351
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Abstract
The idea that the brain learns generative models of the world has been widely promulgated. Most approaches have assumed that the brain learns an explicit density model that assigns a probability to each possible state of the world. However, explicit density models are difficult to learn, requiring approximate inference techniques that may find poor solutions. An alternative approach is to learn an implicit density model that can sample from the generative model without evaluating the probabilities of those samples. The implicit model can be trained to fool a discriminator into believing that the samples are real. This is the idea behind generative adversarial algorithms, which have proven adept at learning realistic generative models. This paper develops an adversarial framework for probabilistic computation in the brain. It first considers how generative adversarial algorithms overcome some of the problems that vex prior theories based on explicit density models. It then discusses the psychological and neural evidence for this framework, as well as how the breakdown of the generator and discriminator could lead to delusions observed in some mental disorders.
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Affiliation(s)
- Samuel J. Gershman
- Department of Psychology and Center for Brain Science, Harvard University, Cambridge, MA, United States
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352
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Brower R, Wang HR, Bansal S, Joiner WM. Using Corollary Discharge and Predictive Coding to Understand False Sensations and Beliefs. BIOLOGICAL PSYCHIATRY: COGNITIVE NEUROSCIENCE AND NEUROIMAGING 2019; 4:770-772. [PMID: 31495401 DOI: 10.1016/j.bpsc.2019.07.004] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/27/2019] [Revised: 07/09/2019] [Accepted: 07/17/2019] [Indexed: 11/25/2022]
Affiliation(s)
- Rylee Brower
- Departments of Neurobiology, Physiology and Behavior, University of California, Davis, Davis, California
| | - Haley R Wang
- Departments of Neurobiology, Physiology and Behavior, University of California, Davis, Davis, California
| | - Sonia Bansal
- Maryland Psychiatric Research Center, Department of Psychiatry, University of Maryland School of Medicine, Baltimore, Maryland
| | - Wilsaan M Joiner
- Departments of Neurobiology, Physiology and Behavior, University of California, Davis, Davis, California; Department of Neurology, University of California, Davis, Sacramento, California.
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353
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Sutherland CAM, Rhodes G, Williams N, Connaughton E, Ewing L, Caruana N, Langdon R. Appearance-based trust processing in schizophrenia. BRITISH JOURNAL OF CLINICAL PSYCHOLOGY 2019; 59:139-153. [PMID: 31490567 DOI: 10.1111/bjc.12234] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2019] [Revised: 07/01/2019] [Indexed: 02/03/2023]
Abstract
OBJECTIVES Schizophrenia is characterized by impaired social interactions and altered trust. In the general population, trust is often based on facial appearance, with limited validity but enormous social consequences. The aim was to examine trust processing in schizophrenia and specifically to examine how people with schizophrenia use facial appearance as well as actual partner fairness to guide trusting decisions. DESIGN An experimental economic game study. METHODS Here, we tested how patients with schizophrenia and control participants (each N = 24) use facial trustworthiness appearance and partner fairness behaviour to guide decisions in a multi-round Trust Game. In the Trust Game, participants lent money to 'partners' whose facial appearance was either untrustworthy or trustworthy, and who either played fairly or unfairly. Clinical symptoms were measured as well as explicit trustworthiness impressions. RESULTS Overall, the patients with schizophrenia showed unimpaired explicit facial trustworthiness impressions and unimpaired facial appearance biases in the Trust Game. Crucially, patients and controls significantly differed so that the patients with schizophrenia did not learn to discriminate in the Trust Game based on actual partner fairness, unlike control participants. CONCLUSION A failure to discriminate trust has important implications for everyday functioning in schizophrenia, as forming accurate trustworthiness beliefs is an essential social skill. Critically, without relying on more valid trust cues, people with schizophrenia may be especially susceptible to the misleading effect of appearance when making trusting decisions. PRACTITIONER POINTS Findings People with schizophrenia made very similar facial trustworthiness impressions to healthy controls and also used facial appearance to guide trust decisions similarly to controls. However, the patient group were less able to explicitly distinguish between fair and unfair partners based on their behaviour compared with the control group. Moreover, people with schizophrenia failed to use actual partner fairness to guide their financial decisions in the Trust Game, unlike controls, and this impairment was specific to a social task. People with schizophrenia may be particularly reliant on facial appearance when trusting others, as they may struggle to incorporate more valid trustworthiness information in their decision-making, such as actual partner fairness.
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Affiliation(s)
- Clare A M Sutherland
- School of Psychological Science, University of Western Australia, Crawley, Western Australia, Australia.,School of Psychology, University of Aberdeen, Aberdeen, Scotland
| | - Gillian Rhodes
- School of Psychological Science, University of Western Australia, Crawley, Western Australia, Australia
| | - Nikolas Williams
- Department of Cognitive Science, Macquarie University, New South Wales, Australia
| | - Emily Connaughton
- Department of Cognitive Science, Macquarie University, New South Wales, Australia
| | - Louise Ewing
- School of Psychology, University of East Anglia, Norwich, UK
| | - Nathan Caruana
- Department of Cognitive Science, Macquarie University, New South Wales, Australia
| | - Robyn Langdon
- Department of Cognitive Science, Macquarie University, New South Wales, Australia
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354
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Abstract
Introduction: In this paper we present and defend a hybrid theory of the development of delusions that incorporates the central ideas of two influential (yet sometimes bitterly opposing) theoretical approaches to delusions-the two-factor theory and the prediction error theory. Method: After introducing the central ideas of the two-factor theory and the prediction error theory, we describe the motivations for our conciliatory project, explain the theoretical details of the hybrid theory we propose, and answer potential objections to our proposal. Results: According to the hybrid theory we advance, the first factor of a delusion is physically grounded in an abnormal prediction error, and the second factor is physically grounded in the overestimation of the precision of the abnormal prediction error. Against anticipated objections, we argue that the hybrid theory is internally coherent, and that it constitutes a genuine hybrid between the two-factor theory and the prediction error theory. Conclusion: A rapprochement between the two-factor theory and the prediction error theory is both possible and desirable. In particular, our hybrid theory provides a parsimonious and unified account of delusions, whether monothematic or polythematic, across a wide variety of medical conditions.
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Affiliation(s)
- Kengo Miyazono
- Graduate School of Integrated Arts and Sciences, Hiroshima University , Higashi-Hiroshima City , Japan
| | - Ryan McKay
- Department of Psychology, Royal Holloway, University of London , Egham , UK
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355
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Thakkar KN, Rolfs M. Disrupted Corollary Discharge in Schizophrenia: Evidence From the Oculomotor System. BIOLOGICAL PSYCHIATRY. COGNITIVE NEUROSCIENCE AND NEUROIMAGING 2019; 4:773-781. [PMID: 31105039 PMCID: PMC6733648 DOI: 10.1016/j.bpsc.2019.03.009] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/12/2019] [Revised: 03/04/2019] [Accepted: 03/22/2019] [Indexed: 01/18/2023]
Abstract
Corollary discharge (CD) signals are motor-related signals that exert an influence on sensory processing. They allow mobile organisms to predict the sensory consequences of their imminent actions. Among the many functions of CD is to provide a means by which we can distinguish sensory experiences caused by our own actions from those with external causes. In this way, they contribute to a subjective sense of agency. A disruption in the sense of agency is central to many of the clinical symptoms of schizophrenia, and abnormalities in CD signaling have been theorized to underpin particularly those agency-related psychotic symptoms of the illness. Characterizing abnormal CD associated with eye movements in schizophrenia and their resulting influence on visual processing and subsequent action plans may have advantages over other sensory and motor systems. That is because the most robust psychophysiological and neurophysiological data regarding the dynamics and influence of CD as well as the neural circuitry implicated in CD generation and transmission comes from the study of eye movements in humans and nonhuman primates. We review studies of oculomotor CD signaling in the schizophrenia spectrum and possible neurobiological correlates of CD disturbances. We conclude by speculating on the ways in which oculomotor CD dysfunction, specifically, may invoke specific experiences, clinical symptoms, and cognitive impairments. These speculations lay the groundwork for empirical study, and we conclude by outlining potentially fruitful research directions.
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Affiliation(s)
- Katharine N Thakkar
- Department of Psychology, Michigan State University, East Lansing, Michigan; Division of Psychiatry and Behavioral Medicine, Michigan State University, East Lansing, Michigan.
| | - Martin Rolfs
- Department of Psychology, Humboldt-Universität zu Berlin, Berlin, Germany; Bernstein Center for Computational Neuroscience, Berlin, Germany
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356
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Abstract
Predictive coding and neural oscillations are two descriptive levels of brain functioning whose overlap is not yet understood. Chao et al. (2018) now show that hierarchical predictive coding is instantiated by asymmetric information channeling in the γ and α/β oscillatory ranges.
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Affiliation(s)
- Anne-Lise Giraud
- Department of Basic Neurosciences, University of Geneva, Biotech Campus, 9 chemin des Mine 1211 Geneva, Switzerland.
| | - Luc H Arnal
- Department of Basic Neurosciences, University of Geneva, Biotech Campus, 9 chemin des Mine 1211 Geneva, Switzerland
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357
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Krajcovic B, Fajnerova I, Horacek J, Kelemen E, Kubik S, Svoboda J, Stuchlik A. Neural and neuronal discoordination in schizophrenia: From ensembles through networks to symptoms. Acta Physiol (Oxf) 2019; 226:e13282. [PMID: 31002202 DOI: 10.1111/apha.13282] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2019] [Revised: 03/27/2019] [Accepted: 04/12/2019] [Indexed: 12/22/2022]
Abstract
Despite the substantial knowledge accumulated by past research, the exact mechanisms of the pathogenesis of schizophrenia and causal treatments still remain unclear. Deficits of cognition and information processing in schizophrenia are today often viewed as the primary and core symptoms of this devastating disorder. These deficits likely result from disruptions in the coordination of neuronal and neural activity. The aim of this review is to bring together convergent evidence of discoordinated brain circuits in schizophrenia at multiple levels of resolution, ranging from principal cells and interneurons, neuronal ensembles and local circuits, to large-scale brain networks. We show how these aberrations could underlie deficits in cognitive control and other higher order cognitive-behavioural functions. Converging evidence from both animal models and patients with schizophrenia is presented in an effort to gain insight into common features of deficits in the brain information processing in this disorder, marked by disruption of several neurotransmitter and signalling systems and severe behavioural outcomes.
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Affiliation(s)
- Branislav Krajcovic
- Department of Neurophysiology of Memory Institute of Physiology of the Czech Academy of Sciences Prague Czech Republic
- Third Faculty of Medicine Charles University Prague Czech Republic
| | - Iveta Fajnerova
- Department of Neurophysiology of Memory Institute of Physiology of the Czech Academy of Sciences Prague Czech Republic
- Research Programme 3 - Applied Neurosciences and Brain Imaging National Institute of Mental Health Klecany Czech Republic
| | - Jiri Horacek
- Third Faculty of Medicine Charles University Prague Czech Republic
- Research Programme 3 - Applied Neurosciences and Brain Imaging National Institute of Mental Health Klecany Czech Republic
| | - Eduard Kelemen
- Research Programme 1 - Experimental Neurobiology National Institute of Mental Health Klecany Czech Republic
| | - Stepan Kubik
- Department of Neurophysiology of Memory Institute of Physiology of the Czech Academy of Sciences Prague Czech Republic
| | - Jan Svoboda
- Department of Neurophysiology of Memory Institute of Physiology of the Czech Academy of Sciences Prague Czech Republic
| | - Ales Stuchlik
- Department of Neurophysiology of Memory Institute of Physiology of the Czech Academy of Sciences Prague Czech Republic
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358
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Gu X, FitzGerald THB, Friston KJ. Modeling subjective belief states in computational psychiatry: interoceptive inference as a candidate framework. Psychopharmacology (Berl) 2019; 236:2405-2412. [PMID: 31230144 PMCID: PMC6697568 DOI: 10.1007/s00213-019-05300-5] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/01/2019] [Accepted: 06/05/2019] [Indexed: 12/28/2022]
Abstract
The nascent field computational psychiatry has undergone exponential growth since its inception. To date, much of the published work has focused on choice behaviors, which are primarily modeled within a reinforcement learning framework. While this initial normative effort represents a milestone in psychiatry research, the reality is that many psychiatric disorders are defined by disturbances in subjective states (e.g., depression, anxiety) and associated beliefs (e.g., dysmorphophobia, paranoid ideation), which are not considered in normative models. In this paper, we present interoceptive inference as a candidate framework for modeling subjective-and associated belief-states in computational psychiatry. We first introduce the notion and significance of modeling subjective states in computational psychiatry. Next, we present the interoceptive inference framework, and in particular focus on the relationship between interoceptive inference (i.e., belief updating) and emotions. Lastly, we will use drug craving as an example of subjective states to demonstrate the feasibility of using interoceptive inference to model the psychopathology of subjective states.
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Affiliation(s)
- Xiaosi Gu
- Department of Psychiatry, Icahn School of Medicine at Mount Sinai, 1 Gustave L Levy Place, Box 1230, New York, NY, 10029, USA.
- Nash Family Department of Neuroscience, Icahn School of Medicine at Mount Sinai, 1 Gustave L Levy Place, Box 1230, New York, NY, 10029, USA.
- Mental Illness Research, Education, and Clinical Center (MIRECC VISN 2) at the James J. Peter Veterans Affairs Medical Center, Bronx, NY, USA.
| | - Thomas H B FitzGerald
- School of Psychology, University of East Anglia, Norwich Research Park, Norwich, Norfolk, NR4 7TJ, UK
- Wellcome Centre for Human Neuroimaging, University College London, London, England
- Max Planck-UCL Centre for Computational Psychiatry and Ageing Research, Russell Square House, London, WC1B 5EH, UK
| | - Karl J Friston
- Wellcome Centre for Human Neuroimaging, University College London, London, England
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359
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Kaliuzhna M, Stein T, Rusch T, Sekutowicz M, Sterzer P, Seymour KJ. No evidence for abnormal priors in early vision in schizophrenia. Schizophr Res 2019; 210:245-254. [PMID: 30587425 DOI: 10.1016/j.schres.2018.12.027] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/04/2018] [Revised: 12/18/2018] [Accepted: 12/18/2018] [Indexed: 12/31/2022]
Abstract
The predictive coding account of psychosis postulates the abnormal formation of prior beliefs in schizophrenia, resulting in psychotic symptoms. One domain in which priors play a crucial role is visual perception. For instance, our perception of brightness, line length, and motion direction are not merely based on a veridical extraction of sensory input but are also determined by expectation (or prior) of the stimulus. Formation of such priors is thought to be governed by the statistical regularities within natural scenes. Recently, the use of such priors has been attributed to a specific set of well-documented visual illusions, supporting the idea that perception is biased toward what is statistically more probable within the environment. The Predictive Coding account of psychosis proposes that patients form abnormal representations of statistical regularities in natural scenes, leading to altered perceptual experiences. Here we use classical vision experiments involving a specific set of visual illusions to directly test this hypothesis. We find that perceptual judgments for both patients and control participants are biased in accordance with reported probability distributions of natural scenes. Thus, despite there being a suggested link between visual abnormalities and psychotic symptoms in schizophrenia, our results provide no support for the notion that altered formation of priors is a general feature of the disorder. These data call for a refinement in the predictions of quantitative models of psychosis.
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Affiliation(s)
- Mariia Kaliuzhna
- ARC Centre of Excellence in Cognition and its Disorders, Department of Cognitive Science, Macquarie University, Sydney, NSW, Australia; Clinical and Experimental Psychopathology Group, Department of Psychiatry, University of Geneva, Switzerland
| | - Timo Stein
- Department of Psychiatry and Psychotherapy, Campus Charité Mitte, Charité Universitätsmedizin Berlin, Germany; Berlin School of Mind and Brain, Humboldt-Universität zu Berlin, Germany; Department of Psychology, University of Amsterdam, the Netherlands
| | - Tessa Rusch
- Institute for Systems Neuroscience, University Medical Center Hamburg-Eppendorf, Martinistrasse 52, 20246 Hamburg, Germany
| | - Maria Sekutowicz
- Department of Psychiatry and Psychotherapy, Campus Charité Mitte, Charité Universitätsmedizin Berlin, Germany; Berlin School of Mind and Brain, Humboldt-Universität zu Berlin, Germany
| | - Philipp Sterzer
- Department of Psychiatry and Psychotherapy, Campus Charité Mitte, Charité Universitätsmedizin Berlin, Germany; Berlin School of Mind and Brain, Humboldt-Universität zu Berlin, Germany
| | - Kiley J Seymour
- ARC Centre of Excellence in Cognition and its Disorders, Department of Cognitive Science, Macquarie University, Sydney, NSW, Australia; Department of Psychiatry and Psychotherapy, Campus Charité Mitte, Charité Universitätsmedizin Berlin, Germany; School of Social Sciences and Psychology, Western Sydney University, New South Wales, Australia.
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360
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Valton V, Karvelis P, Richards KL, Seitz AR, Lawrie SM, Seriès P. Acquisition of visual priors and induced hallucinations in chronic schizophrenia. Brain 2019; 142:2523-2537. [PMID: 31257444 PMCID: PMC6734996 DOI: 10.1093/brain/awz171] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2018] [Revised: 04/01/2019] [Accepted: 04/21/2019] [Indexed: 01/10/2023] Open
Abstract
Prominent theories suggest that symptoms of schizophrenia stem from learning deficiencies resulting in distorted internal models of the world. To test these theories further, we used a visual statistical learning task known to induce rapid implicit learning of the stimulus statistics. In this task, participants are presented with a field of coherently moving dots and are asked to report the presented direction of the dots (estimation task), and whether they saw any dots or not (detection task). Two of the directions were more frequently presented than the others. In controls, the implicit acquisition of the stimuli statistics influences their perception in two ways: (i) motion directions are perceived as being more similar to the most frequently presented directions than they really are (estimation biases); and (ii) in the absence of stimuli, participants sometimes report perceiving the most frequently presented directions (a form of hallucinations). Such behaviour is consistent with probabilistic inference, i.e. combining learnt perceptual priors with sensory evidence. We investigated whether patients with chronic, stable, treated schizophrenia (n = 20) differ from controls (n = 23) in the acquisition of the perceptual priors and/or their influence on perception. We found that although patients were slower than controls, they showed comparable acquisition of perceptual priors, approximating the stimulus statistics. This suggests that patients have no statistical learning deficits in our task. This may reflect our patients' relative wellbeing on antipsychotic medication. Intriguingly, however, patients experienced significantly fewer (P = 0.016) hallucinations of the most frequently presented directions than controls when the stimulus was absent or when it was very weak (prior-based lapse estimations). This suggests that prior expectations had less influence on patients' perception than on controls when stimuli were absent or below perceptual threshold.
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Affiliation(s)
- Vincent Valton
- Institute for Adaptive and Neural Computation, University of Edinburgh, UK
- Department of Psychiatry, Royal Edinburgh Hospital, University of Edinburgh, UK
- Institute of Cognitive Neuroscience, University College London, London, UK
| | - Povilas Karvelis
- Institute for Adaptive and Neural Computation, University of Edinburgh, UK
| | - Katie L Richards
- Department of Psychiatry, Royal Edinburgh Hospital, University of Edinburgh, UK
| | - Aaron R Seitz
- Department of Psychology, University of California Riverside, CA, USA
| | - Stephen M Lawrie
- Department of Psychiatry, Royal Edinburgh Hospital, University of Edinburgh, UK
- Patrick Wild Centre, University of Edinburgh, Edinburgh, UK
| | - Peggy Seriès
- Institute for Adaptive and Neural Computation, University of Edinburgh, UK
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361
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Siemerkus J, Tomiello S, Stephan KE. Bayesian inference and hallucinations in schizophrenia. Brain 2019; 142:2178-2181. [DOI: 10.1093/brain/awz211] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
This scientific commentary refers to ‘Acquisition of visual priors and induced hallucinations in chronic schizophrenia’, by Valton et al. (doi:10.1093/brain/awz171).
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Affiliation(s)
- Jakob Siemerkus
- Institute for Biomedical Engineering, University of Zurich and ETH Zurich, Zurich, Switzerland
- Department of Psychiatry, Psychotherapy and Psychosomatics, University Hospital of Psychiatry, Zurich, Switzerland
| | - Sara Tomiello
- Institute for Biomedical Engineering, University of Zurich and ETH Zurich, Zurich, Switzerland
| | - Klaas Enno Stephan
- Institute for Biomedical Engineering, University of Zurich and ETH Zurich, Zurich, Switzerland
- Wellcome Centre for Human Neuroimaging, University College London, London, UK
- Max Planck Institute for Metabolism Research, Cologne, Germany
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362
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Crespi B, Dinsdale N. Autism and psychosis as diametrical disorders of embodiment. Evol Med Public Health 2019; 2019:121-138. [PMID: 31402979 PMCID: PMC6682708 DOI: 10.1093/emph/eoz021] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2019] [Accepted: 07/11/2019] [Indexed: 12/12/2022] Open
Abstract
Humans have evolved an elaborate system of self-consciousness, self-identity, self-agency, and self-embodiment that is grounded in specific neurological structures including an expanded insula. Instantiation of the bodily self has been most-extensively studied via the 'rubber hand illusion', whereby parallel stimulation of a hidden true hand, and a viewed false hand, leads to the felt belief that the false hand is one's own. Autism and schizophrenia have both long been regarded as conditions centrally involving altered development of the self, but they have yet to be compared directly with regard to the self and embodiment. Here, we synthesize the embodied cognition literature for these and related conditions, and describe evidence that these two sets of disorders exhibit opposite susceptibilities from typical individuals to the rubber hand illusion: reduced on the autism spectrum and increased in schizophrenia and other psychotic-affective conditions. Moreover, the opposite illusion effects are mediated by a consilient set of associated phenomena, including empathy, interoception, anorexia risk and phenotypes, and patterns of genetic correlation. Taken together, these findings: (i) support the diametric model of autism and psychotic-affective disorders, (ii) implicate the adaptive human system of self-embodiment, and its neural bases, in neurodevelopmental disorders, and suggest new therapies and (iii) experimentally ground Bayesian predictive coding models with regard to autism compared with psychosis. Lay summary: Humans have evolved a highly developed sense of self and perception of one's own body. The 'rubber hand illusion' can be used to test individual variation in sense of self, relative to connection with others. We show that this illusion is reduced in autism spectrum disorders, and increased in psychotic and mood disorders. These findings have important implications for understanding and treatment of mental disorders.
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Affiliation(s)
- Bernard Crespi
- Department of Biological Sciences, Simon Fraser University, 8888 University Drive, Burnaby, BC, Canada
| | - Natalie Dinsdale
- Department of Biological Sciences, Simon Fraser University, 8888 University Drive, Burnaby, BC, Canada
- Department of Psychology, University of Saskatchewan, Saskatoon, SK, Canada
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363
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Carhart-Harris RL, Friston KJ. REBUS and the Anarchic Brain: Toward a Unified Model of the Brain Action of Psychedelics. Pharmacol Rev 2019; 71:316-344. [PMID: 31221820 PMCID: PMC6588209 DOI: 10.1124/pr.118.017160] [Citation(s) in RCA: 352] [Impact Index Per Article: 70.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
This paper formulates the action of psychedelics by integrating the free-energy principle and entropic brain hypothesis. We call this formulation relaxed beliefs under psychedelics (REBUS) and the anarchic brain, founded on the principle that-via their entropic effect on spontaneous cortical activity-psychedelics work to relax the precision of high-level priors or beliefs, thereby liberating bottom-up information flow, particularly via intrinsic sources such as the limbic system. We assemble evidence for this model and show how it can explain a broad range of phenomena associated with the psychedelic experience. With regard to their potential therapeutic use, we propose that psychedelics work to relax the precision weighting of pathologically overweighted priors underpinning various expressions of mental illness. We propose that this process entails an increased sensitization of high-level priors to bottom-up signaling (stemming from intrinsic sources), and that this heightened sensitivity enables the potential revision and deweighting of overweighted priors. We end by discussing further implications of the model, such as that psychedelics can bring about the revision of other heavily weighted high-level priors, not directly related to mental health, such as those underlying partisan and/or overly-confident political, religious, and/or philosophical perspectives. SIGNIFICANCE STATEMENT: Psychedelics are capturing interest, with efforts underway to bring psilocybin therapy to marketing authorisation and legal access within a decade, spearheaded by the findings of a series of phase 2 trials. In this climate, a compelling unified model of how psychedelics alter brain function to alter consciousness would have appeal. Towards this end, we have sought to integrate a leading model of global brain function, hierarchical predictive coding, with an often-cited model of the acute action of psychedelics, the entropic brain hypothesis. The resulting synthesis states that psychedelics work to relax high-level priors, sensitising them to liberated bottom-up information flow, which, with the right intention, care provision and context, can help guide and cultivate the revision of entrenched pathological priors.
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Affiliation(s)
- R L Carhart-Harris
- Centre for Psychedelic Research, Division of Brain Sciences, Imperial College London, London, United Kingdom (R.L.C.-H.); and Institute of Neurology, Wellcome Trust Centre for Neuroimaging, University College London, London, United Kingdom (K.J.F.)
| | - K J Friston
- Centre for Psychedelic Research, Division of Brain Sciences, Imperial College London, London, United Kingdom (R.L.C.-H.); and Institute of Neurology, Wellcome Trust Centre for Neuroimaging, University College London, London, United Kingdom (K.J.F.)
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364
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Boundary effects of expectation in human pain perception. Sci Rep 2019; 9:9443. [PMID: 31263144 PMCID: PMC6602973 DOI: 10.1038/s41598-019-45811-x] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2018] [Accepted: 06/12/2019] [Indexed: 12/19/2022] Open
Abstract
Perception of sensory stimulation is influenced by numerous psychological variables. One example is placebo analgesia, where expecting low pain causes a painful stimulus to feel less painful. Yet, because pain evolved to signal threats to survival, it should be maladaptive for highly-erroneous expectations to yield unrealistic pain experiences. Therefore, we hypothesised that a cue followed by a highly discrepant stimulus intensity, which generates a large prediction error, will have a weaker influence on the perception of that stimulus. To test this hypothesis we collected two independent pain-cueing datasets. The second dataset and the analysis plan were preregistered ( https://osf.io/5r6z7/ ). Regression modelling revealed that reported pain intensities were best explained by a quartic polynomial model of the prediction error. The results indicated that the influence of cues on perceived pain decreased when stimulus intensity was very different from expectations, suggesting that prediction error size has an immediate functional role in pain perception.
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365
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Prediction, Psychosis, and the Cerebellum. BIOLOGICAL PSYCHIATRY: COGNITIVE NEUROSCIENCE AND NEUROIMAGING 2019; 4:820-831. [PMID: 31495402 DOI: 10.1016/j.bpsc.2019.06.001] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/13/2019] [Revised: 05/30/2019] [Accepted: 06/01/2019] [Indexed: 12/19/2022]
Abstract
An increasingly influential hypothesis posits that many of the diverse symptoms of psychosis can be viewed as reflecting dysfunctional predictive mechanisms. Indeed, to perceive something is to take a sensory input and make a prediction of the external source of that signal; thus, prediction is perhaps the most fundamental neural computation. Given the ubiquity of prediction, a more challenging problem is to specify the unique predictive role or capability of a particular brain structure. This question is relevant when considering recent claims that one aspect of the predictive deficits observed in psychotic disorders might be related to cerebellar dysfunction, a subcortical structure known to play a critical role in predictive sensorimotor control and perhaps higher-level cognitive function. Here, we review evidence bearing on this question. We first focus on clinical, behavioral, and neuroimaging findings suggesting cerebellar involvement in psychosis and, specifically, schizophrenia. We then review a relatively novel line of research exploring whether computational models of cerebellar motor function can also account for cerebellar involvement in higher-order human cognition, and in particular, language function. We end the review by highlighting some key gaps in these literatures, limitations that currently preclude strong conclusions regarding cerebellar involvement in psychosis.
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366
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Individual differences in the effects of priors on perception: A multi-paradigm approach. Cognition 2019; 187:167-177. [DOI: 10.1016/j.cognition.2019.03.008] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2018] [Revised: 03/07/2019] [Accepted: 03/08/2019] [Indexed: 01/02/2023]
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367
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Green MF, Horan WP, Lee J. Nonsocial and social cognition in schizophrenia: current evidence and future directions. World Psychiatry 2019; 18:146-161. [PMID: 31059632 PMCID: PMC6502429 DOI: 10.1002/wps.20624] [Citation(s) in RCA: 321] [Impact Index Per Article: 64.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
Cognitive impairment in schizophrenia involves a broad array of nonsocial and social cognitive domains. It is a core feature of the illness, and one with substantial implications for treatment and prognosis. Our understanding of the causes, consequences and interventions for cognitive impairment in schizophrenia has grown substantially in recent years. Here we review a range of topics, including: a) the types of nonsocial cognitive, social cognitive, and perceptual deficits in schizophrenia; b) how deficits in schizophrenia are similar or different from those in other disorders; c) cognitive impairments in the prodromal period and over the lifespan in schizophrenia; d) neuroimaging of the neural substrates of nonsocial and social cognition, and e) relationships of nonsocial and social cognition to functional outcome. The paper also reviews the considerable efforts that have been directed to improve cognitive impairments in schizophrenia through novel psychopharmacology, cognitive remediation, social cognitive training, and alternative approaches. In the final section, we consider areas that are emerging and have the potential to provide future insights, including the interface of motivation and cognition, the influence of childhood adversity, metacognition, the role of neuroinflammation, computational modelling, the application of remote digital technology, and novel methods to evaluate brain network organization. The study of cognitive impairment has provided a way to approach, examine and comprehend a wide range of features of schizophrenia, and it may ultimately affect how we define and diagnose this complex disorder.
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Affiliation(s)
- Michael F. Green
- Semel Institute for Neuroscience and Human Behavior, Department of Psychiatry and Biobehavioral SciencesUniversity of California, Los Angeles (UCLA)Los AngelesCAUSA,Desert Pacific Mental Illness Research, Education and Clinical CenterVeterans Affairs Greater Los Angeles Healthcare SystemLos AngelesCAUSA,Veterans Affairs Program for Enhancing Community Integration for Homeless VeteransLos AngelesCAUSA
| | - William P. Horan
- Semel Institute for Neuroscience and Human Behavior, Department of Psychiatry and Biobehavioral SciencesUniversity of California, Los Angeles (UCLA)Los AngelesCAUSA,Desert Pacific Mental Illness Research, Education and Clinical CenterVeterans Affairs Greater Los Angeles Healthcare SystemLos AngelesCAUSA,Veterans Affairs Program for Enhancing Community Integration for Homeless VeteransLos AngelesCAUSA
| | - Junghee Lee
- Semel Institute for Neuroscience and Human Behavior, Department of Psychiatry and Biobehavioral SciencesUniversity of California, Los Angeles (UCLA)Los AngelesCAUSA,Desert Pacific Mental Illness Research, Education and Clinical CenterVeterans Affairs Greater Los Angeles Healthcare SystemLos AngelesCAUSA,Veterans Affairs Program for Enhancing Community Integration for Homeless VeteransLos AngelesCAUSA
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368
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Baker SC, Konova AB, Daw ND, Horga G. A distinct inferential mechanism for delusions in schizophrenia. Brain 2019; 142:1797-1812. [PMID: 30895299 PMCID: PMC6644849 DOI: 10.1093/brain/awz051] [Citation(s) in RCA: 51] [Impact Index Per Article: 10.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2018] [Revised: 12/27/2018] [Accepted: 01/16/2019] [Indexed: 12/14/2022] Open
Abstract
Delusions, a core symptom of psychosis, are false beliefs that are rigidly held with strong conviction despite contradictory evidence. Alterations in inferential processes have long been proposed to underlie delusional pathology, but previous attempts to show this have failed to yield compelling evidence for a specific relationship between inferential abnormalities and delusional severity in schizophrenia. Using a novel, incentivized information-sampling task (a modified version of the beads task), alongside well-characterized decision-making tasks, we sought a mechanistic understanding of delusions in a sample of medicated and unmedicated patients with schizophrenia who exhibited a wide range of delusion severity. In this novel task, participants chose whether to draw beads from one of two hidden jars or to guess the identity of the hidden jar, in order to minimize financial loss from a monetary endowment, and concurrently reported their probability estimates for the hidden jar. We found that patients with higher delusion severity exhibited increased information seeking (i.e. increased draws-to-decision behaviour). This increase was highly specific to delusion severity as compared to the severity of other psychotic symptoms, working-memory capacity, and other clinical and socio-demographic characteristics. Delusion-related increases in information seeking were present in unmedicated patients, indicating that they were unlikely due to antipsychotic medication. In addition, after adjusting for delusion severity, patients as a whole exhibited decreased information seeking relative to healthy individuals, a decrease that correlated with lower socioeconomic status. Computational analyses of reported probability estimates further showed that more delusional patients exhibited abnormal belief updating characterized by stronger reliance on prior beliefs formed early in the inferential process, a feature that correlated with increased information seeking in patients. Other decision-making parameters that could have theoretically explained the delusion effects, such as those related to subjective valuation, were uncorrelated with both delusional severity and information seeking among the patients. In turn, we found some preliminary evidence that subjective valuation (rather than belief updating) may explain group differences in information seeking unrelated to delusions. Together, these results suggest that abnormalities in belief updating, characterized by stronger reliance on prior beliefs formed by incorporating information presented earlier in the inferential process, may be a core computational mechanism of delusional ideation in psychosis. Our results thus provide direct empirical support for an inferential mechanism that naturally captures the characteristic rigidity associated with delusional beliefs.
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Affiliation(s)
- Seth C Baker
- Department of Psychiatry, New York State Psychiatric Institute, Columbia University Medical Center, 1051 Riverside Drive, New York, NY, USA
| | - Anna B Konova
- Department of Psychiatry, University Behavioral Health Care, and Brain Health Institute, Rutgers University – New Brunswick, 671 Hoes Lane West, Piscataway, NJ, USA
| | - Nathaniel D Daw
- Department of Psychology and Princeton Neuroscience Institute, Princeton University, South Drive, Princeton, NJ, USA
| | - Guillermo Horga
- Department of Psychiatry, New York State Psychiatric Institute, Columbia University Medical Center, 1051 Riverside Drive, New York, NY, USA
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369
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Subramanian D, Alers A, Sommer MA. Corollary Discharge for Action and Cognition. BIOLOGICAL PSYCHIATRY: COGNITIVE NEUROSCIENCE AND NEUROIMAGING 2019; 4:782-790. [PMID: 31351985 DOI: 10.1016/j.bpsc.2019.05.010] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/09/2019] [Revised: 05/22/2019] [Accepted: 05/22/2019] [Indexed: 11/19/2022]
Abstract
In motor systems, a copy of the movement command known as corollary discharge is broadcast to other regions of the brain to warn them of the impending movement. The premise of this review is that the concept of corollary discharge may generalize in revealing ways to the brain's cognitive systems. An oculomotor pathway from the brain stem to frontal cortex provides a well-established example of how corollary discharge is instantiated for sensorimotor processing. Building on causal evidence from inactivation of the pathway, we motivate forward models as a tool for understanding the contributions of corollary discharge to perception and movement. Finally, we extend the definition of corollary discharge to account for signals that may be used for cognitive forward models of decision making. This framework may provide new insights into signals and circuits that contribute to sequential decision processes, the breakdown of which may account for some symptoms of psychiatric disorders.
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Affiliation(s)
- Divya Subramanian
- Department of Neurobiology, Duke University, Durham, North Carolina; Center for Cognitive Neuroscience, Duke University, Durham, North Carolina
| | - Anthony Alers
- Department of Biomedical Engineering, Duke University, Durham, North Carolina
| | - Marc A Sommer
- Department of Neurobiology, Duke University, Durham, North Carolina; Center for Cognitive Neuroscience, Duke University, Durham, North Carolina; Department of Biomedical Engineering, Duke University, Durham, North Carolina.
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370
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Affiliation(s)
| | - Philipp Sterzer
- Department of Psychiatry and Psychotherapy, Charité – Universitätsmedizin Berlin, Germany
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371
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Ramsay IS. An Activation Likelihood Estimate Meta-analysis of Thalamocortical Dysconnectivity in Psychosis. BIOLOGICAL PSYCHIATRY: COGNITIVE NEUROSCIENCE AND NEUROIMAGING 2019; 4:859-869. [PMID: 31202821 DOI: 10.1016/j.bpsc.2019.04.007] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/21/2019] [Revised: 03/26/2019] [Accepted: 04/13/2019] [Indexed: 02/08/2023]
Abstract
BACKGROUND Thalamocortical dysconnectivity is hypothesized to underlie the pathophysiology of psychotic disorders, including schizophrenia and bipolar disorder, and individuals at clinical high risk. Numerous studies have examined connectivity networks seeding from the thalamus during rest, revealing a pattern of thalamo-fronto-cerebellar hypoconnectivity and thalamosensory hyperconnectivity. However, given variability in these networks, as well as their relationships with clinical and cognitive symptoms, thalamocortical connectivity's status as a biomarker and treatment target for psychotic disorders remains unclear. METHODS A literature search was performed to identify thalamic seed-based connectivity studies conducted in patients with psychotic disorders. Activation likelihood estimate analysis examined the reported coordinates for hypoconnectivity (healthy control participants > patients with psychosis) and hyperconnectivity (patients with psychosis > healthy control participants). The relationship between hypoconnectivity and hyperconnectivity, as well as their relationships with clinical and cognitive measures, was meta-analyzed. RESULTS Each activation likelihood estimate included 20 experiments (from 17 publications). Thalamocortical hypoconnectivity was observed in middle frontal, cingulate, and thalamic regions, while hyperconnectivity was observed in motor, somatosensory, temporal, occipital, and insular cortical regions. Meta-analysis of the studies reporting correlations between hypo- and hyperconnectivity showed a strong negative relationship. Meta-analysis of studies reporting correlations between hyperconnectivity and symptoms showed small but significant positive relationships. CONCLUSIONS Activation likelihood estimates of thalamocortical hypoconnectivity revealed a network of prefrontal and thalamic regions, while hyperconnections identified sensory areas. The strong negative relationship between these thalamocortical deflections suggests that they arrive from a common mechanism and may account for aspects of psychosis. These findings identify reliable thalamocortical networks that may guide future studies and serve as crucial treatment targets for psychotic disorders.
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Affiliation(s)
- Ian S Ramsay
- Department of Psychiatry and Behavioral Sciences, University of Minnesota, Minneapolis, Minnesota.
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372
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Varrier RS, Stuke H, Guggenmos M, Sterzer P. Sustained effects of corrupted feedback on perceptual inference. Sci Rep 2019; 9:5537. [PMID: 30940859 PMCID: PMC6445092 DOI: 10.1038/s41598-019-41954-z] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2018] [Accepted: 03/18/2019] [Indexed: 01/05/2023] Open
Abstract
Feedback is central to most forms of learning, and its reliability is therefore critical. Here, we investigated the effects of corrupted, and hence unreliable, feedback on perceptual inference. Within the framework of Bayesian inference, we hypothesised that corrupting feedback in a demanding perceptual task would compromise sensory information processing and bias inference towards prior information if available. These hypotheses were examined by a simulation and in two behavioural experiments with visual detection (experiment 1) and discrimination (experiment 2) tasks. Both experiments consisted of two sessions comprising intervention runs with either corrupted or uncorrupted (correct) feedback, and pre- and post-intervention tests to assess the effects of feedback. In the tests alone, additional prior beliefs were induced through predictive auditory cues to assess sustained effects of feedback on the balance between sensory evidence and prior beliefs. Both experiments and the simulation showed the hypothesised decrease in performance and increased reliance on prior beliefs after corrupted but not uncorrupted feedback. Exploratory analyses indicated reduced confidence regarding perceptual decisions during delivery of corrupted feedback. Our results suggest that corrupted feedback on perceptual decisions leads to sustained changes in perceptual inference, characterised by a shift from sensory likelihood to prior beliefs when those are accessible.
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Affiliation(s)
- R S Varrier
- Department of Psychiatry and Psychotherapy, Charité - Universitätsmedizin Berlin, corporate member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and the Berlin Institute of Health, Berlin, Germany.
- Bernstein Center for Computational Neuroscience, Berlin, Germany.
| | - H Stuke
- Department of Psychiatry and Psychotherapy, Charité - Universitätsmedizin Berlin, corporate member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and the Berlin Institute of Health, Berlin, Germany
| | - M Guggenmos
- Department of Psychiatry and Psychotherapy, Charité - Universitätsmedizin Berlin, corporate member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and the Berlin Institute of Health, Berlin, Germany
| | - P Sterzer
- Department of Psychiatry and Psychotherapy, Charité - Universitätsmedizin Berlin, corporate member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and the Berlin Institute of Health, Berlin, Germany
- Bernstein Center for Computational Neuroscience, Berlin, Germany
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373
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Sterzer P, Voss M, Schlagenhauf F, Heinz A. Decision-making in schizophrenia: A predictive-coding perspective. Neuroimage 2019; 190:133-143. [DOI: 10.1016/j.neuroimage.2018.05.074] [Citation(s) in RCA: 33] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2017] [Revised: 05/22/2018] [Accepted: 05/30/2018] [Indexed: 12/11/2022] Open
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374
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Thakkar KN, Silverstein SM, Brascamp JW. A review of visual aftereffects in schizophrenia. Neurosci Biobehav Rev 2019; 101:68-77. [PMID: 30940436 DOI: 10.1016/j.neubiorev.2019.03.021] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2018] [Revised: 03/13/2019] [Accepted: 03/24/2019] [Indexed: 12/11/2022]
Abstract
Psychosis-a cardinal symptom of schizophrenia-has been associated with a failure to appropriately create or use stored regularities about past states of the world to guide the interpretation of incoming information, which leads to abnormal perceptions and beliefs. The visual system provides a test bed for investigating the role of prior experience and prediction, as accumulated knowledge of the world informs our current perception. More specifically, the strength of visual aftereffects, illusory percepts that arise after prolonged viewing of a visual stimulus, can serve as a valuable measure of the influence of prior experience on current visual processing. In this paper, we review findings from a largely older body of work on visual aftereffects in schizophrenia, attempt to reconcile discrepant findings, highlight the role of antipsychotic medication, consider mechanistic interpretations for behavioral effects, and propose directions for future research.
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Affiliation(s)
- Katharine N Thakkar
- Department of Psychology, Michigan State University, East Lansing, MI, United States; Division of Psychiatry and Behavioral Medicine, Michigan State University, East Lansing, MI, United States.
| | - Steven M Silverstein
- Departments of Psychiatry and Ophthalmology, Rutgers University, Piscataway, NJ, United States
| | - Jan W Brascamp
- Department of Psychology, Michigan State University, East Lansing, MI, United States
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375
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Dudley R, Aynsworth C, Mosimann U, Taylor JP, Smailes D, Collerton D, McCarthy-Jones S, Urwyler P. A comparison of visual hallucinations across disorders. Psychiatry Res 2019; 272:86-92. [PMID: 30579187 DOI: 10.1016/j.psychres.2018.12.052] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/09/2018] [Revised: 12/06/2018] [Accepted: 12/07/2018] [Indexed: 11/17/2022]
Abstract
Research into hallucinations typically regards them as single sensory or unimodal experiences leading to a comparative neglect of co-occurring multi-sensory hallucinations (MSH). People with psychosis who have visual hallucinations (VH) report high rates of hallucinations in other senses (auditory, olfactory, tactile). However, it is not known if this is similar to other groups who report VH. Consequently, this study explored MSH in four different patient groups who all had current VH. Archival data from standardised assessments of visual hallucinations in people with psychosis (n = 22), eye disease (ED) (n = 82), Lewy body Dementia (LBD) (n = 41), and Parkinson's disease (PD) (n = 41) determined the presence of MSH. People with psychosis and visual hallucinations reported significantly higher rates of MSH (auditory, 73%; tactile, 82%; olfactory/gustatory hallucinations, 27%) than the LBD group (auditory, 21%; tactile, 28%; olfactory/gustatory, 6%), ED (auditory, 1%; tactile, 11%; olfactory/gustatory, 0%) and PD patients (auditory, 3%; tactile, 8%; olfactory/gustatory, 3%). Regardless of diagnostic grouping, participants with MSH reported greater conviction that the VH were real, and reported greater distress. People with psychosis with VH report high rates of MSH unlike groups of older adults with VH. These between group differences in MSH prevalence have implications for clinical practice and theory.
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Affiliation(s)
- R Dudley
- Gateshead Early Intervention in Psychosis Service, Northumberland, Tyne and Wear NHS, UK; School of Psychology, Newcastle University, Newcastle upon Tyne, UK.
| | - C Aynsworth
- School of Psychology, Newcastle University, Newcastle upon Tyne, UK
| | - U Mosimann
- University Hospital of Old Age Psychiatry, University of Bern, Bern, Switzerland; ARTORG Center for Biomedical engineering, University of Bern, Bern, Switzerland
| | - J-P Taylor
- Institute of Neuroscience, Newcastle University, Campus for Ageing and Vitality, Newcastle upon Tyne, UK
| | - D Smailes
- Department of Psychology, Northumbria University, Newcastle upon Tyne, NE1 8ST UK
| | - D Collerton
- Institute of Neuroscience, Newcastle University, Campus for Ageing and Vitality, Newcastle upon Tyne, UK; Older People's Psychology Service, Northumberland, Tyne and Wear NHS Foundation Trust, Bensham Hospital Gateshead, UK
| | | | - P Urwyler
- University Hospital of Old Age Psychiatry, University of Bern, Bern, Switzerland; ARTORG Center for Biomedical engineering, University of Bern, Bern, Switzerland; Institute of Neuroscience, Newcastle University, Campus for Ageing and Vitality, Newcastle upon Tyne, UK
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376
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Abstract
Making predictions and validating the predictions against actual sensory information is thought to be one of the most fundamental functions of the nervous system. A growing body of evidence shows that the neural mechanisms controlling behavior, both in motor and non-motor domains, rely on prediction errors, the discrepancy between predicted and actual information. The cerebellum has been viewed as a key component of the motor system providing predictions about upcoming movements and receiving feedback about motor errors. Consequentially, studies of cerebellar function have focused on the motor domain with less consideration for the wider context in which movements are generated. However, motor learning experiments show that cognition makes important contributions to motor adaptation that involves the cerebellum. One of the more successful theoretical frameworks for understanding motor control and cerebellar function is the forward internal model which states that the cerebellum predicts the sensory consequences of the motor commands and is involved in computing sensory prediction errors by comparing the predictions to the sensory feedback. The forward internal model was applied and tested mainly for effector movements, raising the question whether cerebellar encoding of behavior reflects task performance measures associated with cognitive involvement. Electrophysiological studies based on pseudo-random tracking in monkeys show that the discharge of Purkinje cell, the sole output neurons of the cerebellar cortex, encodes predictive and feedback signals not only of the effector kinematics but also of task performance. The implications are that the cerebellum implements both effector and task performance forward models and the latter are consistent with the cognitive contributions observed during motor learning. The implications of these findings include insights into recent psychophysical observations on moving with reduced feedback and motor learning. The findings also support the cerebellum's place in hierarchical generative models that work in concert to refine predictions about behavior and the world. Therefore, cerebellar representations bridge motor and non-motor domains and provide a better understanding of cerebellar function within the functional architecture of the brain.
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Affiliation(s)
| | - Timothy J. Ebner
- Department of Neuroscience, University of Minnesota, Minneapolis, MN, United States
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377
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McCutcheon RA, Abi-Dargham A, Howes OD. Schizophrenia, Dopamine and the Striatum: From Biology to Symptoms. Trends Neurosci 2019; 42:205-220. [PMID: 30621912 PMCID: PMC6401206 DOI: 10.1016/j.tins.2018.12.004] [Citation(s) in RCA: 385] [Impact Index Per Article: 77.0] [Reference Citation Analysis] [Abstract] [Key Words] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2018] [Revised: 12/04/2018] [Accepted: 12/16/2018] [Indexed: 12/15/2022]
Abstract
The mesolimbic hypothesis has been a central dogma of schizophrenia for decades, positing that aberrant functioning of midbrain dopamine projections to limbic regions causes psychotic symptoms. Recently, however, advances in neuroimaging techniques have led to the unanticipated finding that dopaminergic dysfunction in schizophrenia is greatest within nigrostriatal pathways, implicating the dorsal striatum in the pathophysiology and calling into question the mesolimbic theory. At the same time our knowledge of striatal anatomy and function has progressed, suggesting new mechanisms via which striatal dysfunction may contribute to the symptoms of schizophrenia. This Review draws together these developments, to explore what they mean for our understanding of the pathophysiology, clinical manifestations, and treatment of the disorder. Techniques for characterising the mesostriatal dopamine system, both in humans and animal models, have advanced significantly over the past decade. In vivo imaging studies in schizophrenia patients demonstrate that dopaminergic dysfunction in schizophrenia is greatest in nigrostriatal as opposed to mesolimbic pathways. Better understanding of striatal structure and function has enhanced our insight into the neurobiological basis of psychotic symptoms. The role of other neurotransmitters in modulating striatal dopamine function merits further exploration, and modulating these neurotransmitter systems has potential to offer new therapeutic strategies.
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Affiliation(s)
- Robert A McCutcheon
- Department of Psychosis Studies, Institute of Psychiatry, Psychology & Neuroscience, King's College London, De Crespigny Park, London, SE5 8AF, UK; MRC London Institute of Medical Sciences, Hammersmith Hospital, London, W12 0NN, UK; Institute of Clinical Sciences, Faculty of Medicine, Imperial College London, London, W12 0NN, UK; South London and Maudsley NHS Foundation Trust, London, SE5 8AF, UK
| | - Anissa Abi-Dargham
- Department of Psychiatry, School of Medicine, Stony Brook University, New York, USA
| | - Oliver D Howes
- Department of Psychosis Studies, Institute of Psychiatry, Psychology & Neuroscience, King's College London, De Crespigny Park, London, SE5 8AF, UK; MRC London Institute of Medical Sciences, Hammersmith Hospital, London, W12 0NN, UK; Institute of Clinical Sciences, Faculty of Medicine, Imperial College London, London, W12 0NN, UK; South London and Maudsley NHS Foundation Trust, London, SE5 8AF, UK.
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378
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Schmidt TT, Prein JC. The Ganzfeld experience—A stably inducible altered state of consciousness: Effects of different auditory homogenizations. Psych J 2019; 8:66-81. [DOI: 10.1002/pchj.262] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2018] [Revised: 10/16/2018] [Accepted: 10/21/2018] [Indexed: 11/06/2022]
Affiliation(s)
- Timo T. Schmidt
- Neurocomputation and Neuroimaging Unit, Department of Education and PsychologyFree University of Berlin Berlin Germany
- Institute of Cognitive ScienceOsnabrück University Osnabrück Germany
| | - Julia C. Prein
- Institute of Cognitive ScienceOsnabrück University Osnabrück Germany
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379
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Diaconescu AO, Hauke DJ, Borgwardt S. Models of persecutory delusions: a mechanistic insight into the early stages of psychosis. Mol Psychiatry 2019; 24:1258-1267. [PMID: 31076646 PMCID: PMC6756090 DOI: 10.1038/s41380-019-0427-z] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/10/2018] [Revised: 02/27/2019] [Accepted: 04/11/2019] [Indexed: 12/16/2022]
Abstract
Identifying robust markers for predicting the onset of psychosis has been a key challenge for early detection research. Persecutory delusions are core symptoms of psychosis, and social cognition is particularly impaired in first-episode psychosis patients and individuals at risk for developing psychosis. Here, we propose new avenues for translation provided by hierarchical Bayesian models of behaviour and neuroimaging data applied in the context of social learning to target persecutory delusions. As it comprises a mechanistic model embedded in neurophysiology, the findings of this approach may shed light onto inference and neurobiological causes of transition to psychosis.
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Affiliation(s)
- Andreea Oliviana Diaconescu
- Department of Psychiatry (UPK), University of Basel, Basel, Switzerland. .,Translational Neuromodeling Unit (TNU), Institute for Biomedical Engineering, University of Zurich & Swiss Federal Institute of Technology (ETH Zurich), Zurich, Switzerland.
| | - Daniel Jonas Hauke
- 0000 0004 1937 0642grid.6612.3Department of Psychiatry (UPK), University of Basel, Basel, Switzerland ,0000 0004 1937 0642grid.6612.3Department of Mathematics and Computer Science, University of Basel, Basel, Switzerland
| | - Stefan Borgwardt
- 0000 0004 1937 0642grid.6612.3Department of Psychiatry (UPK), University of Basel, Basel, Switzerland ,0000 0001 2322 6764grid.13097.3cDepartment of Psychosis Studies PO63, Institute of Psychiatry, Psychology and Neuroscience, King’s College London, London, UK
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380
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Benrimoh D, Parr T, Vincent P, Adams RA, Friston K. Active Inference and Auditory Hallucinations. COMPUTATIONAL PSYCHIATRY (CAMBRIDGE, MASS.) 2018; 2:183-204. [PMID: 30627670 PMCID: PMC6317754 DOI: 10.1162/cpsy_a_00022] [Citation(s) in RCA: 32] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/02/2018] [Accepted: 10/03/2018] [Indexed: 01/27/2023]
Abstract
Auditory verbal hallucinations (AVH) are often distressing symptoms of several neuropsychiatric conditions, including schizophrenia. Using a Markov decision process formulation of active inference, we develop a novel model of AVH as false (positive) inference. Active inference treats perception as a process of hypothesis testing, in which sensory data are used to disambiguate between alternative hypotheses about the world. Crucially, this depends upon a delicate balance between prior beliefs about unobserved (hidden) variables and the sensations they cause. A false inference that a voice is present, even in the absence of auditory sensations, suggests that prior beliefs dominate perceptual inference. Here we consider the computational mechanisms that could cause this imbalance in perception. Through simulation, we show that the content of (and confidence in) prior beliefs depends on beliefs about policies (here sequences of listening and talking) and on beliefs about the reliability of sensory data. We demonstrate several ways in which hallucinatory percepts could occur when an agent expects to hear a voice in the presence of imprecise sensory data. This model expresses, in formal terms, alternative computational mechanisms that underwrite AVH and, speculatively, can be mapped onto neurobiological changes associated with schizophrenia. The interaction of action and perception is important in modeling AVH, given that speech is a fundamentally enactive and interactive process-and that hallucinators often actively engage with their voices.
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Affiliation(s)
| | - Thomas Parr
- Wellcome Trust Centre for Neuroimaging, Institute of Neurology, University College London, London, UK
| | - Peter Vincent
- Wellcome Trust Centre for Neuroimaging, Institute of Neurology, University College London, London, UK
| | - Rick A. Adams
- Division of Psychiatry, University College London, London, UK,Institute of Cognitive Neuroscience, University College London, London, UK
| | - Karl Friston
- Wellcome Trust Centre for Neuroimaging, Institute of Neurology, University College London, London, UK
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381
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Palmer CJ, Caruana N, Clifford CWG, Seymour KJ. Adaptive sensory coding of gaze direction in schizophrenia. ROYAL SOCIETY OPEN SCIENCE 2018; 5:180886. [PMID: 30662722 PMCID: PMC6304156 DOI: 10.1098/rsos.180886] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 06/07/2018] [Accepted: 10/30/2018] [Indexed: 06/09/2023]
Abstract
Schizophrenia has been associated with differences in how the visual system processes sensory input. A fundamental mechanism that regulates sensory processing in the brain is gain control, whereby the responses of sensory neurons to a given stimulus are modulated in accordance with the spatial and temporal context. Some studies indicate an impairment of certain cortical gain control mechanisms in schizophrenia in low-level vision, reflected, for instance, in how the visual appearance of a stimulus is affected by the presence of other stimuli around it. In the present study, we investigated higher-level, social vision in schizophrenia, namely the perception of other people's direction of gaze (i.e. a type of face processing). Recent computational modelling work indicates that perceptual aftereffects-changes in perception that occur following repeated exposure to faces that display a specific direction of gaze-are indicative of two distinct forms of gain control involved in the coding of gaze direction across sensory neurons. We find that individuals with schizophrenia display strong perceptual aftereffects following repeated exposure to faces with averted gaze, and a modelling analysis indicates similarly robust gain control in the form of (i) short-term adjustment of channel sensitivities in response to the recent sensory history and (ii) divisive normalization of the encoded gaze direction. Together, this speaks to the typical coding of other people's direction of gaze in the visual system in schizophrenia, including flexible gain control, despite the social-cognitive impairments that can occur in this condition.
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Affiliation(s)
- Colin J. Palmer
- School of Psychology, UNSWSydney, Sydney, New South Wales 2052, Australia
| | - Nathan Caruana
- Department of Cognitive Science, Macquarie University, Sydney, New South Wales 2109, Australia
- ARC Centre of Excellence for Cognition and Its Disorders, Sydney, Australia
| | | | - Kiley J. Seymour
- School of Psychology, UNSWSydney, Sydney, New South Wales 2052, Australia
- Department of Cognitive Science, Macquarie University, Sydney, New South Wales 2109, Australia
- ARC Centre of Excellence for Cognition and Its Disorders, Sydney, Australia
- School of Social Sciences and Psychology, Western Sydney University, Sydney, New South Wales 2150, Australia
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382
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Benrimoh D, Parr T, Vincent P, Adams RA, Friston K. Active Inference and Auditory Hallucinations. COMPUTATIONAL PSYCHIATRY (CAMBRIDGE, MASS.) 2018. [PMID: 30627670 DOI: 10.1162/cpsy˙a˙00022] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Subscribe] [Scholar Register] [Indexed: 05/12/2023]
Abstract
Auditory verbal hallucinations (AVH) are often distressing symptoms of several neuropsychiatric conditions, including schizophrenia. Using a Markov decision process formulation of active inference, we develop a novel model of AVH as false (positive) inference. Active inference treats perception as a process of hypothesis testing, in which sensory data are used to disambiguate between alternative hypotheses about the world. Crucially, this depends upon a delicate balance between prior beliefs about unobserved (hidden) variables and the sensations they cause. A false inference that a voice is present, even in the absence of auditory sensations, suggests that prior beliefs dominate perceptual inference. Here we consider the computational mechanisms that could cause this imbalance in perception. Through simulation, we show that the content of (and confidence in) prior beliefs depends on beliefs about policies (here sequences of listening and talking) and on beliefs about the reliability of sensory data. We demonstrate several ways in which hallucinatory percepts could occur when an agent expects to hear a voice in the presence of imprecise sensory data. This model expresses, in formal terms, alternative computational mechanisms that underwrite AVH and, speculatively, can be mapped onto neurobiological changes associated with schizophrenia. The interaction of action and perception is important in modeling AVH, given that speech is a fundamentally enactive and interactive process-and that hallucinators often actively engage with their voices.
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Affiliation(s)
- David Benrimoh
- Wellcome Trust Centre for Neuroimaging, Institute of Neurology, University College London, London, UK
| | - Thomas Parr
- Wellcome Trust Centre for Neuroimaging, Institute of Neurology, University College London, London, UK
| | - Peter Vincent
- Wellcome Trust Centre for Neuroimaging, Institute of Neurology, University College London, London, UK
| | - Rick A Adams
- Division of Psychiatry, University College London, London, UK
| | - Karl Friston
- Wellcome Trust Centre for Neuroimaging, Institute of Neurology, University College London, London, UK
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383
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Dzafic I, Burianová H, Martin AK, Mowry B. Neural correlates of dynamic emotion perception in schizophrenia and the influence of prior expectations. Schizophr Res 2018; 202:129-137. [PMID: 29910121 DOI: 10.1016/j.schres.2018.06.015] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/17/2017] [Revised: 05/31/2018] [Accepted: 06/09/2018] [Indexed: 12/30/2022]
Abstract
Impaired emotion perception is a well-established and stable deficit in schizophrenia; however, there is limited knowledge about the underlying aberrant cognitive and brain processes that result in emotion perception deficits. Recent influential work has shown that perceptual deficits in schizophrenia may result from aberrant precision in prior expectations, associated with disrupted activity in frontal regions. In the present study, we investigated the perception of dynamic, multisensory emotion, the influence of prior expectations and the underlying aberrant brain processes in schizophrenia. During a functional Magnetic Resonance Imaging scan, participants completed the Dynamic Emotion Perception task, which induces prior expectations with emotion instruction cues. We delineated neural responses and functional connectivity in whole-brain large-scale networks underlying emotion perception. Compared to healthy individuals, schizophrenia patients had lower accuracy specifically for emotions that were congruent with prior expectations. At the neural level, schizophrenia patients had less engagement of right inferior frontal and parietal regions, as well as right amygdala dysconnectivity during discrimination of emotions congruent with prior expectations. The results indicate that individuals with schizophrenia may have aberrant prior expectations about emotional expressions, associated with under-activity in inferior frontoparietal regions and right amygdala dysconnectivity, which results in impaired perception of emotion.
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Affiliation(s)
- Ilvana Dzafic
- Queensland Brain Institute, University of Queensland, Brisbane, Australia; Centre for Advanced Imaging, University of Queensland, Brisbane, Australia.
| | - Hana Burianová
- Centre for Advanced Imaging, University of Queensland, Brisbane, Australia; Department of Psychology, Swansea University, Swansea, United Kingdom
| | - Andrew K Martin
- University of Queensland Centre for Clinical Research, Brisbane, Australia
| | - Bryan Mowry
- Queensland Brain Institute, University of Queensland, Brisbane, Australia; Queensland Centre for Mental Health Research, Brisbane, Australia
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