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Neural correlates of consciousness

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https://www.readbyqxmd.com/read/28422113/increased-spontaneous-meg-signal-diversity-for-psychoactive-doses-of-ketamine-lsd-and-psilocybin
#1
Michael M Schartner, Robin L Carhart-Harris, Adam B Barrett, Anil K Seth, Suresh D Muthukumaraswamy
What is the level of consciousness of the psychedelic state? Empirically, measures of neural signal diversity such as entropy and Lempel-Ziv (LZ) complexity score higher for wakeful rest than for states with lower conscious level like propofol-induced anesthesia. Here we compute these measures for spontaneous magnetoencephalographic (MEG) signals from humans during altered states of consciousness induced by three psychedelic substances: psilocybin, ketamine and LSD. For all three, we find reliably higher spontaneous signal diversity, even when controlling for spectral changes...
April 19, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28398813/neural-correlates-of-consciousness-at-near-electrocerebral-silence-in-an-asphyxial-cardiac-arrest-model
#2
Donald E Lee, Lauren G Lee, Danny Siu, Afsheen K Bazrafkan, Maryam H Farahabadi, Tin J Dinh, Josue Orellana, Wei Xiong, Beth A Lopour, Yama Akbari
Recent electrophysiological studies have suggested surges in electrical correlates of consciousness (i.e., elevated gamma power and connectivity) after cardiac arrest (CA). This study examines electrocorticogram (ECoG) activity and coherence of the dying brain during asphyxial CA. Male Wistar rats (n = 16) were induced with isoflurane anesthesia, which was washed out before asphyxial CA. Mean phase coherence and ECoG power were compared during different stages of the asphyxial period to assess potential neural correlates of consciousness...
April 2017: Brain Connectivity
https://www.readbyqxmd.com/read/28394322/the-neural-correlates-of-dreaming
#3
Francesca Siclari, Benjamin Baird, Lampros Perogamvros, Giulio Bernardi, Joshua J LaRocque, Brady Riedner, Melanie Boly, Bradley R Postle, Giulio Tononi
Consciousness never fades during waking. However, when awakened from sleep, we sometimes recall dreams and sometimes recall no experiences. Traditionally, dreaming has been identified with rapid eye-movement (REM) sleep, characterized by wake-like, globally 'activated', high-frequency electroencephalographic activity. However, dreaming also occurs in non-REM (NREM) sleep, characterized by prominent low-frequency activity. This challenges our understanding of the neural correlates of conscious experiences in sleep...
April 10, 2017: Nature Neuroscience
https://www.readbyqxmd.com/read/28392004/-paradox-of-slow-frequencies-are-slow-frequencies-in-upper-cortical-layers-a-neural-predisposition-of-the-level-state-of-consciousness-npc
#4
Georg Northoff
Consciousness research has much focused on faster frequencies like alpha or gamma while neglecting the slower ones in the infraslow (0.001-0.1Hz) and slow (0.1-1Hz) frequency range. These slower frequency ranges have a "bad reputation" though; their increase in power can observed during the loss of consciousness as in sleep, anesthesia, and vegetative state. However, at the same time, slower frequencies have been conceived instrumental for consciousness. The present paper aims to resolve this paradox which I describe as "paradox of slow frequencies"...
April 5, 2017: Consciousness and Cognition
https://www.readbyqxmd.com/read/28283789/cerebral-metabolic-changes-related-to-clinical-parameters-in-idiopathic-anosmic-patients-during-olfactory-stimulation-a-pilot-investigation
#5
Alessandro Micarelli, Agostino Chiaravalloti, Roberta Danieli, Orazio Schillaci, Marco Alessandrini
Idiopathic olfactory loss neural consequences have been studied especially by means of magnetic resonance imaging. Since other functional neuroimaging technique findings are lacking in the literature, present study used a validated (18)F-2-fluoro-2-deoxy-D-glucose (FDG) functional positron emission tomography procedure under olfactory stimulation (OS) to assess brain changes in idiopathic anosmic patients (IAPs) in comparison with healthy subjects (HS). A voxel-based analysis between these groups was used to evaluate FDG uptake in the brain and perform a correlation analysis between metabolic responses and the Sniffin' stick test as well as intensity visuo-analogue scores and disease duration (DD)...
March 10, 2017: European Archives of Oto-rhino-laryngology
https://www.readbyqxmd.com/read/28258035/raising-the-alarm-individual-differences-in-the-perceptual-awareness-of-masked-facial-expressions
#6
Ljubica Damjanovic, Marcel Meyer, Francisco Sepulveda
A theoretical concern in addressing the unconscious perception of emotion is the extent to which participants can access experiential properties of masked facial stimuli. Performance on a two alternative forced choice (2AFC) task as a measure of objective awareness was compared with a new measure developed to access experiential phenomena of the target-mask transition, the perceptual contrast-change sensitivity (PCCS) measure in a backward-masking paradigm with angry, happy and neutral facial expressions. Whilst 2AFC performance indicated that the targets were successfully masked, PCCS values were significantly higher in the happy-neutral face condition than in the angry-neutral face and the neutral-neutral face conditions (Experiment 1)...
June 2017: Brain and Cognition
https://www.readbyqxmd.com/read/28215463/markers-of-tms-evoked-visual-conscious-experience-in-a-patient-with-altitudinal-hemianopia
#7
Chiara Mazzi, Gaetano Mazzeo, Silvia Savazzi
Transcranial magnetic stimulation (TMS) of the occipital and parietal cortices can induce phosphenes, i.e. visual sensations of light without light entering the eyes. In this paper, we adopted a TMS-EEG interactive co-registration approach with a patient (AM) showing altitudinal hemianopia. Occipital and parietal cortices in both hemispheres were stimulated while concurrently recording EEG signal. Results showed that, for all sites, neural activity differentially encoding for the presence vs. absence of a conscious experience could be found in a cluster of electrodes close to the stimulation site at an early (70ms) time-period after TMS...
February 16, 2017: Consciousness and Cognition
https://www.readbyqxmd.com/read/28195526/regulating-the-access-to-awareness-brain-activity-related-to-probe-related-and-spontaneous-reversals-in-binocular-rivalry
#8
Brian A Metzger, Kyle E Mathewson, Evelina Tapia, Monica Fabiani, Gabriele Gratton, Diane M Beck
Research on the neural correlates of consciousness (NCC) has implicated an assortment of brain regions, ERP components, and network properties associated with visual awareness. Recently, the P3b ERP component has emerged as a leading NCC candidate. However, typical P3b paradigms depend on the detection of some stimulus change, making it difficult to separate brain processes elicited by the stimulus itself from those associated with updates or changes in visual awareness. Here we used binocular rivalry to ask whether the P3b is associated with changes in awareness even in the absence of changes in the object of awareness...
February 14, 2017: Journal of Cognitive Neuroscience
https://www.readbyqxmd.com/read/28165171/less-is-more-neural-activity-during-very-brief-and-clearly-visible-exposure-to-phobic-stimuli
#9
Paul Siegel, Richard Warren, Zhishun Wang, Jie Yang, Don Cohen, Jason F Anderson, Lilly Murray, Bradley S Peterson
Research on automatic processes in fear has emphasized the provocation of fear responses rather than their attenuation. We have previously shown that the repeated presentation of feared images without conscious awareness via backward masking reduces avoidance of a live tarantula in spider-phobic participants. Herein we investigated the neural basis for these adaptive effects of masked exposure. 21 spider-phobic and 21 control participants, identified by a psychiatric interview, fear questionnaire, and approaching a live tarantula, viewed stimuli in each of three conditions: (1) very brief exposure (VBE) to masked images of spiders, severely limited awareness; (2) clearly visible exposure (CVE) to spiders, full awareness; and (3) masked images of flowers (control), severely limited awareness...
May 2017: Human Brain Mapping
https://www.readbyqxmd.com/read/28110456/facial-skin-blood-flow-responses-during-exposures-to-emotionally-charged-movies
#10
Kanji Matsukawa, Kana Endo, Kei Ishii, Momoka Ito, Nan Liang
The changes in regional facial skin blood flow and vascular conductance have been assessed for the first time with noninvasive two-dimensional laser speckle flowmetry during audiovisually elicited emotional challenges for 2 min (comedy, landscape, and horror movie) in 12 subjects. Limb skin blood flow and vascular conductance and systemic cardiovascular variables were simultaneously measured. The extents of pleasantness and consciousness for each emotional stimulus were estimated by the subjective rating from -5 (the most unpleasant; the most unconscious) to +5 (the most pleasant; the most conscious)...
January 21, 2017: Journal of Physiological Sciences: JPS
https://www.readbyqxmd.com/read/28107727/neural-correlates-of-subliminally-presented-visual-sexual-stimuli
#11
Martina Wernicke, Corinna Hofter, Kirsten Jordan, Peter Fromberger, Peter Dechent, Jürgen L Müller
In the context of forensic psychiatry, it is crucial that diagnoses of deviant sexual interests are resistant to manipulation. In a first attempt to promote the development of such tools, the current fMRI study focusses on the examination of hemodynamic responses to preferred, in contrast to non-preferred, sexual stimuli with and without explicit sexual features in 24 healthy heterosexual subjects. The subliminal stimulus presentation of sexual stimuli could be a new approach to reduce vulnerability to manipulation...
March 2017: Consciousness and Cognition
https://www.readbyqxmd.com/read/28092321/dexmedetomidine-disrupts-the-local-and-global-efficiencies-of-large-scale-brain-networks
#12
Javeria A Hashmi, Marco L Loggia, Sheraz Khan, Lei Gao, Jieun Kim, Vitaly Napadow, Emery N Brown, Oluwaseun Akeju
BACKGROUND: A clear understanding of the neural basis of consciousness is fundamental to research in clinical and basic neuroscience disciplines and anesthesia. Recently, decreased efficiency of information integration was suggested as a core network feature of propofol-induced unconsciousness. However, it is unclear whether this finding can be generalized to dexmedetomidine, which has a different molecular target. METHODS: Dexmedetomidine was administered as a 1-μg/kg bolus over 10 min, followed by a 0...
March 2017: Anesthesiology
https://www.readbyqxmd.com/read/28072803/neural-correlates-of-maladaptive-pain-behavior-in-chronic-neck-pain-a-single-case-control-fmri-study
#13
Konstantin Beinert, Audrey Mouthon, Martin Keller, Michael Mouthon, Jean-Marie Annoni, Wolfgang Taube
Chronic neck pain patients display functional impairments like decreased range of motion, decreased strength, and reduced sensorimotor function. In patients without structural damage, the reason for the persistence of pain is not well understood. Therefore, it is assumed that in chronic pain states, memory processes play an important role. We have now detected and tested a patient that might help us to better understand the neural correlates of maladaptive pain expectation/memory. This patient displays chronic neck pain and restricted unilateral motion of the cervical spine to the left...
January 2017: Pain Physician
https://www.readbyqxmd.com/read/28069540/multi-modal-analysis-of-functional-connectivity-and-cerebral-blood-flow-reveals-shared-and-unique-effects-of-propofol-in-large-scale-brain-networks
#14
Maolin Qiu, Dustin Scheinost, Ramachandran Ramani, R Todd Constable
Anesthesia-induced changes in functional connectivity and cerebral blow flow (CBF) in large-scale brain networks have emerged as key markers of reduced consciousness. However, studies of functional connectivity disagree on which large-scale networks are altered or preserved during anesthesia, making it difficult to find a consensus amount studies. Additionally, pharmacological alterations in CBF could amplify or occlude changes in connectivity due to the shared variance between CBF and connectivity. Here, we used data-driven connectivity methods and multi-modal imaging to investigate shared and unique neural correlates of reduced consciousness for connectivity in large-scale brain networks...
January 6, 2017: NeuroImage
https://www.readbyqxmd.com/read/28044014/a-roadmap-for-the-study-of-conscious-audition-and-its-neural-basis
#15
REVIEW
Andrew R Dykstra, Peter A Cariani, Alexander Gutschalk
How and which aspects of neural activity give rise to subjective perceptual experience-i.e. conscious perception-is a fundamental question of neuroscience. To date, the vast majority of work concerning this question has come from vision, raising the issue of generalizability of prominent resulting theories. However, recent work has begun to shed light on the neural processes subserving conscious perception in other modalities, particularly audition. Here, we outline a roadmap for the future study of conscious auditory perception and its neural basis, paying particular attention to how conscious perception emerges (and of which elements or groups of elements) in complex auditory scenes...
February 19, 2017: Philosophical Transactions of the Royal Society of London. Series B, Biological Sciences
https://www.readbyqxmd.com/read/27921217/don-t-make-me-angry-you-wouldn-t-like-me-when-i-m-angry-volitional-choices-to-act-or-inhibit-are-modulated-by-subliminal-perception-of-emotional-faces
#16
Jim Parkinson, Sarah Garfinkel, Hugo Critchley, Zoltan Dienes, Anil K Seth
Volitional action and self-control-feelings of acting according to one's own intentions and in being control of one's own actions-are fundamental aspects of human conscious experience. However, it is unknown whether high-level cognitive control mechanisms are affected by socially salient but nonconscious emotional cues. In this study, we manipulated free choice decisions to act or withhold an action by subliminally presenting emotional faces: In a novel version of the Go/NoGo paradigm, participants made speeded button-press responses to Go targets, withheld responses to NoGo targets, and made spontaneous, free choices to execute or withhold the response for Choice targets...
December 5, 2016: Cognitive, Affective & Behavioral Neuroscience
https://www.readbyqxmd.com/read/27882594/-cuts-in-action-a-high-density-eeg-study-investigating-the-neural-correlates-of-different-editing-techniques-in-film
#17
Katrin S Heimann, Sebo Uithol, Marta Calbi, Maria A Umiltà, Michele Guerra, Vittorio Gallese
In spite of their striking differences with real-life perception, films are perceived and understood without effort. Cognitive film theory attributes this to the system of continuity editing, a system of editing guidelines outlining the effect of different cuts and edits on spectators. A major principle in this framework is the 180° rule, a rule recommendation that, to avoid spectators' attention to the editing, two edited shots of the same event or action should not be filmed from angles differing in a way that expectations of spatial continuity are strongly violated...
November 24, 2016: Cognitive Science
https://www.readbyqxmd.com/read/27857199/neural-correlates-underlying-impaired-memory-facilitation-and-suppression-of-negative-material-in-depression
#18
Dandan Zhang, Hui Xie, Yunzhe Liu, Yuejia Luo
Previous behavioral studies demonstrated that depressed individuals have difficulties in forgetting unwanted, especially negative, event. However, inconsistent results still exit and the neural mechanism of this phenomenon has not been investigated. This study examined the intentional memory facilitation/suppression of negative and neutral materials in depression using Think/No-Think paradigm. We found that compared with nondepressed group, depressed group recalled more negative items, irrespective of either "Think" or "No-Think" instructions...
November 18, 2016: Scientific Reports
https://www.readbyqxmd.com/read/27829654/minimally-conscious-state-evolution-of-concept-diagnosis-and-treatment
#19
Ricardo Hodelín-Tablada
The study of consciousness disorders is a scientific challenge, and clinical differentiation among the various sorts of alterations in consciousness is difficult. Persistent vegetative state was defined in 1972, but years later cases appeared in which diagnosed patients showed signs of cognitive activity, and therefore could not be considered vegetative. Minimally conscious state was defined in 2002. This article discusses minimally conscious state based on a literature review and the author's clinical experience...
October 2016: MEDICC Review
https://www.readbyqxmd.com/read/27814457/functional-connectivity-during-masked-and-unmasked-face-emotion-processing-in-bipolar-disorder
#20
Wan-Ling Tseng, Laura A Thomas, Elizabeth Harkins, Joel Stoddard, Carlos A Zarate, Daniel S Pine, Ellen Leibenluft, Melissa A Brotman
Little is known regarding the neural connectivity and correlates during automatic, unconscious face emotion processing in individuals with bipolar disorder (BD). In this study, 14 adults with BD and 14 healthy volunteers (HV) underwent fMRI scanning while completing an affective priming task with unconsciously perceived and consciously perceived faces (angry, happy, neutral, blank oval). We found that, regardless of awareness level and emotion types, BD patients exhibited diminished functional connectivity between amygdala and ventromedial prefrontal cortex (vmPFC) compared to HV...
December 30, 2016: Psychiatry Research
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