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  • 1.
    Fingelkurts, Alexander
    et al.
    BM-SCIENCE – Brain & Mind Technologies Research Centre, Finland.
    Fingelkurts, Andrew
    BM-SCIENCE – Brain & Mind Technologies Research Centre, Finland.
    Kallio, Sakari
    University of Skövde, School of Humanities and Informatics.
    Revonsuo, Antti
    University of Skövde, School of Humanities and Informatics.
    Hypnosis Induces Reorganization in the Composition of Brain Oscillations in EEG: A case study2007In: Contemporary Hypnosis, ISSN 0960-5290, E-ISSN 1557-0711, Vol. 24, no 1, p. 3-18Article in journal (Refereed)
    Abstract [en]

    Cognitive functions associated with the frontal lobes of the brain may be specifically involved in hypnosis. Thus, the frontal area of the brain has recently been of great interest when searching for neural changes associated with hypnosis. We tested the hypothesis that EEG during pure hypnosis would differ from the normal non-hypnotic EEG especially above the frontal area of the brain. The composition of brain oscillations was examined in a broad frequency band (1-30 Hz) in the electroencephalogram (EEG) of a single virtuoso subject. Data was collected in two independent data collection periods separated by one year. The hypnotic and non-hypnotic conditions were repeated multiple times during each data acquisition session. We found that pure hypnosis induced reorganization in the composition of brain oscillations especially in prefrontal and right occipital EEG channels. Additionally, hypnosis was characterized by consistent right-side-dominance asymmetry. In the prefrontal EEG channels the composition of brain oscillations included spectral patterns during hypnosis that were completely different from those observed during non-hypnosis. Furthermore, the EEG spectral patterns observed overall during the hypnotic condition did not return to the pre-hypnotic baseline EEG immediately when hypnosis was terminated. This suggests that for the brain, the return to a normal neurophysiological baseline condition after hypnosis is a time-consuming process. The present results suggest that pure hypnosis is characterized by an increase in alertness and heightened attention, reflected as cognitive and neuronal activation. Taken together, the present data provide support for the hypothesis that in a very highly hypnotizable person (a hypnotic virtuoso) hypnosis as such may be accompanied by a changed pattern of neural activity in the brain. Copyright © 2007 British Society of Experimental & Clinical Hypnosis. Published by John Wiley & Sons, Ltd.

  • 2.
    Fingelkurts, Andrew
    et al.
    BM-SCIENCE - Brain and Mind Technologies Research Centre, P.O. Box 77, FI-02601 Espoo, Finland.
    Fingelkurts, Alexander
    BM-SCIENCE - Brain and Mind Technologies Research Centre, P.O. Box 77, FI-02601 Espoo, Finland.
    Kallio, Sakari
    University of Skövde, School of Humanities and Informatics.
    Revonsuo, Antti
    University of Skövde, School of Humanities and Informatics.
    Cortex Functional Connectivity as a Neurophysiological Correlate of Hypnosis: an EEG Case Study2007In: Neuropsychologia, ISSN 0028-3932, E-ISSN 1873-3514, Vol. 45, no 7, p. 1452-1462Article in journal (Refereed)
    Abstract [en]

    Cortex functional connectivity associated with hypnosis was investigated in a single highly hypnotizable subject in a normal baseline condition and under neutral hypnosis during two sessions separated by a year. After the hypnotic induction, but without further suggestions as compared to the baseline condition, all studied parameters of local and remote functional connectivity were significantly changed. The significant differences between hypnosis and the baseline condition were observable (to different extent) in five studied independent frequency bands (delta, theta, alpha, beta, and gamma). The results were consistent and stable after 1 year. Based on these findings we conclude that alteration in functional connectivity of the brain may be regarded as a neuronal correlate of hypnosis (at least in very highly hypnotizable subjects) in which separate cognitive modules and subsystems may be temporarily incapable of communicating with each other normally

  • 3.
    Gavie, Josefin
    et al.
    University of Skövde, School of Humanities and Informatics.
    Revonsuo, Antti
    University of Skövde, School of Humanities and Informatics. Center for Cognitive Neuroscience, University of Turku, Finland.
    The future of lucid dreaming treatment: Commentary on "The neurobiology of consciousness: Lucid dreaming wakes up" by J. Allan Hobson2010In: International Journal of Dream Research, ISSN 1866-7953, E-ISSN 1866-7953, Vol. 3, no 1, p. 13-15Article in journal (Refereed)
  • 4.
    Grassini, Simone
    et al.
    Department of Psychology, University of Turku, Finland.
    Railo, Henry
    Department of Psychology, University of Turku, Finland.
    Valli, Katja
    University of Skövde, School of Bioscience. University of Skövde, The Systems Biology Research Centre. Department of Psychology, University of Turku, Finland.
    Revonsuo, Antti
    University of Skövde, School of Bioscience. University of Skövde, The Systems Biology Research Centre. Department of Psychology, University of Turku, Finland.
    Koivisto, Mika
    Department of Psychology, University of Turku, Finland.
    Visual features and perceptual context modulate attention towards evolutionarily relevant threatening stimuli: Electrophysiological evidence2018In: Emotion, ISSN 1528-3542, E-ISSN 1931-1516, article id 10.1037/emo0000434Article in journal (Refereed)
    Abstract [en]

    The snake detection hypothesis claims that predatory pressure from snakes has shaped the primate visual system, but we still know very little about how the brain processes evolutionarily important visual cues, and which factors are crucial for quick detection of snakes. We investigated how visual features modulate the electrophysiological markers of early attentional processes. In Experiment 1, we compared snake, rope, gun, and bird images to isolate the effects due to curvilinearity of the stimuli. The results showed that both snake and rope images elicited enhanced P1 and N1 event-related potential components as well as early posterior negativity (EPN). In Experiment 2, we studied whether nonthreatening curvilinear images (i.e., ropes) still elicit the enhanced electrophysiological responses when snake images are not presented as stimuli, and therefore the context does not provoke top-down attention to curvilinear shapes. Rope images still evoked an enhanced EPN, suggesting that curvilinear shapes are preferably captured by attentional processes. However, this effect was smaller than in Experiment 1, in which snake images were present. Thus, our results hint to the possibility that the perceptual context may interact with processing of shape information, drawing attention to curvilinear shapes when the presence of snakes is expectable. Furthermore, we observed that spatial frequency of the visual stimuli modulated especially the early electrophysiological responses, and decreased the differences between stimulus categories in EPN without completely eliminating them. The findings suggest that low-level and high-level mechanisms interact to give an attentional priority to potentially threatening stimuli.

  • 5.
    Hurme, Mikko
    et al.
    Department of Psychology, University of Turku, Finland / Centre for Cognitive Neuroscience, University of Turku, Finland / Turku Brain and Mind Centre, University of Turku, Finland.
    Koivisto, Mika
    Department of Psychology, University of Turku, Finland / Centre for Cognitive Neuroscience, University of Turku, Finland / Turku Brain and Mind Centre, University of Turku, Finland.
    Revonsuo, Antti
    University of Skövde, School of Bioscience. University of Skövde, The Systems Biology Research Centre. Department of Psychology, University of Turku, Finland / Centre for Cognitive Neuroscience, University of Turku, Finland / Turku Brain and Mind Centre, University of Turku, Finland.
    Railo, Henry
    Department of Psychology, University of Turku, Finland / Centre for Cognitive Neuroscience, University of Turku, Finland / Turku Brain and Mind Centre, University of Turku, Finland.
    Early processing in primary visual cortex is necessary for conscious and unconscious vision while late processing is necessary only for conscious vision in neurologically healthy humans2017In: NeuroImage, ISSN 1053-8119, E-ISSN 1095-9572, Vol. 150, p. 230-238Article in journal (Refereed)
    Abstract [en]

    The neural mechanisms underlying conscious and unconscious visual processes remain controversial. Blindsight patients may process visual stimuli unconsciously despite their VI lesion, promoting anatomical models, which suggest that pathways bypassing the VI support unconscious vision. On the other hand, physiological models argue that the major geniculostriate pathway via VI is involved in both unconscious and conscious vision, but in different time windows and in different types of neural activity. According to physiological models, feedforward activity via VI to higher areas mediates unconscious processes whereas feedback loops of recurrent activity from higher areas back to VI support conscious vision. With transcranial magnetic stimulation (TMS) it is possible to study the causal role of a brain region during specific time points in neurologically healthy participants. In the present study, we measured unconscious processing with redundant target effect, a phenomenon where participants respond faster to two stimuli than one even when one of the stimuli is not consciously perceived. We tested the physiological feedforward-feedback model of vision by suppressing conscious vision by interfering selectively either with early or later VI activity with TMS. Our results show that early VI activity (60 ms) is necessary for both unconscious and conscious vision. During later processing stages (90 ms), VI contributes selectively to conscious vision. These findings support the feedforward-feedback-model of consciousness.

  • 6.
    Intaite, Monika
    et al.
    Visual Neuroscience Laboratory, IBILI, Faculty of Medicine, University of Coimbra, Coimbra, Portugal.
    Koivisto, Mika
    Centre for Cognitive Neuroscience, University of Turku, Turku, Finland / Department of Psychology, University of Turku, Turku, Finland.
    Revonsuo, Antti
    University of Skövde, School of Humanities and Informatics. University of Skövde, The Systems Biology Research Centre. Centre for Cognitive Neuroscience, University of Turku, Turku, Finland / Department of Psychology, University of Turku, Turku, Finland.
    Perceptual reversals of Necker stimuli during intermittent presentation with limited attentional resources2013In: Psychophysiology, ISSN 0048-5772, E-ISSN 1469-8986, Vol. 50, no 1, p. 82-96Article in journal (Refereed)
    Abstract [en]

    During prolonged viewing of ambiguous stimuli, such as Necker cubes, sudden perceptual reversals occur from one perceptual interpretation to another. The role of attention in such reversals is not clear. We tested whether perceptual reversals depend on attentional resources by manipulating perceptual load and recording event-related potentials (ERPs) during intermittent presentation of Necker stimuli. The results did not reveal any influence for perceptual load on the frequency of reversals. The ERPs showed that perceptual load influenced electrophysiological activity over parieto-central areas in the P1 time window (110–140 ms), but load did not modify the early enhancements of positivity (30–140 ms), which correlated with perceptual reversals at occipito-temporal sites. We conclude that disambiguation of ambiguous figures is based on early mechanisms that can work efficiently with only a minimal amount of attentional resources.

  • 7. Intaité, Monika
    et al.
    Koivisto, Mika
    Ruksenas, Osvaldas
    Revonsuo, Antti
    University of Skövde, School of Humanities and Informatics.
    Reversal negativity and bistable stimuli: Attention, awareness, or something else?2010In: Brain and Cognition, ISSN 0278-2626, E-ISSN 1090-2147, Vol. 74, no 1, p. 24-34Article in journal (Refereed)
    Abstract [en]

    Ambiguous (or bistable) figures are visual stimuli that have two mutually exclusive perceptual interpretations that spontaneously alternate with each other. Perceptual reversals, as compared with non-reversals, typically elicit a negative difference called reversal negativity (RN), peaking around 250 ms from stimulus onset. The cognitive interpretation of RN remains unclear: it may reflect either bottom-up processes, attentional processes that select between the alternative views of the stimulus, or it may reflect the change in the contents of subjective awareness. In the present study, event-related potentials in response to endogenous unilateral and bilateral reversals of two Necker lattices were compared with exogenously induced reversals of unambiguous lattices. The RN neither resembled the attention-related N2pc response, nor did it correlate with the content of subjective visual awareness. Thus, we conclude that RN is a non-attentional ERP correlate of the changes in the perceptual configuration of the presented object.

  • 8.
    Johanson, Mirja
    et al.
    Stora Skondal Fdn, Neurol Rehabil Clin, S-12885 Skondal, Sweden .
    Valli, Katja
    University of Skövde, School of Humanities and Informatics.
    Revonsuo, Antti
    University of Skövde, School of Humanities and Informatics.
    How to assess ictal consciousness?2011In: Behavioural Neurology, ISSN 0953-4180, E-ISSN 1875-8584, Vol. 24, no 1, p. 11-20Article in journal (Refereed)
    Abstract [en]

    Despite the complexity and methodological difficulties in defining the concept consciousness, it is a central concept in epileptology, and should thus be tractable for scientific analysis. In the present article, a two-dimensional model consisting of concepts related to the level and the contents of consciousness will be presented. This model has been found to be well suited for the description of seizure-induced alterations of consciousness, and is supported both by findings from neuroimaging and electrophysiological studies as well as from phenomenological studies. Further, we will review both traditional introspective methods as well as methods that have recently been developed or utilized in epilepsy research, summarize the main findings concerning first person experiences during epileptic seizures acquired with some of these methods, and discuss their strengths and weaknesses.

  • 9.
    Johanson, Mirja
    et al.
    Stora Sköndal Fdn, Neurol Rehabil Clin, S-12885 Sköndal, Sweden / Åbo Akad Univ, Dept Psychol, SF-20500 Turku, Finland.
    Valli, Katja
    University of Skövde, School of Humanities and Informatics.
    Revonsuo, Antti
    University of Skövde, School of Humanities and Informatics.
    Chaplin, John E
    Univ Gothenburg, Dept Pediat, Sahlgrenska Acad, Gothenburg, Sweden.
    Wedlund, Jan-Eric
    Stora Sköndal Fdn, Neurol Rehabil Clin, S-12885 Sköndal, Sweden.
    Alterations in the contents of consciousness in partial epileptic seizures2008In: Epilepsy & Behavior, ISSN 1525-5050, E-ISSN 1525-5069, Vol. 13, no 2, p. 366-371Article in journal (Refereed)
    Abstract [en]

    Epilepsy research suffers from a deficiency of systematic studies concerning the phenomenology of the contents of consciousness during seizures, partially because of the lack of suitable research methods. The Phenomenology of Consciousness Inventory (PCI), a standardized, valid, and reliable questionnaire, was used here to study which dimensions of the contents of consciousness are distorted during partial epileptic seizures compared with baseline. Further, the similarity of the altered pattern of subjective experiences across recurring seizures was also explored. Our results indicate that patients with epilepsy report alterations on most dimensions of the contents of consciousness in conjunction with seizures, but individual seizure experiences remain similar from one seizure to another. The PCI was found suitable for the assessment of subjective experiences during epileptic seizures and could be a valuable tool in providing new information about phenomenal consciousness in epilepsy in both the research and clinical settings.

  • 10.
    Johanson, Mirja
    et al.
    Stora Sköndal Fdn, Neurol Rehabilitat Clin, S-12885 Sköndal, Sweden / Åbo Akad Univ, Dept Psychol, SF-20500 Turku, Finland.
    Valli, Katja
    University of Skövde, School of Humanities and Informatics.
    Revonsuo, Antti
    University of Skövde, School of Humanities and Informatics.
    Wedlund, Jan-Eric
    Stora Sköndal Fdn, Neurol Rehabilitat Clin, S-12885 Sköndal, Sweden.
    Content analysis of subjective experiences in partial epileptic seizures2008In: Epilepsy & Behavior, ISSN 1525-5050, E-ISSN 1525-5069, Vol. 12, no 1, p. 170-182Article in journal (Refereed)
    Abstract [en]

    A new content analysis method for systematically describing the phenomenology of subjective experiences in connection with partial epileptic seizures is described. Forty patients provided 262 descriptions of subjective experience relative to their partial epileptic seizures. The results revealed that subjective experiences during seizures consist mostly of sensory and bodily sensations, hallucinatory experiences, and thinking. The majority of subjective experiences during seizures are bizarre and distorted; nevertheless, the patients are able to engage in adequate behavior. To the best of our knowledge, this is the first study for which detailed subjective seizure descriptions were collected immediately after each seizure and the first study in which the content of verbal reports of subjective experiences during seizures, including both the ictal and postictal experiences, has been analyzed in detail.

  • 11.
    Kallio, Sakari
    et al.
    University of Skövde, School of Humanities and Informatics. Centre for Cognitive Neuroscience, University of Turku, Turku, Finland / Department of Psychology, University of Turku, Turku, Finland.
    Hyönä, Jukka
    Department of Psychology, University of Turku, Turku, Finland.
    Revonsuo, Antti
    University of Skövde, School of Humanities and Informatics. Centre for Cognitive Neuroscience, University of Turku, Turku, Finland / Department of Psychology, University of Turku, Turku, Finland.
    Sikka, Pilleriin
    University of Skövde, School of Humanities and Informatics. Centre for Cognitive Neuroscience, University of Turku, Turku, Finland / Department of Psychology, University of Turku, Turku, Finland.
    Nummenmaa, Lauri
    Brain Research Unit, Low Temperature Laboratory, Aalto University School of Science, Espoo, Finland / Department of Biomedical Engineering and Computational Science, Aalto University School of Science, Espoo, Finland / Turku PET Centre, University of Turku, Turku, Finland.
    The Existence of a Hypnotic State Revealed by Eye Movements2011In: PLoS ONE, ISSN 1932-6203, E-ISSN 1932-6203, Vol. 6, no 10, article id e26374Article in journal (Refereed)
  • 12.
    Kallio, Sakari
    et al.
    University of Skövde, School of Humanities and Informatics.
    Revonsuo, Antti
    University of Skövde, School of Humanities and Informatics.
    Altering the state of the altered state debate: reply to commentaries2005In: Contemporary Hypnosis, ISSN 0960-5290, E-ISSN 1557-0711, Vol. 22, no 1, p. 46-55Article in journal (Refereed)
    Abstract [en]

    The main point of our article Hypnotic phenomena and altered states of consciousness: A multilevel framework of description and explanation was to clarify, explicate and reveal the differences between current theoretical viewpoints in explaining hypnosis. Furthermore, we wanted to present a research programme and propose some experiments that if carried out, might lend decisive support to either the Nonstate View (NSV) or the State View (SV) approaches to hypnosis. The commentaries revealed that the concept of altered state of consciousness (ASC) still lacks a commonly accepted definition and is in need of further clarification. The controversy between NSV and SV of hypnosis seems to boil down to the question concerning the explanatory power of the neural level and especially to what the results at this level tell us. In this reply we further clarify the multilevel framework of explanation, the problems associated with the concept of ASC, and we explain the rationale for our proposal of using virtuosos as a model system in hypnosis research. Copyright © 2005 British Society of Experimental and Clinical Hypnosis

  • 13.
    Kallio, Sakari
    et al.
    University of Skövde, School of Humanities and Informatics.
    Revonsuo, Antti
    University of Skövde, School of Humanities and Informatics.
    Hypnotic phenomena and altered states of consciousness: A multilevel framework of description and explanation2003In: Contemporary Hypnosis, ISSN 0960-5290, Vol. 20, no 3, p. 111-164Article in journal (Refereed)
    Abstract [en]

    There is currently agreement that, in addition to the changes in external behaviour, suggestions presented in a hypnotic context may give rise to changes in subjective experience. Yet, there is no general agreement about the theoretical framework within which these changes in experience should be explained. Though different theories about hypnosis overlap in many respects, there is still disagreement on whether reference to a specific internal state of the individual is necessary in order to explain these changes. We place the explanatory task in the context of a multilevel framework of explanation, which reveals that the disagreement between the state and nonstate view is about the level of description at which the phenomenon hypnosis should be conceptualized. We propose a novel approach using the multilevel explanation which helps to formulate empirically testable hypotheses about the nature of hypnosis. We will outline the basic elements of such an approach and hope that our proposition will help hypnosis research to integrate with the multidisciplinary research on other phenomena of consciousness.

  • 14.
    Kallio, Sakari
    et al.
    University of Skövde, School of Humanities and Informatics.
    Revonsuo, Antti
    University of Skövde, School of Humanities and Informatics.
    The observer remains hidden2005In: Contemporary Hypnosis, ISSN 0960-5290, E-ISSN 1557-0711, Vol. 22, no 3, p. 138-143Article in journal (Refereed)
    Abstract [en]

    The concept of hidden observer is one of the most controversial issues in hypnosis research. Green, Page, Handley and Rasekhy (this issue) approach it by using an ideomotor task which has not previously been used in association with the hidden observer. We regard their experiment as interesting; however, there are conceptual and methodological problems that hamper the impact of their study. In our commentary, we take the opportunity to point out some problems in their paper as well as to stress the importance to integrate concepts used in hypnosis research to mainstream cognitive neuroscience and consciousness research. Copyright © 2005 British Society of Experimental & Clinical Hypnosis. Published by John Wiley & Sons, Ltd.

  • 15.
    Kallio, Sakari
    et al.
    University of Skövde, School of Humanities and Informatics.
    Revonsuo, Antti
    University of Skövde, School of Humanities and Informatics.
    Fingelkurts, Andrew A.
    Fingelkurts, Alexander A.
    Change in the cortical functional connectivity as a candidate for psychophysiological correlate of hypnosis2006In: International Journal of Psychophysiology, ISSN 0167-8760, E-ISSN 1872-7697, Vol. 61, no 3, p. 301-302Article in journal (Other academic)
  • 16.
    Kallio, Sakari
    et al.
    University of Skövde, School of Humanities and Informatics.
    Revonsuo, Antti
    University of Skövde, School of Humanities and Informatics.
    Lang, H
    University of Skövde, School of Humanities and Informatics.
    Can hypnosis and hypnotic hallucination change information processing in the brain: A case report2005In: Hypnos: Swedish journal of hypnosis in psychotherapy and psychosomatic medicine, ISSN 0282-5090, Vol. 32, no 1, p. 25-35Article in journal (Refereed)
  • 17.
    Kallionpää, R. E.
    et al.
    Department of Psychology and Speech-Language Pathology, and Turku Brain and Mind Center, University of Turku, Turku, Finland / Department of Perioperative Services, Intensive Care and Pain Medicine, Turku University Hospital, Turku, Finland.
    Scheinin, A.
    Department of Perioperative Services, Intensive Care and Pain Medicine, Turku University Hospital, Turku, Finland / Turku PET Centre, University of Turku and Turku University Hospital,Turku, Finland.
    Kallionpää, R. A.
    Institute of Biomedicine, University of Turku, Turku, Finland.
    Sandman, N.
    Department of Psychology and Speech-Language Pathology, and Turku Brain and Mind Center, Universityof Turku, Turku, Finland.
    Kallioinen, M.
    Department of Perioperative Services, Intensive Care and Pain Medicine, Turku University Hospital, Turku, Finland.
    Laitio, R.
    Turku PET Centre, University of Turku and Turku University Hospital,Turku, Finland.
    Laitio, T.
    Turku PET Centre, University of Turku and Turku University Hospital,Turku, Finland.
    Kaskinoro, K.
    Turku PET Centre, University of Turku and Turku University Hospital,Turku, Finland.
    Kuusela, T.
    Department of Physics and Astronomy, University of Turku, Turku, Finland.
    Revonsuo, Antti
    University of Skövde, School of Bioscience. University of Skövde, The Systems Biology Research Centre. Department of Psychology and Speech-Language Pathology, and Turku Brain and Mind Center, University of Turku, Turku, Finland.
    Scheinin, H.
    Department of Perioperative Services, Intensive Care and Pain Medicine, Turku University Hospital, Turku, Finland / Turku PET Centre, University of Turku and Turku University Hospital,Turku, Finland / Integrative Physiology and Pharmacology,Institute of Biomedicine, University of Turku, Turku, Finland.
    Valli, Katja
    University of Skövde, School of Bioscience. University of Skövde, The Systems Biology Research Centre. Department of Psychology and Speech-Language Pathology, and Turku Brain and Mind Center, University of Turku, Turku, Finland / Department of Perioperative Services, Intensive Care and Pain Medicine, Turku University Hospital, Turku, Finland.
    Spoken words are processed during dexmedetomidine-induced unresponsiveness2018In: British Journal of Anaesthesia, ISSN 0007-0912, E-ISSN 1471-6771, Vol. 121, no 1, p. 270-280Article in journal (Refereed)
    Abstract [en]

    Background: Studying the effects of anaesthetic drugs on the processing of semantic stimuli could yield insights into how brain functions change in the transition from wakefulness to unresponsiveness. Here, we explored the N400 event-related potential during dexmedetomidine- and propofol-induced unresponsiveness. Methods: Forty-seven healthy subjects were randomised to receive either dexmedetomidine (n = 23) or propofol (n = 24) in this open-label parallel-group study. Loss of responsiveness was achieved by stepwise increments of pseudo-steady-state plasma concentrations, and presumed loss of consciousness was induced using 1.5 times the concentration required for loss of responsiveness. Pre-recorded spoken sentences ending either with an expected (congruous) or an unexpected (incongruous) word were presented during unresponsiveness. The resulting electroencephalogram data were analysed for the presence of the N400 component, and for the N400 effect defined as the difference between the N400 components elicited by congruous and incongruous stimuli, in the time window 300-600 ms post-stimulus. Recognition of the presented stimuli was tested after recovery of responsiveness. Results: The N400 effect was not observed during dexmedetomidine- or propofol-induced unresponsiveness. The N400 component, however, persisted during dexmedetomidine administration. The N400 component elicited by congruous stimuli during unresponsiveness in the dexmedetomidine group resembled the large component evoked by incongruous stimuli at the awake baseline. After recovery, no recognition of the stimuli heard during unresponsiveness occurred. Conclusions: Dexmedetomidine and propofol disrupt the discrimination of congruous and incongruous spoken sentences, and recognition memory at loss of responsiveness. However, the processing of words is partially preserved during dexmedetomidine-induced unresponsiveness.

  • 18.
    Koivisto, Mika
    et al.
    Department of Psychology, University of Turku, Turun yliopisto, Finland / Centre for Cognitive Neuroscience, University of Turku, Turun yliopisto, Finland.
    Grassini, Simone
    Department of Psychology, University of Turku, Turun yliopisto, Finland / Centre for Cognitive Neuroscience, University of Turku, Turun yliopisto, Finland.
    Hurme, Mikko
    Department of Psychology, University of Turku, Turun yliopisto, Finland / Centre for Cognitive Neuroscience, University of Turku, Turun yliopisto, Finland.
    Salminen-Vaparanta, Niina
    Department of Psychology, University of Turku, Turun yliopisto, Finland / Centre for Cognitive Neuroscience, University of Turku, Turun yliopisto, Finland.
    Railo, Henry
    Department of Psychology, University of Turku, Turun yliopisto, Finland / Centre for Cognitive Neuroscience, University of Turku, Turun yliopisto, Finland.
    Vorobyev, Victor
    Department of Psychology, University of Turku, Turun yliopisto, Finland / Centre for Cognitive Neuroscience, University of Turku, Turun yliopisto, Finland.
    Tallus, Jussi
    Department of Radiology, Turku University Hospital, Turun yliopisto, Finland.
    Paavilainen, Teemu
    Department of Radiology, Turku University Hospital, Turun yliopisto, Finland.
    Revonsuo, Antti
    University of Skövde, School of Bioscience. University of Skövde, The Systems Biology Research Centre. Department of Psychology, University of Turku, Turun yliopisto, Finland / Centre for Cognitive Neuroscience, University of Turku, Turun yliopisto, Finland.
    TMS-EEG reveals hemispheric asymmetries in top-down influences of posterior intraparietal cortex on behavior and visual event-related potentials2017In: Neuropsychologia, ISSN 0028-3932, E-ISSN 1873-3514, Vol. 107, p. 94-101Article in journal (Refereed)
    Abstract [en]

    Clinical data and behavioral studies using transcranial magnetic stimulation (TMS) suggest right-hemisphere dominance for top-down modulation of visual processing in humans. We used concurrent TMS-EEG to directly test for hemispheric differences in causal influences of the right and left intraparietal cortex on visual event-related potentials (ERPs). We stimulated the left and right posterior part of intraparietal sulcus (IPS1) while the participants were viewing and rating the visibility of bilaterally presented Gabor patches. Subjective visibility ratings showed that TMS of right IPS shifted the visibility toward the right hemifield, while TMS of left IPS did not have any behavioral effect. TMS of right IPS, but not left one, reduced the amplitude of posterior N1 potential, 180–220 ms after stimulus-onset. The attenuation of N1 occurred bilaterally over the posterior areas of both hemispheres. Consistent with previous TMS-fMRI studies, this finding suggests that the right IPS has top-down control on the neural processing in visual cortex. As N1 most probably reflects reactivation of early visual areas, the current findings support the view that the posterior parietal cortex in the right hemisphere amplifies recurrent interactions in ventral visual areas during the time-window that is critical for conscious perception.

  • 19.
    Koivisto, Mika
    et al.
    University of Turku, Turku, Finland.
    Grassini, Simone
    University of Turku, Turku, Finland.
    Salminen-Vaparanta, Niina
    University of Turku, Turku, Finland.
    Revonsuo, Antti
    University of Skövde, School of Bioscience. University of Skövde, The Systems Biology Research Centre. University of Turku, Turku, Finland.
    Different Electrophysiological Correlates of Visual Awareness for Detection and Identification2017In: Journal of cognitive neuroscience, ISSN 0898-929X, E-ISSN 1530-8898, Vol. 29, no 9, p. 1621-1631Article in journal (Refereed)
    Abstract [en]

    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.

  • 20.
    Koivisto, Mika
    et al.
    Department of Psychology, University of Turku, Finland / Centre for Cognitive Neuroscience, University of Turku, Finland.
    Harjuniemi, Inari
    Department of Psychology, University of Turku, Finland / Centre for Cognitive Neuroscience, University of Turku, Finland.
    Railo, Henry
    Department of Psychology, University of Turku, Finland / Centre for Cognitive Neuroscience, University of Turku, Finland.
    Salminen-Vaparanta, Niina
    Department of Psychology, University of Turku, Finland / Centre for Cognitive Neuroscience, University of Turku, Finland.
    Revonsuo, Antti
    Department of Psychology, University of Turku, Finland / Centre for Cognitive Neuroscience, University of Turku, Finland.
    Transcranial magnetic stimulation of early visual cortex suppresses conscious representations in a dichotomous manner without gradually decreasing their precision2017In: NeuroImage, ISSN 1053-8119, E-ISSN 1095-9572, Vol. 158, p. 308-318Article in journal (Refereed)
    Abstract [en]

    Transcranial magnetic stimulation (TMS) of early visual cortex can suppresses visual perception at early stages of processing. The suppression can be measured both with objective forced-choice tasks and with subjective ratings of visual awareness, but there is lack of objective evidence on how and whether the TMS influences the quality of representations. Does TMS decrease the precision of representations in graded manner, or does it lead to dichotomous, "all-or-nothing" suppression. We resolved this question by using a continuous measure of the perceptual error: the observers had to perceive the orientation of a target (Landort-C) and to adjust the orientation of a probe to match that of the target. Mixture modeling was applied to estimate the probability of guess trials and the standard deviation of the non-guess trials. TMS delivered 60-150 ms after stimulus-onset influenced only the guessing rate, whereas the standard deviation (i.e., precision) was not affected. This suggests that TMS suppressed representations dichotomously without affecting their precision. The guessing probability correlated with subjective visibility ratings, suggesting that it measured visual awareness. In a control experiment, manipulation of the stimulus contrast affected the standard deviation of the errors, indicating that contrast has a gradual influence on the precision of representations. The findings suggest that TMS of early visual cortex suppresses perception in dichotomous manner by decreasing the signal-to-noise ratio by increasing the noise level, whereas reduction of the signal level (i.e., contrast) decreases the precision of representations.

  • 21.
    Koivisto, Mika
    et al.
    Univ Turku, Ctr Cognit Neurosci, Turku, Finland / Univ Turku, Dept Psychol, Turku, Finland .
    Henriksson, Linda
    Aalto Univ, Sch Sci, Brain Res Unit, Low Temp Lab, Helsinki, Finland / Aalto Univ, Sch Sci, Adv Magnet Imaging Ctr, Helsinki, Finland .
    Revonsuo, Antti
    University of Skövde, School of Humanities and Informatics.
    Railo, Henry
    Univ Turku, Ctr Cognit Neurosci, Turku, Finland / Univ Turku, Dept Psychol, Turku, Finland .
    Unconscious response priming by shape depends on geniculostriate visual projection2012In: European Journal of Neuroscience, ISSN 0953-816X, E-ISSN 1460-9568, Vol. 35, no 4, p. 623-633Article in journal (Refereed)
    Abstract [en]

    It has been suggested that unconscious visual processing of some stimulus features might occur without the contribution of early visual cortex (V1/V2). In the present study, the causal role of V1/V2 in unconscious processing of simple shapes in intact human brain was studied by applying transcranial magnetic stimulation (TMS) on early visual cortex or lateral occipital cortex (LO) while observers performed a metacontrast-masked response priming task with arrow figures as visual stimuli. Magnetic stimulation of V1/V2 impaired masked priming 3090 ms after the onset of the prime. Stimulation of LO reduced the magnitude of masked priming at 90120 ms, but this effect occurred only in the early parts of the priming experiment. A control task measuring the visibility of masked primes indicated that the orientation of masked primes could not be consciously discriminated and that TMS did not influence the conscious visibility of the primes indirectly by reducing the effectiveness of the mask in the critical time windows. We conclude that feedforward sweep of processing from V1/V2 (3090 ms) to LO (90 ms and above) is necessary for unconscious priming of shape, whereas conscious perception requires also the contribution of recurrent (feedback) processing.

  • 22.
    Koivisto, Mika
    et al.
    Centre for Cognitive Neuroscience, University of Turku, Finland / Department of Psychology, University of Turku, Finland.
    Kainulainen, Pasi
    Centre for Cognitive Neuroscience, University of Turku, Finland / Department of Psychology, University of Turku, Finland.
    Revonsuo, Antti
    University of Skövde, School of Humanities and Informatics.
    The relationship between awareness and attention: Evidence from ERP responses2009In: Neuropsychologia, ISSN 0028-3932, E-ISSN 1873-3514, Vol. 47, no 13, p. 2891-2899Article in journal (Refereed)
    Abstract [en]

    The relationship between attention and awareness is complex, because both concepts can be understood in different ways. Here we review our recent series of experiments which have tracked the independent contributions of different types of visual attention and awareness to electrophysiological brain responses, and then we report a new experiment focusing on spatial attention, nonspatial selection of objects, and visual consciousness at the same time. The results indicate that the earliest electrophysiological correlate of consciousness, assumed to correlate with “phenomenal consciousness”, was dependent on spatial attention, suggesting that spatial attention is a prerequisite for the internal representations of space that provide the medium for phenomenal experience. The correlate of phenomenal consciousness emerged independent of nonspatial selection of objects, but its later part was modified by it. By contrast, the correlate of access to later conscious processing stages (“reflective consciousness”) that take the selected contents of phenomenal consciousness as input for conceptual thought and working memory, was dependent on both spatial attention and nonspatial selection. These results imply that one should distinguish between different types of attention and different forms of awareness, when describing the relationship between attention and awareness.

  • 23.
    Koivisto, Mika
    et al.
    University of Turku, Finland.
    Kastrati, Granit
    University of Skövde.
    Revonsuo, Antti
    University of Skövde, School of Bioscience. University of Skövde, The Systems Biology Research Centre.
    Recurrent processing enhances visual awareness but is not necessary for fast categorization of natural scenes2014In: Journal of cognitive neuroscience, ISSN 0898-929X, E-ISSN 1530-8898, Vol. 26, no 2, p. 223-231Article in journal (Refereed)
    Abstract [en]

    Humans are rapid in categorizing natural scenes. Electrophysiological recordings reveal that scenes containing animals can be categorized within 150 msec, which has been interpreted to indicate that feedforward flow of information from V1 to higher visual areas is sufficient for visual categorization. However, recent studies suggest that recurrent interactions between higher and lower levels in the visual hierarchy may also be involved in categorization. To clarify the role of recurrent processing in scene categorization, we recorded EEG and manipulated recurrent processing with object substitution masking while the participants performed a go/no-go animal/nonanimal categorization task. The quality of visual awareness was measured with a perceptual awareness scale after each trial. Masking reduced the clarity of perceptual awareness, slowed down categorization speed for scenes that were not clearly perceived, and reduced the electrophysiological difference elicited by animal and nonanimal scenes after 150 msec. The results imply that recurrent processes enhance the resolution of conscious representations and thus support categorization of stimuli that are difficult to categorize on the basis of the coarse feedforward representations alone.

  • 24.
    Koivisto, Mika
    et al.
    University of Turku, Finland.
    Kirjanen, Svetlana
    University of Helsinki, Finland.
    Revonsuo, Antti
    University of Skövde, School of Humanities and Informatics. University of Skövde, The Systems Biology Research Centre.
    Kallio, Sakari
    University of Skövde, School of Humanities and Informatics. University of Skövde, The Systems Biology Research Centre.
    A Preconscious Neural Mechanism of Hypnotically Altered Colors: A Double Case Study2013In: PLoS ONE, ISSN 1932-6203, E-ISSN 1932-6203, Vol. 8, no 8, article id e70900Article in journal (Refereed)
    Abstract [en]

    Hypnotic suggestions may change the perceived color of objects. Given that chromatic stimulus information is processed rapidly and automatically by the visual system, how can hypnotic suggestions affect perceived colors in a seemingly immediate fashion? We studied the mechanisms of such color alterations by measuring electroencephalography in two highly suggestible participants as they perceived briefly presented visual shapes under posthypnotic color alternation suggestions such as "all the squares are blue''. One participant consistently reported seeing the suggested colors. Her reports correlated with enhanced evoked upper beta-band activity (22 Hz) 70-120 ms after stimulus in response to the shapes mentioned in the suggestion. This effect was not observed in a control condition where the participants merely tried to simulate the effects of the suggestion on behavior. The second participant neither reported color alterations nor showed the evoked beta activity, although her subjective experience and event-related potentials were changed by the suggestions. The results indicate a preconscious mechanism that first compares early visual input with a memory representation of the suggestion and consequently triggers the color alteration process in response to the objects specified by the suggestion. Conscious color experience is not purely the result of bottom-up processing but it can be modulated, at least in some individuals, by top-down factors such as hypnotic suggestions.

  • 25.
    Koivisto, Mika
    et al.
    Univ Turku, Ctr Cognit Fdn, Turku 20014, Finland / Univ Turku, Dept Philosophy, Turku 20014, Finland.
    Lähteenmäki, Mikko
    Univ Turku, Ctr Cognit Fdn, Turku 20014, Finland / Univ Turku, Dept Psychol, Turku 20014, Finland.
    Sörensen, Thomas Alrik
    Univ Copenhagen, Dept Psychol, DK-1361 Copenhagen K, Denmark.
    Vangkilde, Signe
    Univ Copenhagen, Dept Psychol, DK-1361 Copenhagen K, Denmark.
    Overgaard, Morten
    Hammel Neuroctr, DK-8250 Hammel, Denmark.
    Revonsuo, Antti
    University of Skövde, School of Humanities and Informatics.
    The earliest electrophysiological correlate of visual awareness?2008In: Brain and Cognition, ISSN 0278-2626, E-ISSN 1090-2147, Vol. 66, no 1, p. 91-103Article in journal (Refereed)
    Abstract [en]

    To examine the neural correlates and timing of human visual awareness, we recorded event-related potentials (ERPs) in two experiments while the observers were detecting a grey dot that was presented near subjective threshold. ERPs were averaged for conscious detections of the stimulus (hits) and nondetections (misses) separately. Our results revealed that hits, as compared to misses, showed a negativity around 180–350 ms at occipital and posterior temporal sites. It was followed by a positive wave after 400–500 ms, peaking at parietal sites. These correlates were not affected by a manipulation of attention. The early negativity, called ‘visual awareness negativity’ (VAN), may be a general, primary electrophysiological correlate of visual awareness. The present data show that it can be observed in response to appearance of a stimulus in visual awareness and that it generalizes across different manipulations of stimulus visibility.

  • 26.
    Koivisto, Mika
    et al.
    Centre for Cognitive Neuroscience and Department of Psychology, University of Turku, 20014 Turku, Finland.
    Railo, Henry
    Centre for Cognitive Neuroscience and Department of Psychology, University of Turku, 20014 Turku, Finland.
    Revonsuo, Antti
    University of Skövde, School of Humanities and Informatics.
    Vanni, Simo
    Brain Research Unit and AMI centre, Low Temperature Laboratory, Aalto University School of Science and Technology, 00076 Aalto, Espoo, Finland.
    Salminen-Vaparanta, Niina
    Centre for Cognitive Neuroscience and Department of Psychology, University of Turku, 20014 Turku, Finland.
    Recurrent Processing in V1/V2 Contributes ot Categorization of Natural Scenes2011In: Journal of Neuroscience, ISSN 0270-6474, E-ISSN 1529-2401, Vol. 31, no 7, p. 2488-2492Article in journal (Refereed)
    Abstract [en]

    Humans are able to categorize complex natural scenes very rapidly and effortlessly, which has led to an assumption that such ultra-rapid categorization is driven by feedforward activation of ventral brain areas. However, recent accounts of visual perception stress the role of recurrent interactions that start rapidly after the activation of V1. To study whether or not recurrent processes play a causal role in categorization, we applied fMRI-guided transcranial magnetic stimulation on early visual cortex (V1/V2) and lateral occipital cortex (LO) while the participants categorized natural images as containing animals or not. The results showed that V1/V2 contributed to categorization speed and to subjective perception during a long activity period before and after the contribution of LO had started. This pattern of results suggests that recurrent interactions in visual cortex between areas along the ventral stream and striate cortex play a causal role in categorization and perception of natural scenes.

  • 27.
    Koivisto, Mika
    et al.
    Univ Turku, Ctr Cognit Neurosci, Turku, Finland / Univ Turku, Dept Philosophy, SF-20500 Turku, Finland.
    Revonsuo, Antti
    University of Skövde, School of Humanities and Informatics.
    Comparison of event-related potentials in attentional blink and repetition blindness2008In: Brain Research, ISSN 0006-8993, E-ISSN 1872-6240, Vol. 1189, p. 115-126Article in journal (Refereed)
    Abstract [en]

    Attending to the first target in rapid serial visual presentation (RSVP) interferes with processing of the second target so that the participants fail to recognize the second target if the targets are separated by a stimulus onset asynchrony of 200–500 ms. This phenomenon is attentional blink (AB). Repetition blindness (RB) is an additional difficulty to recognize the second occurrence of the same stimulus in RSVP. A controversial issue in studies of both deficits is the processing level at which they occur. To compare the timing and mechanisms of AB and RB directly during the same RSVP stream, we recorded event-related potentials (ERPs) in response to repeated and unrepeated targets. Comparable to earlier ERP studies on visual awareness, the results showed for both types of targets a negative amplitude difference between ERPs to consciously recognized and unrecognized targets during 250-350 ms from stimulus onset, suggesting that both AB and RB are associated with deficits of conscious perception, occurring at earlier stages than access to working memory. However, the perceptual deficit in RB is more severe, which may be related to higher overall negativity in response to repeated targets observed 150–300 ms after stimulus onset, suggesting stronger cortical baseline activation and higher perceptual threshold for repeated targets as compared with unrepeated ones.

  • 28.
    Koivisto, Mika
    et al.
    Centre for Cognitive Neuroscience, University of Turku, Turku, Finland / Department of Philosophy, University of Turku, Turku, Finland.
    Revonsuo, Antti
    University of Skövde, School of Humanities and Informatics. Centre for Cognitive Neuroscience, University of Turku, Turku, Finland / Department of Psychology, University of Turku, Turku, Finland.
    Electrophysiological correlates of visual consciousness and selective attention2007In: NeuroReport, ISSN 0959-4965, E-ISSN 1473-558X, Vol. 18, no 8, p. 753-756Article in journal (Refereed)
    Abstract [en]

    It is not clear whether attention is necessary or not for consciousness. We studied the relationship between attention and consciousness by tracking their electrophysiological correlates. The participants attended to visual targets, ignored nontargets in the prespecified visual field and ignored all stimuli in the opposite field. Visual consciousness was varied by masking. Our results showed that the earliest electrophysiological correlate of consciousness emerged independent of the manipulations of spatial and nonspatial attention. Conversely, the electrophysiological correlate of attention, selection negativity, was elicited regardless of the presence or absence of consciousness. Only the correlates of later, higher-level conscious processes strongly depended on attention. Thus, the electrophysiological brain responses reflecting visual consciousness and attention are initially independent of each other.

  • 29.
    Koivisto, Mika
    et al.
    Centre for Cognitive Neuroscience, University of Turku, Finland / Department of Psychology, University of Turku, Finland.
    Revonsuo, Antti
    University of Skövde, School of Humanities and Informatics.
    Event-related brain potential correlates of visual awareness2010In: Neuroscience and Biobehavioral Reviews, ISSN 0149-7634, E-ISSN 1873-7528, Vol. 34, no 6, p. 922-934Article, review/survey (Refereed)
    Abstract [en]

    Electrophysiological recordings during visual tasks can shed light on the temporal dynamics of the subjective experience of seeing, visual awareness. This paper reviews studies on electrophysiological correlates of visual awareness operationalized as the difference between event-related potentials (ERPs) in response to stimuli that enter awareness and stimuli that do not. There are three candidates for such a correlate: enhancement of P1 around 100 ms, enhancement of early posterior negativity around 200 ms (visual awareness negativity, VAN), and enhancement of late positivity (LP) in the P3 time window around 400 ms. Review of studies using different manipulations of awareness suggests that VAN is the correlate of visual awareness that most consistently emerges across different manipulations of visual awareness. VAN emerges also relatively independent of manipulations of nonspatial attention, but seems to be dependent on spatial attention. The results suggest that visual awareness emerges about 200 ms after the onset of visual stimulation as a consequence of the activation of posterior occipitotemporal and parietal networks.

  • 30.
    Koivisto, Mika
    et al.
    Centre for Cognitive Neuroscience, University of Turku, Turku, Finland / Department of Philosophy, University of Turku, Turku, Finland / Centre for Cognitive Neuroscience, University of Turku, 20014 Turku, Finland.
    Revonsuo, Antti
    University of Skövde, School of Humanities and Informatics.
    How meaning shapes seeing2007In: Psychological Science, ISSN 0956-7976, E-ISSN 1467-9280, Vol. 18, no 10, p. 845-849Article in journal (Refereed)
    Abstract [en]

    yInattentional blindness refers to the failure to see an unexpected object that one may be looking at directly when one's attention is elsewhere. We studied whether a stimulus whose meaning is relevant to the attentional goals of the observer will capture attention and escape inattentional blindness. The results showed that an unexpected stimulus belonging to the attended semantic category but not sharing physical features with the attended stimuli was detected more often than a semantically unrelated stimulus. This effect was larger when the unexpected stimuli were words than when they were pictures. The results imply that the semantic relation between the observer's attentional set and the unexpected stimulus plays a crucial role in inattentional blindness: An unexpected stimulus semantically related to the observer's current interests is likely to be seen, whereas unrelated unexpected stimuli are unseen. Attentional selection may thus be driven by purely semantic features: Meaning may determine whether or not one sees a stimulus.

  • 31.
    Koivisto, Mika
    et al.
    University of Turku, Turku, Finland.
    Revonsuo, Antti
    University of Skövde, School of Humanities and Informatics.
    The effects of perceptual load on semantic processing under inattention2009In: Psychonomic Bulletin & Review, ISSN 1069-9384, E-ISSN 1531-5320, Vol. 16, no 5, p. 864-868Article in journal (Refereed)
    Abstract [en]

    Inattentional blindness refers to a failure to consciously detect an irrelevant object that appears without any expectation when attention is engaged with another task. The perceptual load theory predicts that task-irrelevant stimuli will reach awareness only when the primary task is of low load, which allows processing resources to spill over to processing task-irrelevant stimuli as well. We studied whether perceptual load has an effect on inattentional blindness for a task-irrelevant stimulus whose meaning is or is not relevant to the attentional goals of the observer. In the critical trial, a word appeared without any expectation in the center of a display of attended pictures. The results showed that, under both high and low load, unexpected words belonging to the attended semantic category were detected more often than semantically unrelated words. These results imply that task-irrelevant stimuli, whose meanings are relevant to the observer’s task, enter awareness irrespective of perceptual load.

  • 32.
    Koivisto, Mika
    et al.
    Univ Turku, Ctr Cognit Neurosci, Turku 20014, Finland.
    Revonsuo, Antti
    University of Skövde, School of Humanities and Informatics.
    The role of selective attention in visual awareness of stimulus features: Electrophysiological studies2008In: Cognitive, Affective, & Behavioral Neuroscience, ISSN 1530-7026, E-ISSN 1531-135X, Vol. 8, no 2, p. 195-210Article in journal (Refereed)
    Abstract [en]

    Attention and awareness are closely related, but the nature of their relationship is unclear. The present study explores the timing and temporal evolution of their interaction with event-related potentials. The participants attended to specific conjunctions of spatial frequency and orientation in masked (unaware) and unmasked (aware) visual stimuli. A correlate of awareness appeared 100-200 msec from stimulus onset similarly to both attended and unattended features. Selection negativity (SN), a correlate of attentional selection, emerged in response to both masked and unmasked stimuli after 200 msec. This double dissociation between correlates of awareness and SN suggests that the electrophysiological processes associated with feature-based attentional selection and visual awareness of features can be dissociated from each other at early stages of processing. In a passive task, requiring no attention to the stimuli, early electrophysiological responses (before 200 msec) related to awareness were attenuated, suggesting that focal attention modulates visual awareness earlier than does selective feature-beased attention.

  • 33.
    Koivisto, Mika
    et al.
    Centre for Cognitive Neuroscience, University of Turku, 20014 Turku, Finland / Department of Philosophy, University of Turku, 20014 Turku, Finland.
    Revonsuo, Antti
    University of Skövde, School of Humanities and Informatics.
    The role of unattended distractors in sustained inattentional blindness2008In: Psychological Research, ISSN 0340-0727, E-ISSN 1430-2772, Vol. 72, no 1, p. 39-48Article in journal (Refereed)
    Abstract [en]

    When participants are attending to a subset of visual targets or events and ignore irrelevant distractors ("selective looking"), they often fail to detect the appearance of an unexpected visual object or event even when the object is visible for several seconds ("sustained inattentional blindness"). An important factor influencing detection rates in selective looking is the attentional set of the participant: the more similar the features of the unexpected object are to the attended ones, the more probably it will be detected. We examined the possible contribution of active ignoring to this similarity effect by studying the role of the distractor objects in sustained inattentional blindness. First we showed the similarity effect for chromatic colors and then we manipulated the similarity of the unexpected object in relation to the distractor objects and did not find any effects. Moreover, we found that inattentional blindness was present even when the displays did not contain any irrelevant to-be-ignored objects. We conclude that attending to target items on the bais of attentional set, but not active ignoring of nontargets items, is sufficient for the occurrence of sustained inattentional blindness.

  • 34.
    Koivisto, Mika
    et al.
    Department of Psychology, University of Turku, Turku, Finland / Centre for Cognitive Neuroscience, University of Turku, Turku, Finland.
    Salminen-Vaparanta, Niina
    Department of Psychology, University of Turku, Turku, Finland / Centre for Cognitive Neuroscience, University of Turku, Turku, Finland.
    Grassini, Simone
    Department of Psychology, University of Turku, Turku, Finland / Centre for Cognitive Neuroscience, University of Turku, Turku, Finland.
    Revonsuo, Antti
    University of Skövde, School of Bioscience. University of Skövde, The Systems Biology Research Centre. Department of Psychology, University of Turku, Turku, Finland / Centre for Cognitive Neuroscience, University of Turku, Turku, Finland.
    Subjective visual awareness emerges prior to P32016In: European Journal of Neuroscience, ISSN 0953-816X, E-ISSN 1460-9568, Vol. 43, no 12, p. 1601-1611Article in journal (Refereed)
    Abstract [en]

    Studies on the neural basis of visual awareness, the subjective experience of seeing, have found several potential neural corre- lates of visual awareness. Some of them may not directly correlate with awareness but with post-perceptual processes, such as reporting one’s awareness of the stimulus. We dissociated potential electrophysiological correlates of visual awareness from those occurring during response selection and thus co-occurring with post-perceptual processing. The participants performed two GO-NOGO conditions. In the aware-GO condition they responded with a key press when they were aware of the stimulus and withheld responding when they were unaware of it. In the unaware-GO condition they withheld responding when they were aware and responded when they were not aware of the stimulus. Thus, event-related potentials could be measured to aware and una- ware trials when responding was required and when not required. The results revealed that the N200 amplitude (180–280 ms) over the occipital and posterior temporal cortex was enhanced in aware trials as compared with trials without awareness. This effect (visual awareness negativity, VAN) did not depend on responding. The amplitude of P3 (350–450 ms) also was enhanced in aware trials as compared with unaware trials. In addition, the amplitudes in the P3 time window depended on responding: they were greater when awareness was mapped to GO-response than when not, suggesting that P3 reflects post-perceptual process- ing, that is, it occurs after awareness has emerged. These findings support theories of visual awareness that assume a relatively early onset of visual awareness before P3. 

  • 35.
    Laaksonen, L.
    et al.
    University of Turku, Turku, Finland / Turku University Hospital, Turku, Finland.
    Kallioinen, M.
    Turku University Hospital, Turku, Finland.
    Långsjö, J.
    Tampere University Hospital, Tampere, Finland.
    Laitio, T.
    Turku University Hospital, Turku, Finland.
    Scheinin, A.
    University of Turku. Turku, Finland / Turku University Hospital, Turku, Finland.
    Scheinin, J.
    Kuopio University Hospital, Kuopio, Finland.
    Kaisti, K.
    Oulu University Hospital, Oulu, Finland.
    Maksimow, A.
    Turku University Hospital, Turku, Finland.
    Kallionpää, R. E.
    Turku University Hospital, Turku, Finland / University of Turku, Turku, Finland.
    Rajala, V.
    Turku University Hospital, Turku, Finland.
    Johansson, J.
    University of Turku, Turku, Finland / Turku University Hospital, Turku, Finland / Umeå University, Umeå, Sweden.
    Kantonen, O.
    University of Turku, Turku, Finland / Turku University Hospital, Turku, Finland / University of California, Irvine, CA, USA.
    Nyman, M.
    Turku University Hospital, Turku, Finland.
    Sirén, S.
    Turku University Hospital, Turku, Finland.
    Valli, Katja
    University of Skövde, School of Bioscience. University of Skövde, The Systems Biology Research Centre. Turku University Hospital, Turku, Finland / University of Turku, Turku, Finland.
    Revonsuo, Antti
    University of Skövde, School of Bioscience. University of Skövde, The Systems Biology Research Centre. University of Turku, Turku, Finland.
    Solin, O.
    University of Turku, Turku, Finland / Turku University Hospital, Turku, Finland.
    Vahlberg, T.
    University of Turku, Turku, Finland / Turku University Hospital, Turku, Finland.
    Alkire, M.
    University of California, Irvine, CA, USA.
    Scheinin, Harry
    University of Turku, Turku, Finland / Turku University Hospital, Turku, Finland.
    Comparative effects of dexmedetomidine, propofol, sevoflurane, and S-ketamine on regional cerebral glucose metabolism in humans: a positron emission tomography study2018In: British Journal of Anaesthesia, ISSN 0007-0912, E-ISSN 1471-6771, Vol. 121, no 1, p. 281-290Article in journal (Refereed)
    Abstract [en]

    IntroductionThe highly selective α2-agonist dexmedetomidine has become a popular sedative for neurointensive care patients. However, earlier studies have raised concern that dexmedetomidine might reduce cerebral blood flow without a concomitant decrease in metabolism. Here, we compared the effects of dexmedetomidine on the regional cerebral metabolic rate of glucose (CMRglu) with three commonly used anaesthetic drugs at equi-sedative doses.

    MethodsOne hundred and sixty healthy male subjects were randomised to EC50 for verbal command of dexmedetomidine (1.5 ng ml−1n=40), propofol (1.7 μg ml−1n=40), sevoflurane (0.9% end-tidal; n=40) or S-ketamine (0.75 μg ml−1n=20) or placebo (n=20). Anaesthetics were administered using target-controlled infusion or vapouriser with end-tidal monitoring. 18F-labelled fluorodeoxyglucose was administered 20 min after commencement of anaesthetic administration, and high-resolution positron emission tomography with arterial blood activity samples was used to quantify absolute CMRglu for whole brain and 15 brain regions.

    ResultsAt the time of [F18]fluorodeoxyglucose injection, 55% of dexmedetomidine, 45% of propofol, 85% of sevoflurane, 45% of S-ketamine, and 0% of placebo subjects were unresponsive. Whole brain CMRglu was 63%, 71%, 71%, and 96% of placebo in the dexmedetomidine, propofol, sevoflurane, and S-ketamine groups, respectively (P<0.001 between the groups). The lowest CMRglu was observed in nearly all brain regions with dexmedetomidine (P<0.05 compared with all other groups). With S-ketamine, CMRgludid not differ from placebo.

    ConclusionsAt equi-sedative doses in humans, potency in reducing CMRglu was dexmedetomidine>propofol>ketamine=placebo. These findings alleviate concerns for dexmedetomidine-induced vasoconstriction and cerebral ischaemia.

  • 36.
    Långsjö, Jaakko W.
    et al.
    Turku PET Centre, University of Turku and Turku University Hospital, FI-20521 Turku, Finland / Department of Anesthesiology, Seinäjoki Central Hospital, 60220 Seinäjoki, Finland, .
    Alkire, Michael T.
    VA Long Beach Healthcare system (Long Beach, California, 90822), Department of Anesthesiology & Perioperative Care and the Center for the Neurobiology of Learning and Memory, University of California-Irvine, California 92868, .
    Kaskinoro, Kimmo
    Department of Anesthesiology, Intensive Care, Emergency Care, and Pain Medicine, Turku University Hospital, FI-20521 Turku, Finland, .
    Hayama, Hiroki
    VA Long Beach Healthcare system (Long Beach, California, 90822), Department of Anesthesiology & Perioperative Care and the Center for the Neurobiology of Learning and Memory, University of California-Irvine, California 92868, .
    Maksimow, Anu
    Department of Anesthesiology, Intensive Care, Emergency Care, and Pain Medicine, Turku University Hospital, FI-20521 Turku, Finland, .
    Kaisti, Kaike K.
    Turku PET Centre, University of Turku and Turku University Hospital, FI-20521 Turku, Finland, .
    Aalto, Sargo
    Turku PET Centre, University of Turku and Turku University Hospital, FI-20521 Turku, Finland, .
    Aantaa, Riku
    Department of Anesthesiology, Intensive Care, Emergency Care, and Pain Medicine, Turku University Hospital, FI-20521 Turku, Finland, .
    Jääskeläinen, Satu K.
    Department of Clinical Neurophysiology, Turku University Hospital, FI-20521 Turku, Finland, .
    Revonsuo, Antti
    University of Skövde, School of Humanities and Informatics.
    Scheinin, Harry
    Turku PET Centre, University of Turku and Turku University Hospital, FI-20521 Turku, Finland, / Department of Pharmacology, Drug Development and Therapeutics, University of Turku, FI-20014 Turku, Finland, / Pulssi Medical Centre, 20100 Turku, Finland.
    Returning from Oblivion: Imaging the Neural Core of Consciousness2012In: Journal of Neuroscience, ISSN 0270-6474, E-ISSN 1529-2401, Vol. 32, no 14, p. 4935-4943Article in journal (Refereed)
    Abstract [en]

    One of the greatest challenges of modern neuroscience is to discover the neural mechanisms of consciousness and to explain how they produce the conscious state. We sought the underlying neural substrate of human consciousness by manipulating the level of consciousness in volunteers with anesthetic agents and visualizing the resultant changes in brain activity using regional cerebral blood flow imaging with positron emission tomography. Study design and methodology were chosen to dissociate the state-related changes in consciousness from the effects of the anesthetic drugs. We found the emergence of consciousness, as assessed with a motor response to a spoken command, to be associated with the activation of a core network involving subcortical and limbic regions that become functionally coupled with parts of frontal and inferior parietal cortices upon awakening from unconsciousness. The neural core of consciousness thus involves forebrain arousal acting to link motor intentions originating in posterior sensory integration regions with motor action control arising in more anterior brain regions. These findings reveal the clearest picture yet of the minimal neural correlates required for a conscious state to emerge.

  • 37.
    Långsjö, Jaakko W.
    et al.
    Turku PET Centre, University of Turku and Turku University hospital, Finland / Intensive Care Unit, Tampere University Hospital, Central Hospital, Tampere, Finland.
    Revonsuo, Antti
    University of Skövde, School of Bioscience. University of Skövde, The Systems Biology Research Centre. Department of Psychology, University of Turku, Finland.
    Scheinin, Harry
    Turku PET Centre, University of Turku and Turku University hospital, Finland / Department of Pharmacology, Drug Development and Therapeutics, University of Turku, Finland.
    Harnessing anaesthesia and brain imaging for the study of human consciousness2014In: Current pharmaceutical design, ISSN 1381-6128, E-ISSN 1873-4286, Vol. 20, no 26, p. 4211-4224Article in journal (Refereed)
  • 38.
    Móró, Levente
    et al.
    University of Turku, Centre for Cognitive Neuroscience, Turku, FI-20014, Finland.
    Noreika, Valdas
    University of Turku, Centre for Cognitive Neuroscience, Turku, FI-20014, Finland.
    Revonsuo, Antti
    University of Skövde, School of Humanities and Informatics.
    Sakari, Kallio
    University of Turku, Centre for Cognitive Neuroscience, Turku, FI-20014, Finland.
    Hypnotizability, sleepiness, and subjective experience2011In: International journal of clinical and experimental hypnosis, ISSN 0020-7144, E-ISSN 1744-5183, Vol. 59, no 2, p. 211-224Article in journal (Refereed)
    Abstract [en]

    The relationships between hypnotizability, sleepiness, and the subjective experience of hypnotic suggestions were investigated in 90 participants. Scores from the Harvard Group Scale of Hypnotic Susceptibility Form A (HGSHS:A), the Karolinska Sleepiness Scale (KSS), the Epworth Sleepiness Scale (ESS), the Pittsburgh Sleep Quality Index (PSQI), and our self-developed Questionnaire on Subjective Hypnotic Experiences (QSHE) were analyzed. Findings show that hypnotizability correlates with both habitual daytime sleepiness and instantaneous sleepiness after the hypnotic procedure. Results also indicate that subjective self-evaluation of responses to hypnotic suggestions may be a useful tool in some cases when comparing with other subjectively rated scales, such as those concerning sleepiness.

  • 39.
    Noreika, Valdas
    et al.
    Centre for Cognitive Neuroscience, Department of Psychology, University of Turku, 20014 Turku, Finland.
    Jylhänkangas, Leila
    Centre for Cognitive Neuroscience, Department of Psychology, University of Turku, 20014 Turku, Finland.
    Móró, Levente
    Centre for Cognitive Neuroscience, Department of Psychology, University of Turku, 20014 Turku, Finland.
    Valli, Katja
    University of Skövde, School of Humanities and Informatics.
    Kaskinoro, Kimmo
    Department of Anesthesia, Intensive Care, Emergency Medicine and Pain Therapy, Turku University Hospital, Turku, Finland.
    Aantaa, Riku
    Department of Anesthesia, Intensive Care, Emergency Medicine and Pain Therapy, Turku University Hospital, Turku, Finland.
    Scheinin, Harry
    Department of Pharmacology and Clinical Pharmacology, and Turku PET Centre, University of Turku, Turku, Finland.
    Revonsuo, Antti
    University of Skövde, School of Humanities and Informatics.
    Consciousness lost and found: Subjective experiences in an unresponsive state2011In: Brain and Cognition, ISSN 0278-2626, E-ISSN 1090-2147, Vol. 77, no 3, p. 327-334Article in journal (Refereed)
    Abstract [en]

    Anesthetic-induced changes in the neural activity of the brain have been recently utilized as a research model to investigate the neural mechanisms of phenomenal consciousness. However, the anesthesiologic definition of consciousness as ‘‘responsiveness to the environment’’ seems to sidestep the possibility that an unresponsive individual may have subjective experiences. The aim of the present study was to analyze subjective reports in sessions where sedation and the loss of responsiveness were induced by dexmedetomidine, propofol, sevoflurane or xenon in a nonsurgical experimental setting. After regaining responsiveness, participants recalled subjective experiences in almost 60% of sessions. During dexmedetomidine sessions, subjective experiences were associated with shallower ‘‘depth of sedation’’ as measured by an electroencephalography-derived anesthesia depth monitor. Results confirm that subjective experiences may occur during clinically defined unresponsiveness, and that studies aiming to investigate phenomenal consciousness under sedative and anesthetic effects should control the subjective state of unresponsive participants with post-recovery interviews.

  • 40.
    Noreika, Valdas
    et al.
    Centre for Cognitive Neuroscience, Department of Psychology, University of Turku, Turku, Finland.
    Valli, Katja
    University of Skövde, School of Humanities and Informatics. Centre for Cognitive Neuroscience, Department of Psychology, University of Turku, Turku, Finland.
    Lahtela, Hetti
    Centre for Cognitive Neuroscience, Department of Psychology, University of Turku, Turku, Finland.
    Revonsuo, Antti
    University of Skövde, School of Humanities and Informatics. Centre for Cognitive Neuroscience, Department of Psychology, University of Turku, Turku, Finland.
    Early-night serial awakenings as a new paradigm for studies on NREM dreaming2009In: International Journal of Psychophysiology, ISSN 0167-8760, E-ISSN 1872-7697, Vol. 74, no 1, p. 14-18Article in journal (Refereed)
    Abstract [en]

    A new experimental paradigm called "Early-Night Serial Awakenings" (ENSA) was explored to find out its strengths and weaknesses for psychophysiological studies of NREM sleep dreaming. Five participants spent 20 experimental nights in the sleep laboratory, and were serially awakened with approximately 24-minute intervals during Stages 2 and 3 of NREM sleep. As a total, 164 awakenings were conducted during the sessions that lasted on average 193 min. Altogether, 30% of NREM sleep awakenings led to dream reports, 39% to reports of white dreaming, and 31% to reports of dreamless sleep. Results also show that sleep EEG spectral power, dream recall frequency as well as dream complexity remained stable throughout the serial awakening sessions. We conclude that, as ENSA dreams appeared to be static and very limited in content, the paradigm we identified could be used in future studies to reveal the psychophysiological mechanisms of relatively simple forms of early-night NREM sleep dreaming. (c) 2009 Elsevier B.V. All rights reserved.

  • 41.
    Noreika, Valdas
    et al.
    Univ Turku, Dept Behav Sci & Philosophy, Ctr Cognit Neurosci, Turku, Finland.
    Valli, Katja
    University of Skövde, School of Humanities and Informatics.
    Markkula, Juha
    Turku Univ Hosp, Neuropsychiat Clin, FIN-20520 Turku, Finland / Turku Mental Hlth Care, Turku Psychiat Clin, Turku, Finland / Univ Turku, Dept Physiol, Sleep Res Unit, Turku, Finland.
    Seppälä, Katriina
    Univ Turku, Dept Behav Sci & Philosophy, Ctr Cognit Neurosci, Turku, Finland.
    Revonsuo, Antti
    University of Skövde, School of Humanities and Informatics.
    Dream bizarreness and waking thought in schizophrenia2010In: Psychiatry Research, ISSN 0165-1781, E-ISSN 1872-7123, Vol. 178, no 3, p. 562-564Article in journal (Refereed)
    Abstract [en]

    Dream diaries and reports of daytime waking thought were collected from five schizophrenia patients and matched controls. It was more difficult for blind judges to differentiate the patients' than the controls' dream reports from reports of waking thought, and patients reported shorter but more bizarre dreams than did the controls.

  • 42.
    Overgaard, Morten
    et al.
    Hammel Neurocenter, Aarhus University Hospital, DK-8000 Aarhus, Denmark.
    Koivisto, Mika
    Center for Cognitive Neuroscience, University of Turku, Finland / Department of Philosophy, University of Turku, SF-20500 Turku, Finland.
    Sørensen, Tomas Alrik
    Department of Psychology, University of Copenhagen, DK-1168 Copenhagen, Denmark.
    Vangkilde, Signe
    Department of Psychology, University of Copenhagen, DK-1168 Copenhagen, Denmark.
    Revonsuo, Antti
    University of Skövde, School of Humanities and Informatics.
    The electrophysiology of introspection2006In: Consciousness and Cognition, ISSN 1053-8100, E-ISSN 1090-2376, Vol. 15, no 4, p. 662-672Article in journal (Refereed)
    Abstract [en]

    To study whether the distinction between introspective and non-introspective states of mind is an empirical reality or merely a conceptual distinction, we measured event-related potentials (ERPs) elicited in introspective and non-introspective instruction conditions while the observers were trying to detect the presence of a masked stimulus. The ERPs indicated measurable differences related to introspection in both preconscious and conscious processes. Our data support the hypothesis that introspective states empirically differ from non-introspective states.

  • 43.
    Radek, L.
    et al.
    Turku PET Centre, University of Turku and Turku University Hospital, Turku, Finland.
    Kallionpää, R. E.
    Department of Psychology and Speech-Language Pathology, and Turku Brain and Mind Center, University of Turku, Turku,Finland / Department of Perioperative Services, Intensive Care and Pain Medicine, Turku University Hospital, Turku, Finland.
    Karvonen, M.
    Department of Psychology and Speech-Language Pathology, and Turku Brain and Mind Center, University of Turku, Turku,Finland.
    Scheinin, A.
    Turku PET Centre, University of Turku and Turku University Hospital, Turku, Finland / Department of Perioperative Services, Intensive Care and Pain Medicine, Turku University Hospital, Turku, Finland.
    Maksimow, A.
    Department of Perioperative Services, Intensive Care and Pain Medicine, Turku University Hospital, Turku, Finland.
    Långsjö, J.
    Turku PET Centre, University of Turku and Turku University Hospital, Turku, Finland / Department of Intensive Care, Tampere University Hospital, Tampere,Finland.
    Kaisti, K.
    Turku PET Centre, University of Turku and Turku University Hospital, Turku, Finland.
    Vahlberg, T.
    Department of Clinical Medicine, Biostatistics, University of Turku and Turku University Hospital,Turku, Finland.
    Revonsuo, Antti
    University of Skövde, School of Bioscience. University of Skövde, The Systems Biology Research Centre. Department of Psychology and Speech-Language Pathology, and Turku Brain and Mind Center, University of Turku, Turku, Finland.
    Scheinin, H.
    Turku PET Centre, University of Turku and Turku University Hospital, Turku, Finland / Department of Perioperative Services, Intensive Care and Pain Medicine, Turku University Hospital, Turku, Finland / Integrative Physiology and Pharmacology, Institute of Biomedicine, University of Turku, Turku, Finland.
    Valli, Katja
    University of Skövde, School of Bioscience. University of Skövde, The Systems Biology Research Centre. Department of Psychology and Speech-Language Pathology, and Turku Brain and Mind Center, University of Turku, Turku,Finland / Department of Perioperative Services, Intensive Care and Pain Medicine, Turku University Hospital, Turku, Finland.
    Dreaming and awareness during dexmedetomidine- and propofol-induced unresponsiveness2018In: British Journal of Anaesthesia, ISSN 0007-0912, E-ISSN 1471-6771, Vol. 121, no 1, p. 260-269Article in journal (Refereed)
    Abstract [en]

    Background: Experiences during anaesthetic-induced unresponsiveness have previously been investigated by interviews after recovery. To explore whether experiences occur during drug administration, we interviewed participants during target-controlled infusion (TCI) of dexmedetomidine or propofol and after recovery. Methods: Healthy participants received dexmedetomidine (n = 23) or propofol (n = 24) in stepwise increments until loss of responsiveness (LOR1). During TCI we attempted to arouse them for interview (return of responsiveness, ROR1). After the interview, if unresponsiveness ensued with the same dose (LOR2), the procedure was repeated (ROR2). Finally, the concentration was increased 1.5-fold to achieve presumable loss of consciousness (LOC), infusion terminated, and the participants interviewed upon recovery (ROR3). An emotional sound stimulus was presented during LORs and LOC, and memory for stimuli was assessed with recognition task after recovery. Interview transcripts were content analysed. Results: Of participants receiving dexmedetomidine, 18/23 were arousable from LOR1 and LOR2. Of participants receiving propofol, 10/24 were arousable from LOR1 and two of four were arousable from LOR2. Of 93 interviews performed, 84% included experiences from periods of unresponsiveness (dexmedetomidine 90%, propofol 74%). Internally generated experiences (dreaming) were present in 86% of reports from unresponsive periods, while externally generated experiences (awareness) were rare and linked to brief arousals. No within drug differences in the prevalence or content of experiences during infusion vs after recovery were observed, but participants receiving dexmedetomidine reported dreaming and awareness more often. Participants receiving dexmedetomidine recognised the emotional sounds better than participants receiving propofol (42% vs 15%), but none reported references to sounds spontaneously. Conclusion: Anaesthetic-induced unresponsiveness does not induce unconsciousness or necessarily even disconnectedness.

  • 44.
    Railo, Henry
    et al.
    Department of Psychology, University of Turku, 20014 Turku, Finland / Centre for Cognitive Neuroscience, University of Turku, Turku, Finland.
    Koivisto, Mika
    Department of Psychology, University of Turku, 20014 Turku, Finland / Centre for Cognitive Neuroscience, University of Turku, Turku, Finland.
    Revonsuo, Antti
    University of Skövde, School of Humanities and Informatics.
    Tracking the processes behind conscious perception: A review of event-related potential correlates of visual consciousness2011In: Consciousness and Cognition, ISSN 1053-8100, E-ISSN 1090-2376, Vol. 20, no 3, p. 972-983Article, review/survey (Refereed)
    Abstract [en]

    Event-related potential (ERP) studies have attempted to discover the processes that underlie conscious visual perception by contrasting ERPs produced by stimuli that are consciously perceived with those that are not. Variability of the proposed ERP correlates of consciousness is considerable: the earliest proposed ERP correlate of consciousness (P1) coincides with sensory processes and the last one (P3) marks postperceptual processes. A negative difference wave called visual awareness negativity (VAN), typically observed around 200 ms after stimulus onset in occipitotemporal sites, gains strong support for eflecting the processes that correlate with, and possibly enable, aware visual perception. Research suggests that the early parts of conscious processing can proceed independently of top-down attention, although top-down attention may modulate visual processing even before consciousness. Evidence implies that the contents of consciousness are provided by interactions in the ventral stream, but indispensable contributions from dorsal regions influence already low level visual responses.

  • 45.
    Railo, Henry
    et al.
    Turku Univ, Ctr Cognit Neurosci, Turku, Finland / Turku Univ, Dept Psychol, Turku, Finland.
    Koivisto, Mika
    Turku Univ, Ctr Cognit Neurosci, Turku, Finland / Turku Univ, Dept Psychol, Turku, Finland / Turku Univ, Dept Philosophy, Turku, Finland.
    Revonsuo, Antti
    University of Skövde, School of Humanities and Informatics.
    Hannula, Minna M.
    Cornell Univ, Weill Med Coll, Sackler Inst Dev Psychobiol, Ithaca, NY 14853 USA / Turku Univ, Dept Educ, Turku, Finland.
    The role of attention in subitizing2008In: Cognition, ISSN 0010-0277, E-ISSN 1873-7838, Vol. 107, no 1, p. 82-104Article in journal (Refereed)
    Abstract [en]

    The process of rapidly and accurately enumerating small numbers of items without counting, i.e. subitizing, is often believed to rest on parallel preattentive processes. However, the possibility that enumeration of small numbers of items would also require attentional processes has remained an open question. The present study is the first that directly contrasts the preattentive and attentive models of subitizing. We used an inattentional blindness paradigm to manipulate the availability of attentional resources during enumeration. In the inattention condition, the items to be enumerated were presented unexpectedly while participants focused on a line length comparison task. Divided- and full-attention conditions were also included. The results showed that only numbers one and two could be enumerated when the effects of attention were minimized. Freeing attentional resources increased the enumeration accuracies considerably, including for number two. The results suggest that even for enumerating small numbers, the attentional demands increase as the number of objects increases.

  • 46.
    Railo, Henry
    et al.
    Department of Psychology, University of Turku, Finland / Centre for Cognitive Neuroscience, University of Turku, Finland / Brain and Mind Centre, University of Turku, Finland.
    Revonsuo, Antti
    University of Skövde, School of Bioscience. University of Skövde, The Systems Biology Research Centre. Department of Psychology, University of Turku, Finland / Centre for Cognitive Neuroscience, University of Turku, Finland / Brain and Mind Centre, University of Turku, Finland.
    Koivisto, Mika
    Department of Psychology, University of Turku, Finland / Centre for Cognitive Neuroscience, University of Turku, Finland / Brain and Mind Centre, University of Turku, Finland.
    Behavioral and electrophysiological evidence for fast emergence of visual consciousness2015In: Neuroscience of Consciousness, ISSN 2057-2107, Vol. 1, no 1Article in journal (Refereed)
    Abstract [en]

    A fundamental unsettled dispute concerns how fast the brain generates subjective visual experiences. Both early visual cortical activation and later activity in fronto-parietal global neuronal workspace correlate with conscious vision, but resolving which of the correlates causally triggers conscious vision has proved a methodological impasse. We show that participants can report whether or not they consciously perceived a stimulus in just over 200 ms. These fast consciousness reports were extremely reliable, and did not include reflexive, unconscious responses. The neural events that causally generate conscious vision must have occurred before these behavioral reports. Analyses on single-trial neural correlates of consciousness revealed that the late cortical processing in fronto-parietal global neuronal workspace (∼300 ms) started after the fastest consciousness reports, ruling out the possibility that this late activity directly reflects the emergence of visual consciousness. The consciousness reports were preceded by a negative amplitude difference (∼160–220 ms) that spread from occipital to frontal cortex, suggesting that this correlate underlies the emergence of conscious vision.

  • 47.
    Railo, Henry
    et al.
    Univ Turku, Dept Psychol, Turku 20014, Finland .
    Salminen-Vaparanta, Niina
    University of Turku, Finland.
    Henriksson, Linda
    Aalto Univ, Espoo, Finland .
    Revonsuo, Antti
    University of Skövde, School of Humanities and Informatics.
    Koivisto, Mika
    University of Turku, Finland.
    Unconscious and Conscious Processing of Color Rely on Activity in Early Visual Cortex: A TMS Study2012In: Journal of cognitive neuroscience, ISSN 0898-929X, E-ISSN 1530-8898, Vol. 24, no 4, p. 819-829Article in journal (Refereed)
    Abstract [en]

    Chromatic information is processed by the visual system both at an unconscious level and at a level that results in conscious perception of color. It remains unclear whether both conscious and unconscious processing of chromatic information depend on activity in the early visual cortex or whether unconscious chromatic processing can also rely on other neural mechanisms. In this study, the contribution of early visual cortex activity to conscious and unconscious chromatic processing was studied using single-pulse TMS in three time windows 40-100 msec after stimulus onset in three conditions: conscious color recognition, forced-choice discrimination of consciously invisible color, and unconscious color priming. We found that conscious perception and both measures of unconscious processing of chromatic information depended on activity in early visual cortex 70-100 msec after stimulus presentation. Unconscious forced-choice discrimination was above chance only when participants reported perceiving some stimulus features (but not color).

  • 48.
    Revonsuo, Antti
    University of Skövde, School of Humanities and Informatics.
    Altered and Exceptional States of Consciousness2009In: Encyclopedia of Consciousness / [ed] William P. Banks, London: Academic Press, 2009, p. 9-21Chapter in book (Other academic)
  • 49.
    Revonsuo, Antti
    University of Skövde, School of Humanities and Informatics.
    Consciousness: The Science of Subjectivity2010 (ed. 1)Book (Other academic)
  • 50.
    Revonsuo, Antti
    University of Skövde, School of Bioscience. University of Skövde, The Systems Biology Research Centre. University of Turku, Finland.
    Foundations of Consciousness2018Book (Refereed)
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