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Chambon V, Pacherie E, Barbalat G, Jacquet P, Franck N, Farrer C. Mentalizing under influence: abnormal dependence on prior expectations in patients with schizophrenia. ACTA ACUST UNITED AC 2011; 134:3728-41. [PMID: 22108577 DOI: 10.1093/brain/awr306] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022]
Abstract
An impaired ability to appreciate other people's mental states is a well-established and stable cognitive deficit in schizophrenia, which might explain some aspects of patients' social dysfunction. Yet, despite a wealth of literature on this topic, the basic mechanisms underlying these impairments are still poorly understood, and their links with the clinical dimensions of schizophrenia remain unclear. The present study aimed to investigate the extent to which patients' impaired ability to appreciate other people's intentions (known as mentalizing) may be accounted for by abnormal interaction between the two types of information that contribute to this ability: (i) the sensory evidence conveyed by movement kinematics; and (ii) the observer's prior expectations. We hypothesized that this is not a generalized impairment, but one confined to certain types of intentions. To test this assumption, we designed four tasks in which participants were required to infer either: (i) basic intentions (i.e. the simple goal of a motor act); (ii) superordinate intentions (i.e. the general goal of a sequence of motor acts); (iii) social basic; or (iv) social superordinate intentions (i.e. simple or general goals achieved within the context of a reciprocal interaction). In each of these tasks, both prior expectations and sensory information were manipulated. We found that patients correctly inferred non-social, basic intentions, but experienced difficulties when inferring non-social superordinate intentions and both basic and superordinate social intentions. These poor performances were associated with two abnormal patterns of interaction between prior expectations and sensory evidence. In the non-social superordinate condition, patients relied heavily on their prior expectations, while disregarding sensory evidence. This pattern of interaction predicted the severity of 'positive' symptoms. Social conditions prompted exactly the opposite pattern of interaction: patients exhibited weaker dependence on prior expectations while relying strongly on sensory evidence, and this predicted the severity of 'negative' symptoms. We suggest both these patterns can be accounted for by a disturbance in the Bayesian inferential mechanism that integrates sensory evidence (conveyed by movement kinematics) into prior beliefs (about others' mental states and attitudes) to produce accurate inferences about other people's intentions.
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Affiliation(s)
- Valerian Chambon
- Centre de Neuroscience Cognitive - UMR 5229 CNRS; 67, bd Pinel, 69675 BRON Cedex, France.
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752
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Rünker AE, O'Tuathaigh C, Dunleavy M, Morris DW, Little GE, Corvin AP, Gill M, Henshall DC, Waddington JL, Mitchell KJ. Mutation of Semaphorin-6A disrupts limbic and cortical connectivity and models neurodevelopmental psychopathology. PLoS One 2011; 6:e26488. [PMID: 22132072 PMCID: PMC3221675 DOI: 10.1371/journal.pone.0026488] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2011] [Accepted: 09/28/2011] [Indexed: 12/18/2022] Open
Abstract
Psychiatric disorders such as schizophrenia and autism are characterised by cellular disorganisation and dysconnectivity across the brain and can be caused by mutations in genes that control neurodevelopmental processes. To examine how neurodevelopmental defects can affect brain function and behaviour, we have comprehensively investigated the consequences of mutation of one such gene, Semaphorin-6A, on cellular organisation, axonal projection patterns, behaviour and physiology in mice. These analyses reveal a spectrum of widespread but subtle anatomical defects in Sema6A mutants, notably in limbic and cortical cellular organisation, lamination and connectivity. These mutants display concomitant alterations in the electroencephalogram and hyper-exploratory behaviour, which are characteristic of models of psychosis and reversible by the antipsychotic clozapine. They also show altered social interaction and deficits in object recognition and working memory. Mice with mutations in Sema6A or the interacting genes may thus represent a highly informative model for how neurodevelopmental defects can lead to anatomical dysconnectivity, resulting, either directly or through reactive mechanisms, in dysfunction at the level of neuronal networks with associated behavioural phenotypes of relevance to psychiatric disorders. The biological data presented here also make these genes plausible candidates to explain human linkage findings for schizophrenia and autism.
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Affiliation(s)
- Annette E. Rünker
- Smurfit Institute of Genetics and Institute of Neuroscience, Trinity College Dublin, Dublin, Ireland
| | - Colm O'Tuathaigh
- Molecular and Cellular Therapeutics, Royal College of Surgeons in Ireland, Dublin, Ireland
| | - Mark Dunleavy
- Physiology and Medical Physics, Royal College of Surgeons in Ireland, Dublin, Ireland
| | - Derek W. Morris
- Neuropsychiatric Genetics Research Group, Institute of Molecular Medicine and Department of Psychiatry, Trinity College Dublin, Dublin, Ireland
| | - Graham E. Little
- Smurfit Institute of Genetics and Institute of Neuroscience, Trinity College Dublin, Dublin, Ireland
| | - Aiden P. Corvin
- Neuropsychiatric Genetics Research Group, Institute of Molecular Medicine and Department of Psychiatry, Trinity College Dublin, Dublin, Ireland
| | - Michael Gill
- Neuropsychiatric Genetics Research Group, Institute of Molecular Medicine and Department of Psychiatry, Trinity College Dublin, Dublin, Ireland
| | - David C. Henshall
- Physiology and Medical Physics, Royal College of Surgeons in Ireland, Dublin, Ireland
| | - John L. Waddington
- Molecular and Cellular Therapeutics, Royal College of Surgeons in Ireland, Dublin, Ireland
| | - Kevin J. Mitchell
- Smurfit Institute of Genetics and Institute of Neuroscience, Trinity College Dublin, Dublin, Ireland
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753
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Altered axonal targeting and short-term plasticity in the hippocampus of Disc1 mutant mice. Proc Natl Acad Sci U S A 2011; 108:E1349-58. [PMID: 22049344 DOI: 10.1073/pnas.1114113108] [Citation(s) in RCA: 85] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Carefully designed animal models of genetic risk factors are likely to aid our understanding of the pathogenesis of schizophrenia. Here, we study a mouse strain with a truncating lesion in the endogenous Disc1 ortholog designed to model the effects of a schizophrenia-predisposing mutation and offer a detailed account of the consequences that this mutation has on the development and function of a hippocampal circuit. We uncover widespread and cumulative cytoarchitectural alterations in the dentate gyrus during neonatal and adult neurogenesis, which include errors in axonal targeting and are accompanied by changes in short-term plasticity at the mossy fiber/CA3 circuit. We also provide evidence that cAMP levels are elevated as a result of the Disc1 mutation, leading to altered axonal targeting and dendritic growth. The identified structural alterations are, for the most part, not consistent with the growth-promoting and premature maturation effects inferred from previous RNAi-based Disc1 knockdown. Our results provide support to the notion that modest disturbances of neuronal connectivity and accompanying deficits in short-term synaptic dynamics is a general feature of schizophrenia-predisposing mutations.
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754
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Morris SE, Holroyd CB, Mann-Wrobel MC, Gold JM. Dissociation of response and feedback negativity in schizophrenia: electrophysiological and computational evidence for a deficit in the representation of value. Front Hum Neurosci 2011; 5:123. [PMID: 22065618 PMCID: PMC3203413 DOI: 10.3389/fnhum.2011.00123] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2011] [Accepted: 10/10/2011] [Indexed: 11/20/2022] Open
Abstract
Contrasting theories of schizophrenia propose that the disorder is characterized by a deficit in phasic changes in dopamine activity in response to ongoing events or, alternatively, by a weakness in the representation of the value of responses. Schizophrenia patients have reliably reduced brain activity following incorrect responses but other research suggests that they may have intact feedback-related potentials, indicating that the impairment may be specifically response-related. We used event-related brain potentials and computational modeling to examine this issue by comparing the neural response to outcomes with the neural response to behaviors that predict outcomes in patients with schizophrenia and psychiatrically healthy comparison subjects. We recorded feedback-related activity in a passive gambling task and a time estimation task and error-related activity in a flanker task. Patients' brain activity following an erroneous response was reduced compared to comparison subjects but feedback-related activity did not differ between groups. To test hypotheses about the possible causes of this pattern of results, we used computational modeling of the electrophysiological data to simulate the effects of an overall reduction in patients' sensitivity to feedback, selective insensitivity to positive or negative feedback, reduced learning rate, and a decreased representation of the value of the response given the stimulus on each trial. The results of the computational modeling suggest that schizophrenia patients exhibit weakened representation of response values, possibly due to failure of the basal ganglia to strongly associate stimuli with appropriate response alternatives.
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Affiliation(s)
- Sarah E. Morris
- VISN 5 Mental Illness Research, Education, and Clinical CenterBaltimore, MD, USA
- Department of Psychiatry, University of Maryland School of MedicineBaltimore, MD, USA
| | - Clay B. Holroyd
- Department of Psychology, University of VictoriaVictoria, BC, Canada
| | | | - James M. Gold
- Maryland Psychiatric Research Center, University of Maryland School of MedicineCatonsville, MD, USA
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755
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Wong HY. A measure of my agency? Conscious Cogn 2011; 21:48-51; discussion 55-8. [PMID: 21945814 DOI: 10.1016/j.concog.2011.08.017] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2011] [Revised: 08/05/2011] [Accepted: 08/29/2011] [Indexed: 10/17/2022]
Affiliation(s)
- Hong Yu Wong
- Philosophy of Neuroscience Group, Werner Reichardt Centre for Integrative Neuroscience, Eberhard-Karls-Universität Tübingen, Paul Ehrlich Strasse 17, Tübingen 72076, Germany.
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756
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Ford JM, Mathalon DH. Anticipating the future: automatic prediction failures in schizophrenia. Int J Psychophysiol 2011; 83:232-9. [PMID: 21959054 DOI: 10.1016/j.ijpsycho.2011.09.004] [Citation(s) in RCA: 74] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2011] [Revised: 08/16/2011] [Accepted: 09/01/2011] [Indexed: 10/17/2022]
Abstract
People with schizophrenia often misperceive sensations and misinterpret experiences, perhaps contributing to psychotic symptoms. These misperceptions and misinterpretations might result from an inability to make valid predictions about expected sensations and experiences. Healthy normal people take advantage of neural mechanisms that allow them to make predictions unconsciously, facilitating processing of expected sensations and distinguishing the expected from the unexpected. In this paper, we focus on two types of automatic, unconscious mechanisms that allow us to predict our perceptions. The first involves predictions made via innate mechanisms basic to all species in the animal kingdom - the efference copy and corollary discharge mechanisms. They accompany our voluntary movements and allow us to suppress sensations resulting from our actions. We study this during talking, and show that auditory cortical response to the speech sounds during talking is reduced compared to when they are played back. This suppression is reduced in schizophrenia, suggesting a failure to predict the sensations resulting from talking. The second mechanism involves implicitly learning what to expect from the current context of events. We study this by observing the brain's response to an unexpected repetition of an event, when a change would have been predicted. That patients have a reduced response suggests they failed to predict that it was time for a change. Both types of predictions should happen automatically and effortlessly, allowing for economic processing of expected events and orientation to unexpected ones. These prediction failures characterize the diagnosis of schizophrenia rather than reflecting specific symptoms.
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Affiliation(s)
- Judith M Ford
- Psychiatry Service, San Francisco VA Medical Center, 4150 Clement Street, San Francisco, CA 94121, USA.
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757
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Moore JW, Fletcher PC. Sense of agency in health and disease: a review of cue integration approaches. Conscious Cogn 2011; 21:59-68. [PMID: 21920777 PMCID: PMC3315009 DOI: 10.1016/j.concog.2011.08.010] [Citation(s) in RCA: 230] [Impact Index Per Article: 17.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2011] [Revised: 08/13/2011] [Accepted: 08/17/2011] [Indexed: 11/12/2022]
Abstract
Sense of agency (SoA) is a compelling but fragile experience that is augmented or attenuated by internal signals and by external cues. A disruption in SoA may characterise individual symptoms of mental illness such as delusions of control. Indeed, it has been argued that generic SoA disturbances may lie at the heart of delusions and hallucinations that characterise schizophrenia. A clearer understanding of how sensorimotor, perceptual and environmental cues complement, or compete with, each other in engendering SoA may prove valuable in deepening our understanding the agency disruptions that characterise certain focal neurological disorders and mental illnesses. Here we examine the integration of SoA cues in health and illness, describing a simple framework of this integration based on Bayesian principles. We extend this to consider how alterations in cue integration may lead to aberrant experiences of agency.
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Affiliation(s)
- J W Moore
- Institute of Cognitive Neuroscience, University College London, Queen Square, London, UK
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758
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Albrecht MA, Martin-Iverson MT, Price G, Lee J, Iyyalol R, Waters F. Dexamphetamine effects on separate constructs in the rubber hand illusion test. Psychopharmacology (Berl) 2011; 217:39-50. [PMID: 21431312 DOI: 10.1007/s00213-011-2255-y] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/16/2010] [Accepted: 03/02/2011] [Indexed: 11/26/2022]
Abstract
RATIONALE Corporeal awareness is an integral component of self-consciousness and is distorted in several neurological and psychiatric disorders. Research regarding the neural underpinnings of corporeal awareness has made much progress recently using the rubber hand illusion (RHI) procedure. However, more studies are needed to investigate the possibility of several dissociable constructs related to the RHI specifically, and corporeal awareness generally. OBJECTIVES Considering dopamine's involvement in many perceptual-motor learning processes, as well as its apparent relationship with disorders such as schizophrenia that are linked to body ownership disturbances, we gave 0.45 mg/kg dexamphetamine (a dopamine transporter reverser) to 20 healthy participants to examine the effects of increased dopamine transmission on the RHI. METHODS The effect of dexamphetamine on separate quantitative constructs underlying RHI were examined including embodiment of rubber hand, loss of ownership of real hand, perception of movement, affect, deafference, and proprioceptive drift. The experiment was a double-blind, placebo-controlled, cross-over design. RESULTS Dexamphetamine increased participants' ratings of embodiment (particularly "ownership") of the rubber hand and was associated with the experience of loss of ownership of the person's real hand. There were significant increases from asynchronous to synchronous stroking for the measures of movement and proprioceptive drift after placebo but not dexamphetamine. There were no changes in the measures of other constructs. CONCLUSIONS These results show a novel pharmacological manipulation of separate constructs of the RHI. This finding may aid in our understanding of disorders that have overlapping disturbances in both dopamine activity and body representations, particularly schizophrenia.
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Affiliation(s)
- Matthew A Albrecht
- Pharmacology and Anaesthesiology Unit, School of Medicine and Pharmacology, The University of Western Australia, Perth, Australia.
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759
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Gaebel W, Zielasek J. Integrative etiopathogenetic models of psychotic disorders: methods, evidence and concepts. Schizophr Bull 2011; 37 Suppl 2:S5-12. [PMID: 21860047 PMCID: PMC3160124 DOI: 10.1093/schbul/sbr078] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
Integrative models of the etiopathogesnesis of psychotic disorders are needed since a wealth of information from such diverse fields as neurobiology, psychology, and the social sciences is currently changing the concepts of mental disorders. Several approaches to integrate these streams of information into coherent concepts of psychosis are feasible and will need to be assessed in future experimental studies. Common to these concepts are the notion of psychotic disorders as brain disorders and a polythetic approach in that it is increasingly realized that a multitude of interindividually partially different pathogenetic factors interact in individual persons in a complex fashion resulting in the clinical symptoms of psychosis.
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Affiliation(s)
- Wolfgang Gaebel
- Department of Psychiatry and Psychotherapy, Medical Faculty, Heinrich-Heine University, LVR-Klinikum Düsseldorf, Bergische Landstrasse 2, D-40629 Düsseldorf, Germany.
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760
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Birkett PBL. Hodological resonance, hodological variance, psychosis, and schizophrenia: a hypothetical model. Front Psychiatry 2011; 2:46. [PMID: 21811475 PMCID: PMC3144467 DOI: 10.3389/fpsyt.2011.00046] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/08/2010] [Accepted: 07/08/2011] [Indexed: 11/13/2022] Open
Abstract
Schizophrenia is a disorder with a large number of clinical, neurobiological, and cognitive manifestations, none of which is invariably present. However it appears to be a single nosological entity. This article considers the likely characteristics of a pathology capable of such diverse consequences. It is argued that both deficit and psychotic symptoms can be manifestations of a single pathology. A general model of psychosis is proposed in which the informational sensitivity or responsivity of a network ("hodological resonance") becomes so high that it activates spontaneously, to produce a hallucination, if it is in sensory cortex, or another psychotic symptom if it is elsewhere. It is argued that this can come about because of high levels of modulation such as those assumed present in affective psychosis, or because of high levels of baseline resonance, such as those expected in deafferentation syndromes associated with hallucinations, for example, Charles Bonnet. It is further proposed that schizophrenia results from a process (probably neurodevelopmental) causing widespread increases of variance in baseline resonance; consequently some networks possess high baseline resonance and become susceptible to spontaneous activation. Deficit symptoms might result from the presence of networks with increased activation thresholds. This hodological variance model is explored in terms of schizo-affective disorder, transient psychotic symptoms, diathesis-stress models, mechanisms of antipsychotic pharmacotherapy and persistence of genes predisposing to schizophrenia. Predictions and implications of the model are discussed. In particular it suggests a need for more research into psychotic states and for more single case-based studies in schizophrenia.
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761
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Cole MW, Anticevic A, Repovs G, Barch D. Variable global dysconnectivity and individual differences in schizophrenia. Biol Psychiatry 2011; 70:43-50. [PMID: 21496789 PMCID: PMC3204885 DOI: 10.1016/j.biopsych.2011.02.010] [Citation(s) in RCA: 170] [Impact Index Per Article: 13.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/09/2010] [Revised: 01/25/2011] [Accepted: 02/10/2011] [Indexed: 11/18/2022]
Abstract
BACKGROUND A fundamental challenge for understanding neuropsychiatric disease is identifying sources of individual differences in psychopathology, especially when there is substantial heterogeneity of symptom expression, such as is found in schizophrenia (SCZ). We hypothesized that such heterogeneity might arise in part from consistently widespread yet variably patterned alterations in the connectivity of focal brain regions. METHODS We used resting state functional connectivity magnetic resonance imaging to identify variable global dysconnectivity in 23 patients with DSM-IV SCZ relative to 22 age-, gender-, and parental socioeconomic status-matched control subjects with a novel global brain connectivity method that is robust to high variability across individuals. We examined cognitive functioning with a modified Sternberg task and subtests from the Wechsler Adult Intelligence Scale-Third Edition. We measured symptom severity with the Scale for Assessment of Positive and Negative Symptoms. RESULTS We identified a dorsolateral prefrontal cortex (PFC) region with global and highly variable dysconnectivity involving within-PFC underconnectivity and non-PFC overconnectivity in patients. Variability in this "under/over" pattern of dysconnectivity strongly predicted the severity of cognitive deficits (matrix reasoning IQ, verbal IQ, and working memory performance) as well as individual differences in every cardinal symptom domain of SCZ (poverty, reality distortion, and disorganization). CONCLUSIONS These results suggest that global dysconnectivity underlies dorsolateral PFC involvement in the neuropathology of SCZ. Furthermore, these results demonstrate the possibility that specific patterns of dysconnectivity with a given network hub region might explain individual differences in symptom presentation in SCZ. Critically, such findings might extend to other neuropathologies with diverse presentation.
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Affiliation(s)
- Michael W Cole
- Department of Psychology, Washington University, St. Louis, Missouri 63130, USA.
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762
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763
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Moore JW, Turner DC, Corlett PR, Arana FS, Morgan HL, Absalom AR, Adapa R, de Wit S, Everitt JC, Gardner JM, Pigott JS, Haggard P, Fletcher PC. Ketamine administration in healthy volunteers reproduces aberrant agency experiences associated with schizophrenia. Cogn Neuropsychiatry 2011; 16:364-81. [PMID: 21302161 PMCID: PMC3144485 DOI: 10.1080/13546805.2010.546074] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/31/2022]
Abstract
INTRODUCTION Aberrant experience of agency is characteristic of schizophrenia. An understanding of the neurobiological basis of such experience is therefore of considerable importance for developing successful models of the disease. We aimed to characterise the effects of ketamine, a drug model for psychosis, on sense of agency (SoA). SoA is associated with a subjective compression of the temporal interval between an action and its effects: This is known as "intentional binding". This action-effect binding provides an indirect measure of SoA. Previous research has found that the magnitude of binding is exaggerated in patients with schizophrenia. We therefore investigated whether ketamine administration to otherwise healthy adults induced a similar pattern of binding. METHODS 14 right-handed healthy participants (8 female; mean age 22.4 years) were given low-dose ketamine (100 ng/mL plasma) and completed the binding task. They also underwent structured clinical interviews. RESULTS Ketamine mimicked the performance of schizophrenia patients on the intentional binding task, significantly increasing binding relative to placebo. The size of this effect also correlated with aberrant bodily experiences engendered by the drug. CONCLUSIONS These data suggest that ketamine may be able to mimic certain aberrant agency experiences that characterise schizophrenia. The link to individual changes in bodily experience suggests that the fundamental change produced by the drug has wider consequences in terms of individuals' experiences of their bodies and movements.
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Affiliation(s)
- James W. Moore
- Department of Psychiatry, Brain Mapping Unit, University of Cambridge, Cambridge, UK,*Correspondence should be addressed to James Moore, Department of Psychiatry, Brain Mapping Unit, Downing Site, University of Cambridge, Cambridge CB2 3EB, UK. E-mail:
| | | | - Philip R. Corlett
- Department of Psychiatry, Brain Mapping Unit, University of Cambridge, Cambridge, UK,Yale University School of Medicine, Department of Psychiatry, Connecticut Mental Health Centre, Abraham Ribicoff Research Facility, New Haven, CT, USA
| | - Fernando S. Arana
- Department of Psychiatry, Brain Mapping Unit, University of Cambridge, Cambridge, UK,Clinical Brain Disorders Branch, Genes, Cognition and Psychosis Program, National Institute of Mental Health, National Institutes of Health, Bethesda, MD, USA
| | - Hannah L. Morgan
- Department of Psychiatry, Brain Mapping Unit, University of Cambridge, Cambridge, UK
| | - Antony R. Absalom
- Department of Anesthesiology, University Medical Center Groningen, University of Groningen, Groningen, The Netherlands,University Division of Anaesthesia, Addenbrooke's Hospital, Cambridge, UK
| | - Ram Adapa
- University Division of Anaesthesia, Addenbrooke's Hospital, Cambridge, UK
| | - Sanne de Wit
- Department of Psychiatry, Brain Mapping Unit, University of Cambridge, Cambridge, UK,Amsterdam Center for the Study of Adaptive Control in Brain and Behavior (Acacia), Department of Psychology, University of Amsterdam, The Netherlands
| | - Jessica C. Everitt
- Department of Psychiatry, Brain Mapping Unit, University of Cambridge, Cambridge, UK
| | - Jenny M. Gardner
- Cambridge University School of Clinical Medicine, Addenbrooke's Hospital, Cambridge, UK
| | | | - Patrick Haggard
- Institute of Cognitive Neuroscience, University College London, London, UK
| | - Paul C. Fletcher
- Department of Psychiatry, Brain Mapping Unit, University of Cambridge, Cambridge, UK
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764
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Whitford TJ, Mathalon DH, Shenton ME, Roach BJ, Bammer R, Adcock RA, Bouix S, Kubicki M, De Siebenthal J, Rausch AC, Schneiderman JS, Ford JM. Electrophysiological and diffusion tensor imaging evidence of delayed corollary discharges in patients with schizophrenia. Psychol Med 2011; 41:959-969. [PMID: 20663254 PMCID: PMC3807011 DOI: 10.1017/s0033291710001376] [Citation(s) in RCA: 79] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
BACKGROUND Patients with schizophrenia (SZ) characteristically exhibit supranormal levels of cortical activity to self-induced sensory stimuli, ostensibly because of abnormalities in the neural signals (corollary discharges, CDs) normatively involved in suppressing the sensory consequences of self-generated actions. The nature of these abnormalities is unknown. This study investigated whether SZ patients experience CDs that are abnormally delayed in their arrival at the sensory cortex. METHOD Twenty-one patients with SZ and 25 matched control participants underwent electroencephalography (EEG). Participants' level of cortical suppression was calculated as the amplitude of the N1 component evoked by a button press-elicited auditory stimulus, subtracted from the N1 amplitude evoked by the same stimulus presented passively. In the three experimental conditions, the auditory stimulus was delivered 0, 50 or 100 ms subsequent to the button-press. Fifteen SZ patients and 17 healthy controls (HCs) also underwent diffusion tensor imaging (DTI), and the fractional anisotropy (FA) of participants' arcuate fasciculus was used to predict their level of cortical suppression in the three conditions. RESULTS While the SZ patients exhibited subnormal N1 suppression to undelayed, self-generated auditory stimuli, these deficits were eliminated by imposing a 50-ms, but not a 100-ms, delay between the button-press and the evoked stimulus. Furthermore, the extent to which the 50-ms delay normalized a patient's level of N1 suppression was linearly related to the FA of their arcuate fasciculus. CONCLUSIONS These data suggest that SZ patients experience temporally delayed CDs to self-generated auditory stimuli, putatively because of structural damage to the white-matter (WM) fasciculus connecting the sites of discharge initiation and destination.
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Affiliation(s)
- T J Whitford
- Psychiatry Neuroimaging Laboratory, Department of Psychiatry, Brigham and Women's Hospital, Harvard Medical School, 1249 Boylston Street, Boston, MA 02215, USA.
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765
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Drew LJ, Crabtree GW, Markx S, Stark KL, Chaverneff F, Xu B, Mukai J, Fenelon K, Hsu PK, Gogos JA, Karayiorgou M. The 22q11.2 microdeletion: fifteen years of insights into the genetic and neural complexity of psychiatric disorders. Int J Dev Neurosci 2011; 29:259-81. [PMID: 20920576 PMCID: PMC3074020 DOI: 10.1016/j.ijdevneu.2010.09.007] [Citation(s) in RCA: 104] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2010] [Revised: 09/17/2010] [Accepted: 09/20/2010] [Indexed: 12/22/2022] Open
Abstract
Over the last fifteen years it has become established that 22q11.2 deletion syndrome (22q11DS) is a true genetic risk factor for schizophrenia. Carriers of deletions in chromosome 22q11.2 develop schizophrenia at rate of 25-30% and such deletions account for as many as 1-2% of cases of sporadic schizophrenia in the general population. Access to a relatively homogeneous population of individuals that suffer from schizophrenia as the result of a shared etiological factor and the potential to generate etiologically valid mouse models provides an immense opportunity to better understand the pathobiology of this disease. In this review we survey the clinical literature associated with the 22q11.2 microdeletions with a focus on neuroanatomical changes. Then, we highlight results from work modeling this structural mutation in animals. The key biological pathways disrupted by the mutation are discussed and how these changes impact the structure and function of neural circuits is described.
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Affiliation(s)
- Liam J. Drew
- Department of Physiology and Cellular Biophysics, Columbia University, New York, New York 10032, USA
| | - Gregg W. Crabtree
- Department of Physiology and Cellular Biophysics, Columbia University, New York, New York 10032, USA
| | - Sander Markx
- Department of Psychiatry, Columbia University, New York, New York 10032, USA
| | - Kimberly L. Stark
- Department of Physiology and Cellular Biophysics, Columbia University, New York, New York 10032, USA
- Department of Psychiatry, Columbia University, New York, New York 10032, USA
| | - Florence Chaverneff
- Department of Physiology and Cellular Biophysics, Columbia University, New York, New York 10032, USA
| | - Bin Xu
- Department of Physiology and Cellular Biophysics, Columbia University, New York, New York 10032, USA
- Department of Psychiatry, Columbia University, New York, New York 10032, USA
| | - Jun Mukai
- Department of Physiology and Cellular Biophysics, Columbia University, New York, New York 10032, USA
| | - Karine Fenelon
- Department of Physiology and Cellular Biophysics, Columbia University, New York, New York 10032, USA
| | - Pei-Ken Hsu
- Department of Physiology and Cellular Biophysics, Columbia University, New York, New York 10032, USA
- Integrated Program in Cellular, Molecular, and Biophysical Studies, Columbia University, New York, New York 10032, USA
| | - Joseph A. Gogos
- Department of Physiology and Cellular Biophysics, Columbia University, New York, New York 10032, USA
- Department of Neuroscience, College of Physicians and Surgeons, Columbia University, New York, New York 10032, USA
| | - Maria Karayiorgou
- Department of Psychiatry, Columbia University, New York, New York 10032, USA
- New York State Psychiatric Institute, New York, New York 10032, USA
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766
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Hauser M, Knoblich G, Repp BH, Lautenschlager M, Gallinat J, Heinz A, Voss M. Altered sense of agency in schizophrenia and the putative psychotic prodrome. Psychiatry Res 2011; 186:170-6. [PMID: 20826001 DOI: 10.1016/j.psychres.2010.08.003] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/07/2009] [Revised: 06/04/2010] [Accepted: 08/10/2010] [Indexed: 01/12/2023]
Abstract
The mechanisms underlying distortions in sense of agency, i.e. the experience of controlling one's own actions and their consequences, in schizophrenia are not fully understood and have barely been investigated in patients classified as being in a putative psychotic prodrome. This study aims to expound the contribution of early and late illness-related processes. Thirty schizophrenia patients, 30 putatively prodromal patients and 30 healthy controls were instructed to reproduce a computer-generated series of drum sounds on a drum pad. While tapping, subjects heard either their self-produced tones or a computer-controlled reproduction of the drum tone series that used either exactly the same, an accelerated or decelerated tempo. Subjects had to determine the source of agency. Results show similar significant impairments in assigning the source of agency under ambiguous conditions in schizophrenia and putatively prodromal patients and an exaggerated self-attribution bias, both of which were significantly correlated with increased (ego-)psychopathology. Patient groups, however, benefited significantly more than controls from additional sensorimotor cues to agency. Sensorimotor input seems to be a compensatory mechanism involved in correctly attributing agency. We deduce that altered awareness of agency may hold promise as an additional risk factor for psychosis.
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Affiliation(s)
- Marta Hauser
- The Zucker Hillside Hospital, North Shore - Long Island Jewish Health System, Glen Oaks, NY, USA.
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767
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Gradin VB, Kumar P, Waiter G, Ahearn T, Stickle C, Milders M, Reid I, Hall J, Steele JD. Expected value and prediction error abnormalities in depression and schizophrenia. Brain 2011; 134:1751-64. [DOI: 10.1093/brain/awr059] [Citation(s) in RCA: 346] [Impact Index Per Article: 26.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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768
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How can the brain's resting state activity generate hallucinations? A 'resting state hypothesis' of auditory verbal hallucinations. Schizophr Res 2011; 127:202-14. [PMID: 21146961 DOI: 10.1016/j.schres.2010.11.009] [Citation(s) in RCA: 142] [Impact Index Per Article: 10.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/18/2010] [Revised: 09/16/2010] [Accepted: 11/08/2010] [Indexed: 11/20/2022]
Abstract
While several hypotheses about the neural mechanisms underlying auditory verbal hallucinations (AVH) have been suggested, the exact role of the recently highlighted intrinsic resting state activity of the brain remains unclear. Based on recent findings, we therefore developed what we call the 'resting state hypotheses' of AVH. Our hypothesis suggest that AVH may be traced back to abnormally elevated resting state activity in auditory cortex itself, abnormal modulation of the auditory cortex by anterior cortical midline regions as part of the default-mode network, and neural confusion between auditory cortical resting state changes and stimulus-induced activity. We discuss evidence in favour of our 'resting state hypothesis' and show its correspondence with phenomenological accounts.
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769
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Hauser M, Moore JW, de Millas W, Gallinat J, Heinz A, Haggard P, Voss M. Sense of agency is altered in patients with a putative psychotic prodrome. Schizophr Res 2011; 126:20-7. [PMID: 21112189 DOI: 10.1016/j.schres.2010.10.031] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/25/2010] [Revised: 10/26/2010] [Accepted: 10/28/2010] [Indexed: 10/18/2022]
Abstract
BACKGROUND Sense of agency (SoAg)--the experience of controlling one's own actions and their consequences--has been studied in schizophrenia but not in the earlier stages of the disease, i.e. in patients with a putative psychotic prodrome (PP). Previous research has shown that time judgments of voluntary actions can provide an implicit measure of the SoAg. METHOD 30 PP patients and 30 healthy controls performed voluntary key presses while watching a rotating clock hand on a monitor. After each key press they had to estimate the time of the action (based on the perceived position of the clock hand at the time of the key press). By varying the probability with which the simple manual action was followed by a tone, we investigated whether shifts in perceptual estimates of the operant action towards a resulting effect depended on the actual occurrence of the effect (retrospective process) or on the prediction that the effect will occur. RESULTS PP patients differed from healthy controls but their results did not resemble previous findings in schizophrenia patients. PP patients showed numerically--but not significantly--stronger temporal linkage between action and consequence than healthy controls. Retrospective and predictive influences on action binding were stronger in PP patients. Furthermore, the altered influence of prediction was significantly correlated to ego-psychopathology. DISCUSSION Distortions of agency constitute a core feature of the disease that is already present in the PP but may evolve further with progression of the illness. Distortions of agency may thus represent a promising additional predictive risk factor for transition to psychosis in PP patients.
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Affiliation(s)
- Marta Hauser
- Department of Psychiatry and Psychotherapy, Charité University Medicine Campus Mitte, Charitéplatz 1, 10117 Berlin, Germany.
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770
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Deficiency of Dgcr8, a gene disrupted by the 22q11.2 microdeletion, results in altered short-term plasticity in the prefrontal cortex. Proc Natl Acad Sci U S A 2011; 108:4447-52. [PMID: 21368174 DOI: 10.1073/pnas.1101219108] [Citation(s) in RCA: 155] [Impact Index Per Article: 11.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023] Open
Abstract
Individuals with 22q11.2 microdeletions have cognitive and behavioral impairments and the highest known genetic risk for developing schizophrenia. One gene disrupted by the 22q11.2 microdeletion is DGCR8, a component of the "microprocessor" complex that is essential for microRNA production, resulting in abnormal processing of specific brain miRNAs and working memory deficits. Here, we determine the effect of Dgcr8 deficiency on the structure and function of cortical circuits by assessing their laminar organization, as well as the neuronal morphology, and intrinsic and synaptic properties of layer 5 pyramidal neurons in the prefrontal cortex of Dgcr8(+/-) mutant mice. We found that heterozygous Dgcr8 mutant mice have slightly fewer cortical layer 2/4 neurons and that the basal dendrites of layer 5 pyramidal neurons have slightly smaller spines. In addition to the modest structural changes, field potential and whole-cell electrophysiological recordings performed in layer 5 of the prefrontal cortex revealed greater short-term synaptic depression during brief stimulation trains applied at 50 Hz to superficial cortical layers. This finding was accompanied by a decrease in the initial phase of synaptic potentiation. Our results identify altered short-term plasticity as a neural substrate underlying the cognitive dysfunction and the increased risk for schizophrenia associated with the 22q11.2 microdeletions.
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771
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Sense of agency, associative learning, and schizotypy. Conscious Cogn 2011; 20:792-800. [PMID: 21295497 PMCID: PMC3161182 DOI: 10.1016/j.concog.2011.01.002] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2010] [Revised: 12/03/2010] [Accepted: 01/06/2011] [Indexed: 11/21/2022]
Abstract
Despite the fact that the role of learning is recognised in empirical and theoretical work on sense of agency (SoA), the nature of this learning has, rather surprisingly, received little attention. In the present study we consider the contribution of associative mechanisms to SoA. SoA can be measured quantitatively as a temporal linkage between voluntary actions and their external effects. Using an outcome blocking procedure, it was shown that training action-outcome associations under conditions of increased surprise augmented this temporal linkage. Moreover, these effects of surprise were correlated with schizotypy scores, suggesting that individual differences in higher level experiences are related to associative learning and to its impact on SoA. These results are discussed in terms of models of SoA, and our understanding of disrupted SoA in certain disorders.
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772
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Morgan HL, Turner DC, Corlett PR, Absalom AR, Adapa R, Arana FS, Pigott J, Gardner J, Everitt J, Haggard P, Fletcher PC. Exploring the impact of ketamine on the experience of illusory body ownership. Biol Psychiatry 2011; 69:35-41. [PMID: 20947068 PMCID: PMC3025328 DOI: 10.1016/j.biopsych.2010.07.032] [Citation(s) in RCA: 63] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/12/2010] [Revised: 05/25/2010] [Accepted: 07/08/2010] [Indexed: 11/29/2022]
Abstract
BACKGROUND Our sense of body ownership is profound and familiar, yet it may be misleading. In the rubber-hand illusion, synchronous tactile and visual stimulation lead to the experience that a rubber hand is actually one's own. This illusion is stronger in schizophrenia. Given the evidence that ketamine, a noncompetitive N-methyl-D-aspartate antagonist reproduces symptoms of schizophrenia, we sought to determine whether the rubber-hand illusion is augmented by ketamine. METHODS We studied 15 healthy volunteers in a within-subjects placebo-controlled study. All volunteers carried out two versions of the rubber-hand task, each under both placebo and ketamine infusions. In one task, they saw a rubber hand being stroked in synchrony with tactile stimulation of their real, hidden hand. In the other, stroking of the real and rubber hands was asynchronous. We recorded subjective changes in sense of ownership, as well as participants' ability to localize their hidden hand. RESULTS Ketamine was associated with significant increases in subjective measures of the illusion and in hand mislocalization. Although asynchronous visuotactile stimulation attenuates the strength of the illusion during both placebo and ketamine, there remained a significant illusory effect during asynchronous visuotactile stimulation under ketamine compared with placebo. The strength of the illusion during asynchronous visuotactile stimulation correlated with other subjective effects of the drug. CONCLUSIONS Ketamine mimics the perturbed sense of body ownership seen in schizophrenia, suggesting that it produces a comparable alteration in integration of information across sensory domains and in the subjective and behavioral consequences of such integration.
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Affiliation(s)
- Hannah L. Morgan
- Department of Psychiatry, Brain Mapping Unit, University of Cambridge, Downing Site, United Kingdom
| | | | - Philip R. Corlett
- Department of Psychiatry, Ribicoff Research Facility, Yale University, Connecticut Mental Health Center, New Haven, Connecticut
| | - Anthony R. Absalom
- Anaesthetic Department, University Medical Center Groningen, Groningen, Netherlands,University Division of Anaesthesia, Addenbrooke's Hospital, Cambridge, United Kingdom
| | - Ram Adapa
- University Division of Anaesthesia, Addenbrooke's Hospital, Cambridge, United Kingdom
| | - Fernando S. Arana
- Department of Psychiatry, Brain Mapping Unit, University of Cambridge, Downing Site, United Kingdom,Clinical Brain Disorders Branch, Genes, Cognition, and Psychosis Program, National Institute of Mental Health, National Institutes of Health, Bethesda, Maryland
| | - Jennifer Pigott
- University College London Medical School, London, United Kingdom
| | - Jenny Gardner
- Cambridge University School of Clinical Medicine, Addenbrooke's Hospital, Cambridge
| | - Jessica Everitt
- Department of Psychiatry, Brain Mapping Unit, University of Cambridge, Downing Site, United Kingdom
| | - Patrick Haggard
- Institute of Cognitive Neuroscience, University College London, United Kingdom
| | - Paul C. Fletcher
- Department of Psychiatry, Brain Mapping Unit, University of Cambridge, Downing Site, United Kingdom,Address correspondence to Paul C. Fletcher, Ph.D., M.R.C.Psych, Department of Psychiatry, Addenbrooke's Hospital, Box 189, University of Cambridge, Cambridge CB2 2QQl, United Kingdom
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773
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Bürgy M. Ego disturbances in the sense of Kurt Schneider: historical and phenomenological aspects. Psychopathology 2011; 44:320-8. [PMID: 21734435 DOI: 10.1159/000325059] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/08/2010] [Accepted: 01/17/2011] [Indexed: 11/19/2022]
Abstract
The phenomena which were grouped together by Kurt Schneider to constitute the ego disturbances have always been of particular diagnostic relevance for schizophrenia. The manner in which these symptoms are described and distinguished from other psychopathological symptoms has generally been rather imprecise. The introduction of phenomenological methods into the field of psychiatry led to considerable improvements in symptom descriptions and to a clearer distinction between psychotic and nonpsychotic experience. Continued developments in phenomenology have further incorporated aspects of schizophrenic symptom development and in doing so have brought so-called transitional phenomena and the core schizophrenic syndrome into focus. The ego disturbances accordingly appear to stem from a particular form of depersonalization which is described as a modified sense of mineness and which can be distinguished from the neurotic experience of depersonalization.
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Affiliation(s)
- Martin Bürgy
- Center of Mental Health, Klinikum Stuttgart, Stuttgart, Germany.
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774
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Abstract
This article examines a model of how delusions may arise, not just in schizophrenia but also in a number of neurological and psychiatric conditions, through a combination of dysregulated dopamine release from ascending midbrain pathways and reasoning bias. Negative symptoms may also be related to dopamine dysregulation, with the precise mixture of positive and negative symptoms depending on the relative degree of dopamine dysregulation in particular mesocorticolimbic circuits. Evidence for this model is examined, and predictions arising from this model are described.
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775
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Corlett PR, Honey GD, Krystal JH, Fletcher PC. Glutamatergic model psychoses: prediction error, learning, and inference. Neuropsychopharmacology 2011; 36:294-315. [PMID: 20861831 PMCID: PMC3055519 DOI: 10.1038/npp.2010.163] [Citation(s) in RCA: 156] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/18/2010] [Revised: 08/16/2010] [Accepted: 08/18/2010] [Indexed: 01/01/2023]
Abstract
Modulating glutamatergic neurotransmission induces alterations in conscious experience that mimic the symptoms of early psychotic illness. We review studies that use intravenous administration of ketamine, focusing on interindividual variability in the profundity of the ketamine experience. We will consider this individual variability within a hypothetical model of brain and cognitive function centered upon learning and inference. Within this model, the brains, neural systems, and even single neurons specify expectations about their inputs and responding to violations of those expectations with new learning that renders future inputs more predictable. We argue that ketamine temporarily deranges this ability by perturbing both the ways in which prior expectations are specified and the ways in which expectancy violations are signaled. We suggest that the former effect is predominantly mediated by NMDA blockade and the latter by augmented and inappropriate feedforward glutamatergic signaling. We suggest that the observed interindividual variability emerges from individual differences in neural circuits that normally underpin the learning and inference processes described. The exact source for that variability is uncertain, although it is likely to arise not only from genetic variation but also from subjects' previous experiences and prior learning. Furthermore, we argue that chronic, unlike acute, NMDA blockade alters the specification of expectancies more profoundly and permanently. Scrutinizing individual differences in the effects of acute and chronic ketamine administration in the context of the Bayesian brain model may generate new insights about the symptoms of psychosis; their underlying cognitive processes and neurocircuitry.
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Affiliation(s)
- Philip R Corlett
- Department of Psychiatry, Yale University School of Medicine, New Haven, CT 06519, USA.
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776
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Nadel L, Hardt O. Update on memory systems and processes. Neuropsychopharmacology 2011; 36:251-73. [PMID: 20861829 PMCID: PMC3055510 DOI: 10.1038/npp.2010.169] [Citation(s) in RCA: 142] [Impact Index Per Article: 10.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/25/2010] [Revised: 08/11/2010] [Accepted: 08/23/2010] [Indexed: 12/29/2022]
Abstract
Ideas about how the brain organizes learning and memory have been evolving in recent years, with potentially important ramifications. We review traditional thinking about learning and memory and consider more closely emerging trends from both human and animal research that could lead to profound shifts in how we understand the neural basis of memory.
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Affiliation(s)
- Lynn Nadel
- Department of Psychology, University of Arizona, Tucson, AZ 85721, USA.
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777
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Baggott MJ, Siegrist JD, Galloway GP, Robertson LC, Coyle JR, Mendelson JE. Investigating the mechanisms of hallucinogen-induced visions using 3,4-methylenedioxyamphetamine (MDA): a randomized controlled trial in humans. PLoS One 2010; 5:e14074. [PMID: 21152030 PMCID: PMC2996283 DOI: 10.1371/journal.pone.0014074] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2010] [Accepted: 10/20/2010] [Indexed: 11/19/2022] Open
Abstract
BACKGROUND The mechanisms of drug-induced visions are poorly understood. Very few serotonergic hallucinogens have been studied in humans in decades, despite widespread use of these drugs and potential relevance of their mechanisms to hallucinations occurring in psychiatric and neurological disorders. METHODOLOGY/PRINCIPAL FINDINGS We investigated the mechanisms of hallucinogen-induced visions by measuring the visual and perceptual effects of the hallucinogenic serotonin 5-HT2AR receptor agonist and monoamine releaser, 3,4-methylenedioxyamphetamine (MDA), in a double-blind placebo-controlled study. We found that MDA increased self-report measures of mystical-type experience and other hallucinogen-like effects, including reported visual alterations. MDA produced a significant increase in closed-eye visions (CEVs), with considerable individual variation. Magnitude of CEVs after MDA was associated with lower performance on measures of contour integration and object recognition. CONCLUSIONS/SIGNIFICANCE Drug-induced visions may have greater intensity in people with poor sensory or perceptual processing, suggesting common mechanisms with other hallucinatory syndromes. MDA is a potential tool to investigate mystical experiences and visual perception. TRIAL REGISTRATION Clinicaltrials.gov NCT00823407.
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Affiliation(s)
- Matthew J Baggott
- Addiction and Pharmacology Research Laboratory, California Pacific Medical Center Research Institute, St Luke's Hospital, San Francisco, California, United States of America.
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778
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Lawrie SM, Hall J, McIntosh AM, Owens DGC, Johnstone EC. The 'continuum of psychosis': scientifically unproven and clinically impractical. Br J Psychiatry 2010; 197:423-5. [PMID: 21119144 DOI: 10.1192/bjp.bp.109.072827] [Citation(s) in RCA: 61] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
The limitations of current diagnostic categories are well recognised but their rationale, advantages and utility are often ignored. The scientific support for a 'continuum of psychosis' is limited, and the examination of whether categories, a continuum or more than one continua, and alternatives such as subtypes or hybrid models, best account for the distributions of symptoms in populations has simply not been done. There is a lack of discussion, let alone consensus, about the critical aspects of psychosis to measure, the best ways to quantify those and how these would be applied in clinical practice. Systematic studies are needed to evaluate which of a range of plausible approaches to the classification of psychosis is most useful before change could be justified.
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779
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Kindler J, Hubl D, Strik WK, Dierks T, Koenig T. Resting-state EEG in schizophrenia: auditory verbal hallucinations are related to shortening of specific microstates. Clin Neurophysiol 2010; 122:1179-82. [PMID: 21123110 DOI: 10.1016/j.clinph.2010.10.042] [Citation(s) in RCA: 103] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2010] [Revised: 10/15/2010] [Accepted: 10/19/2010] [Indexed: 10/18/2022]
Abstract
OBJECTIVE Abnormal perceptions and cognitions in schizophrenia might be related to abnormal resting states of the brain. Previous research found that a specific class (class D) of sub-second electroencephalography (EEG) microstates was shortened in schizophrenia. This shortening correlated with positive symptoms. We questioned if this reflected positive psychotic traits or present psychopathology. METHODS Resting-state EEGs of frequently hallucinating patients, indicating on- and offset of hallucinations by button press, were analyzed. Microstate class D duration was related to spontaneous within-subject fluctuations of auditory hallucinations. RESULTS Microstate D was significantly shorter in periods with hallucinations. CONCLUSIONS Microstates of class D resemble topographies associated with error monitoring. Its premature termination may facilitate the misattribution of self-generated inner speech to external sources during hallucinations. SIGNIFICANCE These results suggest that microstate D represents a biological state marker for hallucinatory experiences.
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Affiliation(s)
- J Kindler
- University Hospital of Psychiatry and Psychotherapy, University of Bern, Switzerland
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780
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The cognitive neuropsychiatry of delusional belief. WILEY INTERDISCIPLINARY REVIEWS. COGNITIVE SCIENCE 2010; 2:449-460. [DOI: 10.1002/wcs.121] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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781
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Corlett PR, Taylor JR, Wang XJ, Fletcher PC, Krystal JH. Toward a neurobiology of delusions. Prog Neurobiol 2010; 92:345-69. [PMID: 20558235 PMCID: PMC3676875 DOI: 10.1016/j.pneurobio.2010.06.007] [Citation(s) in RCA: 246] [Impact Index Per Article: 17.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2010] [Revised: 05/06/2010] [Accepted: 06/08/2010] [Indexed: 12/21/2022]
Abstract
Delusions are the false and often incorrigible beliefs that can cause severe suffering in mental illness. We cannot yet explain them in terms of underlying neurobiological abnormalities. However, by drawing on recent advances in the biological, computational and psychological processes of reinforcement learning, memory, and perception it may be feasible to account for delusions in terms of cognition and brain function. The account focuses on a particular parameter, prediction error--the mismatch between expectation and experience--that provides a computational mechanism common to cortical hierarchies, fronto-striatal circuits and the amygdala as well as parietal cortices. We suggest that delusions result from aberrations in how brain circuits specify hierarchical predictions, and how they compute and respond to prediction errors. Defects in these fundamental brain mechanisms can vitiate perception, memory, bodily agency and social learning such that individuals with delusions experience an internal and external world that healthy individuals would find difficult to comprehend. The present model attempts to provide a framework through which we can build a mechanistic and translational understanding of these puzzling symptoms.
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Affiliation(s)
- P R Corlett
- Department of Psychiatry, Yale University School of Medicine, Connecticut Mental Health Centre, Abraham Ribicoff Research Facility, 34 Park Street, New Haven, CT 06519, USA.
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782
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Deficits in sensory prediction are related to delusional ideation in healthy individuals. Neuropsychologia 2010; 48:4169-72. [PMID: 20974159 PMCID: PMC3142618 DOI: 10.1016/j.neuropsychologia.2010.10.024] [Citation(s) in RCA: 54] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2010] [Revised: 10/13/2010] [Accepted: 10/19/2010] [Indexed: 11/24/2022]
Abstract
Motor control strongly relies on neural processes that predict the sensory consequences of self-generated actions. Previous research has demonstrated deficits in such sensory-predictive processes in schizophrenic patients and these low-level deficits are thought to contribute to the emergence of delusions of control. Here, we examined the extent to which individual differences in sensory prediction are associated with a tendency towards delusional ideation in healthy participants. We used a force-matching task to quantify sensory-predictive processes, and administered questionnaires to assess schizotypy and delusion-like thinking. Individuals with higher levels of delusional ideation showed more accurate force matching suggesting that such thinking is associated with a reduced tendency to predict and attenuate the sensory consequences of self-generated actions. These results suggest that deficits in sensory prediction in schizophrenia are not simply consequences of the deluded state and are not related to neuroleptic medication. Rather they appear to be stable, trait-like characteristics of an individual, a finding that has important implications for our understanding of the neurocognitive basis of delusions.
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783
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Eickhoff SB, Pomjanski W, Jakobs O, Zilles K, Langner R. Neural correlates of developing and adapting behavioral biases in speeded choice reactions--an fMRI study on predictive motor coding. Cereb Cortex 2010; 21:1178-91. [PMID: 20956614 DOI: 10.1093/cercor/bhq188] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023] Open
Abstract
In reaction-time (RT) tasks with unequally probable stimuli, people respond faster and more accurately in high-probability trials than in low-probability trials. We used functional magnetic resonance imaging to investigate brain activity during the acquisition and adaptation of such biases. Participants responded to arrows pointing to either side with different and previously unknown probabilities across blocks, which were covertly reversed in the middle of some blocks. Changes in response bias were modeled using the development of the selective RT bias at the beginning of a block and after the reversal as parametric regressors. Both fresh development and reversal of an existing response bias were associated with bilateral activations in inferior parietal lobule, intraparietal sulcus, and supplementary motor cortex. Further activations were observed in right temporoparietal junction, dorsolateral prefrontal cortex, and dorsal premotor cortex. Only during initial development of biases at the beginning of a block, we observed additional activity in ventral premotor cortex and anterior insula, whereas the basal ganglia (bilaterally) were recruited when the bias was adapted to reversed probabilities. Taken together, these areas constitute a network that updates and applies implicit predictions to create an attention and motor bias according to environmental probabilities that transform into specific facilitation.
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Affiliation(s)
- Simon B Eickhoff
- Department of Psychiatry and Psychotherapy, RWTH Aachen University, 52074 Aachen, Germany.
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784
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Berniker M, Voss M, Kording K. Learning priors for Bayesian computations in the nervous system. PLoS One 2010; 5. [PMID: 20844766 PMCID: PMC2937037 DOI: 10.1371/journal.pone.0012686] [Citation(s) in RCA: 92] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2010] [Accepted: 07/28/2010] [Indexed: 11/18/2022] Open
Abstract
Our nervous system continuously combines new information from our senses with information it has acquired throughout life. Numerous studies have found that human subjects manage this by integrating their observations with their previous experience (priors) in a way that is close to the statistical optimum. However, little is known about the way the nervous system acquires or learns priors. Here we present results from experiments where the underlying distribution of target locations in an estimation task was switched, manipulating the prior subjects should use. Our experimental design allowed us to measure a subject's evolving prior while they learned. We confirm that through extensive practice subjects learn the correct prior for the task. We found that subjects can rapidly learn the mean of a new prior while the variance is learned more slowly and with a variable learning rate. In addition, we found that a Bayesian inference model could predict the time course of the observed learning while offering an intuitive explanation for the findings. The evidence suggests the nervous system continuously updates its priors to enable efficient behavior.
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Affiliation(s)
- Max Berniker
- Department of Physical Medicine and Rehabilitation, Northwestern University and Rehabilitation Institute of Chicago, Chicago, Illinois, United States of America.
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785
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Dima D, Dietrich DE, Dillo W, Emrich HM. Impaired top-down processes in schizophrenia: A DCM study of ERPs. Neuroimage 2010; 52:824-32. [DOI: 10.1016/j.neuroimage.2009.12.086] [Citation(s) in RCA: 93] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2009] [Revised: 12/18/2009] [Accepted: 12/18/2009] [Indexed: 11/26/2022] Open
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786
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Hallucinations, conscience et psychoses. Encephale 2010; 36:348-54. [DOI: 10.1016/j.encep.2010.07.001] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2010] [Accepted: 07/09/2010] [Indexed: 11/18/2022]
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787
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Bürgy M. [The psychopathology of ego disturbances: history and phenomenology]. DER NERVENARZT 2010; 81:1097-107. [PMID: 20803188 DOI: 10.1007/s00115-010-3122-5] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The phenomena which Kurt Schneider grouped together to form the ego disturbances have always been of particular diagnostic relevance for schizophrenia. While little importance was historically attached to accurately describing and distinguishing psychopathological symptoms, Karl Jaspers' and Kurt Schneider's descriptive psychopathology aims to draw a sharp yet differentiated distinction between psychotic and non-psychotic disorders at the symptom level. New developments in phenomenology including aspects of symptom development are presented. The depersonalization experience is focused on as a transitional phenomenon which is distinguishes from neurotic depersonalization through a disturbed sense of mineness. The ego disturbances indicate that disturbed mineness can be seen as the common denominator of first-rank symptoms of schizophrenia.
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Affiliation(s)
- M Bürgy
- Klinik für Spezielle Psychiatrie, Sozialpsychiatrie und Psychotherapie, Zentrum für Seelische Gesundheit, Klinikum Stuttgart, Tunzhofer Strasse 14-16, 70191, Stuttgart, Deutschland.
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788
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Voss M, Moore J, Hauser M, Gallinat J, Heinz A, Haggard P. Altered awareness of action in schizophrenia: a specific deficit in predicting action consequences. ACTA ACUST UNITED AC 2010; 133:3104-12. [PMID: 20685805 DOI: 10.1093/brain/awq152] [Citation(s) in RCA: 216] [Impact Index Per Article: 15.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Patients suffering from schizophrenia may report unusual experiences of their own actions. They may either feel that external forces are controlling their actions or even their thoughts, or they may feel in control of events that in fact are not caused by their actions. Most theories link these disturbances in the sense of agency to deficits in motor prediction, resulting in a mismatch between predicted and actual sensory feedback at a central comparator mechanism. Such theories therefore can account for situations in which the sense of agency is reduced. However, other experiments as well as clinical observations show an enhanced rather than reduced sense of agency in schizophrenic patients. Here, we distinguish between a predictive and a retrospective mechanism where both contribute to the experience of agency, and show that schizophrenia is associated with a specific impairment to the predictive component. We measured subjective time estimates of self-initiated voluntary action (a key press) that were followed by a sensory effect (a tone). When the voluntary actions had a high probability of causing tones, healthy volunteers showed a predictive shift of the perceptual estimate of the action towards the tone, even on occasional trials where the tone was omitted. No such shift occurred in the absence of the tone on blocks when tones were less frequent. The predictive component of action awareness was calculated as the difference between time estimates on 'action only' trials from blocks with lower and higher tone probabilities. Schizophrenic patients lacked this predictive component of action awareness, showing a shift on 'action only' trials, regardless of the probability of the tone. Importantly, the schizophrenic deficit in predicting the relation between action and effect was strongly correlated with severity of positive psychotic symptoms, specifically delusions and hallucinations. Furthermore, the patients showed an exaggerated retrospective binding between action and tone, shifting the perceived time of action whenever the tone occurred, relative to when it did not occur. Our quantitative, implicit measures show how basic sensory and motor experience may be altered in acute psychosis. The enhanced sense of agency in schizophrenia reflects reliance on retrospection, rather than prediction, to associate actions with external events. The failure to predict the effects of one's own actions may underlie the blurring and confusion in the relationship between the self and the world that characterizes acute psychosis.
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Affiliation(s)
- Martin Voss
- Department of Psychiatry and Psychotherapy, Charité University Hospital, St. Hedwig Hospital, Grosse Hamburger Strasse 5-11, Berlin, Germany.
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789
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Seeing other minds: attributed mental states influence perception. Trends Cogn Sci 2010; 14:376-82. [PMID: 20576464 DOI: 10.1016/j.tics.2010.05.005] [Citation(s) in RCA: 107] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2010] [Revised: 05/21/2010] [Accepted: 05/24/2010] [Indexed: 11/23/2022]
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790
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L’expérience subjective de l’effort volontaire dans la schizophrénie : approche neurophénoménologique. EVOLUTION PSYCHIATRIQUE 2010. [DOI: 10.1016/j.evopsy.2010.06.007] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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791
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Abstract
Work in the field of cognitive neuropsychiatry over the past 20 years has made it plain that various forms of delusional belief are scientifically understandable in the sense that plausible neuropsychological explanations of their nature and genesis have been formulated. A two-factor theory of delusional belief has emerged from this work. According to this theory, explaining the presence of a delusion requires (a) the presence a neuropsychological impairment that initially prompts the delusional belief and (b) the presence of a second neuropsychological impairment that interferes with processes of belief evaluation that would otherwise cause the delusional belief to be rejected. A very similar account of delusion has recently emerged from research on hypothesis evaluation using the associative-learning paradigm with healthy control subjects and people with psychosis. Neuroimaging studies in this context suggest that the region of the brain specifically involved in hypothesis evaluation (and therefore, according to the two-factor theory, impaired in people with delusions) is the right lateral prefrontal cortex.
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Affiliation(s)
- Max Coltheart
- Macquarie Centre for Cognitive Science, Macquarie University, Sydney, NSW, Australia.
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792
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Carhart-Harris RL, Friston KJ. The default-mode, ego-functions and free-energy: a neurobiological account of Freudian ideas. Brain 2010; 133:1265-83. [PMID: 20194141 PMCID: PMC2850580 DOI: 10.1093/brain/awq010] [Citation(s) in RCA: 221] [Impact Index Per Article: 15.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2009] [Revised: 12/23/2009] [Accepted: 12/23/2009] [Indexed: 01/01/2023] Open
Abstract
This article explores the notion that Freudian constructs may have neurobiological substrates. Specifically, we propose that Freud's descriptions of the primary and secondary processes are consistent with self-organized activity in hierarchical cortical systems and that his descriptions of the ego are consistent with the functions of the default-mode and its reciprocal exchanges with subordinate brain systems. This neurobiological account rests on a view of the brain as a hierarchical inference or Helmholtz machine. In this view, large-scale intrinsic networks occupy supraordinate levels of hierarchical brain systems that try to optimize their representation of the sensorium. This optimization has been formulated as minimizing a free-energy; a process that is formally similar to the treatment of energy in Freudian formulations. We substantiate this synthesis by showing that Freud's descriptions of the primary process are consistent with the phenomenology and neurophysiology of rapid eye movement sleep, the early and acute psychotic state, the aura of temporal lobe epilepsy and hallucinogenic drug states.
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Affiliation(s)
- R L Carhart-Harris
- Neuropsychopharmacology Unit, Imperial College London, Hammersmith Campus, Du Cane Road, London, W12 ONN, UK.
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793
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Henseler I, Falkai P, Gruber O. Disturbed functional connectivity within brain networks subserving domain-specific subcomponents of working memory in schizophrenia: relation to performance and clinical symptoms. J Psychiatr Res 2010; 44:364-72. [PMID: 19837416 DOI: 10.1016/j.jpsychires.2009.09.003] [Citation(s) in RCA: 99] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/16/2009] [Revised: 08/07/2009] [Accepted: 09/08/2009] [Indexed: 12/01/2022]
Abstract
INTRODUCTION Disturbed interregional functional connectivity has been hypothesized to be a promising marker of schizophrenia. The relationship between working memory (WM) impairment, disturbed functional connectivity, and the characteristic symptoms of schizophrenia, however, remains elusive. METHODS We used functional MRI (fMRI) to investigate in patients with schizophrenia and matched controls the patterns of functional connectivity during the performance of different tasks selectively engaging subcomponent processes of working memory. RESULTS Compared with controls, patients showed reduced connectivity of the prefrontal cortex with the intraparietal cortex and the hippocampus and abnormal negative interactions between the ventrolateral and dorsolateral prefrontal cortex during the non-articulatory maintenance of phonological information. During the maintenance of visuospatial information, patients presented reduced connectivity between regions in the superior parietal and occipital cortex, as well as enhanced positive connectivity of the frontal eye field with visual processing areas. DISCUSSION Our findings suggest complex dysregulations within the networks supporting working memory functions in schizophrenia, which manifest as decreased positive and abnormal negative interactions. Correlations between the connection strength and WM performance suggest that these dysregulations may be neurofunctional correlates of the WM deficits seen in schizophrenia. Altered prefronto-hippocampal and parieto-occipital connectivity was further found to be associated with higher positive symptoms, providing a possible explanation for the development of delusions and disorganization symptoms. CONCLUSION The present findings can help to better understand the relationship between altered patterns of synchronized brain activity and the cognitive and clinical symptoms of schizophrenia.
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Affiliation(s)
- Ilona Henseler
- Centre for Translational Research in Systems Neuroscience and Clinical Psychiatry, Department of Psychiatry and Psychotherapy, Georg August University, D-37075 Goettingen, Germany.
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794
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Abstract
PURPOSE OF REVIEW There has been a resurgence of interest in the field of reward processing in schizophrenia in recent years, aided by insights from functional neuroimaging. We examine how disturbances in reward-related processes relate to the pathophysiology and symptomatology of this disorder. RECENT FINDINGS Behavioural and functional neuroimaging studies in psychosis demonstrate impairments in the representation of reward value and in reward-related learning and a failure to motivate behaviour for incentives. These impairments are linked to abnormal mesocorticolimbic and mesostriatal function. SUMMARY Abnormalities in reward processing offer insights into the symptomatology of schizophrenia and its underlying neurobiology. Further investigation is required into the specificity of these deficits to particular symptom expression and to what extent they are improved by antipsychotic treatment.
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795
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Dopaminergic modulation of rapid reality adaptation in thinking. Neuroscience 2010; 167:583-7. [PMID: 20219638 DOI: 10.1016/j.neuroscience.2010.02.044] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2010] [Revised: 02/14/2010] [Accepted: 02/18/2010] [Indexed: 11/20/2022]
Abstract
Dopamine has long held a prominent role in the interpretation of schizophrenia and other psychoses. Clinical studies on confabulation and disorientation, disorders marked by a confusion of reality in thinking, indicated that the ability to keep thinking in phase with reality depends on a process suppressing the interference of upcoming memories that do not refer to ongoing reality. A host of animal studies and a recent clinical study suggested that this suppression might correspond to the phasic inhibition of dopaminergic neurons in response to the absence of expected outcomes. In this study, we tested healthy subjects with a difficult version of a memory paradigm on which confabulating patients had failed. Subjects participated in three test sessions, in which they received in double-blind, randomized fashion L-dopa, risperidone, or placebo. We found that l-dopa, in comparison with risperidone, impaired performance in a highly specific way, which corresponded to the pattern of patients with reality confusion. Specifically, they had an increase of false positive responses, while overall memory performance and reaction times were unaffected. We conclude that dopaminergic transmission influences the ability to rapidly adapt thinking to ongoing reality.
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796
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Hohwy J, Paton B. Explaining away the body: experiences of supernaturally caused touch and touch on non-hand objects within the rubber hand illusion. PLoS One 2010; 5:e9416. [PMID: 20195378 PMCID: PMC2827559 DOI: 10.1371/journal.pone.0009416] [Citation(s) in RCA: 102] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2009] [Accepted: 01/31/2010] [Indexed: 11/18/2022] Open
Abstract
Background In rubber hand illusions and full body illusions, touch sensations are projected to non-body objects such as rubber hands, dolls or virtual bodies. The robustness, limits and further perceptual consequences of such illusions are not yet fully explored or understood. A number of experiments are reported that test the limits of a variant of the rubber hand illusion. Methodology/Principal Findings A variant of the rubber hand illusion is explored, in which the real and foreign hands are aligned in personal space. The presence of the illusion is ascertained with participants' scores and temperature changes of the real arm. This generates a basic illusion of touch projected to a foreign arm. Participants are presented with further, unusual visuotactile stimuli subsequent to onset of the basic illusion. Such further visuotactile stimulation is found to generate very unusual experiences of supernatural touch and touch on a non-hand object. The finding of touch on a non-hand object conflicts with prior findings, and to resolve this conflict a further hypothesis is successfully tested: that without prior onset of the basic illusion this unusual experience does not occur. Conclusions/Significance A rubber hand illusion is found that can arise when the real and the foreign arm are aligned in personal space. This illusion persists through periods of no tactile stimulation and is strong enough to allow very unusual experiences of touch felt on a cardboard box and experiences of touch produced at a distance, as if by supernatural causation. These findings suggest that one's visual body image is explained away during experience of the illusion and they may be of further importance to understanding the role of experience in delusion formation. The findings of touch on non-hand objects may help reconcile conflicting results in this area of research. In addition, new evidence is provided that relates to the recently discovered psychologically induced temperature changes that occur during the illusion.
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Affiliation(s)
- Jakob Hohwy
- Philosophy Program, Monash University, Clayton, Victoria, Australia.
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797
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798
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Abstract
AbstractIn their target article, McKay & Dennett (M&D) conclude that only “positive illusions” are adaptive misbeliefs. Relying on overly strict conceptual schisms (deficit vs. motivational, functional vs. organic, perception vs. belief), they prematurely discount delusions as biologically adaptive. In contrast to their view that “motivation” plays a psychological but not a biological function in a two-factor model of the forming and maintenance of delusions, we propose a single impairment in prediction-error–driven (i.e., motivational) learning in three stages in which delusions play a biologically adaptive role.
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799
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Abstract
A free-energy principle has been proposed recently that accounts for action, perception and learning. This Review looks at some key brain theories in the biological (for example, neural Darwinism) and physical (for example, information theory and optimal control theory) sciences from the free-energy perspective. Crucially, one key theme runs through each of these theories - optimization. Furthermore, if we look closely at what is optimized, the same quantity keeps emerging, namely value (expected reward, expected utility) or its complement, surprise (prediction error, expected cost). This is the quantity that is optimized under the free-energy principle, which suggests that several global brain theories might be unified within a free-energy framework.
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Affiliation(s)
- Karl Friston
- The Wellcome Trust Centre for Neuroimaging, University College London, Queen Square, London, WC1N 3BG, UK.
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800
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Synofzik M, Thier P, Leube DT, Schlotterbeck P, Lindner A. Misattributions of agency in schizophrenia are based on imprecise predictions about the sensory consequences of one's actions. ACTA ACUST UNITED AC 2009; 133:262-71. [PMID: 19995870 DOI: 10.1093/brain/awp291] [Citation(s) in RCA: 204] [Impact Index Per Article: 13.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
The experience of being the initiator of one's own actions seems to be infallible at first glance. Misattributions of agency of one's actions in certain neurological or psychiatric patients reveal, however, that the central mechanisms underlying this experience can go astray. In particular, delusions of influence in schizophrenia might result from deficits in an inferential mechanism that allows distinguishing whether or not a sensory event has been self-produced. This distinction is made by comparing the actual sensory information with the consequences of one's action as predicted on the basis of internal action-related signals such as efference copies. If this internal prediction matches the actual sensory event, an action is registered as self-caused; in case of a mismatch, the difference is interpreted as externally produced. We tested the hypothesis that delusions of influence are based on deficits in this comparator mechanism. In particular, we tested whether patients' impairments in action attribution tasks are caused by imprecise predictions about the sensory consequences of self-action. Schizophrenia patients and matched controls performed pointing movements in a virtual-reality setup in which the visual consequences of movements could be rotated with respect to the actual movement. Experiment 1 revealed higher thresholds for detecting experimental feedback rotations in the patient group. The size of these thresholds correlated positively with patients' delusions of influence. Experiment 2 required subjects to estimate their direction of pointing visually in the presence of constantly rotated visual feedback. When compared to controls, patients' estimates were significantly better adapted to the feedback rotation and exhibited an increased variability. In interleaved trials without visual feedback, i.e. when pointing estimates relied solely on internal action-related signals, this variability was likewise increased and correlated with both delusions of influence and the size of patients' detection thresholds as assessed in the first experiment. These findings support the notion that delusions of influence are based on imprecise internal predictions about the sensory consequences of one's actions. Moreover, we suggest that such imprecise predictions prompt patients to rely more strongly on (and thus adapt to) external agency cues, in this case vision. Such context-dependent weighted integration of imprecise internal predictions and alternative agency cues might thus reflect the common basis for the various misattributions of agency in schizophrenia patients.
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Affiliation(s)
- Matthis Synofzik
- Department of Neurodegeneration, Hertie-Institute for Clinical Brain Research, Hoppe-Seyler-Strasse 3, 72076 Tübingen, Germany.
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