101
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Belief, delusion, hypnosis, and the right dorsolateral prefrontal cortex: A transcranial magnetic stimulation study. Cortex 2018; 101:234-248. [DOI: 10.1016/j.cortex.2018.01.001] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2017] [Revised: 10/23/2017] [Accepted: 01/03/2018] [Indexed: 11/18/2022]
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102
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Huber M, Wolf RC, Lepping P, Kirchler E, Karner M, Sambataro F, Herrnberger B, Corlett PR, Freudenmann RW. Regional gray matter volume and structural network strength in somatic vs. non-somatic delusional disorders. Prog Neuropsychopharmacol Biol Psychiatry 2018; 82:115-122. [PMID: 29180231 DOI: 10.1016/j.pnpbp.2017.11.022] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/13/2017] [Revised: 11/11/2017] [Accepted: 11/23/2017] [Indexed: 12/31/2022]
Abstract
BACKGROUND Monothematic delusional disorders are characterized by a single tenacious belief. They provide a great opportunity to study underlying brain structures in the absence of confounding symptoms that accompany delusions in schizophrenia. Delusional beliefs include persecution, jealousy or somatic delusions including infestation. It is unclear whether specific delusional content is associated with distinct neural substrates. METHODS We used magnetic resonance imaging in patients presenting with somatic vs. non-somatic delusional disorders. Patients with delusional infestation (DI, n=18), and individuals with non-somatic delusional disorders (n=19) were included, together with healthy volunteers (n=20). Uni- and multivariate techniques for structural data analysis were applied to provide a comprehensive characterization of abnormal brain volume at both the regional and neural network level. RESULTS Patients with DI showed lower gray matter volume in thalamic, striatal (putamen), insular and medial prefrontal brain regions in contrast to non-somatic delusional disorders and healthy controls. Importantly, these differences were consistently detected at regional and network level. Compared to healthy controls, patients with delusional disorders other than DI showed lower gray matter volume in temporal cortical regions. CONCLUSION The data support the notion that dysfunctional somatosensory and peripersonal networks could mediate somatic delusions in patients with DI in contrast to delusional disorders without somatic content. The data also suggest putative content-specific neural signatures in delusional disorders and in delusion formation per se.
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Affiliation(s)
- Markus Huber
- Department of Psychiatry, General Hospital Bruneck, South Tyrol, Italy
| | - Robert Christian Wolf
- Department of General Psychiatry, Center for Psychosocial Medicine, Heidelberg University, Germany.
| | - Peter Lepping
- Betsi Cadwaladr University Health Board, Maelor Hospital, Centre for Mental Health and Society, Wrexham, Wales, UK
| | - Erwin Kirchler
- Department of Psychiatry, General Hospital Bruneck, South Tyrol, Italy
| | - Martin Karner
- Department of Radiology, General Hospital Bruneck, South Tyrol, Italy
| | - Fabio Sambataro
- Department of Experimental & Clinical Medical Sciences, Udine University, Italy
| | | | - Philip R Corlett
- Department of Psychiatry, Yale University, Connecticut Mental Health Center, New Haven, CT, USA
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103
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Abstract
Ketamine, principally an antagonist of N-methyl-ᴅ-aspartate receptors, induces schizophrenia-like symptoms in adult humans, warranting its use in the investigation of psychosis-related phenotypes in animal models. Genomic studies further implicate N-methyl-ᴅ-aspartate receptor-mediated processes in schizophrenia pathology, together with more broadly-defined synaptic plasticity and associative learning processes. Strong pathophysiological links have been demonstrated between fear learning and psychiatric disorders such as schizophrenia. To further investigate the impact of ketamine on associative fear learning, we studied the effects of pre- and post-training ketamine on the consolidation and extinction of contextual fear memory in rats. Administration of 25 mg/kg ketamine prior to fear conditioning did not affect consolidation when potentially confounding effects of state dependency were controlled for. Pre-training ketamine (25 mg/kg) impaired the extinction of the conditioned fear response, which was mirrored with the use of a lower dose (8 mg/kg). Post-training ketamine (25 mg/kg) had no effect on the consolidation or extinction of conditioned fear. These observations implicate processes relating to the extinction of contextual fear memory in the manifestation of ketamine-induced phenotypes, and are consistent with existing hypotheses surrounding abnormal associative learning in schizophrenia.
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Affiliation(s)
- Nicholas E Clifton
- Neuroscience and Mental Health Research Institute, Cardiff University, Cardiff, UK
| | - Kerrie L Thomas
- Neuroscience and Mental Health Research Institute, Cardiff University, Cardiff, UK
- School of Biosciences, Cardiff University, Cardiff, UK
| | - Jeremy Hall
- Neuroscience and Mental Health Research Institute, Cardiff University, Cardiff, UK
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104
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Parlikar R, Dinakaran D, Bose A, Rao NP, Venkatasubramanian G. Neural Basis of Delusions in Schizophrenia: Translational Implications for Therapeutic Neuromodulation. J Indian Inst Sci 2017. [DOI: 10.1007/s41745-017-0058-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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105
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Abstract
INTRODUCTION Many theoretical treatments assume (often implicitly) that delusions ought to be taxonomised by the content of aberrant beliefs. A theoretically sound, and comparatively under-explored, alternative would split and combine delusions according to their underlying cognitive aetiology. METHODS We give a theoretical review of several cases, focusing on monothematic delusions of misidentification and on somatoparaphrenia. RESULTS We show that a purely content-based taxonomy is empirically problematic. It does not allow for projectability of discoveries across all members of delusions so delineated, and lumps together delusions that ought to be separated. We demonstrate that an aetiological approach is defensible, and further that insofar as content-based approaches are plausible, it is only to the extent that they implicitly link content to aetiology. CONCLUSIONS We recommend a more explicit focus on cognitive aetiology as the grounds for delusion taxonomy, even when that would undermine traditional content-based boundaries. We also highlight the iterative and complex nature of evidence about aetiologically grounded taxonomies.
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Affiliation(s)
- Peter Clutton
- a Department of Philosophy , Macquarie University , Sydney , NSW , Australia
| | - Stephen Gadsby
- b School of Philosophical, Historical and International Studies , Monash University , Melbourne , VIC , Australia
| | - Colin Klein
- a Department of Philosophy , Macquarie University , Sydney , NSW , Australia
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106
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Robbins TW. Cross-species studies of cognition relevant to drug discovery: a translational approach. Br J Pharmacol 2017; 174:3191-3199. [PMID: 28432778 PMCID: PMC5595762 DOI: 10.1111/bph.13826] [Citation(s) in RCA: 77] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2017] [Revised: 03/15/2017] [Accepted: 04/11/2017] [Indexed: 02/05/2023] Open
Abstract
This review advances the case that bidirectional, cross-species translation of findings from experimental animals to and from humans is an important strategy for drug discovery. Animal models of mental disorders require appropriate behavioural or cognitive outcome variables that can be generalized cross-species. One example is the treatment of impulsive behaviour in attention deficit hyperactivity disorder (ADHD) with stimulant drugs. Performance on the stop signal reaction task as an index of impulsivity is improved both in healthy human volunteers and in patients with adult ADHD by stimulant drugs and also by the selective noradrenaline reuptake blocker atomoxetine. Functional neuroimaging evidence suggests a modulation of circuitry including the inferior prefrontal cortex by this drug. Parallel work in rats had shown that atomoxetine improves stop signal performance by affecting possibly homologous regions of the rodent prefrontal cortex. This parallel effect of atomoxetine in rodents and humans could potentially be exploited in other disorders in which impulsivity plays a role, such as stimulant abuse and Parkinson's disease. A contrasting relative lack of involvement of 5-HT mechanisms in the stop signal reaction time task will also be described. Research in humans and experimental animals that demonstrate effects of serotoninergic agents such as the selective serotonin (5-HT) reuptake inhibitor citalopram on probabilistic learning and reversal (upon which atomoxetine has little effect) will also be reviewed, possibly relevant to the treatment of clinical depression, Finally, other promising examples of parallel studies of behavioural effects of CNS-active drugs in animals and humans will also be described. Linked Articles This article is part of a themed section on Pharmacology of Cognition: a Panacea for Neuropsychiatric Disease? To view the other articles in this section visit http://onlinelibrary.wiley.com/doi/10.1111/bph.v174.19/issuetoc.
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Affiliation(s)
- T W Robbins
- Department of Psychology and Behavioural and Clinical Neuroscience InstituteUniversity of CambridgeCambridgeUK
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107
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Abstract
The timing of thoughts and perceptions plays an essential role in belief formation. Just as people can experience in-the-moment perceptual illusions, however, they can also be deceived about how events unfold in time. Here, we consider how a particular type of temporal distortion, in which the apparent future influences "earlier" events in conscious awareness, might affect people's most fundamental beliefs about themselves and the world. Making use of a task that has been shown to elicit such reversals in the temporal experience of prediction and observation, we find that people who are more prone to think that they predicted an event that they actually already observed are also more likely to report holding delusion-like beliefs. Moreover, this relationship appears to be specific to how people experience prediction and is not explained by domain-general deficits in temporal discrimination. These findings may help uncover low-level perceptual mechanisms underlying delusional belief or schizotypy more broadly and may ultimately prove useful as a tool for identifying those at risk for psychotic illness.
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108
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Humpston CS, Evans LH, Teufel C, Ihssen N, Linden DE. Evidence of absence: no relationship between behaviourally measured prediction error response and schizotypy. Cogn Neuropsychiatry 2017; 22:373-390. [PMID: 28697644 PMCID: PMC5646181 DOI: 10.1080/13546805.2017.1348289] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
INTRODUCTION The predictive processing framework has attracted much interest in the field of schizophrenia research in recent years, with an increasing number of studies also carried out in healthy individuals with nonclinical psychosis-like experiences. The current research adopted a continuum approach to psychosis and aimed to investigate different types of prediction error responses in relation to psychometrically defined schizotypy. METHODS One hundred and two healthy volunteers underwent a battery of behavioural tasks including (a) a force-matching task, (b) a Kamin blocking task, and (c) a reversal learning task together with three questionnaires measuring domains of schizotypy from different approaches. RESULTS Neither frequentist nor Bayesian statistical methods supported the notion that alterations in prediction error responses were related to schizotypal traits in any of the three tasks. CONCLUSIONS These null results suggest that deficits in predictive processing associated with clinical states of psychosis are not always present in healthy individuals with schizotypal traits.
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Affiliation(s)
- Clara S. Humpston
- CUBRIC, School of Psychology, Cardiff University, Cardiff, UK, Clara S. Humpston
| | - Lisa H. Evans
- CUBRIC, School of Psychology, Cardiff University, Cardiff, UK
| | | | - Niklas Ihssen
- Department of Psychology, Durham University, Durham, UK
| | - David E. J. Linden
- CUBRIC, School of Psychology, Cardiff University, Cardiff, UK,School of Medicine, Cardiff University, Cardiff, UK
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109
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Comprehensive review: Computational modelling of schizophrenia. Neurosci Biobehav Rev 2017; 83:631-646. [PMID: 28867653 DOI: 10.1016/j.neubiorev.2017.08.022] [Citation(s) in RCA: 47] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2016] [Revised: 07/08/2017] [Accepted: 08/30/2017] [Indexed: 12/21/2022]
Abstract
Computational modelling has been used to address: (1) the variety of symptoms observed in schizophrenia using abstract models of behavior (e.g. Bayesian models - top-down descriptive models of psychopathology); (2) the causes of these symptoms using biologically realistic models involving abnormal neuromodulation and/or receptor imbalance (e.g. connectionist and neural networks - bottom-up realistic models of neural processes). These different levels of analysis have been used to answer different questions (i.e. understanding behavioral vs. neurobiological anomalies) about the nature of the disorder. As such, these computational studies have mostly supported diverging hypotheses of schizophrenia's pathophysiology, resulting in a literature that is not always expanding coherently. Some of these hypotheses are however ripe for revision using novel empirical evidence. Here we present a review that first synthesizes the literature of computational modelling for schizophrenia and psychotic symptoms into categories supporting the dopamine, glutamate, GABA, dysconnection and Bayesian inference hypotheses respectively. Secondly, we compare model predictions against the accumulated empirical evidence and finally we identify specific hypotheses that have been left relatively under-investigated.
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110
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Martin B, Franck N, Cermolacce M, Falco A, Benair A, Etienne E, Weibel S, Coull JT, Giersch A. Fragile temporal prediction in patients with schizophrenia is related to minimal self disorders. Sci Rep 2017; 7:8278. [PMID: 28811493 PMCID: PMC5557764 DOI: 10.1038/s41598-017-07987-y] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2017] [Accepted: 07/05/2017] [Indexed: 01/03/2023] Open
Abstract
Patients with schizophrenia have difficulty in making sensory predictions, in the time domain, which have been proposed to be related to self-disorders. However experimental evidence is lacking. We examined both voluntary and automatic forms of temporal prediction in 28 patients and 24 matched controls. A visual cue predicted (temporal cue) or not (neutral cue) the time (400 ms/1000 ms) at which a subsequent target was presented. In both patients and controls, RTs were faster for targets presented after long versus short intervals due to the temporal predictability inherent in the elapse of time ("hazard function"). This RT benefit was correlated with scores on the EASE scale, which measures disorders of the self: patients with a high 'self-awareness and presence' score did not show any significant benefit of the hazard function, whereas this ability was preserved in patients with a low score. Moreover, all patients were abnormally sensitive to the presence of "catch" trials (unexpected absence of a target) within a testing block, with RTs actually becoming slower at long versus short intervals. These results indicate fragility in patients' ability to continuously extract temporally predictive information from the elapsing interval. This deficit might contribute to perturbations of the minimal self in patients.
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Affiliation(s)
- Brice Martin
- Centre Ressource de Réhabilitation psychosociale et de remédiation cognitive, Centre Référent Lyonnais en Réhabilitation et en Remédiation cognitive (CL3R) Hôpital du Vinatier; CNRS UMR 5229, Lyon, France
| | - Nicolas Franck
- Centre Ressource de Réhabilitation psychosociale et de remédiation cognitive, Centre Référent Lyonnais en Réhabilitation et en Remédiation cognitive (CL3R) Hôpital du Vinatier; CNRS UMR 5229, Lyon, France
| | - Michel Cermolacce
- Service Universitaire de Psychiatrie, Centre Hospitalier Universitaire Ste Marguerite, 13009, Marseille, France
- Laboratoire des Neurosciences Cognitives (UMR 7291), Aix-Marseille Université & CNRS, 3 Place Victor Hugo, 13331, Marseille cedex 3, France
| | - Agnès Falco
- Centre Ressource de Réhabilitation psychosociale et de remédiation cognitive, Centre Référent Lyonnais en Réhabilitation et en Remédiation cognitive (CL3R) Hôpital du Vinatier; CNRS UMR 5229, Lyon, France
| | - Anabel Benair
- Centre Ressource de Réhabilitation psychosociale et de remédiation cognitive, Centre Référent Lyonnais en Réhabilitation et en Remédiation cognitive (CL3R) Hôpital du Vinatier; CNRS UMR 5229, Lyon, France
| | - Estelle Etienne
- Centre Ressource de Réhabilitation psychosociale et de remédiation cognitive, Centre Référent Lyonnais en Réhabilitation et en Remédiation cognitive (CL3R) Hôpital du Vinatier; CNRS UMR 5229, Lyon, France
| | - Sébastien Weibel
- INSERM U1114, Pôle de Psychiatrie, Fédération de Médecine Translationnelle de Strasbourg (FMTS), Centre Hospitalier Régional Universitaire of Strasbourg, Université de Strasbourg, Strasbourg, France
| | - Jennifer T Coull
- Laboratoire des Neurosciences Cognitives (UMR 7291), Aix-Marseille Université & CNRS, 3 Place Victor Hugo, 13331, Marseille cedex 3, France
| | - Anne Giersch
- INSERM U1114, Pôle de Psychiatrie, Fédération de Médecine Translationnelle de Strasbourg (FMTS), Centre Hospitalier Régional Universitaire of Strasbourg, Université de Strasbourg, Strasbourg, France.
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111
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Coffman BA, Haigh SM, Murphy TK, Salisbury DF. Impairment in Mismatch Negativity but not Repetition Suppression in Schizophrenia. Brain Topogr 2017; 30:521-530. [PMID: 28516227 DOI: 10.1007/s10548-017-0571-1] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2016] [Accepted: 05/11/2017] [Indexed: 10/19/2022]
Abstract
Schizophrenia is characterized by impaired auditory-evoked potentials (AEPs), mismatch negativity (MMN), and sensory gating of AEPs to repeated stimuli (repetition suppression, RS). In the predictive modeling framework, MMN and RS reflect encoding of prediction error and model sharpening, respectively. We compared P50, N100, P200 RS, and pitch and duration MMN in 26 participants diagnosed with schizophrenia (SZ) and 26 matched healthy controls (HC), and assessed relationships between MMN, RS, and SZ diagnosis. RS was measured by comparing responses to individual tones presented as 5-tone groups (1 kHz, 75 dB, 50 ms, 5 ms rise/fall times, 330 ms SOA), separated by a 750 ms inter-trial interval. For MMN, the same tones were presented, with occasional pitch (1.2 kHz, 10%) or duration deviants (100 ms, 10%) interspersed. Pitch and duration MMN were reduced in SZ (p < 0.01). There were no group differences in P50 RS, N100 RS, or P200 RS (p's > 0.1). Importantly, although pitch and duration MMN both correlated with RS of AEPs within the MMN time range (p's < 0.01), SZ diagnosis predicted MMN over and above RS (p < 0.05) and shared little variance with RS in prediction of MMN amplitude (tolerance > 0.93). We suggest that reduced MMN in SZ is related to deficits in encoding prediction error but not repetition suppression.
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Affiliation(s)
- Brian A Coffman
- Clinical Neurophysiology Research Laboratory, Western Psychiatric Institute & Clinic, University of Pittsburgh School of Medicine, 3501 Forbes Ave, Suite 420, Pittsburgh, PA, 15213, USA.
| | - Sarah M Haigh
- Clinical Neurophysiology Research Laboratory, Western Psychiatric Institute & Clinic, University of Pittsburgh School of Medicine, 3501 Forbes Ave, Suite 420, Pittsburgh, PA, 15213, USA
| | - Tim K Murphy
- Clinical Neurophysiology Research Laboratory, Western Psychiatric Institute & Clinic, University of Pittsburgh School of Medicine, 3501 Forbes Ave, Suite 420, Pittsburgh, PA, 15213, USA
| | - Dean F Salisbury
- Clinical Neurophysiology Research Laboratory, Western Psychiatric Institute & Clinic, University of Pittsburgh School of Medicine, 3501 Forbes Ave, Suite 420, Pittsburgh, PA, 15213, USA
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112
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Garofalo S, Justicia A, Arrondo G, Ermakova AO, Ramachandra P, Tudor-Sfetea C, Robbins TW, Barker RA, Fletcher PC, Murray GK. Cortical and Striatal Reward Processing in Parkinson's Disease Psychosis. Front Neurol 2017; 8:156. [PMID: 28484422 PMCID: PMC5402044 DOI: 10.3389/fneur.2017.00156] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2017] [Accepted: 04/03/2017] [Indexed: 01/29/2023] Open
Abstract
Psychotic symptoms frequently occur in Parkinson's disease (PD), but their pathophysiology is poorly understood. According to the National Institute of Health RDoc programme, the pathophysiological basis of neuropsychiatric symptoms may be better understood in terms of dysfunction of underlying domains of neurocognition in a trans-diagnostic fashion. Abnormal cortico-striatal reward processing has been proposed as a key domain contributing to the pathogenesis of psychotic symptoms in schizophrenia. This theory has received empirical support in the study of schizophrenia spectrum disorders and preclinical models of psychosis, but has not been tested in the psychosis associated with PD. We, therefore, investigated brain responses associated with reward expectation and prediction error signaling during reinforcement learning in PD-associated psychosis. An instrumental learning task with monetary gains and losses was conducted during an fMRI study in PD patients with (n = 12), or without (n = 17), a history of psychotic symptoms, along with a sample of healthy controls (n = 24). We conducted region of interest analyses in the ventral striatum (VS), ventromedial prefrontal and posterior cingulate cortices, and whole-brain analyses. There was reduced activation in PD patients with a history of psychosis, compared to those without, in the posterior cingulate cortex and the VS during reward anticipation (p < 0.05 small volume corrected). The results suggest that cortical and striatal abnormalities in reward processing, a putative pathophysiological mechanism of psychosis in schizophrenia, may also contribute to the pathogenesis of psychotic symptoms in PD. The finding of posterior cingulate dysfunction is in keeping with prior results highlighting cortical dysfunction in the pathogenesis of PD psychosis.
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Affiliation(s)
- Sara Garofalo
- Department of Psychiatry, University of Cambridge, Cambridge, UK
- Behavioural and Clinical Neuroscience Institute, University of Cambridge, Cambridge, UK
| | - Azucena Justicia
- Department of Psychiatry, University of Cambridge, Cambridge, UK
| | - Gonzalo Arrondo
- Department of Psychiatry, University of Cambridge, Cambridge, UK
| | - Anna O. Ermakova
- Department of Psychiatry, University of Cambridge, Cambridge, UK
| | | | | | - Trevor W. Robbins
- Behavioural and Clinical Neuroscience Institute, University of Cambridge, Cambridge, UK
- Department of Psychology, University of Cambridge, Cambridge, UK
| | - Roger A. Barker
- Department of Clinical Neuroscience, University of Cambridge, Cambridge, UK
| | - Paul C. Fletcher
- Department of Psychiatry, University of Cambridge, Cambridge, UK
- Cambridgeshire and Peterborough NHS Foundation Trust, Cambridge, UK
- Cambridge University Hospitals NHS Foundation Trust, Cambridge, UK
| | - Graham K. Murray
- Department of Psychiatry, University of Cambridge, Cambridge, UK
- Behavioural and Clinical Neuroscience Institute, University of Cambridge, Cambridge, UK
- Cambridgeshire and Peterborough NHS Foundation Trust, Cambridge, UK
- Cambridge University Hospitals NHS Foundation Trust, Cambridge, UK
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113
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Broyd A, Balzan RP, Woodward TS, Allen P. Dopamine, cognitive biases and assessment of certainty: A neurocognitive model of delusions. Clin Psychol Rev 2017; 54:96-106. [PMID: 28448827 DOI: 10.1016/j.cpr.2017.04.006] [Citation(s) in RCA: 50] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2016] [Revised: 01/24/2017] [Accepted: 04/15/2017] [Indexed: 12/17/2022]
Abstract
This paper examines the evidence that delusions can be explained within the framework of a neurocognitive model of how the brain assesses certainty. Here, 'certainty' refers to both low-level interpretations of one's environment and high-level (conscious) appraisals of one's beliefs and experiences. A model is proposed explaining how the brain systems responsible for assigning certainty might dysfunction, contributing to the cause and maintenance of delusional beliefs. It is suggested that delusions arise through a combination of perturbed striatal dopamine and aberrant salience as well as cognitive biases such as the tendency to jump to conclusions (JTC) and hypersalience of evidence-hypothesis matches. The role of emotion, stress, trauma and sociocultural factors in forming and modifying delusions is also considered. Understanding the mechanisms involved in forming and maintaining delusions has important clinical implications, as interventions that improve cognitive flexibility (e.g. cognitive remediation therapy and mindfulness training) could potentially attenuate neurocognitive processes.
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Affiliation(s)
- Annabel Broyd
- Department of Psychosis Studies, Institute of Psychiatry, Psychology and Neuroscience (IoPPN), King's College, London, UK
| | - Ryan P Balzan
- School of Psychology, Flinders University, Adelaide, SA, Australia
| | - Todd S Woodward
- Department of Psychiatry, University of British Columbia, Vancouver, BC, Canada; BC Mental Health and Addictions Research Institute, Provincial Health Services Authority, Vancouver, BC, Canada
| | - Paul Allen
- Department of Psychosis Studies, Institute of Psychiatry, Psychology and Neuroscience (IoPPN), King's College, London, UK; Department of Psychology, University of Roehampton, London, UK.
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114
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Yahata N, Kasai K, Kawato M. Computational neuroscience approach to biomarkers and treatments for mental disorders. Psychiatry Clin Neurosci 2017; 71:215-237. [PMID: 28032396 DOI: 10.1111/pcn.12502] [Citation(s) in RCA: 60] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/31/2016] [Revised: 12/19/2016] [Accepted: 12/25/2016] [Indexed: 01/21/2023]
Abstract
Psychiatry research has long experienced a stagnation stemming from a lack of understanding of the neurobiological underpinnings of phenomenologically defined mental disorders. Recently, the application of computational neuroscience to psychiatry research has shown great promise in establishing a link between phenomenological and pathophysiological aspects of mental disorders, thereby recasting current nosology in more biologically meaningful dimensions. In this review, we highlight recent investigations into computational neuroscience that have undertaken either theory- or data-driven approaches to quantitatively delineate the mechanisms of mental disorders. The theory-driven approach, including reinforcement learning models, plays an integrative role in this process by enabling correspondence between behavior and disorder-specific alterations at multiple levels of brain organization, ranging from molecules to cells to circuits. Previous studies have explicated a plethora of defining symptoms of mental disorders, including anhedonia, inattention, and poor executive function. The data-driven approach, on the other hand, is an emerging field in computational neuroscience seeking to identify disorder-specific features among high-dimensional big data. Remarkably, various machine-learning techniques have been applied to neuroimaging data, and the extracted disorder-specific features have been used for automatic case-control classification. For many disorders, the reported accuracies have reached 90% or more. However, we note that rigorous tests on independent cohorts are critically required to translate this research into clinical applications. Finally, we discuss the utility of the disorder-specific features found by the data-driven approach to psychiatric therapies, including neurofeedback. Such developments will allow simultaneous diagnosis and treatment of mental disorders using neuroimaging, thereby establishing 'theranostics' for the first time in clinical psychiatry.
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Affiliation(s)
- Noriaki Yahata
- Department of Youth Mental Health, Graduate School of Medicine, The University of Tokyo, Tokyo, Japan.,Department of Molecular Imaging and Theranostics, National Institute of Radiological Sciences, National Institutes for Quantum and Radiological Science and Technology, Chiba, Japan.,ATR Brain Information Communication Research Laboratory Group, Kyoto, Japan
| | - Kiyoto Kasai
- Department of Neuropsychiatry, Graduate School of Medicine, The University of Tokyo, Tokyo, Japan
| | - Mitsuo Kawato
- ATR Brain Information Communication Research Laboratory Group, Kyoto, Japan
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115
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Abstract
A comprehensive understanding of psychosis requires models that link multiple levels of explanation: the neurobiological, the cognitive, the subjective, and the social. Until we can bridge several explanatory gaps, it is difficult to explain how neurobiological perturbations can manifest in bizarre beliefs or hallucinations, or how trauma or social adversity can perturb lower-level brain processes. We propose that the predictive processing framework has much to offer in this respect. We show how this framework may underpin and complement source monitoring theories of delusions and hallucinations and how, when considered in terms of a dynamic and hierarchical system, it may provide a compelling model of several key clinical features of psychosis. We see little conflict between source monitoring theories and predictive coding. The former act as a higher-level description of a set of capacities, and the latter aims to provide a deeper account of how these and other capacities may emerge.
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Affiliation(s)
- Juliet D Griffin
- Department of Psychiatry, University of Cambridge, Cambridge CB2 0SZ, United Kingdom; ,
| | - Paul C Fletcher
- Department of Psychiatry, University of Cambridge, Cambridge CB2 0SZ, United Kingdom; ,
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116
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Joseph J, Depp C, Shih PAB, Cadenhead KS, Schmid-Schönbein G. Modified Mediterranean Diet for Enrichment of Short Chain Fatty Acids: Potential Adjunctive Therapeutic to Target Immune and Metabolic Dysfunction in Schizophrenia? Front Neurosci 2017; 11:155. [PMID: 28396623 PMCID: PMC5366345 DOI: 10.3389/fnins.2017.00155] [Citation(s) in RCA: 41] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2016] [Accepted: 03/10/2017] [Indexed: 12/14/2022] Open
Abstract
Growing interest in gut and digestive processes and their potential link to brain and peripheral based inflammation or biobehavioral phenotypes has led to an increasing number of basic and translational scientific reports focused on the role of gut microbiota within the context of neuropsychiatric disorders. However, the effect of dietary modification on specific gut metabolites, in association with immune, metabolic, and psychopathological functioning in schizophrenia spectrum disorders has not been well characterized. The short chain fatty acids (SCFA) acetate, butyrate, and propionate, major metabolites derived from fermentation of dietary fibers by gut microbes, interact with multiple immune and metabolic pathways. The specific pathways that SCFA are thought to target, are dysregulated in cardiovascular disease, type II diabetes, and systemic inflammation. Most notably, these disorders are consistently linked to an attenuated lifespan in schizophrenia. Although, unhealthy dietary intake patterns and increased prevalence of immune and metabolic dysfunction has been observed in people with schizophrenia; dietary interventions have not been well utilized to target immune or metabolic illness. Prior schizophrenia patient trials primarily focused on the effects of gluten free diets. Findings from these studies indicate that a diet avoiding gluten benefits a limited subset of patients, individuals with celiac disease or non-celiac gluten sensitivity. Therefore, alternative dietary and nutritional modifications such as high-fiber, Mediterranean style, diets that enrich the production of SCFA, while being associated with a minimal likelihood of adverse events, may improve immune and cardiovascular outcomes linked to premature mortality in schizophrenia. With a growing literature demonstrating that SCFA can cross the blood brain barrier and target key inflammatory and metabolic pathways, this article highlights enriching dietary intake for SCFA as a potential adjunctive therapy for people with schizophrenia.
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Affiliation(s)
- Jamie Joseph
- Department of Psychiatry, University of CaliforniaSan Diego, La Jolla, CA, USA
| | - Colin Depp
- Department of Psychiatry, University of CaliforniaSan Diego, La Jolla, CA, USA
- Department of Psychology, VA San Diego Healthcare SystemSan Diego, CA, USA
| | - Pei-an B. Shih
- Department of Psychiatry, University of CaliforniaSan Diego, La Jolla, CA, USA
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117
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Abstract
BACKGROUND The symptom "delusions" is a central psychopathological symptom in psychiatric diseases. Since the beginning of psychiatry various disciplines have attempted to explain and understand delusions but even now no generally accepted definition of this phenomenon exists. AIM A comprehensive review of current psychopathological and neurobiological theories of delusions is given. MATERIAL AND METHODS PubMed and Google scholar searches were performed using the keywords "delusion", "psychodynamic" and "neurobiology", both in English and German. Relevant German textbooks of psychiatry were also included. DISCUSSION A differentiated perspective of the phenomenon of delusions appears to be necessary to approach this complex and fascinating symptom. A one-dimensional approach does not do justice to the complexity of delusions. The various explanatory approaches can increasingly be linked to each other and are no longer considered to be mutually exclusive.
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Affiliation(s)
- R Knorr
- Klinik für Psychiatrie und Psychotherapie, Zentrum für Psychiatrie Reichenau, Feursteinstraße 55, 78479, Reichenau, Deutschland.
| | - K Hoffmann
- Klinik für Forensische Psychiatrie und Psychotherapie, Zentrum für Psychiatrie Reichenau, Feursteinstraße 55, 78479, Reichenau, Deutschland
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118
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MacDonald AW. Studying Delusions Within Research Domain Criteria: The Challenge of Configural Traits When Building a Mechanistic Foundation for Abnormal Beliefs. Schizophr Bull 2017; 43:260-262. [PMID: 28177083 PMCID: PMC5605261 DOI: 10.1093/schbul/sbw190] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/14/2022]
Abstract
Our understanding of belief formation, maintenance, and change is in its infancy, yet it is absolutely essential to make progress in understanding these processes to parse the puzzle of psychotic delusions. In this companion to Bebbington and Freeman, I consider a number of Research Domain Criteria constructs that may be helpful for exploring these processes but ultimately conclude (following Risen) that delusions are likely the result of several systems failing. I close with 4 recommendations for making progress: (1) prepare to study a variable space defined by several relevant constructs, (2) include the study of "unsanctioned" constructs, (3) examine the relationships between brain regions, rather than the local abnormalities, and (4) develop rigorous computational models of delusions.
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Affiliation(s)
- Angus W. MacDonald
- Departments of Psychology and Psychiatry, University of Minnesota, Minneapolis, MN
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119
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Nasser HM, Calu DJ, Schoenbaum G, Sharpe MJ. The Dopamine Prediction Error: Contributions to Associative Models of Reward Learning. Front Psychol 2017; 8:244. [PMID: 28275359 PMCID: PMC5319959 DOI: 10.3389/fpsyg.2017.00244] [Citation(s) in RCA: 52] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2016] [Accepted: 02/07/2017] [Indexed: 12/31/2022] Open
Abstract
Phasic activity of midbrain dopamine neurons is currently thought to encapsulate the prediction-error signal described in Sutton and Barto’s (1981) model-free reinforcement learning algorithm. This phasic signal is thought to contain information about the quantitative value of reward, which transfers to the reward-predictive cue after learning. This is argued to endow the reward-predictive cue with the value inherent in the reward, motivating behavior toward cues signaling the presence of reward. Yet theoretical and empirical research has implicated prediction-error signaling in learning that extends far beyond a transfer of quantitative value to a reward-predictive cue. Here, we review the research which demonstrates the complexity of how dopaminergic prediction errors facilitate learning. After briefly discussing the literature demonstrating that phasic dopaminergic signals can act in the manner described by Sutton and Barto (1981), we consider how these signals may also influence attentional processing across multiple attentional systems in distinct brain circuits. Then, we discuss how prediction errors encode and promote the development of context-specific associations between cues and rewards. Finally, we consider recent evidence that shows dopaminergic activity contains information about causal relationships between cues and rewards that reflect information garnered from rich associative models of the world that can be adapted in the absence of direct experience. In discussing this research we hope to support the expansion of how dopaminergic prediction errors are thought to contribute to the learning process beyond the traditional concept of transferring quantitative value.
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Affiliation(s)
- Helen M Nasser
- Department of Anatomy and Neurobiology, University of Maryland School of Medicine, Baltimore MD, USA
| | - Donna J Calu
- Department of Anatomy and Neurobiology, University of Maryland School of Medicine, Baltimore MD, USA
| | - Geoffrey Schoenbaum
- Department of Anatomy and Neurobiology, University of Maryland School of Medicine, BaltimoreMD, USA; Cellular Neurobiology Research Branch, National Institute on Drug Abuse Intramural Research Program, BaltimoreMD, USA; Solomon H. Snyder Department of Neuroscience, Johns Hopkins University, BaltimoreMD, USA
| | - Melissa J Sharpe
- Cellular Neurobiology Research Branch, National Institute on Drug Abuse Intramural Research Program, BaltimoreMD, USA; Princeton Neuroscience Institute, Princeton University, PrincetonNJ, USA
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120
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Schnider A, Nahum L, Ptak R. What does extinction have to do with confabulation? Cortex 2017; 87:5-15. [DOI: 10.1016/j.cortex.2016.10.015] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2016] [Revised: 07/31/2016] [Accepted: 10/21/2016] [Indexed: 10/20/2022]
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121
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McKay R, Furl N. Doppelgängers and dissociations: lesion network mapping illuminates misidentification delusions. Brain 2017; 140:262-265. [DOI: 10.1093/brain/aww323] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
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122
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Ekman CJ, Petrovic P, Johansson AGM, Sellgren C, Ingvar M, Landén M. A History of Psychosis in Bipolar Disorder is Associated With Gray Matter Volume Reduction. Schizophr Bull 2017; 43:99-107. [PMID: 27289116 PMCID: PMC5216851 DOI: 10.1093/schbul/sbw080] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Psychotic symptoms are prevalent in schizophrenia, bipolar disorder, and other psychiatric and neurological disorders, yet the neurobiological underpinnings of psychosis remain obscure. In the last decade, a large number of magnetic resonance imaging studies have shown differences in local gray matter volume between patients with different psychiatric syndromes and healthy controls. Few studies have focused on the symptoms, which these syndromes are constituted of. Here, we test the association between psychosis and gray matter volume by using a sample of 167 subjects with bipolar disorder, with and without a history of psychosis, and 102 healthy controls. Magnetic resonance images were analyzed on group level using a voxel-wise mass univariate analysis (Voxel-Based Morphometry). We found that patients with a history of psychosis had smaller gray matter volume in left fusiform gyrus, the right rostral dorsolateral prefrontal cortex, and the left inferior frontal gyrus compared with patients without psychosis and with healthy controls. There was no volume difference in these areas between the no-psychosis group and healthy controls. These areas have previously been structurally and functionally coupled to delusions and hallucinations. Our finding adds further evidence to the probability of these regions as key areas in the development of psychotic symptoms.
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Affiliation(s)
- Carl Johan Ekman
- Department of Clinical Neuroscience, Karolinska Institutet, Stockholm, Sweden;
| | - Predrag Petrovic
- Department of Clinical Neuroscience, Karolinska Institutet, Stockholm, Sweden
| | | | - Carl Sellgren
- Department of Medical Epidemiology and Biostatistics, Karolinska Institutet, Stockholm, Sweden
| | - Martin Ingvar
- Department of Clinical Neuroscience, Karolinska Institutet, Stockholm, Sweden
| | - Mikael Landén
- Department of Medical Epidemiology and Biostatistics, Karolinska Institutet, Stockholm, Sweden;,Institute of Neuroscience and Physiology, The Sahlgrenska Academy at Gothenburg University, Gothenburg, Sweden
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123
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Robbins TW. Neurobehavioural sequelae of social deprivation in rodents revisited: Modelling social adversity for developmental neuropsychiatric disorders. J Psychopharmacol 2016; 30:1082-1089. [PMID: 27678088 DOI: 10.1177/0269881116664450] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
The significance of investigating effects of deprivation of social experience in rodents is reviewed in the context of the review by Robbins et al. (1996) in the Journal of Psychopharmacology (10: 39-47). The early development of the paradigm by which rats were reared post-weaning in social isolation is described and compared with other early experience manipulations. The specification of the neural and behavioural phenotype of the isolate is brought up-to-date, focusing on changes in motivation and cognitive function, as well as on contrasting changes in the dopamine and serotonin systems, and in cortical (including hippocampal) structure and function. The relevance of the isolate for animal models of psychiatric disorders such as attention deficit hyperactivity disorder and schizophrenia is reviewed, and it is considered that the paradigm best exemplifies a manipulation that can be applied to test effects of certain forms of social adversity during adolescence on brain development and behaviour.
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Affiliation(s)
- T W Robbins
- Behavioural and Clinical Neuroscience Institute, University of Cambridge, Cambridge, UK
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124
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Abstract
In 2007, we proposed an explanation of delusion formation as aberrant prediction error-driven associative learning. Further, we argued that the NMDA receptor antagonist ketamine provided a good model for this process. Subsequently, we validated the model in patients with psychosis, relating aberrant prediction error signals to delusion severity. During the ensuing period, we have developed these ideas, drawing on the simple principle that brains build a model of the world and refine it by minimising prediction errors, as well as using it to guide perceptual inferences. While previously we focused on the prediction error signal per se, an updated view takes into account its precision, as well as the precision of prior expectations. With this expanded perspective, we see several possible routes to psychotic symptoms - which may explain the heterogeneity of psychotic illness, as well as the fact that other drugs, with different pharmacological actions, can produce psychotomimetic effects. In this article, we review the basic principles of this model and highlight specific ways in which prediction errors can be perturbed, in particular considering the reliability and uncertainty of predictions. The expanded model explains hallucinations as perturbations of the uncertainty mediated balance between expectation and prediction error. Here, expectations dominate and create perceptions by suppressing or ignoring actual inputs. Negative symptoms may arise due to poor reliability of predictions in service of action. By mapping from biology to belief and perception, the account proffers new explanations of psychosis. However, challenges remain. We attempt to address some of these concerns and suggest future directions, incorporating other symptoms into the model, building towards better understanding of psychosis.
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Affiliation(s)
| | | | - Paul C Fletcher
- Department of Psychiatry, University of Cambridge, Cambridge, UK .,Cambridgeshire and Peterborough NHS Foundation Trust, Cambridge, UK
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125
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Chang WC, Waltz JA, Gold JM, Chan TCW, Chen EYH. Mild Reinforcement Learning Deficits in Patients With First-Episode Psychosis. Schizophr Bull 2016; 42:1476-1485. [PMID: 27179125 PMCID: PMC5049533 DOI: 10.1093/schbul/sbw060] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/14/2022]
Abstract
Numerous studies have identified reinforcement learning (RL) deficits in schizophrenia. Most have focused on chronic patients with longstanding antipsychotic treatment, however, and studies of RL in early-illness patients have produced mixed results, particularly regarding gradual/procedural learning. No study has directly contrasted both rapid and gradual RL in first-episode psychosis (FEP) samples. We examined probabilistic RL in 34 FEP patients and 36 controls, using Go/NoGo (GNG) and Gain vs Loss-Avoidance (GLA) paradigms. Our results were mixed, with FEP patients exhibiting greater impairment in the ability to use positive, as opposed to negative, feedback to drive rapid RL on the GLA, but not the GNG. By contrast, patients and controls showed similar improvement across the acquisition. Finally, we found no significant between-group differences in the postacquisition expression of value-based preference in both tasks. Negative symptoms were modestly associated with RL measures, while the overall bias to engage in Go-responding correlated significantly with psychosis severity in FEP patients, consistent with striatal hyperdopaminergia. Taken together, FEP patients demonstrated more circumscribed RL impairments than previous studies have documented in chronic samples, possibly reflecting differential symptom profiles between first-episode and chronic samples. Our finding of relatively preserved gradual/procedural RL, in briefly medicated FEP patients, might suggest spared or restored basal ganglia function. Our findings of preserved abilities to use representations of expected value to guide decision making, and our mixed results regarding rapid RL, may reflect a lesser degree of prefrontal cortical functional impairment in FEP than in chronic samples. Further longitudinal research, in larger samples, is required.
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Affiliation(s)
- Wing Chung Chang
- Department of Psychiatry, The University of Hong Kong, Queen Mary Hospital, Pok Fu Lam, Hong Kong;,State Key Laboratory of Brain and Cognitive Sciences, The University of Hong Kong, Pok Fu Lam, Hong Kong;,These authors contributed equally to the article
| | - James A. Waltz
- Maryland Psychiatric Research Center, Department of Psychiatry, University of Maryland School of Medicine, Baltimore, MD,These authors contributed equally to the article
| | - James M. Gold
- Maryland Psychiatric Research Center, Department of Psychiatry, University of Maryland School of Medicine, Baltimore, MD
| | - Tracey Chi Wan Chan
- Department of Psychiatry, The University of Hong Kong, Queen Mary Hospital, Pok Fu Lam, Hong Kong
| | - Eric Yu Hai Chen
- Department of Psychiatry, The University of Hong Kong, Queen Mary Hospital, Pok Fu Lam, Hong Kong;,State Key Laboratory of Brain and Cognitive Sciences, The University of Hong Kong, Pok Fu Lam, Hong Kong
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126
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127
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Giraud K, Pontin M, Sharples LD, Fletcher P, Dalgleish T, Eden A, Jenkins DP, Vuylsteke A. Use of a Structured Mirrors Intervention Does Not Reduce Delirium Incidence But May Improve Factual Memory Encoding in Cardiac Surgical ICU Patients Aged Over 70 Years: A Pilot Time-Cluster Randomized Controlled Trial. Front Aging Neurosci 2016; 8:228. [PMID: 27733826 PMCID: PMC5039170 DOI: 10.3389/fnagi.2016.00228] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2015] [Accepted: 09/13/2016] [Indexed: 11/13/2022] Open
Abstract
Introduction: Post-operative delirium remains a significant problem, particularly in the older surgical patient. Previous evidence suggests that the provision of supplementary visual feedback about ones environment via the use of a mirror may positively impact on mental status and attention (core delirium diagnostic domains). We aimed to explore whether use of an evidence-based mirrors intervention could be effective in reducing delirium and improving post-operative outcomes such as factual memory encoding of the Intensive Care Unit (ICU) environment in older cardiac surgical patients. Methods: This was a pilot time-cluster randomized controlled trial at a 32-bed ICU, enrolling 223 patients aged 70 years and over, admitted to ICU after elective or urgent cardiac surgery from October 29, 2012 to June 23, 2013. The Mirrors Group received a structured mirrors intervention at set times (e.g., following change in mental status). The Usual Care Group received the standard care without mirrors. Primary outcome was ICU delirium incidence; secondary outcomes were ICU delirium days, ICU days with altered mental status or inattention, total length of ICU stay, physical mobilization (balance confidence) at ICU discharge, recall of factual and delusional ICU memories at 12 weeks, Health-Related Quality of Life at 12 weeks, and acceptability of the intervention. Results: The intervention was not associated with a significant reduction in ICU delirium incidence [Mirrors: 20/115 (17%); Usual Care: 17/108 (16%)] or duration [Mirrors: 1 (1-3); Usual Care: 2 (1-8)]. Use of the intervention on ICU was predictive of significantly higher recall of factual (but not delusional) items at 12 weeks after surgery (p = 0.003) and acceptability was high, with clinicians using mirrors at 86% of all recorded hourly observations. The intervention did not significantly impact on other secondary outcomes. Conclusion: Use of a structured mirrors intervention on the post-operative ICU does not reduce delirium, but may result in improved factual memory encoding in older cardiac surgical patients. This effect may occur via mechanisms unrelated to delirium, altered mental status, or inattention. The intervention may provide a new means of improving outcomes in patients at risk of post-ICU anxiety and/or Post-Traumatic Stress Disorder. Trial Registration: Clinicaltrials.gov identifier NCT01599689.
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Affiliation(s)
- Kimberly Giraud
- Cognitive Research Unit, Research & Development Department, Papworth Hospital NHS Foundation Trust Cambridge, UK
| | - Megan Pontin
- Critical Care Unit, Papworth Hospital NHS Foundation Trust Cambridge, UK
| | - Linda D Sharples
- Leeds Institute of Clinical Trials Research, Faculty of Medicine and Health, University of Leeds Leeds, UK
| | - Paul Fletcher
- Department of Psychiatry, School of Clinical Medicine, University of Cambridge Cambridge, UK
| | - Tim Dalgleish
- Cognition, Emotion, and Mental Health Programme, Medical Research Council Cognition and Brain Sciences Unit Cambridge, UK
| | - Allaina Eden
- Physiotherapy Department, Papworth Hospital NHS Foundation Trust Cambridge, UK
| | - David P Jenkins
- Cardiac Services, Papworth Hospital NHS Foundation Trust Cambridge, UK
| | - Alain Vuylsteke
- Department of Cardiothoracic Anaesthesia & Intensive Care, Papworth Hospital NHS Foundation Trust Cambridge, UK
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128
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Neural substrates underlying delusions in schizophrenia. Sci Rep 2016; 6:33857. [PMID: 27651212 PMCID: PMC5030611 DOI: 10.1038/srep33857] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2016] [Accepted: 09/05/2016] [Indexed: 11/30/2022] Open
Abstract
Delusions are cardinal positive symptoms in schizophrenia; however, the neural substrates of delusions remain unknown. In the present study, we investigated the neural correlates of delusions in schizophrenia using multi-modal magnetic resonance imaging (MRI) techniques. Diffusion, structural and perfusion MRIs were performed in 19 schizophrenia patients with severe delusions, 30 patients without delusions and 30 healthy controls. Fractional anisotropy (FA), gray matter volume (GMV) and cerebral blood flow (CBF) were voxel-wisely compared among the three groups. Although patients without delusions exhibited decreased FA in white matter regions and decreased GMV in gray matter regions relative to controls, patients with severe delusions demonstrated comparable FA in all of these white matter regions and similar GMV in most of these gray matter regions. Both patient subgroups had less GMV in the amygdala and anterior cingulate cortex than controls. Although two patient subgroups showed consistent CBF changes relative to controls, only CBF in the anterior cingulate cortex was lower in patients with severe delusions than in patients without delusions. These findings suggest that schizophrenia patients with severe delusions have relatively normal structural integrity. Importantly, the excessively reduced perfusion in the anterior cingulate cortex may be associated with the development of delusions in schizophrenia.
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129
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Culbreth AJ, Westbrook A, Xu Z, Barch DM, Waltz JA. Intact Ventral Striatal Prediction Error Signaling in Medicated Schizophrenia Patients. BIOLOGICAL PSYCHIATRY: COGNITIVE NEUROSCIENCE AND NEUROIMAGING 2016; 1:474-483. [PMID: 28239676 DOI: 10.1016/j.bpsc.2016.07.007] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
BACKGROUND Midbrain dopaminergic neurons code a computational quantity, reward prediction error (RPE), which has been causally related to learning. Recently, this insight has been leveraged to link phenomenological and biological levels of understanding in psychiatric disorders, such as schizophrenia. However, results have been mixed, possibly due to small sample sizes. Here we present results from two studies with relatively large Ns to assess VS RPE in schizophrenia. METHODS In the current study we analyzed data from two independent studies, involving a total of 87 chronic medicated schizophrenia patients and 61 controls. Subjects completed a probabilistic reinforcement-learning task in conjunction with fMRI scanning. We fit each participant's choice behavior to a Q-learning model and derived trial-wise RPEs. We then modeled BOLD signal data with parametric regressor functions using these values to determine whether patient and control groups differed in prediction-error-related BOLD signal modulations. RESULTS Both groups demonstrated robust VS RPE BOLD activations. Interestingly, these BOLD activation patterns did not differ between groups in either study. This was true when we included all participants in the analysis, as well as when we excluded participants whose data was not sufficiently fit by the models. CONCLUSIONS These data demonstrate the utility of computational methods in isolating/testing underlying mechanisms of interest in psychiatric disorders. Importantly, similar VS RPE signal encoding across groups suggests that this mechanism does not drive task deficits in these patients. Deficits may instead stem from aberrant prefrontal/parietal circuits associated with maintenance and selection of goal-relevant information.
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Affiliation(s)
- Adam J Culbreth
- Department of Psychological and Brain Sciences, Washington University in Saint Louis
| | - Andrew Westbrook
- Department of Psychological and Brain Sciences, Washington University in Saint Louis
| | - Ziye Xu
- University of Maryland School of Medicine, Department of Psychiatry and Maryland Psychiatric Research Center
| | - Deanna M Barch
- Department of Psychological and Brain Sciences, Washington University in Saint Louis; Department of Psychiatry & Radiology, Washington University in Saint Louis
| | - James A Waltz
- University of Maryland School of Medicine, Department of Psychiatry and Maryland Psychiatric Research Center
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130
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Bortolotti L. Epistemic Benefits of Elaborated and Systematized Delusions in Schizophrenia. THE BRITISH JOURNAL FOR THE PHILOSOPHY OF SCIENCE 2016; 67:879-900. [PMID: 27924116 PMCID: PMC4990704 DOI: 10.1093/bjps/axv024] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
In this article I ask whether elaborated and systematized delusions emerging in the context of schizophrenia have the potential for epistemic innocence. Cognitions are epistemically innocent if they have significant epistemic benefits that could not be attained otherwise. In particular, I propose that a cognition is epistemically innocent if it delivers some significant epistemic benefit to a given agent at a given time, and if alternative cognitions delivering the same epistemic benefit are unavailable to that agent at that time. Elaborated and systematized delusions in schizophrenia are typically false and exemplify failures of rationality and self-knowledge. Empirical studies suggest that they may have psychological benefits by relieving anxiety and enhancing meaningfulness. Moreover, these delusions have been considered as adaptive in virtue of the fact that they enable automated learning to resume after a significant disruption caused by incorrect prediction-error signalling. I argue that such psychological benefits and adaptive features also have positive epistemic consequences. More precisely, delusions can be a means to restoring epistemic functionality in agents who are overwhelmed by hypersalient experiences in the prodromal stage of psychosis. The analysis leads to a more complex view of the epistemic status of delusions than is found in the contemporary philosophical literature and has some implications for clinical practice. 1 Introduction2 Types of Delusions3 What Is Wrong with Elaborated and Systematized Delusions?4 Finding Life Meaningful5 Learning Resumed6 Epistemic Innocence7 Epistemic Benefit8 No Alternatives9 Conclusions and Implications.
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131
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Corlett P. Social neuroscience: Brain, mind, and society. AMERICAN JOURNAL OF PSYCHIATRIC REHABILITATION 2016. [DOI: 10.1080/15487768.2016.1203688] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
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132
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Kraus M, Rapisarda A, Lam M, Thong JYJ, Lee J, Subramaniam M, Collinson SL, Chong SA, Keefe RSE. Disrupted latent inhibition in individuals at ultra high-risk for developing psychosis. SCHIZOPHRENIA RESEARCH-COGNITION 2016; 6:1-8. [PMID: 28740818 PMCID: PMC5514297 DOI: 10.1016/j.scog.2016.07.003] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/24/2016] [Revised: 07/22/2016] [Accepted: 07/23/2016] [Indexed: 11/29/2022]
Abstract
The addition of off-the-shelf cognitive measures to established prodromal criteria has resulted in limited improvement in the prediction of conversion to psychosis. Tests that assess cognitive processes central to schizophrenia might better identify those at highest risk. The latent inhibition paradigm assesses a subject's tendency to ignore irrelevant stimuli, a process integral to healthy perceptual and cognitive function that has been hypothesized to be a key deficit underlying the development of schizophrenia. In this study, 142 young people at ultra high-risk for developing psychosis and 105 controls were tested on a within-subject latent inhibition paradigm. Additionally, we later inquired about the strategy that each subject employed to complete the test, and further investigated the relationship between reported strategy and the extent of latent inhibition exhibited. Unlike controls, ultra high-risk subjects did not demonstrate a significant latent inhibition effect. This difference between groups became greater when controlling for strategy. The lack of latent inhibition effect in our ultra high-risk sample suggests that individuals at ultra high-risk for psychosis are impaired in their allocation of attentional resources based on past predictive value of repeated stimuli. This fundamental deficit in the allocation of attention may contribute to the broader array of cognitive impairments and clinical symptoms displayed by individuals at ultra high-risk for psychosis.
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Affiliation(s)
- Michael Kraus
- Department of Psychiatry & Behavioral Sciences, Duke University Medical Center, 200 Trent Drive, Durham, NC, 27710
| | - Attilio Rapisarda
- Research Division, Institute of Mental Health, Buangkok Green Medical Park, 10 Buangkok View, Singapore, 539747.,Neuroscience & Behavioral Disorders, Duke-National University of Singapore, Graduate Medical School, 8 College Road, Singapore, 169857
| | - Max Lam
- Research Division, Institute of Mental Health, Buangkok Green Medical Park, 10 Buangkok View, Singapore, 539747
| | - Jamie Y J Thong
- Department of Bioengineering, National University of Singapore, Block E4, #04-08, 4 Engineering Drive 3, Singapore, 117583
| | - Jimmy Lee
- Research Division, Institute of Mental Health, Buangkok Green Medical Park, 10 Buangkok View, Singapore, 539747.,Department of General Psychiatry 1, Institute of Mental Health, Buangkok Green Medical Park, 10 Buangkok View, Singapore, 539747.,Office of Clinical Sciences, Duke-National University of Singapore, Graduate Medical School, National University of Singapore, 8 College Road, Singapore, 169857
| | - Mythily Subramaniam
- Research Division, Institute of Mental Health, Buangkok Green Medical Park, 10 Buangkok View, Singapore, 539747
| | - Simon L Collinson
- Neuroscience & Behavioral Disorders, Duke-National University of Singapore, Graduate Medical School, 8 College Road, Singapore, 169857
| | - Siow Ann Chong
- Research Division, Institute of Mental Health, Buangkok Green Medical Park, 10 Buangkok View, Singapore, 539747
| | - Richard S E Keefe
- Department of Psychiatry & Behavioral Sciences, Duke University Medical Center, 200 Trent Drive, Durham, NC, 27710.,Neuroscience & Behavioral Disorders, Duke-National University of Singapore, Graduate Medical School, 8 College Road, Singapore, 169857
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133
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Kremláček J, Kreegipuu K, Tales A, Astikainen P, Põldver N, Näätänen R, Stefanics G. Visual mismatch negativity (vMMN): A review and meta-analysis of studies in psychiatric and neurological disorders. Cortex 2016; 80:76-112. [DOI: 10.1016/j.cortex.2016.03.017] [Citation(s) in RCA: 85] [Impact Index Per Article: 10.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2015] [Revised: 01/31/2016] [Accepted: 03/17/2016] [Indexed: 12/18/2022]
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134
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Vinckier F, Gaillard R, Palminteri S, Rigoux L, Salvador A, Fornito A, Adapa R, Krebs MO, Pessiglione M, Fletcher PC. Confidence and psychosis: a neuro-computational account of contingency learning disruption by NMDA blockade. Mol Psychiatry 2016; 21:946-55. [PMID: 26055423 PMCID: PMC5414075 DOI: 10.1038/mp.2015.73] [Citation(s) in RCA: 41] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/21/2014] [Revised: 03/28/2015] [Accepted: 04/13/2015] [Indexed: 02/02/2023]
Abstract
A state of pathological uncertainty about environmental regularities might represent a key step in the pathway to psychotic illness. Early psychosis can be investigated in healthy volunteers under ketamine, an NMDA receptor antagonist. Here, we explored the effects of ketamine on contingency learning using a placebo-controlled, double-blind, crossover design. During functional magnetic resonance imaging, participants performed an instrumental learning task, in which cue-outcome contingencies were probabilistic and reversed between blocks. Bayesian model comparison indicated that in such an unstable environment, reinforcement learning parameters are downregulated depending on confidence level, an adaptive mechanism that was specifically disrupted by ketamine administration. Drug effects were underpinned by altered neural activity in a fronto-parietal network, which reflected the confidence-based shift to exploitation of learned contingencies. Our findings suggest that an early characteristic of psychosis lies in a persistent doubt that undermines the stabilization of behavioral policy resulting in a failure to exploit regularities in the environment.
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Affiliation(s)
- F Vinckier
- Service de Psychiatrie, Centre Hospitalier Sainte-Anne, Université Paris Descartes, Sorbonne Paris Cité, Faculté de Médecine Paris Descartes, Paris, France
- Motivation, Brain, and Behavior Lab, Centre de Neuro-Imagerie de Recherche, Institut du Cerveau et de la Moelle épinière, Groupe Hospitalier Pitié-Salpêtrière, Paris, France
- INSERM U975, CNRS UMR 7225, UPMC-P6, UMR S 1127, Paris Cedex 13, France
| | - R Gaillard
- Service de Psychiatrie, Centre Hospitalier Sainte-Anne, Université Paris Descartes, Sorbonne Paris Cité, Faculté de Médecine Paris Descartes, Paris, France
- Department of Psychiatry and Behavioural and Clinical Neuroscience Institute, University of Cambridge, Cambridge, UK
- Laboratoire de "Physiopathologie des maladies Psychiatriques", Centre de Psychiatrie et Neurosciences U894, INSERM; Université Paris Descartes, Sorbonne Paris Cité, Paris, France
| | - S Palminteri
- Laboratoire de Neurosciences Cognitives (LNC), INSERM U960, Ecole Normale Supérieure (ENS), Paris, France
- Institute of Cognitive Neurosciences (ICN), University College London (UCL), London, UK
| | - L Rigoux
- Motivation, Brain, and Behavior Lab, Centre de Neuro-Imagerie de Recherche, Institut du Cerveau et de la Moelle épinière, Groupe Hospitalier Pitié-Salpêtrière, Paris, France
- INSERM U975, CNRS UMR 7225, UPMC-P6, UMR S 1127, Paris Cedex 13, France
| | - A Salvador
- Service de Psychiatrie, Centre Hospitalier Sainte-Anne, Université Paris Descartes, Sorbonne Paris Cité, Faculté de Médecine Paris Descartes, Paris, France
- Laboratoire de "Physiopathologie des maladies Psychiatriques", Centre de Psychiatrie et Neurosciences U894, INSERM; Université Paris Descartes, Sorbonne Paris Cité, Paris, France
| | - A Fornito
- Monash Clinical and Imaging Neuroscience, School of Psychological Sciences and Monash Biomedical Imaging, Monash University, Victoria, Australia
| | - R Adapa
- Division of Anaesthesia, University of Cambridge, Cambridge, UK
- Addenbrooke‘s Hospital, Cambridge, UK
| | - M O Krebs
- Service de Psychiatrie, Centre Hospitalier Sainte-Anne, Université Paris Descartes, Sorbonne Paris Cité, Faculté de Médecine Paris Descartes, Paris, France
- Laboratoire de "Physiopathologie des maladies Psychiatriques", Centre de Psychiatrie et Neurosciences U894, INSERM; Université Paris Descartes, Sorbonne Paris Cité, Paris, France
| | - M Pessiglione
- Motivation, Brain, and Behavior Lab, Centre de Neuro-Imagerie de Recherche, Institut du Cerveau et de la Moelle épinière, Groupe Hospitalier Pitié-Salpêtrière, Paris, France
- INSERM U975, CNRS UMR 7225, UPMC-P6, UMR S 1127, Paris Cedex 13, France
| | - P C Fletcher
- Department of Psychiatry and Behavioural and Clinical Neuroscience Institute, University of Cambridge, Cambridge, UK
- Cambridge and Peterborough Foundation Trust, Cambridge, UK
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135
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Abboud R, Roiser JP, Khalifeh H, Ali S, Harrison I, Killaspy HT, Joyce EM. Are persistent delusions in schizophrenia associated with aberrant salience? SCHIZOPHRENIA RESEARCH-COGNITION 2016; 4:32-38. [PMID: 27284531 PMCID: PMC4884769 DOI: 10.1016/j.scog.2016.04.002] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/03/2016] [Revised: 04/22/2016] [Accepted: 04/25/2016] [Indexed: 10/25/2022]
Abstract
OBJECTIVE It has been suggested that positive psychotic symptoms reflect 'aberrant salience'. Previously we provided support for this hypothesis in first-episode schizophrenia patients, demonstrating that delusional symptoms were associated with aberrant reward processing, indexed by the Salience Attribution Test (SAT). Here we tested whether salience processing is abnormal in schizophrenia patients with long-standing treatment-refractory persistent delusions (TRS). METHOD Eighteen medicated TRS patients and 31 healthy volunteers completed the SAT, on which participants made a speeded response to earn money in the presence of cues. Each cue comprised two visual dimensions, colour and form. Reinforcement probability varied over one of these dimensions (task-relevant), but not the other (task-irrelevant). RESULTS Participants responded significantly faster on high-probability relative to low-probability trials, representing implicit adaptive salience; this effect was intact in TRS patients. By contrast, TRS patients were impaired on the explicit adaptive salience measure, rating high-probability stimuli less likely to be associated with reward than controls. There was little evidence for elevated aberrant salience in the TRS group. CONCLUSION These findings do not support the hypothesis that persistent delusions are related to aberrant motivational salience processing in TRS patients. However, they do support the view that patients with schizophrenia have impaired reward learning.
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Affiliation(s)
- Rafeef Abboud
- Institute of Cognitive Neuroscience, University College London, 17 Queen Square, London, WC1N 3AZ, UK
| | - Jonathan P Roiser
- Institute of Cognitive Neuroscience, University College London, 17 Queen Square, London, WC1N 3AZ, UK
| | - Hind Khalifeh
- Camden and Islington NHS Foundation Trust, St Pancras Hospital, 4 St. Pancras Way, London, NW1 0PE, UK; Division of Psychiatry, University College London, 6th Floor, Maple House, 149 Tottenham Court Road, London, W1T 7NF, UK; Institute of Psychiatry, Psychology and Neuroscience, Kings College London, De Crespigny Park, London, SE5 8AF
| | - Sheila Ali
- Institute of Cognitive Neuroscience, University College London, 17 Queen Square, London, WC1N 3AZ, UK
| | - Isobel Harrison
- Camden and Islington NHS Foundation Trust, St Pancras Hospital, 4 St. Pancras Way, London, NW1 0PE, UK; Division of Psychiatry, University College London, 6th Floor, Maple House, 149 Tottenham Court Road, London, W1T 7NF, UK
| | - Helen T Killaspy
- Camden and Islington NHS Foundation Trust, St Pancras Hospital, 4 St. Pancras Way, London, NW1 0PE, UK; Division of Psychiatry, University College London, 6th Floor, Maple House, 149 Tottenham Court Road, London, W1T 7NF, UK
| | - Eileen M Joyce
- Institute of Neurology, University College London, Queen Square, London, WC1N 3BG, UK
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136
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Kaplan CM, Saha D, Molina JL, Hockeimer WD, Postell EM, Apud JA, Weinberger DR, Tan HY. Estimating changing contexts in schizophrenia. Brain 2016; 139:2082-95. [PMID: 27217338 DOI: 10.1093/brain/aww095] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2015] [Accepted: 03/14/2016] [Indexed: 01/21/2023] Open
Abstract
SEE STEPHAN ET AL DOI101093/AWW120 FOR A SCIENTIFIC COMMENTARY ON THIS WORK: Real world information is often abstract, dynamic and imprecise. Deciding if changes represent random fluctuations, or alterations in underlying contexts involve challenging probability estimations. Dysfunction may contribute to erroneous beliefs, such as delusions. Here we examined brain function during inferences about context change from noisy information. We examined cortical-subcortical circuitry engaging anterior and dorsolateral prefrontal cortex, and midbrain. We hypothesized that schizophrenia-related deficits in prefrontal function might overestimate context change probabilities, and that this more chaotic worldview may subsequently gain familiarity and be over-reinforced, with implications for delusions. We then examined these opposing information processing biases against less expected versus familiar information patterns in relation to genetic risk for schizophrenia in unaffected siblings. In one experiment, 17 patients with schizophrenia and 24 normal control subjects were presented in 3 T magnetic resonance imaging with numerical information varying noisily about a context integer, which occasionally shifted up or down. Subjects were to indicate when the inferred numerical context had changed. We fitted Bayesian models to estimate probabilities associated with change inferences. Dynamic causal models examined cortical-subcortical circuitry interactions at context change inference, and at subsequent reduced uncertainty. In a second experiment, genetic risk for schizophrenia associated with similar cortical-subcortical findings were explored in an independent sample of 36 normal control subjects and 35 unaffected siblings during processing of intuitive number sequences along the number line, or during the inverse, less familiar, sequence. In the first experiment, reduced Bayesian models fitting subject behaviour suggest that patients with schizophrenia overestimated context change probabilities. Here, patients engaged anterior prefrontal cortex relatively less than healthy controls, in part driven by reduced effective connectivity from dorsolateral prefrontal cortex to anterior prefrontal cortex. In processing subsequent information indicating reduced uncertainty of their predictions, patients engaged relatively increased mid-brain activation, driven in part by increased dorsolateral prefrontal cortex to midbrain connectivity. These dissociable reduced and exaggerated prefrontal and subcortical circuit functions were accentuated in patients with delusions. In the second experiment, analogous dissociable reduced anterior prefrontal cortex and exaggerated midbrain engagement occurred in unaffected siblings when processing less expected versus more familiar number sequences. In conclusion, patients overestimated ambiguous context change probabilities with relatively reduced anterior frontal engagement. Subsequent reduced uncertainty about contextual state appeared over-reinforced, potentially contributing to confirmation bias and a cascade of aberrant belief processing about a more chaotic world relevant to delusions. These opposing cortical-subcortical effects relate in part to genetic risk for schizophrenia, with analogous imbalances in neural processing of less expected versus familiar information patterns.
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Affiliation(s)
- Claire M Kaplan
- 1 Lieber Institute for Brain Development, Baltimore, Maryland, USA 2 Clinical Brain Disorders Branch, National Institute of Mental Health, Bethesda, Maryland, USA
| | - Debjani Saha
- 1 Lieber Institute for Brain Development, Baltimore, Maryland, USA
| | - Juan L Molina
- 2 Clinical Brain Disorders Branch, National Institute of Mental Health, Bethesda, Maryland, USA
| | | | | | - Jose A Apud
- 2 Clinical Brain Disorders Branch, National Institute of Mental Health, Bethesda, Maryland, USA
| | - Daniel R Weinberger
- 1 Lieber Institute for Brain Development, Baltimore, Maryland, USA 2 Clinical Brain Disorders Branch, National Institute of Mental Health, Bethesda, Maryland, USA 3 Psychiatry and Behavioral Sciences, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA 4 Neurology, Neuroscience, Institute of Genetic Medicine, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA
| | - Hao Yang Tan
- 1 Lieber Institute for Brain Development, Baltimore, Maryland, USA 2 Clinical Brain Disorders Branch, National Institute of Mental Health, Bethesda, Maryland, USA 3 Psychiatry and Behavioral Sciences, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA
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137
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Koychev I, Joyce D, Barkus E, Ettinger U, Schmechtig A, Dourish CT, Dawson GR, Craig KJ, Deakin JFW. Cognitive and oculomotor performance in subjects with low and high schizotypy: implications for translational drug development studies. Transl Psychiatry 2016; 6:C. [PMID: 27187233 PMCID: PMC5070057 DOI: 10.1038/tp.2016.64] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/02/2015] [Revised: 02/17/2016] [Accepted: 02/19/2016] [Indexed: 12/14/2022] Open
Abstract
The development of drugs to improve cognition in patients with schizophrenia is a major unmet clinical need. A number of promising compounds failed in recent clinical trials, a pattern linked to poor translation between preclinical and clinical stages of drug development. Seeking proof of efficacy in early Phase 1 studies in surrogate patient populations (for example, high schizotypy individuals where subtle cognitive impairment is present) has been suggested as a strategy to reduce attrition in the later stages of drug development. However, there is little agreement regarding the pattern of distribution of schizotypal features in the general population, creating uncertainty regarding the optimal control group that should be included in prospective trials. We aimed to address this question by comparing the performance of groups derived from the general population with low, average and high schizotypy scores over a range of cognitive and oculomotor tasks. We found that tasks dependent on frontal inhibitory mechanisms (N-Back working memory and anti-saccade oculomotor tasks), as well as a smooth-pursuit oculomotor task were sensitive to differences in the schizotypy phenotype. In these tasks the cognitive performance of 'low schizotypes' was significantly different from 'high schizotypes' with 'average schizotypes' having an intermediate performance. These results indicate that for evaluating putative cognition enhancers for treating schizophrenia in early-drug development studies the maximum schizotypy effect would be achieved using a design that compares low and high schizotypes.
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Affiliation(s)
- I Koychev
- Department of Community-Based Psychiatry, Neuroscience and Psychiatry Unit, The University of Manchester, School of Community-Based Medicine, Manchester, UK
- Department of Psychiatry, University of Oxford, Warneford Hospital, Oxford, UK
| | - D Joyce
- Cognition, Schizophrenia and Imaging Lab, Department of Psychosis Studies, Institute of Psychiatry, Psychology and Neuroscience, Denmark Hill, London
| | - E Barkus
- Department of Psychology, University of Wollongong, Wollongong, New South Wales, Australia
- Department of Psychiatry, School of Community-Based Medicine, The University of Manchester, Manchester, UK
| | - U Ettinger
- Department of Psychology, University of Bonn, Bonn, Germany
| | - A Schmechtig
- Department of Neuroimaging, Institute of Psychiatry, King's College London, London, UK
| | - C T Dourish
- P1vital, Manor House, Howbery Park, Wallingford, UK
| | - G R Dawson
- P1vital, Manor House, Howbery Park, Wallingford, UK
| | - K J Craig
- P1vital, Manor House, Howbery Park, Wallingford, UK
| | - J F W Deakin
- Department of Community-Based Psychiatry, Neuroscience and Psychiatry Unit, The University of Manchester, School of Community-Based Medicine, Manchester, UK
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138
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Abstract
We reconsider delusions in terms of a "doxastic shear pin", a mechanism that errs so as to prevent the destruction of the machine (brain) and permit continued function (in an attenuated capacity). Delusions may disable flexible (but energetically expensive) inference. With each recall, delusions may be reinforced further and rendered resistant to contradiction. We aim to respond to deficit accounts of delusions - that delusions are only a problem without any benefit - by considering delusion formation and maintenance in terms of predictive coding. We posit that brains conform to a simple computational principle: to minimize prediction error (the mismatch between prior top-down expectation and current bottom-up input) across hierarchies of brain regions and psychological representation. Recent data suggest that delusions may form in the absence of constraining top-down expectations. Then, once formed, they become new priors that motivate other beliefs, perceptions, and actions by providing strong (sometimes overriding) top-down expectation. We argue that delusions form when the shear-pin breaks, permitting continued engagement with an overwhelming world, and ongoing function in the face of paralyzing difficulty. This crucial role should not be ignored when we treat delusions: we need to consider how a person will function in the world without them..
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Affiliation(s)
- S.K. Fineberg
- Yale University, Department of Psychiatry, Ribicoff Research Facility. 34 Park Street, New Haven, CT, USA 06519
| | - P.R. Corlett
- Yale University, Department of Psychiatry, Ribicoff Research Facility. 34 Park Street, New Haven, CT, USA 06519
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139
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Treviño M. Associative Learning Through Acquired Salience. Front Behav Neurosci 2016; 9:353. [PMID: 26793078 PMCID: PMC4708076 DOI: 10.3389/fnbeh.2015.00353] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2015] [Accepted: 12/04/2015] [Indexed: 11/29/2022] Open
Abstract
Most associative learning studies describe the salience of stimuli as a fixed learning-rate parameter. Presumptive saliency signals, however, have also been linked to motivational and attentional processes. An interesting possibility, therefore, is that discriminative stimuli could also acquire salience as they become powerful predictors of outcomes. To explore this idea, we first characterized and extracted the learning curves from mice trained with discriminative images offering varying degrees of structural similarity. Next, we fitted a linear model of associative learning coupled to a series of mathematical representations for stimulus salience. We found that the best prediction, from the set of tested models, was one in which the visual salience depended on stimulus similarity and a non-linear function of the associative strength. Therefore, these analytic results support the idea that the net salience of a stimulus depends both on the items' effective salience and the motivational state of the subject that learns about it. Moreover, this dual salience model can explain why learning about a stimulus not only depends on the effective salience during acquisition but also on the specific learning trajectory that was used to reach this state. Our mathematical description could be instrumental for understanding aberrant salience acquisition under stressful situations and in neuropsychiatric disorders like schizophrenia, obsessive-compulsive disorder, and addiction.
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Affiliation(s)
- Mario Treviño
- Laboratorio de Plasticidad Cortical y Aprendizaje Perceptual, Instituto de Neurociencias, Universidad de Guadalajara Guadalajara, Mexico
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140
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Adams RA, Huys QJM, Roiser JP. Computational Psychiatry: towards a mathematically informed understanding of mental illness. J Neurol Neurosurg Psychiatry 2016; 87:53-63. [PMID: 26157034 PMCID: PMC4717449 DOI: 10.1136/jnnp-2015-310737] [Citation(s) in RCA: 84] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/02/2015] [Accepted: 06/19/2015] [Indexed: 01/11/2023]
Abstract
Computational Psychiatry aims to describe the relationship between the brain's neurobiology, its environment and mental symptoms in computational terms. In so doing, it may improve psychiatric classification and the diagnosis and treatment of mental illness. It can unite many levels of description in a mechanistic and rigorous fashion, while avoiding biological reductionism and artificial categorisation. We describe how computational models of cognition can infer the current state of the environment and weigh up future actions, and how these models provide new perspectives on two example disorders, depression and schizophrenia. Reinforcement learning describes how the brain can choose and value courses of actions according to their long-term future value. Some depressive symptoms may result from aberrant valuations, which could arise from prior beliefs about the loss of agency ('helplessness'), or from an inability to inhibit the mental exploration of aversive events. Predictive coding explains how the brain might perform Bayesian inference about the state of its environment by combining sensory data with prior beliefs, each weighted according to their certainty (or precision). Several cortical abnormalities in schizophrenia might reduce precision at higher levels of the inferential hierarchy, biasing inference towards sensory data and away from prior beliefs. We discuss whether striatal hyperdopaminergia might have an adaptive function in this context, and also how reinforcement learning and incentive salience models may shed light on the disorder. Finally, we review some of Computational Psychiatry's applications to neurological disorders, such as Parkinson's disease, and some pitfalls to avoid when applying its methods.
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Affiliation(s)
- Rick A Adams
- Institute of Cognitive Neuroscience, University College London, London, UK Division of Psychiatry, University College London, London, UK
| | - Quentin J M Huys
- Translational Neuromodeling Unit, University of Zürich and Swiss Federal Institute of Technology, Zürich, Zürich, Switzerland Department of Psychiatry, Psychotherapy and Psychosomatics, Hospital of Psychiatry, University of Zürich, Zürich, Switzerland
| | - Jonathan P Roiser
- Institute of Cognitive Neuroscience, University College London, London, UK
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141
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Strauss GP, Whearty KM, Frost KH, Carpenter WT. An Affective Neuroscience Model of Impaired Approach Motivation in Schizophrenia. NEBRASKA SYMPOSIUM ON MOTIVATION. NEBRASKA SYMPOSIUM ON MOTIVATION 2016; 63:159-203. [PMID: 27627827 DOI: 10.1007/978-3-319-30596-7_6] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
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142
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Medial-Frontal Stimulation Enhances Learning in Schizophrenia by Restoring Prediction Error Signaling. J Neurosci 2015; 35:12232-40. [PMID: 26338333 DOI: 10.1523/jneurosci.1717-15.2015] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
UNLABELLED Posterror learning, associated with medial-frontal cortical recruitment in healthy subjects, is compromised in neuropsychiatric disorders. Here we report novel evidence for the mechanisms underlying learning dysfunctions in schizophrenia. We show that, by noninvasively passing direct current through human medial-frontal cortex, we could enhance the event-related potential related to learning from mistakes (i.e., the error-related negativity), a putative index of prediction error signaling in the brain. Following this causal manipulation of brain activity, the patients learned a new task at a rate that was indistinguishable from healthy individuals. Moreover, the severity of delusions interacted with the efficacy of the stimulation to improve learning. Our results demonstrate a causal link between disrupted prediction error signaling and inefficient learning in schizophrenia. These findings also demonstrate the feasibility of nonpharmacological interventions to address cognitive deficits in neuropsychiatric disorders. SIGNIFICANCE STATEMENT When there is a difference between what we expect to happen and what we actually experience, our brains generate a prediction error signal, so that we can map stimuli to responses and predict outcomes accurately. Theories of schizophrenia implicate abnormal prediction error signaling in the cognitive deficits of the disorder. Here, we combine noninvasive brain stimulation with large-scale electrophysiological recordings to establish a causal link between faulty prediction error signaling and learning deficits in schizophrenia. We show that it is possible to improve learning rate, as well as the neural signature of prediction error signaling, in patients to a level quantitatively indistinguishable from that of healthy subjects. The results provide mechanistic insight into schizophrenia pathophysiology and suggest a future therapy for this condition.
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143
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Ranlund S, Adams RA, Díez Á, Constante M, Dutt A, Hall MH, Maestro Carbayo A, McDonald C, Petrella S, Schulze K, Shaikh M, Walshe M, Friston K, Pinotsis D, Bramon E. Impaired prefrontal synaptic gain in people with psychosis and their relatives during the mismatch negativity. Hum Brain Mapp 2015; 37:351-65. [PMID: 26503033 PMCID: PMC4843949 DOI: 10.1002/hbm.23035] [Citation(s) in RCA: 47] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2015] [Revised: 09/30/2015] [Accepted: 10/13/2015] [Indexed: 12/11/2022] Open
Abstract
The mismatch negativity (MMN) evoked potential, a preattentive brain response to a discriminable change in auditory stimulation, is significantly reduced in psychosis. Glutamatergic theories of psychosis propose that hypofunction of NMDA receptors (on pyramidal cells and inhibitory interneurons) causes a loss of synaptic gain control. We measured changes in neuronal effective connectivity underlying the MMN using dynamic causal modeling (DCM), where the gain (excitability) of superficial pyramidal cells is explicitly parameterised. EEG data were obtained during a MMN task—for 24 patients with psychosis, 25 of their first‐degree unaffected relatives, and 35 controls—and DCM was used to estimate the excitability (modeled as self‐inhibition) of (source‐specific) superficial pyramidal populations. The MMN sources, based on previous research, included primary and secondary auditory cortices, and the right inferior frontal gyrus. Both patients with psychosis and unaffected relatives (to a lesser degree) showed increased excitability in right inferior frontal gyrus across task conditions, compared to controls. Furthermore, in the same region, both patients and their relatives showed a reversal of the normal response to deviant stimuli; that is, a decrease in excitability in comparison to standard conditions. Our results suggest that psychosis and genetic risk for the illness are associated with both context‐dependent (condition‐specific) and context‐independent abnormalities of the excitability of superficial pyramidal cell populations in the MMN paradigm. These abnormalities could relate to NMDA receptor hypofunction on both pyramidal cells and inhibitory interneurons, and appear to be linked to the genetic aetiology of the illness, thereby constituting potential endophenotypes for psychosis. Hum Brain Mapp 37:351–365, 2016. © 2015 The Authors Human Brain Mapping Published by Wiley Periodicals, Inc.
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Affiliation(s)
- Siri Ranlund
- Division of Psychiatry, University College London, London, United Kingdom
| | - Rick A Adams
- Division of Psychiatry, University College London, London, United Kingdom.,Institute of Cognitive Neuroscience, University College London, London, United Kingdom
| | - Álvaro Díez
- Division of Psychiatry, University College London, London, United Kingdom
| | - Miguel Constante
- Department of Psychiatry, Hospital Beatriz Angelo, Lisbon, Portugal
| | - Anirban Dutt
- The South London and Maudsley NHS Foundation Trust, NIHR Biomedical Research Centre for Mental Health at the Institute of Psychiatry, Psychology and Neuroscience, King's College London, United Kingdom
| | - Mei-Hua Hall
- Psychology Research Laboratory, Harvard Medical School, McLean Hospital, Belmont, Massachusetts, USA
| | - Amparo Maestro Carbayo
- The South London and Maudsley NHS Foundation Trust, NIHR Biomedical Research Centre for Mental Health at the Institute of Psychiatry, Psychology and Neuroscience, King's College London, United Kingdom
| | - Colm McDonald
- Department of Psychiatry, Clinical Science Institute, National University of Ireland, Galway, Ireland
| | - Sabrina Petrella
- The South London and Maudsley NHS Foundation Trust, NIHR Biomedical Research Centre for Mental Health at the Institute of Psychiatry, Psychology and Neuroscience, King's College London, United Kingdom.,Department of Psychiatry, Clinical and Experimental Science Institute, University of Foggia, Italy
| | - Katja Schulze
- The South London and Maudsley NHS Foundation Trust, University Hospital Lewisham, London, United Kingdom
| | - Madiha Shaikh
- The South London and Maudsley NHS Foundation Trust, NIHR Biomedical Research Centre for Mental Health at the Institute of Psychiatry, Psychology and Neuroscience, King's College London, United Kingdom.,Neuroepidemiology and Ageing Research Unit, Imperial College, London, United Kingdom
| | - Muriel Walshe
- Division of Psychiatry, University College London, London, United Kingdom.,The South London and Maudsley NHS Foundation Trust, NIHR Biomedical Research Centre for Mental Health at the Institute of Psychiatry, Psychology and Neuroscience, King's College London, United Kingdom
| | - Karl Friston
- The Wellcome Trust Centre for Neuroimaging, Institute of Neurology, University College London, London, United Kingdom
| | - Dimitris Pinotsis
- The Wellcome Trust Centre for Neuroimaging, Institute of Neurology, University College London, London, United Kingdom
| | - Elvira Bramon
- Division of Psychiatry, University College London, London, United Kingdom.,Institute of Cognitive Neuroscience, University College London, London, United Kingdom.,The South London and Maudsley NHS Foundation Trust, NIHR Biomedical Research Centre for Mental Health at the Institute of Psychiatry, Psychology and Neuroscience, King's College London, United Kingdom
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144
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Cannon TD. How Schizophrenia Develops: Cognitive and Brain Mechanisms Underlying Onset of Psychosis. Trends Cogn Sci 2015; 19:744-756. [PMID: 26493362 DOI: 10.1016/j.tics.2015.09.009] [Citation(s) in RCA: 133] [Impact Index Per Article: 14.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2015] [Revised: 09/10/2015] [Accepted: 09/11/2015] [Indexed: 12/12/2022]
Abstract
Identifying cognitive and neural mechanisms involved in the development of schizophrenia requires longitudinal observation of individuals prior to onset. Here recent studies of prodromal individuals who progress to full psychosis are briefly reviewed in relation to models of schizophrenia pathophysiology. Together, this body of work suggests that disruption in brain connectivity, driven primarily by a progressive reduction in dendritic spines on cortical pyramidal neurons, may represent a key triggering mechanism. The earliest disruptions appear to be in circuits involved in referencing experiences according to time, place, and agency, which may result in a failure to recognize particular cognitions as self-generated or to constrain interpretations of the meaning of events based on prior experiences, providing the scaffolding for faulty reality testing.
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Affiliation(s)
- Tyrone D Cannon
- Department of Psychology, Yale University, 2 Hillhouse Avenue, P.O. Box 208205, New Haven, CT 06520, USA.
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145
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Turner BO, Marinsek N, Ryhal E, Miller MB. Hemispheric lateralization in reasoning. Ann N Y Acad Sci 2015; 1359:47-64. [PMID: 26426534 DOI: 10.1111/nyas.12940] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2015] [Revised: 08/17/2015] [Accepted: 08/20/2015] [Indexed: 11/30/2022]
Abstract
A growing body of evidence suggests that reasoning in humans relies on a number of related processes whose neural loci are largely lateralized to one hemisphere or the other. A recent review of this evidence concluded that the patterns of lateralization observed are organized according to two complementary tendencies. The left hemisphere attempts to reduce uncertainty by drawing inferences or creating explanations, even at the cost of ignoring conflicting evidence or generating implausible explanations. Conversely, the right hemisphere aims to reduce conflict by rejecting or refining explanations that are no longer tenable in the face of new evidence. In healthy adults, the hemispheres work together to achieve a balance between certainty and consistency, and a wealth of neuropsychological research supports the notion that upsetting this balance results in various failures in reasoning, including delusions. However, support for this model from the neuroimaging literature is mixed. Here, we examine the evidence for this framework from multiple research domains, including an activation likelihood estimation analysis of functional magnetic resonance imaging studies of reasoning. Our results suggest a need to either revise this model as it applies to healthy adults or to develop better tools for assessing lateralization in these individuals.
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Affiliation(s)
- Benjamin O Turner
- Department of Psychological & Brain Sciences, University of California Santa Barbara, Santa Barbara, California
| | - Nicole Marinsek
- Dynamical Neuroscience, University of California Santa Barbara, Santa Barbara, California
| | - Emily Ryhal
- Department of Psychological & Brain Sciences, University of California Santa Barbara, Santa Barbara, California
| | - Michael B Miller
- Department of Psychological & Brain Sciences, University of California Santa Barbara, Santa Barbara, California
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146
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Schmack K, Rössler H, Sekutowicz M, Brandl EJ, Müller DJ, Petrovic P, Sterzer P. Linking unfounded beliefs to genetic dopamine availability. Front Hum Neurosci 2015; 9:521. [PMID: 26483654 PMCID: PMC4588007 DOI: 10.3389/fnhum.2015.00521] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2015] [Accepted: 09/07/2015] [Indexed: 12/17/2022] Open
Abstract
Unfounded convictions involving beliefs in the paranormal, grandiosity ideas or suspicious thoughts are endorsed at varying degrees among the general population. Here, we investigated the neurobiopsychological basis of the observed inter-individual variability in the propensity toward unfounded beliefs. One hundred two healthy individuals were genotyped for four polymorphisms in the COMT gene (rs6269, rs4633, rs4818, and rs4680, also known as val158met) that define common functional haplotypes with substantial impact on synaptic dopamine degradation, completed a questionnaire measuring unfounded beliefs, and took part in a behavioral experiment assessing perceptual inference. We found that greater dopamine availability was associated with a stronger propensity toward unfounded beliefs, and that this effect was statistically mediated by an enhanced influence of expectations on perceptual inference. Our results indicate that genetic differences in dopaminergic neurotransmission account for inter-individual differences in perceptual inference linked to the formation and maintenance of unfounded beliefs. Thus, dopamine might be critically involved in the processes underlying one's interpretation of the relationship between the self and the world.
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Affiliation(s)
- Katharina Schmack
- Department of Psychiatry, Charité Campus Mitte, Charité Universitätsmedizin Berlin Berlin, Germany
| | - Hannes Rössler
- Department of Psychiatry, Charité Campus Mitte, Charité Universitätsmedizin Berlin Berlin, Germany
| | - Maria Sekutowicz
- Department of Psychiatry, Charité Campus Mitte, Charité Universitätsmedizin Berlin Berlin, Germany
| | - Eva J Brandl
- Department of Psychiatry, Charité Campus Mitte, Charité Universitätsmedizin Berlin Berlin, Germany
| | - Daniel J Müller
- Neurogenetics Section, Centre for Addiction and Mental Health Toronto, ON, Canada
| | - Predrag Petrovic
- Department of Clinical Neuroscience, Karolinska Institutet Stockholm, Sweden
| | - Philipp Sterzer
- Department of Psychiatry, Charité Campus Mitte, Charité Universitätsmedizin Berlin Berlin, Germany
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147
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Aberrant Salience Is Related to Reduced Reinforcement Learning Signals and Elevated Dopamine Synthesis Capacity in Healthy Adults. J Neurosci 2015; 35:10103-11. [PMID: 26180188 DOI: 10.1523/jneurosci.0805-15.2015] [Citation(s) in RCA: 40] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
The striatum is known to play a key role in reinforcement learning, specifically in the encoding of teaching signals such as reward prediction errors (RPEs). It has been proposed that aberrant salience attribution is associated with impaired coding of RPE and heightened dopamine turnover in the striatum, and might be linked to the development of psychotic symptoms. However, the relationship of aberrant salience attribution, RPE coding, and dopamine synthesis capacity has not been directly investigated. Here we assessed the association between a behavioral measure of aberrant salience attribution, the salience attribution test, to neural correlates of RPEs measured via functional magnetic resonance imaging while healthy participants (n = 58) performed an instrumental learning task. A subset of participants (n = 27) also underwent positron emission tomography with the radiotracer [(18)F]fluoro-l-DOPA to quantify striatal presynaptic dopamine synthesis capacity. Individual variability in aberrant salience measures related negatively to ventral striatal and prefrontal RPE signals and in an exploratory analysis was found to be positively associated with ventral striatal presynaptic dopamine levels. These data provide the first evidence for a specific link between the constructs of aberrant salience attribution, reduced RPE processing, and potentially increased presynaptic dopamine function.
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148
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Bortolotti L, Miyazono K. Recent Work on the Nature and Development of Delusions. PHILOSOPHY COMPASS 2015; 10:636-645. [PMID: 27478490 PMCID: PMC4950134 DOI: 10.1111/phc3.12249] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
In this paper we review two debates in the current literature on clinical delusions. One debate is about what delusions are. If delusions are beliefs, why are they described as failing to play the causal roles that characterise beliefs, such as being responsive to evidence and guiding action? The other debate is about how delusions develop. What processes lead people to form delusions and maintain them in the face of challenges and counter-evidence? Do the formation and maintenance of delusions require abnormal experience alone, or also reasoning biases or deficits? We hope to show that the focus on delusions has made a substantial contribution to the philosophy of the mind and continues to raise issues that are central to defining the concept of belief and gaining a better understanding of how people process information and learn about the world.
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149
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Stephan K, Iglesias S, Heinzle J, Diaconescu A. Translational Perspectives for Computational Neuroimaging. Neuron 2015; 87:716-32. [DOI: 10.1016/j.neuron.2015.07.008] [Citation(s) in RCA: 132] [Impact Index Per Article: 14.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
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150
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Gilmour G, Gastambide F, Marston HM, Walton ME. Using Intermediate Cognitive Endpoints to Facilitate Translational Research in Psychosis. Curr Opin Behav Sci 2015; 4:128-135. [PMID: 26937447 PMCID: PMC4770458 DOI: 10.1016/j.cobeha.2015.04.011] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Abstract
Recent advances in the understanding of psychosis have uncovered potential for a paradigm shift in related drug discovery efforts. The study of psychosis is evolving from its origins in serendipity and empiricism to more formal, hypothesis driven accounts of the cognitive substrates underlying hallucinations and delusions. Recent evidence suggests that misattribution of salience and abnormal prediction error might underlie some forms of psychosis. If substantiated, such intermediate constructs could significantly facilitate translational research for drug discovery. Aberrant salience and prediction error can be assayed with simple tests of associative learning in both species, and a convincing back translation of effects, when combined with measures of neurotransmitter release and brain activity could for the first time allow robust, causal connections to be made between molecular mechanisms in rodents and symptoms in patients.
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Affiliation(s)
- Gary Gilmour
- In Vivo Pharmacology, Eli Lilly & Co. Ltd., Erl Wood Manor, Sunninghill Road, Windlesham, Surrey, GU20 6PH, UK
| | - Francois Gastambide
- In Vivo Pharmacology, Eli Lilly & Co. Ltd., Erl Wood Manor, Sunninghill Road, Windlesham, Surrey, GU20 6PH, UK
| | - Hugh M Marston
- In Vivo Pharmacology, Eli Lilly & Co. Ltd., Erl Wood Manor, Sunninghill Road, Windlesham, Surrey, GU20 6PH, UK
| | - Mark E Walton
- Department of Experimental Psychology, University of Oxford, 9 South Parks Road, Oxford, OX1 3UD, U.K
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