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The ConTraSt database for analysing and comparing empirical studies of consciousness theories. Nat Hum Behav 2022; 6:593-604. [DOI: 10.1038/s41562-021-01284-5] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2021] [Accepted: 12/17/2021] [Indexed: 12/21/2022]
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Northoff G, Lamme V. Neural signs and mechanisms of consciousness: Is there a potential convergence of theories of consciousness in sight? Neurosci Biobehav Rev 2020; 118:568-587. [PMID: 32783969 DOI: 10.1016/j.neubiorev.2020.07.019] [Citation(s) in RCA: 81] [Impact Index Per Article: 20.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2020] [Revised: 07/03/2020] [Accepted: 07/16/2020] [Indexed: 11/18/2022]
Abstract
Various theories for the neural basis of consciousness have been proposed, suggesting a diversity of neural signs and mechanisms. We ask to what extent this diversity is real, or whether many theories share the same basic ideas with a potential for convergence towards a more unified theory of the neural basis of consciousness. For that purpose, we review and compare the various neural signs, measures, and mechanisms proposed in the different theories. We demonstrate that different theories focus on neural signs and measures of distinct aspects of neural activity including stimulus-related, prestimulus, and resting state activity as well as on distinct features of consciousness. Therefore, the various mechanisms proposed in the different theories may, in part, complement each other. Together, we provide insight into the shared basis and convergences (and, in part, discrepancies) of the different theories of consciousness. We conclude that the different theories concern distinct aspects of both neural activity and consciousness which, as we suppose, may be integrated and nested within the brain's overall temporo-spatial dynamics.
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Affiliation(s)
- Georg Northoff
- Mental Health Center, Zhejiang University School of Medicine, Hangzhou, Zhejiang, China; Mind, Brain Imaging and Neuroethics, Institute of Mental Health Research, University of Ottawa, Ottawa, Canada; Centre for Research Ethics & Bioethics, University of Uppsala, Uppsala, Sweden.
| | - Victor Lamme
- Amsterdam Brain and Cognition (ABC), Department of Psychology, University of Amsterdam, the Netherlands
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Lamme VAF. Challenges for theories of consciousness: seeing or knowing, the missing ingredient and how to deal with panpsychism. Philos Trans R Soc Lond B Biol Sci 2019; 373:rstb.2017.0344. [PMID: 30061458 DOI: 10.1098/rstb.2017.0344] [Citation(s) in RCA: 53] [Impact Index Per Article: 10.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 05/21/2018] [Indexed: 12/24/2022] Open
Abstract
Significant progress has been made in the study of consciousness. Promising theories have been developed and a wealth of experimental data has been generated, both guiding us towards a better understanding of this complex phenomenon. However, new challenges have surfaced. Is visual consciousness about the seeing or the knowing that you see? Controversy about whether the conscious experience is better explained by theories that focus on phenomenal (P-consciousness) or cognitive aspects (A-consciousness) remains, and the debate seems to reach a stalemate. Can we ever resolve this? A further challenge is that many theories of consciousness seem to endorse high degrees of panpsychism-the notion that all beings or even lifeless objects have conscious experience. Should we accept this, or does it imply that these theories require further ingredients that would put a lower bound on beings or devices that have conscious experience? If so, what could these 'missing ingredients' be? These challenges are discussed, and potential solutions are offered.This article is part of the theme issue 'Perceptual consciousness and cognitive access'.
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Affiliation(s)
- Victor A F Lamme
- Amsterdam Brain and Cognition (ABC), Department of Psychology, University of Amsterdam, 1001 NK Amsterdam, The Netherlands
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Yeo JM, Carson A, Stone J. Seeing again: treatment of functional visual loss. Pract Neurol 2019; 19:168-172. [PMID: 30872460 DOI: 10.1136/practneurol-2018-002092] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/28/2018] [Indexed: 11/03/2022]
Abstract
There is very little published literature on treatment strategies for functional visual loss. We present two people with long duration of functional visual loss who achieved complete recovery with a novel combination of therapeutic approaches. These included: (1) the clinician being transparent regarding positive signs such as optokinetic nystagmus, in order to persuade family members of the diagnosis, (2) regularly positively acknowledging everyday events that indicated visual ability, (3) using occipital transcranial magnetic stimulation to induce phosphenes as an artificial temporary visual experience and (4) using hypnotherapy to promote visual recovery. We discuss these individual therapeutic approaches in further detail including their background and rationale and include patients' reflection on their treatment experiences.
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Affiliation(s)
- Jing Ming Yeo
- Department of Neurology, Queen's Medical Centre, Nottingham University Hospitals NHS Trust, Nottingham, UK
| | - Alan Carson
- Centre for Clinical Brain Sciences, University of Edinburgh, Western General Hospital, Edinburgh, UK.,Department of Rehabilitation Medicine, NHS Lothian, Edinburgh, UK
| | - Jon Stone
- Centre for Clinical Brain Sciences, University of Edinburgh, Western General Hospital, Edinburgh, UK
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Magazzini L, Ruhnau P, Weisz N. Alpha suppression and connectivity modulations in left temporal and parietal cortices index partial awareness of words. Neuroimage 2016; 133:279-287. [PMID: 27001501 PMCID: PMC4907686 DOI: 10.1016/j.neuroimage.2016.03.025] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2016] [Revised: 02/25/2016] [Accepted: 03/12/2016] [Indexed: 11/25/2022] Open
Abstract
The partial awareness hypothesis is a theoretical proposal that recently provided a reconciling solution to graded and dichotomous accounts of consciousness. It suggests that we can become conscious of distinct properties of an object independently, ranging from low-level features to complex forms of representation. We investigated this hypothesis using classic visual word masking adapted to a near-threshold paradigm. The masking intensity was adjusted to the individual perception threshold, at which individual alphabetical letters, but not words, could be perceived in approximately half of the trials. We confined perception to a pre-lexical stage of word processing that corresponded to a clear condition of partial awareness. At this level of representation, the stimulus properties began to emerge within consciousness, yet they did not escalate to full stimulus awareness. In other words, participants were able to perceive individual letters, while remaining unaware of the whole letter strings presented. Cortical activity measured with MEG was compared between physically identical trials that differed in perception (perceived, not perceived). We found that compared to no awareness, partial awareness of words was characterized by suppression of oscillatory alpha power in left temporal and parietal cortices. The analysis of functional connectivity with seeds based on the power effect in these two regions revealed sparse connections for the parietal seed, and strong connections between the temporal seed and other regions of the language network. We suggest that the engagement of language regions indexed by alpha power suppression is responsible for establishing and maintaining conscious representations of individual pre-lexical units. Near-threshold visual masking is used to characterize partial awareness of words. Partial awareness is indexed by left temporal and parietal alpha power suppression. Functional connectivity dissociates nodes in temporal and parietal cortices.
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Affiliation(s)
- Lorenzo Magazzini
- Cardiff University Brain Research Imaging Centre (CUBRIC), School of Psychology, Cardiff University, Cardiff, UK.
| | - Philipp Ruhnau
- Centre for Cognitive Neuroscience, Paris Lodron Universität Salzburg, Salzburg, Austria; Center for Mind/Brain Sciences (CIMeC), University of Trento, Trento, Italy
| | - Nathan Weisz
- Centre for Cognitive Neuroscience, Paris Lodron Universität Salzburg, Salzburg, Austria; Center for Mind/Brain Sciences (CIMeC), University of Trento, Trento, Italy
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Peters MAK, Ro T, Lau H. Who's afraid of response bias? Neurosci Conscious 2016; 2016:niw001. [PMID: 27499928 PMCID: PMC4972336 DOI: 10.1093/nc/niw001] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2015] [Revised: 01/05/2016] [Accepted: 01/13/2016] [Indexed: 11/14/2022] Open
Abstract
Response bias (or criterion) contamination is insidious in studies of consciousness: that observers report they do not see a stimulus may not mean they have absolutely no subjective experience; they may be giving such reports in relative terms in the context of other stimuli. Bias-free signal detection theoretic measures provide an excellent method for avoiding response bias confounds, and many researchers correctly adopt this approach. However, here we discuss how a fixation on avoiding criterion effects can also be misleading and detrimental to fruitful inquiry. In a recent paper, Balsdon and Azzopardi (Absolute and relative blindsight. Consciousness and Cognition 2015; 32:79-91.) claimed that contamination by response bias led to flawed findings in a previous report of "relative blindsight". We argue that their criticisms are unfounded. They mistakenly assumed that others were trying (and failing) to apply their preferred methods to remove bias, when there was no such intention. They also dismissed meaningful findings because of their dependence on criterion, but such dismissal is problematic: many real effects necessarily depend on criterion. Unfortunately, these issues are technically tedious, and we discuss how they may have confused others to misapply psychophysical metrics and to draw questionable conclusions about the nature of TMS (transcranial magnetic stimulation)-induced blindsight. We conclude by discussing the conceptual importance of criterion effects in studies of conscious awareness: we need to treat them carefully, but not to avoid them without thinking.
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Affiliation(s)
- Megan A. K. Peters
- Department of Psychology, University of California Los Angeles, 1285 Franz Hall, Box 951563, Los Angeles, CA 90095-1563 USA
| | - Tony Ro
- Programs in Psychology and Biology, The Graduate Center of the City University of New York, 365 Fifth Ave., New York, NY 10016 USA
| | - Hakwan Lau
- Department of Psychology, University of California Los Angeles, 1285 Franz Hall, Box 951563, Los Angeles, CA 90095-1563 USA
- Brain Research Institute, University of California Los Angeles, 695 Charles E. Young Dr. South, Los Angeles, CA 90095 USA
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de Graaf TA, Sack AT. Using brain stimulation to disentangle neural correlates of conscious vision. Front Psychol 2014; 5:1019. [PMID: 25295015 PMCID: PMC4171988 DOI: 10.3389/fpsyg.2014.01019] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2014] [Accepted: 08/26/2014] [Indexed: 02/03/2023] Open
Abstract
Research into the neural correlates of consciousness (NCCs) has blossomed, due to the advent of new and increasingly sophisticated brain research tools. Neuroimaging has uncovered a variety of brain processes that relate to conscious perception, obtained in a range of experimental paradigms. But methods such as functional magnetic resonance imaging or electroencephalography do not always afford inference on the functional role these brain processes play in conscious vision. Such empirical NCCs could reflect neural prerequisites, neural consequences, or neural substrates of a conscious experience. Here, we take a closer look at the use of non-invasive brain stimulation (NIBS) techniques in this context. We discuss and review how NIBS methodology can enlighten our understanding of brain mechanisms underlying conscious vision by disentangling the empirical NCCs.
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Affiliation(s)
- Tom A de Graaf
- Department of Cognitive Neuroscience, Faculty of Psychology and Neuroscience, Maastricht University Maastricht, Netherlands ; Maastricht Brain Imaging Centre Maastricht, Netherlands
| | - Alexander T Sack
- Department of Cognitive Neuroscience, Faculty of Psychology and Neuroscience, Maastricht University Maastricht, Netherlands ; Maastricht Brain Imaging Centre Maastricht, Netherlands
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Silvanto J, Rees G. What does Neural Plasticity Tell us about Role of Primary Visual Cortex (V1) in Visual Awareness? Front Psychol 2011; 2:6. [PMID: 21713187 PMCID: PMC3111426 DOI: 10.3389/fpsyg.2011.00006] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2010] [Accepted: 01/04/2011] [Indexed: 11/21/2022] Open
Abstract
The complete loss of visual awareness resulting from a lesion to the primary visual cortex (V1) suggests that this region is indispensable for conscious visual perception. There are however a number cases of conscious perception in the absence of V1 which appear to challenge this conclusion. These include reports of patients with bilateral V1 lesions sustained at an early age whose conscious vision has spontaneously recovered, as well as stroke patients who have recovered some conscious vision with the help of rehabilitation programs. In addition, the phenomenon of hemianopic completion and percepts induced by brain stimulation suggest that V1 may not be necessary for conscious perception in all circumstances. Furthermore, that the visual abilities in the cat are associated with the recovery of normal extrastriate tuning properties rather than emulation of V1 functions suggests that there is nothing unique about the functional properties of this region in visual awareness. Rather, the dramatic effect of a V1 lesion on visual awareness may be due to its role in providing the majority of extrastriate visual input, the loss of which abolishes normal neural responsiveness throughout the visual cortex.
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Affiliation(s)
- Juha Silvanto
- Brain Research Unit, Low Temperature Laboratory and Advanced Magnetic Imaging Centre, School of Science and Technology, Aalto University Espoo, Finland
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Lancaster BL. The Hard Problem Revisited: From Cognitive Neuroscience to Kabbalah and Back Again. STUDIES IN NEUROSCIENCE, CONSCIOUSNESS AND SPIRITUALITY 2011. [DOI: 10.1007/978-94-007-2079-4_14] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
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Blom JD, Looijestijn J, Goekoop R, Diederen KMJ, Rijkaart AM, Slotema CW, Sommer IEC. Treatment of Alice in Wonderland syndrome and verbal auditory hallucinations using repetitive transcranial magnetic stimulation: a case report with fMRI findings. Psychopathology 2011; 44:337-44. [PMID: 21734437 DOI: 10.1159/000325102] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/07/2009] [Accepted: 01/17/2011] [Indexed: 01/21/2023]
Abstract
BACKGROUND Alice in Wonderland syndrome (AIWS) is a rare cluster of CNS symptoms characterized by visual distortions (i.e. metamorphopsias), body image distortions, time distortions, and déjà experiences. Verbal auditory hallucinations (VAHs) are the most prevalent type of hallucination in adults with or without a history of psychiatric illness. Here, we report the case of a woman with AIWS, long-lasting VAHs, and various additional perceptual and mood symptoms. METHODS Semi-structured interviews were used to assess symptoms, and functional MRI (fMRI) was employed to localize cerebral activity during self-reported VAHs. Treatment consisted of repetitive transcranial magnetic stimulation (rTMS) at a frequency of 1 Hz at T3P3, overlying Brodmann's area 40. RESULTS Activation during VAHs was observed bilaterally in the basal ganglia, the primary auditory cortex, the association auditory cortex, the temporal poles, and the anterior cingulated gyrus. The left and right inferior frontal gyri (Broca's area and its contralateral homologue) were involved, along with the dorsolateral prefrontal cortex. Interestingly, synchronized activation was observed in the primary visual cortex (areas V1 and V2), and the bilateral dorsal visual cortex. The higher visual association cortex also showed significant, but less prominent, activation. During the second week of rTMS treatment, not only the VAHs, but also the other sensory deceptions/distortions and mood symptoms showed complete remission. The patient remained free of any symptoms during a 4-month follow-up phase. After 8 months, when many of the original symptoms had returned, a second treatment phase with rTMS was again followed by complete remission. CONCLUSIONS This case indicates that VAHs and metamorphopsias in AIWS are associated with synchronized activation in both auditory and visual cortices. It also indicates that local rTMS treatment may have global therapeutic effects, suggesting an effect on multiple brain regions in a distributed network. Although a placebo effect cannot be ruled out, this case warrants further investigation of the effects of rTMS treatment in AIWS.
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Chambers CD, Heinen K. TMS and the functional neuroanatomy of attention. Cortex 2010; 46:114-7. [DOI: 10.1016/j.cortex.2009.03.002] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2008] [Revised: 10/04/2008] [Accepted: 03/03/2009] [Indexed: 11/17/2022]
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On tickling brains to investigate minds. Cortex 2009; 45:1021-4. [DOI: 10.1016/j.cortex.2009.05.001] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2009] [Revised: 05/05/2009] [Accepted: 05/07/2009] [Indexed: 11/19/2022]
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