1
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Bachmann T. What do the pre-stimulus brain-process markers really mean vis-à-vis the NCC?: A commentary on "Beyond task response-Pre-stimulus activity modulates contents of consciousness" by Northoff, Zilio, and Zhang. Phys Life Rev 2024; 50:7-9. [PMID: 38762980 DOI: 10.1016/j.plrev.2024.05.002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2024] [Accepted: 05/13/2024] [Indexed: 05/21/2024]
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2
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Motlagh SC, Joanisse M, Wang B, Mohsenzadeh Y. Unveiling the neural dynamics of conscious perception in rapid object recognition. Neuroimage 2024; 296:120668. [PMID: 38848982 DOI: 10.1016/j.neuroimage.2024.120668] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2023] [Revised: 05/23/2024] [Accepted: 06/05/2024] [Indexed: 06/09/2024] Open
Abstract
Our brain excels at recognizing objects, even when they flash by in a rapid sequence. However, the neural processes determining whether a target image in a rapid sequence can be recognized or not remains elusive. We used electroencephalography (EEG) to investigate the temporal dynamics of brain processes that shape perceptual outcomes in these challenging viewing conditions. Using naturalistic images and advanced multivariate pattern analysis (MVPA) techniques, we probed the brain dynamics governing conscious object recognition. Our results show that although initially similar, the processes for when an object can or cannot be recognized diverge around 180 ms post-appearance, coinciding with feedback neural processes. Decoding analyses indicate that gist perception (partial conscious perception) can occur at ∼120 ms through feedforward mechanisms. In contrast, object identification (full conscious perception of the image) is resolved at ∼190 ms after target onset, suggesting involvement of recurrent processing. These findings underscore the importance of recurrent neural connections in object recognition and awareness in rapid visual presentations.
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Affiliation(s)
- Saba Charmi Motlagh
- Western Center for Brain and Mind, Western University, London, Ontario, Canada; Vector Institute for Artificial Intelligence, Toronto, Ontario, Canada
| | - Marc Joanisse
- Western Center for Brain and Mind, Western University, London, Ontario, Canada; Department of Psychology, Western University, London, Ontario, Canada
| | - Boyu Wang
- Western Center for Brain and Mind, Western University, London, Ontario, Canada; Vector Institute for Artificial Intelligence, Toronto, Ontario, Canada; Department of Computer Science, Western University, London, Ontario, Canada
| | - Yalda Mohsenzadeh
- Western Center for Brain and Mind, Western University, London, Ontario, Canada; Vector Institute for Artificial Intelligence, Toronto, Ontario, Canada; Department of Computer Science, Western University, London, Ontario, Canada.
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3
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Chis-Ciure R, Melloni L, Northoff G. A measure centrality index for systematic empirical comparison of consciousness theories. Neurosci Biobehav Rev 2024; 161:105670. [PMID: 38615851 DOI: 10.1016/j.neubiorev.2024.105670] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2024] [Revised: 03/15/2024] [Accepted: 04/08/2024] [Indexed: 04/16/2024]
Abstract
Consciousness science is marred by disparate constructs and methodologies, making it challenging to systematically compare theories. This foundational crisis casts doubts on the scientific character of the field itself. Addressing it, we propose a framework for systematically comparing consciousness theories by introducing a novel inter-theory classification interface, the Measure Centrality Index (MCI). Recognizing its gradient distribution, the MCI assesses the degree of importance a specific empirical measure has for a given consciousness theory. We apply the MCI to probe how the empirical measures of the Global Neuronal Workspace Theory (GNW), Integrated Information Theory (IIT), and Temporospatial Theory of Consciousness (TTC) would fare within the context of the other two. We demonstrate that direct comparison of IIT, GNW, and TTC is meaningful and valid for some measures like Lempel-Ziv Complexity (LZC), Autocorrelation Window (ACW), and possibly Mutual Information (MI). In contrast, it is problematic for others like the anatomical and physiological neural correlates of consciousness (NCC) due to their MCI-based differential weightings within the structure of the theories. In sum, we introduce and provide proof-of-principle of a novel systematic method for direct inter-theory empirical comparisons, thereby addressing isolated evolution of theories and confirmatory bias issues in the state-of-the-art neuroscience of consciousness.
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Affiliation(s)
- Robert Chis-Ciure
- New York University (NYU), New York, USA; International Center for Neuroscience and Ethics (CINET), Tatiana Foundation, Madrid, Spain; Wolfram Physics Project, USA.
| | - Lucia Melloni
- Max Planck Institute for Empirical Aesthetics, Frankfurt am Main, Germany
| | - Georg Northoff
- University of Ottawa, Institute of Mental Health Research at the Royal Ottawa Hospital, Ottawa, Canada
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4
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Huntley J, Bor D, Deng F, Mancuso M, Mediano PAM, Naci L, Owen AM, Rocchi L, Sternin A, Howard R. Assessing awareness in severe Alzheimer's disease. Front Hum Neurosci 2023; 16:1035195. [PMID: 36819296 PMCID: PMC9930987 DOI: 10.3389/fnhum.2022.1035195] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2022] [Accepted: 12/30/2022] [Indexed: 02/04/2023] Open
Abstract
There is an urgent need to understand the nature of awareness in people with severe Alzheimer's disease (AD) to ensure effective person-centered care. Objective biomarkers of awareness validated in other clinical groups (e.g., anesthesia, minimally conscious states) offer an opportunity to investigate awareness in people with severe AD. In this article we demonstrate the feasibility of using Transcranial magnetic stimulation (TMS) combined with EEG, event related potentials (ERPs) and fMRI to assess awareness in severe AD. TMS-EEG was performed in six healthy older controls and three people with severe AD. The perturbational complexity index (PCIST) was calculated as a measure of capacity for conscious awareness. People with severe AD demonstrated a PCIST around or below the threshold for consciousness, suggesting reduced capacity for consciousness. ERPs were recorded during a visual perception paradigm. In response to viewing faces, two patients with severe AD provisionally demonstrated similar visual awareness negativity to healthy controls. Using a validated fMRI movie-viewing task, independent component analysis in two healthy controls and one patient with severe AD revealed activation in auditory, visual and fronto-parietal networks. Activation patterns in fronto-parietal networks did not significantly correlate between the patient and controls, suggesting potential differences in conscious awareness and engagement with the movie. Although methodological issues remain, these results demonstrate the feasibility of using objective measures of awareness in severe AD. We raise a number of challenges and research questions that should be addressed using these biomarkers of awareness in future studies to improve understanding and care for people with severe AD.
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Affiliation(s)
- Jonathan Huntley
- Division of Psychiatry, University College London, London, United Kingdom
| | - Daniel Bor
- Department of Psychology, University of Cambridge, Cambridge, United Kingdom
| | - Feng Deng
- School of Psychology, Trinity College Dublin, Global Brain Health Institute, Dublin, Ireland
| | - Marco Mancuso
- Human Neuroscience Department, Sapienza University of Rome, Rome, Italy
| | - Pedro A. M. Mediano
- Department of Psychology, University of Cambridge, Cambridge, United Kingdom
| | - Lorina Naci
- School of Psychology, Trinity College Dublin, Global Brain Health Institute, Dublin, Ireland
| | - Adrian M. Owen
- Department of Physiology and Pharmacology, Brain and Mind Institute, University of Western Ontario, London, ON, Canada
- Department of Psychology, Brain and Mind Institute, University of Western Ontario, London, ON, Canada
| | - Lorenzo Rocchi
- Institute of Neurology, University College London, London, United Kingdom
| | - Avital Sternin
- Department of Physiology and Pharmacology, Brain and Mind Institute, University of Western Ontario, London, ON, Canada
- Department of Psychology, Brain and Mind Institute, University of Western Ontario, London, ON, Canada
| | - Robert Howard
- Division of Psychiatry, University College London, London, United Kingdom
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5
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Conscious interpretation: A distinct aspect for the neural markers of the contents of consciousness. Conscious Cogn 2023; 108:103471. [PMID: 36736210 DOI: 10.1016/j.concog.2023.103471] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2022] [Revised: 12/22/2022] [Accepted: 01/11/2023] [Indexed: 02/04/2023]
Abstract
Progress in the science of consciousness depends on the experimental paradigms and varieties of contrastive analysis available to researchers. Here we highlight paradigms where the object is represented in consciousness as a set of its features but the interpretation of this set alternates in consciousness. We group experimental paradigms with this property under the label "conscious interpretation". We compare the paradigms studying conscious interpretation of the already consciously perceived objects with other types of experimental paradigms. We review previous and recent studies investigating this interpretative aspect of consciousness and propose future directions. We put forward the hypothesis that there are types of stimuli with a hierarchy of interpretations for which the rule applies: conscious experience is drawn towards higher-level interpretation and reverting back to the lower level of interpretation is impossible. We discuss how theories of consciousness might incorporate knowledge and constraints arising from the characteristics of conscious interpretation.
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6
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Almeida VN. The neural hierarchy of consciousness. Neuropsychologia 2022; 169:108202. [PMID: 35271856 DOI: 10.1016/j.neuropsychologia.2022.108202] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2021] [Revised: 02/25/2022] [Accepted: 03/01/2022] [Indexed: 01/08/2023]
Abstract
The chief undertaking in the studies of consciousness is that of unravelling "the minimal set of neural processes that are together sufficient for the conscious experience of a particular content - the neural correlates of consciousness". To this day, this crusade remains at an impasse, with a clash of two main theories: consciousness may arise either in a graded and cortically-localised fashion, or in an all-or-none and widespread one. In spite of the long-lasting theoretical debates, neurophysiological theories of consciousness have been mostly dissociated from them. Herein, a theoretical review will be put forth with the aim to change that. In its first half, we will cover the hard available evidence on the neurophysiology of consciousness, whereas in its second half we will weave a series of considerations on both theories and substantiate a novel take on conscious awareness: the levels of processing approach, partitioning the conscious architecture into lower- and higher-order, graded and nonlinear.
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Affiliation(s)
- Victor N Almeida
- Faculdade de Letras, Universidade Federal de Minas Gerais (UFMG), Av. Pres. Antônio Carlos, 6627, Pampulha, Belo Horizonte, MG, 31270-901, Brazil.
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7
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Sobolev V, Popov M. Measuring the Duration of the Phase of the Formation of a Physiological Phenomenon as a Predictor of Conscious Sensation at the Visual-Motor Reaction "Go / No-Go" – Type in the Paradigm of Backward Masking. EXPERIMENTAL PSYCHOLOGY (RUSSIA) 2022. [DOI: 10.17759/exppsy.2022150415] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
<p>In a psychophysiological experiment, the effect of inhibition of the “Go/No-go” – type differential visual-motor reaction (DVMR) under the influence of a masker stimulus presented at different periods of its implementation was revealed; this effect is manifested in the range of stimulus onset asynchrony (SOA) from 40 to 100 ms. There is a relationship between the latent period of DVMR and the value of the SOA interval, described in a logarithmic scale by the equation of a straight line: the latency of the sensorimotor response is inversely proportional to the logarithm of SOA. The psychophysiological method based on measuring the degree of inhibition of the “Go/No-go” – type DVMR speed in the backward masking paradigm can be used to measure the duration of the formation of a physiological phenomenon as a predictor of conscious sensation. A possible mechanism of inhibition of the rate of realization of the “Go/No-go” – type "reaction during backward masking consists in a decrease in the intensity of the physiological phenomenon under the influence of the masker, which lengthens the latent period of the sensorimotor reaction.</p>
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Affiliation(s)
- V.I. Sobolev
- V.I. Vernadsky Crimean Federal University in Yalta
| | - M.N. Popov
- Academy of the Humanities and Pedagogics (branch) of V.I. Vernadsky Crimean Federal University in Yalta
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8
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Bachmann T. Representational 'touch' and modulatory 'retouch'-two necessary neurobiological processes in thalamocortical interaction for conscious experience. Neurosci Conscious 2021; 2021:niab045. [PMID: 34925911 PMCID: PMC8672242 DOI: 10.1093/nc/niab045] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2021] [Revised: 11/16/2021] [Accepted: 11/30/2021] [Indexed: 12/01/2022] Open
Abstract
Theories of consciousness using neurobiological data or being influenced by these data have been focused either on states of consciousness or contents of consciousness. These theories have occasionally used evidence from psychophysical phenomena where conscious experience is a dependent experimental variable. However, systematic catalog of many such relevant phenomena has not been offered in terms of these theories. In the perceptual retouch theory of thalamocortical interaction, recently developed to become a blend with the dendritic integration theory, consciousness states and contents of consciousness are explained by the same mechanism. This general-purpose mechanism has modulation of the cortical layer-5 pyramidal neurons that represent contents of consciousness as its core. As a surplus, many experimental psychophysical phenomena of conscious perception can be explained by the workings of this mechanism. Historical origins and current views inherent in this theory are presented and reviewed.
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Affiliation(s)
- Talis Bachmann
- Department of Penal Law, Laboratory of Cognitive Neuroscience, School of Law, University of Tartu (Tallinn Branch), Kaarli puiestee 3, Tallinn 10119, Estonia
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9
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Perceptual awareness negativity: a physiological correlate of sensory consciousness. Trends Cogn Sci 2021; 25:660-670. [PMID: 34172384 DOI: 10.1016/j.tics.2021.05.009] [Citation(s) in RCA: 36] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2021] [Revised: 05/20/2021] [Accepted: 05/21/2021] [Indexed: 11/21/2022]
Abstract
Much research on the neural correlates of consciousness (NCC) has focused on two evoked potentials, the P3b and the visual or auditory awareness negativity (VAN, AAN). Surveying a broad range of recent experimental evidence, we find that repeated failures to observe the P3b during conscious perception eliminate it as a putative NCC. Neither the VAN nor the AAN have been dissociated from consciousness; furthermore, a similar neural signal correlates with tactile consciousness. These awareness negativities can be maximal contralateral to the evoking stimulus, are likely generated in underlying sensory cortices, and point to the existence of a generalized perceptual awareness negativity (PAN) reflecting the onset of sensory consciousness.
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10
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Schröder P, Nierhaus T, Blankenburg F. Dissociating Perceptual Awareness and Postperceptual Processing: The P300 Is Not a Reliable Marker of Somatosensory Target Detection. J Neurosci 2021; 41:4686-4696. [PMID: 33849946 PMCID: PMC8260252 DOI: 10.1523/jneurosci.2950-20.2021] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2020] [Revised: 01/26/2021] [Accepted: 03/13/2021] [Indexed: 11/21/2022] Open
Abstract
A central challenge in the study of conscious perception lies in dissociating the neural correlates of perceptual awareness from those reflecting its precursors and consequences. No-report paradigms have been instrumental in this endeavor, demonstrating that the event-related potential P300, recorded from the human scalp, reflects reports rather than awareness. However, these paradigms cannot probe the degree to which stimuli are consciously processed from trial to trial and, thus, leave open the possibility that the P300 is a genuine correlate of conscious access enabling reports. Here, instead of removing report requirements, we took the opposite approach and equated postperceptual task demands across conscious and unconscious trials by orthogonalizing target detection and overt reports in a somatosensory detection task. We used Bayesian model selection to track the transformation from physical to perceptual processing stages in the EEG data of 24 male and female participants and show that the early P50 component scaled with physical stimulus intensity, whereas the N140 component was the first correlate of target detection. The late P300 component was elicited for both perceived and unperceived stimuli and was not substantially modulated by target detection. This was in stark contrast to a control experiment using a classical direct report task, which replicated the P50 and N140 effects but additionally showed a strong effect of target detection in the P300 time range. Our results demonstrate the task dependence of the P300 in the somatosensory modality and show that late cortical potentials dissociate from perceptual awareness even when stimuli are always reported.SIGNIFICANCE STATEMENT The time it takes for sensory information to enter our conscious experience can be an indicator of the neural processing stages that lead to perceptual awareness. However, because many cognitive processes routinely correlate with perception, isolating those signals that uniquely reflect perceptual awareness is not a trivial task. Here, we show that late electroencephalography signals cease to correlate with somatosensory awareness when common task confounds are controlled. Importantly, by balancing report requirements instead of abolishing them, we show that the lack of late effects cannot be explained by a lack of conscious access. Instead, we propose that conscious access occurs earlier, at ∼150 ms, supporting the view that early activity in sensory cortices is a neural correlate of conscious perception.
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Affiliation(s)
- Pia Schröder
- Neurocomputation and Neuroimaging Unit, Freie Universität Berlin, 14195 Berlin, Germany
| | - Till Nierhaus
- Neurocomputation and Neuroimaging Unit, Freie Universität Berlin, 14195 Berlin, Germany
| | - Felix Blankenburg
- Neurocomputation and Neuroimaging Unit, Freie Universität Berlin, 14195 Berlin, Germany
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11
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Electrophysiological correlates associated with the processing of invisible and visible visual objects. CURRENT PSYCHOLOGY 2021. [DOI: 10.1007/s12144-020-01329-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
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12
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Hartmann D, Schwenck C. Emotion Processing in Children with Conduct Problems and Callous-Unemotional Traits: An Investigation of Speed, Accuracy, and Attention. Child Psychiatry Hum Dev 2020; 51:721-733. [PMID: 32170490 PMCID: PMC7518997 DOI: 10.1007/s10578-020-00976-9] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
This study aimed to assess whether callous-unemotional traits (CU) are associated with deficits in emotion recognition independent of externalizing behavior and whether such deficits can be explained by aberrant attention. As previous studies have produced inconsistent results, the current study included two different emotion recognition paradigms and assessed the potential influence of factors such as processing speed and attention. The study included N = 94 children (eight to 14 years) with an oversampling of children with conduct problems (CP) and varying levels of CU-traits. Independent of externalizing behavior, CU-traits were associated with slower recognition of angry, sad and fearful facial expressions but not with higher error rates. There was no evidence that the association between CU-traits and emotion processing could be explained by misguided attention. Our results implicate that in children with high levels of CU-traits emotion recognition deficits depend on deficits in processing speed.
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Affiliation(s)
- Daniela Hartmann
- Department of Special Needs Educational and Clinical Child and Adolescent Psychology, Justus-Liebig-University of Giessen, Otto-Behaghel-Straße 10 C, 35394, Giessen, Germany.
| | - Christina Schwenck
- Department of Special Needs Educational and Clinical Child and Adolescent Psychology, Justus-Liebig-University of Giessen, Otto-Behaghel-Straße 10 C, 35394, Giessen, Germany
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13
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Teixeira M, Nascimento S, Almeida V, Simões M, Amaral C, Castelo-Branco M. The conscious experience of color constancy and neural responses to subliminal deviations – A behavioral and EEG/ERP oddball study. Conscious Cogn 2020; 84:102987. [DOI: 10.1016/j.concog.2020.102987] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2020] [Revised: 06/06/2020] [Accepted: 07/13/2020] [Indexed: 11/27/2022]
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14
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Lai C, Pellicano GR, Ciacchella C, Guidobaldi L, Altavilla D, Cecchini M, Begotaraj E, Aceto P, Luciani M. Neurophysiological correlates of emotional face perception consciousness. Neuropsychologia 2020; 146:107554. [PMID: 32652090 DOI: 10.1016/j.neuropsychologia.2020.107554] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2019] [Revised: 05/27/2020] [Accepted: 07/03/2020] [Indexed: 01/20/2023]
Abstract
Aim of the present study was to investigate the neurophysiologic correlates of the conscious and not conscious perception of faces (presented for 14, 40, 80 ms) with happy and sad emotional valence. Electroencephalographic data of 22 participants during a report-based visual task were recorded. Both happy and sad faces presented for 14 ms showed a longer N170 latency compared to the faces presented for 40 and 80 ms. A shorter latency of early components (before N170) was found in the right hemisphere and a longer latency in the left one in response to the happy faces presented for 14 ms compared to those presented for longer times. The faces presented for 14 ms, declared as consciously perceived, evoked a higher brain response compared to those declared as not perceived. Parietal and cingulate brain areas showed a lower intensity of the brain response to the consciously perceived faces in the early components. Happy faces showed a greater brain response when consciously detected, while the sad faces induced a greater brain response when not consciously detected. The findings suggest that the N170 may be the epiphenomenon of an earlier consciously detection. Moreover, these preliminary results seem to support a main role of parietal and cingulate brain areas into not conscious perception.
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Affiliation(s)
- Carlo Lai
- Department of Dynamic and Clinical Psychology, Sapienza University of Rome, Via degli Apuli,1, 00185, Rome, Italy.
| | - Gaia Romana Pellicano
- Department of Dynamic and Clinical Psychology, Sapienza University of Rome, Via degli Apuli,1, 00185, Rome, Italy
| | - Chiara Ciacchella
- Department of Dynamic and Clinical Psychology, Sapienza University of Rome, Via degli Apuli,1, 00185, Rome, Italy
| | - Lorenzo Guidobaldi
- Department of Dynamic and Clinical Psychology, Sapienza University of Rome, Via degli Apuli,1, 00185, Rome, Italy
| | - Daniela Altavilla
- Department of Dynamic and Clinical Psychology, Sapienza University of Rome, Via degli Apuli,1, 00185, Rome, Italy
| | - Marco Cecchini
- Department of Dynamic and Clinical Psychology, Sapienza University of Rome, Via degli Apuli,1, 00185, Rome, Italy
| | - Edvaldo Begotaraj
- Department of Dynamic and Clinical Psychology, Sapienza University of Rome, Via degli Apuli,1, 00185, Rome, Italy
| | - Paola Aceto
- Department of Anesthesia, Emergency and Intensive Care Medicine, Fondazione Policlinico Universitario A. Gemelli IRCCS, Largo Francesco Vito, 1, 00168, Rome, Italy; Institute of Anesthesiology and Intensive Care Medicine, Università Cattolica del Sacro Cuore, Largo Francesco Vito, 1, 00168, Rome, Italy
| | - Massimiliano Luciani
- Department of Neuroscience, Catholic University of Sacred Heart, Largo Francesco Vito, 1, 00168, Rome, Italy
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15
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Mazzi C, Mazzeo G, Savazzi S. Late Positivity Does Not Meet the Criteria to be Considered a Proper Neural Correlate of Perceptual Awareness. Front Syst Neurosci 2020; 14:36. [PMID: 32733211 PMCID: PMC7358964 DOI: 10.3389/fnsys.2020.00036] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2019] [Accepted: 05/18/2020] [Indexed: 11/19/2022] Open
Abstract
Contrastive analysis has been widely employed in the search for the electrophysiological neural correlates of consciousness. However, despite its clear logic, it has been argued that it may not succeed in isolating neural processes solely involved in the emergence of perceptual awareness. In fact, data from contrastive analysis would be contaminated by potential confounding factors reflecting distinct, though related, processes either preceding or following the conscious perception. At present, the ERP components representing the proper correlates of perceptual awareness still remain to be identified among those correlating with awareness (i.e., Visual Awareness Negativity, VAN and Late Positivity, LP). In order to dissociate visual awareness from post-perceptual confounds specifically related to decision making, we manipulated the response criterion, which affects how a percept is translated into a decision. In particular, while performing an orientation discrimination task, participants were asked to shift their response criterion across sessions. As a consequence, the resulting modulation should concern the ERP component(s) not exclusively reflecting mechanisms regulating the subjective conscious experience itself but rather the processes accompanying it. Electrophysiological results showed that N1 and P3 were sensitive to the response criterion adopted by participants. Additionally, the more the participants shifted their response criterion, the bigger the ERP modulation was; this was consequently indicative of the critical role of these components in the decision-making processes regardless of awareness level. When considering data independently from the response criterion, the aware vs. unaware contrast showed that both VAN and LP were significant. Crucially, the LP component was also modulated by the interaction of awareness and response criterion, while VAN results to be unaffected. In agreement with previous literature, these findings provide evidence supporting the hypothesis that VAN tracks the emergence of visual awareness by encoding the conscious percept, whereas LP reflects the contribution from post-perceptual processes related to response requirements. This excludes a direct functional role of this later component in giving rise to perceptual awareness.
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Affiliation(s)
- Chiara Mazzi
- Perception and Awareness (PandA) Laboratory, Department of Neuroscience, Biomedicine and Movement Sciences, University of Verona, Verona, Italy
| | - Gaetano Mazzeo
- Perception and Awareness (PandA) Laboratory, Department of Neuroscience, Biomedicine and Movement Sciences, University of Verona, Verona, Italy
| | - Silvia Savazzi
- Perception and Awareness (PandA) Laboratory, Department of Neuroscience, Biomedicine and Movement Sciences, University of Verona, Verona, Italy
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16
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Bachmann T. Account of consciousness by Christof Koch: Review and questions. Conscious Cogn 2020; 82:102937. [PMID: 32388455 DOI: 10.1016/j.concog.2020.102937] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2020] [Revised: 04/16/2020] [Accepted: 04/18/2020] [Indexed: 10/24/2022]
Abstract
This review is set to present the gist of the theoretical account of consciousness recently presented by Christof Koch and pose a couple of questions instigated by this account. The expected answers to these questions would hopefully help to advance our understanding of the basic nature of the conscious mind.
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Affiliation(s)
- Talis Bachmann
- Department of Penal Law, School of Law, University of Tartu (Tallinn Branch), Kaarli Puiestee 3, 10119 Tallinn, Estonia.
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17
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Förster J, Koivisto M, Revonsuo A. ERP and MEG correlates of visual consciousness: The second decade. Conscious Cogn 2020; 80:102917. [PMID: 32193077 DOI: 10.1016/j.concog.2020.102917] [Citation(s) in RCA: 73] [Impact Index Per Article: 18.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2019] [Revised: 02/14/2020] [Accepted: 03/07/2020] [Indexed: 01/04/2023]
Abstract
The first decade of event-related potential (ERP) research had established that the most consistent correlates of the onset of visual consciousness are the early visual awareness negativity (VAN), a posterior negative component in the N2 time range, and the late positivity (LP), an anterior positive component in the P3 time range. Two earlier extensive reviews ten years ago had concluded that VAN is the earliest and most reliable correlate of visual phenomenal consciousness, whereas LP probably reflects later processes associated with reflective/access consciousness. This article provides an update to those earlier reviews. ERP and MEG studies that have appeared since 2010 and directly compared ERPs between aware and unaware conditions are reviewed, and important new developments in the field are discussed. The result corroborates VAN as the earliest and most consistent signature of visual phenomenal consciousness, and casts further doubt on LP as an ERP correlate of phenomenal consciousness.
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Affiliation(s)
- Jona Förster
- Division of Cognitive Neuroscience and Philosophy, University of Skövde, Sweden.
| | - Mika Koivisto
- Department of Psychology, University of Turku, Finland; Turku Brain and Mind Centre, University of Turku, Finland
| | - Antti Revonsuo
- Division of Cognitive Neuroscience and Philosophy, University of Skövde, Sweden; Department of Psychology, University of Turku, Finland; Turku Brain and Mind Centre, University of Turku, Finland
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Anwyl-Irvine AL, Massonnié J, Flitton A, Kirkham N, Evershed JK. Gorilla in our midst: An online behavioral experiment builder. Behav Res Methods 2020; 52:388-407. [PMID: 31016684 PMCID: PMC7005094 DOI: 10.3758/s13428-019-01237-x] [Citation(s) in RCA: 593] [Impact Index Per Article: 148.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
Behavioral researchers are increasingly conducting their studies online, to gain access to large and diverse samples that would be difficult to get in a laboratory environment. However, there are technical access barriers to building experiments online, and web browsers can present problems for consistent timing-an important issue with reaction-time-sensitive measures. For example, to ensure accuracy and test-retest reliability in presentation and response recording, experimenters need a working knowledge of programming languages such as JavaScript. We review some of the previous and current tools for online behavioral research, as well as how well they address the issues of usability and timing. We then present the Gorilla Experiment Builder (gorilla.sc), a fully tooled experiment authoring and deployment platform, designed to resolve many timing issues and make reliable online experimentation open and accessible to a wider range of technical abilities. To demonstrate the platform's aptitude for accessible, reliable, and scalable research, we administered a task with a range of participant groups (primary school children and adults), settings (without supervision, at home, and under supervision, in both schools and public engagement events), equipment (participant's own computer, computer supplied by the researcher), and connection types (personal internet connection, mobile phone 3G/4G). We used a simplified flanker task taken from the attentional network task (Rueda, Posner, & Rothbart, 2004). We replicated the "conflict network" effect in all these populations, demonstrating the platform's capability to run reaction-time-sensitive experiments. Unresolved limitations of running experiments online are then discussed, along with potential solutions and some future features of the platform.
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Affiliation(s)
- Alexander L Anwyl-Irvine
- MRC Cognition and Brain Science Unit, University of Cambridge, Cambridge, UK
- Cauldron.sc: Cauldron Science, St Johns Innovation Centre, Cambridge, UK
| | - Jessica Massonnié
- Centre for Brain and Cognitive Development, Birkbeck College, University of London, London, UK
| | - Adam Flitton
- Cauldron.sc: Cauldron Science, St Johns Innovation Centre, Cambridge, UK
- Human Behaviour and Cultural Evolution Group, University of Exeter, Exeter, UK
| | - Natasha Kirkham
- Centre for Brain and Cognitive Development, Birkbeck College, University of London, London, UK
| | - Jo K Evershed
- Cauldron.sc: Cauldron Science, St Johns Innovation Centre, Cambridge, UK.
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19
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Neuronal correlates of full and partial visual conscious perception. Conscious Cogn 2019; 78:102863. [PMID: 31887533 DOI: 10.1016/j.concog.2019.102863] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2019] [Revised: 12/17/2019] [Accepted: 12/18/2019] [Indexed: 11/20/2022]
Abstract
Stimuli may induce only partial consciousness-an intermediate between null and full consciousness-where the presence but not identity of an object can be reported. The differences in the neuronal basis of full and partial consciousness are poorly understood. We investigated if evoked and oscillatory activity could dissociate full from partial conscious perception. We recorded human cortical activity with magnetoencephalography (MEG) during a visual perception task in which stimulus could be either partially or fully perceived. Partial consciousness was associated with an early increase in evoked activity and theta/low-alpha-band oscillations while full consciousness was also associated with late evoked activity and beta-band oscillations. Full from partial consciousness was dissociated by stronger evoked activity and late increase in theta oscillations that were localized to higher-order visual regions and posterior parietal and prefrontal cortices. Our results reveal both evoked activity and theta oscillations dissociate partial and full consciousness.
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20
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Pérez-Gay Juárez F, Sicotte T, Thériault C, Harnad S. Category learning can alter perception and its neural correlates. PLoS One 2019; 14:e0226000. [PMID: 31810079 PMCID: PMC6897555 DOI: 10.1371/journal.pone.0226000] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2019] [Accepted: 11/18/2019] [Indexed: 11/25/2022] Open
Abstract
Learned Categorical Perception (CP) occurs when the members of different categories come to look more dissimilar ("between-category separation") and/or members of the same category come to look more similar ("within-category compression") after a new category has been learned. To measure learned CP and its physiological correlates we compared dissimilarity judgments and Event Related Potentials (ERPs) before and after learning to sort multi-featured visual textures into two categories by trial and error with corrective feedback. With the same number of training trials and feedback, about half the subjects succeeded in learning the categories ("Learners": criterion 80% accuracy) and the rest did not ("Non-Learners"). At both lower and higher levels of difficulty, successful Learners showed significant between-category separation-and, to a lesser extent, within-category compression-in pairwise dissimilarity judgments after learning, compared to before; their late parietal ERP positivity (LPC, usually interpreted as decisional) also increased and their occipital N1 amplitude (usually interpreted as perceptual) decreased. LPC amplitude increased with response accuracy and N1 amplitude decreased with between-category separation for the Learners. Non-Learners showed no significant changes in dissimilarity judgments, LPC or N1, within or between categories. This is behavioral and physiological evidence that category learning can alter perception. We sketch a neural net model predictive of this effect.
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Affiliation(s)
| | - Tomy Sicotte
- Université du Québec à Montréal, Montréal, Canada
| | | | - Stevan Harnad
- McGill University, Montréal, Canada
- Université du Québec à Montréal, Montréal, Canada
- University of Southampton, Southampton, United Kingdom
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21
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Neural correlates of visual awareness at stimulus low vs. high-levels of processing. Neuropsychologia 2018; 121:144-152. [DOI: 10.1016/j.neuropsychologia.2018.11.001] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2018] [Revised: 10/21/2018] [Accepted: 11/02/2018] [Indexed: 12/13/2022]
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22
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Boncompte G, Cosmelli D. Neural Correlates of Conscious Motion Perception. Front Hum Neurosci 2018; 12:355. [PMID: 30250429 PMCID: PMC6139308 DOI: 10.3389/fnhum.2018.00355] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2018] [Accepted: 08/20/2018] [Indexed: 11/24/2022] Open
Abstract
The nature of the proper neural signature of conscious perception remains a topic of active debate. Theoretical support from integrative theories of consciousness is consistent with such signature being P3b, one of the main candidates in the literature. Recent work has also put forward a mid-latency and more localized component, the Visual Awareness Negativity (VAN), as a proper Neural Correlate of Consciousness (NCC). Early local components like P1 have also been proposed. However, experiments exploring visual NCCs are conducted almost exclusively using static images as the content to be consciously perceived, favoring ventral stream processing, therefore limiting the scope of the NCCs that have been identified. Here we explored the visual NCCs isolating local motion, a dorsally processed feature, as the primary feature being consciously perceived. Physical equality between Seen and Unseen conditions in addition to a minimal contrast difference between target and no-target displays was employed. In agreement with previous literature, we found a P3b with a wide centro-parietal distribution that strongly correlated with the detection of the stimuli. P3b magnitude was larger for Seen vs. Unseen conditions, a result that was consistently observed at the single subject level. In contrast, we were unable to detect VAN in our data, regardless of whether the subject perceived or not the stimuli. In the 200-300 ms time window we found a N2pc component, consistent with the high attentional demands of our task. Early components like P1 were not observed in our data, in agreement with their proposed role in the processing of visual features, but not as proper NCCs. Our results extend the role of P3b as a content independent NCC to conscious visual motion perception.
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Affiliation(s)
- Gonzalo Boncompte
- Laboratorio de Psicofisiología, Escuela de Psicología, Pontificia Universidad Católica de Chile, Santiago, Chile
| | - Diego Cosmelli
- Laboratorio de Psicofisiología, Escuela de Psicología, Pontificia Universidad Católica de Chile, Santiago, Chile
- Centro Interdisciplinario de Neurociencias, Pontificia Universidad Católica de Chile, Santiago, Chile
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23
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Key B, Brown D. Designing Brains for Pain: Human to Mollusc. Front Physiol 2018; 9:1027. [PMID: 30127750 PMCID: PMC6088194 DOI: 10.3389/fphys.2018.01027] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2018] [Accepted: 07/11/2018] [Indexed: 12/16/2022] Open
Abstract
There is compelling evidence that the "what it feels like" subjective experience of sensory stimuli arises in the cerebral cortex in both humans as well as mammalian experimental animal models. Humans are alone in their ability to verbally communicate their experience of the external environment. In other species, sensory awareness is extrapolated on the basis of behavioral indicators. For instance, cephalopods have been claimed to be sentient on the basis of their complex behavior and anecdotal reports of human-like intelligence. We have interrogated the findings of avoidance learning behavioral paradigms and classical brain lesion studies and conclude that there is no evidence for cephalopods feeling pain. This analysis highlighted the questionable nature of anthropometric assumptions about sensory experience with increased phylogenetic distance from humans. We contend that understanding whether invertebrates such as molluscs are sentient should first begin with defining the computational processes and neural circuitries underpinning subjective awareness. Using fundamental design principles, we advance the notion that subjective awareness is dependent on observer neural networks (networks that in some sense introspect the neural processing generating neural representations of sensory stimuli). This introspective process allows the observer network to create an internal model that predicts the neural processing taking place in the network being surveyed. Predictions arising from the internal model form the basis of a rudimentary form of awareness. We develop an algorithm built on parallel observer networks that generates multiple levels of sensory awareness. A network of cortical regions in the human brain has the appropriate functional properties and neural interconnectivity that is consistent with the predicted circuitry of the algorithm generating pain awareness. By contrast, the cephalopod brain lacks the necessary neural circuitry to implement such an algorithm. In conclusion, we find no compelling behavioral, functional, or neuroanatomical evidence to indicate that cephalopods feel pain.
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Affiliation(s)
- Brian Key
- School of Biomedical Sciences, University of Queensland, Brisbane, QLD, Australia
| | - Deborah Brown
- School of Historical and Philosophical Inquiry, University of Queensland, Brisbane, QLD, Australia
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Boly M, Massimini M, Tsuchiya N, Postle BR, Koch C, Tononi G. Are the Neural Correlates of Consciousness in the Front or in the Back of the Cerebral Cortex? Clinical and Neuroimaging Evidence. J Neurosci 2017; 37:9603-9613. [PMID: 28978697 PMCID: PMC5628406 DOI: 10.1523/jneurosci.3218-16.2017] [Citation(s) in RCA: 271] [Impact Index Per Article: 38.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2017] [Revised: 06/28/2017] [Accepted: 06/30/2017] [Indexed: 01/14/2023] Open
Abstract
The role of the frontal cortex in consciousness remains a matter of debate. In this Perspective, we will critically review the clinical and neuroimaging evidence for the involvement of the front versus the back of the cortex in specifying conscious contents and discuss promising research avenues.Dual Perspectives Companion Paper: Should a Few Null Findings Falsify Prefrontal Theories of Conscious Perception?, by Brian Odegaard, Robert T. Knight, and Hakwan Lau.
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Affiliation(s)
- Melanie Boly
- Department of Neurology, University of Wisconsin, Madison, Wisconsin 53705,
- Department of Psychiatry, University of Wisconsin, Madison, Wisconsin 53719
| | - Marcello Massimini
- Department of Biomedical and Clinical Sciences Luigi Sacco, University of Milan, Milan 20157, Italy
- Instituto Di Ricovero e Cura a Carattere Scientifico, Fondazione Don Carlo Gnocchi, Milan 20148, Italy
| | - Naotsugu Tsuchiya
- School of Psychological Sciences, Faculty of Medicine, Nursing, and Health Sciences, Monash University, Melbourne, 3800 Victoria, Australia
- Monash Institute of Cognitive and Clinical Neuroscience, Monash University, Melbourne, 3800 Victoria, Australia
| | - Bradley R Postle
- Department of Psychiatry, University of Wisconsin, Madison, Wisconsin 53719
- Department of Psychology, University of Wisconsin, Madison, Wisconsin 53705, and
| | - Christof Koch
- Allen Institute for Brain Science, Seattle, Washington 98109
| | - Giulio Tononi
- Department of Psychiatry, University of Wisconsin, Madison, Wisconsin 53719,
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Koivisto M, Grassini S, Salminen-Vaparanta N, Revonsuo A. Different Electrophysiological Correlates of Visual Awareness for Detection and Identification. J Cogn Neurosci 2017; 29:1621-1631. [DOI: 10.1162/jocn_a_01149] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
Abstract
Abstract
Detecting the presence of an object is a different process than identifying the object as a particular object. This difference has not been taken into account in designing experiments on the neural correlates of consciousness. We compared the electrophysiological correlates of conscious detection and identification directly by measuring ERPs while participants performed either a task only requiring the conscious detection of the stimulus or a higher-level task requiring its conscious identification. Behavioral results showed that, even if the stimulus was consciously detected, it was not necessarily identified. A posterior electrophysiological signature 200–300 msec after stimulus onset was sensitive for conscious detection but not for conscious identification, which correlated with a later widespread activity. Thus, we found behavioral and neural evidence for elementary visual experiences, which are not yet enriched with higher-level knowledge. The search for the mechanisms of consciousness should focus on the early elementary phenomenal experiences to avoid the confounding effects of higher-level processes.
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Juxtaposing the real-time unfolding of subjective experience and ERP neuromarker dynamics. Conscious Cogn 2017; 54:3-19. [DOI: 10.1016/j.concog.2017.05.003] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2016] [Revised: 05/10/2017] [Accepted: 05/11/2017] [Indexed: 01/08/2023]
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27
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ERP signatures of conscious and unconscious word and letter perception in an inattentional blindness paradigm. Conscious Cogn 2017; 54:56-71. [DOI: 10.1016/j.concog.2017.04.009] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2016] [Revised: 03/23/2017] [Accepted: 04/14/2017] [Indexed: 01/01/2023]
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28
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Northoff G, Huang Z. How do the brain's time and space mediate consciousness and its different dimensions? Temporo-spatial theory of consciousness (TTC). Neurosci Biobehav Rev 2017; 80:630-645. [PMID: 28760626 DOI: 10.1016/j.neubiorev.2017.07.013] [Citation(s) in RCA: 118] [Impact Index Per Article: 16.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2017] [Revised: 05/10/2017] [Accepted: 07/27/2017] [Indexed: 11/19/2022]
Abstract
Time and space are the basic building blocks of nature. As a unique existent in nature, our brain exists in time and takes up space. The brain's activity itself also constitutes and spreads in its own (intrinsic) time and space that is crucial for consciousness. Consciousness is a complex phenomenon including different dimensions: level/state, content/form, phenomenal aspects, and cognitive features. We propose a Temporo-spatial Theory of Consciousness (TTC) focusing primarily on the temporal and spatial features of the brain activity. We postulate four different neuronal mechanisms accounting for the different dimensions of consciousness: (i) "temporo-spatial nestedness" of the spontaneous activity accounts for the level/state of consciousness as neural predisposition of consciousness (NPC); (ii) "temporo-spatial alignment" of the pre-stimulus activity accounts for the content/form of consciousness as neural prerequisite of consciousness (preNCC); (iii) "temporo-spatial expansion" of early stimulus-induced activity accounts for phenomenal consciousness as neural correlates of consciousness (NCC); (iv) "temporo-spatial globalization" of late stimulus-induced activity accounts for the cognitive features of consciousness as neural consequence of consciousness (NCCcon).
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Affiliation(s)
- Georg Northoff
- Mental Health Centre, Zhejiang University School of Medicine, Hangzhou, Zhejiang Province, China; University of Ottawa, Institute of Mental Health Research, University of Ottawa Brain and Mind Research Institute, Ottawa, Canada; Centre for Cognition and Brain Disorders, Hangzhou Normal University, Hangzhou, China; Centre for Brain and Consciousness, Taipei Medical University (TMU), Taipei, Taiwan; College for Humanities and Medicine, Taipei Medical University (TMU), Taipei, Taiwan; Center for the Study of Language and Cognition, Zhejiang University, Hangzhou 310028, China.
| | - Zirui Huang
- Department of Anesthesiology and Center for Consciousness Science, University of Michigan, Ann Arbor, USA.
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Distinct Oscillatory Frequencies Underlie Excitability of Human Occipital and Parietal Cortex. J Neurosci 2017; 37:2824-2833. [PMID: 28179556 DOI: 10.1523/jneurosci.3413-16.2017] [Citation(s) in RCA: 69] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2016] [Revised: 01/26/2017] [Accepted: 01/31/2017] [Indexed: 01/01/2023] Open
Abstract
Transcranial magnetic stimulation (TMS) of human occipital and posterior parietal cortex can give rise to visual sensations called phosphenes. We used near-threshold TMS with concurrent EEG recordings to measure how oscillatory brain dynamics covary, on single trials, with the perception of phosphenes after occipital and parietal TMS. Prestimulus power and phase, predominantly in the alpha band (8-13 Hz), predicted occipital TMS phosphenes, whereas higher-frequency beta-band (13-20 Hz) power (but not phase) predicted parietal TMS phosphenes. TMS-evoked responses related to phosphene perception were similar across stimulation sites and were characterized by an early (200 ms) posterior negativity and a later (>300 ms) parietal positivity in the time domain and an increase in low-frequency (∼5-7 Hz) power followed by a broadband decrease in alpha/beta power in the time-frequency domain. These correlates of phosphene perception closely resemble known electrophysiological correlates of conscious perception of near-threshold visual stimuli. The regionally differential pattern of prestimulus predictors of phosphene perception suggests that distinct frequencies may reflect cortical excitability in occipital versus posterior parietal cortex, calling into question the broader assumption that the alpha rhythm may serve as a general index of cortical excitability.SIGNIFICANCE STATEMENT Alpha-band oscillations are thought to reflect cortical excitability and are therefore ascribed an important role in gating information transmission across cortex. We probed cortical excitability directly in human occipital and parietal cortex and observed that, whereas alpha-band dynamics indeed reflect excitability of occipital areas, beta-band activity was most predictive of parietal cortex excitability. Differences in the state of cortical excitability predicted perceptual outcomes (phosphenes), which were manifest in both early and late patterns of evoked activity, revealing the time course of phosphene perception. Our findings prompt revision of the notion that alpha activity reflects excitability across all of cortex and suggest instead that excitability in different regions is reflected in distinct frequency bands.
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30
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Aru J, Bachmann T. In and Out of Consciousness: How Does Conscious Processing (D)evolve Over Time? Front Psychol 2017; 8:128. [PMID: 28210236 PMCID: PMC5288355 DOI: 10.3389/fpsyg.2017.00128] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2016] [Accepted: 01/18/2017] [Indexed: 11/13/2022] Open
Affiliation(s)
- Jaan Aru
- Department of Penal Law, School of Law, University of TartuTartu, Estonia; Chair of Data Science, Institute of Computer Science, University of TartuTartu, Estonia
| | - Talis Bachmann
- Department of Penal Law, School of Law, University of Tartu Tartu, Estonia
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