitted to download or to forward/distribute the text or part of it without the consent of the author(s) and/or copyright holder(s), other than for strictly personal, individual use, unless the work is under an open content license (like Creative Commons). Disclaimer/Complaints regulationsIf you believe that digital publication of certain material infringes any of your rights or (privacy) interests, please let the Library know, stating your reasons. In case of a legitimate complaint, the Library will make the material inaccessible and/or remove it from the website. Please Ask the Library: http://uba.uva.nl/en/contact, or a letter to: Library of the University of Amsterdam, Secretariat, Singel 425, 1012 WP Amsterdam, The Netherlands. You will be contacted as soon as possible. Thus, the N2 likely reflects the initiation of inhibitory control, irrespective of conscious awareness. The P3 component was much reduced in amplitude and duration on masked versus unmasked stop trials. These patterns of differences and similarities between conscious and unconscious cognitive control processes are discussed in a framework that differentiates between feedforward and feedback connections in yielding conscious experience.

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Fast Backprojections from the Motion to the Primary Visual Area Necessary for Visual Awareness

Cited by 703 publications

References 35 publications

Pop-out from abrupt visual onsets

Pop-out from abrupt visual onsets

The Role of Dendritic Signaling in the Anesthetic Suppression of Consciousness

Dissociable Brain Mechanisms Underlying the Conscious and Unconscious Control of Behavior

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