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Napolitano F, D'Angelo L, de Girolamo P, Avallone L, de Lange P, Usiello A. The Thyroid Hormone-target Gene Rhes a Novel Crossroad for Neurological and Psychiatric Disorders: New Insights from Animal Models. Neuroscience 2018; 384:419-428. [PMID: 29857029 DOI: 10.1016/j.neuroscience.2018.05.027] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2018] [Revised: 05/17/2018] [Accepted: 05/18/2018] [Indexed: 02/08/2023]
Abstract
Ras homolog enriched in striatum (Rhes) is predominantly expressed in the corpus striatum. Rhes mRNA is localized in virtually all dopamine D1 and D2 receptor-bearing medium-sized spiny neurons (MSNs), and cholinergic interneurons of striatum. Early studies in rodents showed that Rhes is developmentally regulated by thyroid hormone, as well as by dopamine innervation in adult rat, monkey and human brains. At cellular level, Rhes interferes with adenosine A2A- and dopamine D1 receptor-dependent cAMP/PKA pathway, upstream of the activation of the heterotrimeric G protein complex. Besides its involvement in GPCR-mediated signaling, Rhes modulates Akt pathway activation, acts as E3-ligase of mutant huntingtin, whose sumoylation accounts for neurotoxicity in Huntington's disease, and physically interacts with Beclin-1, suggesting its potential involvement in autophagy-related cellular events. In addition, this protein can also bind to and activate striatal mTORC1, one of the key players in l-DOPA-induced dyskinesia in rodent models of Parkinson's disease. Accordingly, lack of Rhes attenuated such motor disturbances in 6-OHDA-lesioned Rhes knockout mice. In support of its role in MSN-dependent functions, several studies documented that mutant animals displayed alterations in striatum-related phenotypes reminiscent of psychiatric illness in humans, including deficits in prepulse inhibition of startle reflex and, most interestingly, a striking enhancement of behavioral responses elicited by caffeine, phencyclidine or amphetamine. Overall, these data suggest that Rhes modulates molecular and biochemical events underlying striatal functioning, both in physiological and pathological conditions.
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Affiliation(s)
- Francesco Napolitano
- Department of Molecular Medicine and Medical Biotechnology, University of Naples Federico II, Naples, Italy; Ceinge Biotecnologie Avanzate, Naples, Italy.
| | - Livia D'Angelo
- Department of Veterinary Medicine and Animal Productions, University of Naples Federico II, Naples, Italy; Stazione Zoologica Anton Dohrn, Naples, Italy
| | - Paolo de Girolamo
- Department of Veterinary Medicine and Animal Productions, University of Naples Federico II, Naples, Italy
| | - Luigi Avallone
- Department of Veterinary Medicine and Animal Productions, University of Naples Federico II, Naples, Italy
| | - Pieter de Lange
- Department of Environmental, Biological and Pharmaceutical Sciences and Technologies, University of Campania "Luigi Vanvitelli", Caserta, Italy
| | - Alessandro Usiello
- Ceinge Biotecnologie Avanzate, Naples, Italy; Department of Environmental, Biological and Pharmaceutical Sciences and Technologies, University of Campania "Luigi Vanvitelli", Caserta, Italy.
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102
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Kim M, Lee TH, Yoon YB, Lee TY, Kwon JS. Predicting Remission in Subjects at Clinical High Risk for Psychosis Using Mismatch Negativity. Schizophr Bull 2018; 44:575-583. [PMID: 29036493 PMCID: PMC5890455 DOI: 10.1093/schbul/sbx102] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
BACKGROUND The declining transition rate to psychotic disorder and the increasing rate of nonpsychotic poor outcomes among subjects at clinical high risk (CHR) for psychosis have increased the need for biomarkers to predict remission regardless of transition. This study investigated whether mismatch negativity (MMN) predicts the prognosis of CHR individuals during a 6-year follow-up period. METHODS A total of 47 healthy control (HC) subjects and 48 subjects at CHR for psychosis participated in the MMN assessment. The clinical statuses of the CHR subjects were examined at baseline and regularly for up to 6 years. The CHR subjects were divided into remitter and nonremitter groups, and the baseline MMN amplitudes and latencies were compared across the remitter, nonremitter, and HC groups. Regression analyses were performed to identify the predictive factors of remission, the improvement of attenuated positive symptoms, and functional recovery. RESULTS CHR nonremitters showed reduced MMN amplitudes at baseline compared to CHR remitters and HC subjects. A logistic regression analysis revealed that the baseline MMN amplitude at the frontal electrode site was the only significant predictor of remission. In a multiple regression analysis, the MMN amplitude, antipsychotic use, and years of education predicted an improvement in attenuated positive symptoms. The MMN amplitude at baseline predicted functional recovery. CONCLUSIONS These results suggest that MMN is a putative predictor of prognosis regardless of the transition to psychotic disorder in subjects at CHR. Early prognosis prediction and the provision of appropriate interventions based on the initial CHR status might be aided using MMN.
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Affiliation(s)
- Minah Kim
- Department of Psychiatry, Seoul National University College of Medicine, Seoul, Republic of Korea
| | - Tak Hyung Lee
- Department of Brain and Cognitive Sciences, Seoul National University College of Natural Science, Seoul, Republic of Korea
| | - Youngwoo Bryan Yoon
- Department of Brain and Cognitive Sciences, Seoul National University College of Natural Science, Seoul, Republic of Korea
| | - Tae Young Lee
- Department of Neuropsychiatry, Seoul National University Hospital, Seoul, Republic of Korea
| | - Jun Soo Kwon
- Department of Psychiatry, Seoul National University College of Medicine, Seoul, Republic of Korea,Department of Brain and Cognitive Sciences, Seoul National University College of Natural Science, Seoul, Republic of Korea,To whom correspondence should be addressed; Department of Psychiatry, Seoul National University College of Medicine, 101 Daehak-ro, Chongno-gu, Seoul 03080, Republic of Korea; tel: +82-2-2072-2972, fax: +82-2-747-9063, e-mail:
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103
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Morrison PD, Murray RM. The antipsychotic landscape: dopamine and beyond. Ther Adv Psychopharmacol 2018; 8:127-135. [PMID: 29607005 PMCID: PMC5846922 DOI: 10.1177/2045125317752915] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/28/2017] [Accepted: 11/17/2017] [Indexed: 11/16/2022] Open
Abstract
Until recently, the actions of antipsychotic and pro-psychotic drugs have largely been evaluated in the framework of neuronal doctrine - namely, that neurons communicate by releasing transmitters, and that psychiatric disorders are caused by neurotransmitter imbalances. Moreover, the majority of studies have focused on single transmitter systems - neglecting the fact that in the nervous system, different transmitter systems work in concert and impact on not only their immediate receptors but also downstream pathways that shape structural plasticity. In this review, we discuss the history of understanding the antipsychotic and pro-psychotic actions of drugs, recent developments and future perspectives.
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Affiliation(s)
- Paul D Morrison
- The Institute of Psychiatry, Psychology & Neuroscience, King's College London, De Crespigny Park, Denmark Hill, London, SE5 8AF, UK
| | - Robin M Murray
- The Institute of Psychiatry, Psychology & Neuroscience, King's College London, London, UK
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104
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Michaels TI, Long LL, Stevenson IH, Chrobak JJ, Chen CMA. Effects of chronic ketamine on hippocampal cross-frequency coupling: implications for schizophrenia pathophysiology. Eur J Neurosci 2018; 48:2903-2914. [PMID: 29359413 DOI: 10.1111/ejn.13822] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2017] [Revised: 01/04/2018] [Accepted: 01/11/2018] [Indexed: 11/27/2022]
Abstract
Disrupted neuronal oscillations have been identified as a potentially important biomarker for the perceptual and cognitive symptoms of schizophrenia. Emerging evidences suggest that interactions between different frequency bands, cross-frequency coupling (CFC), serve an important role in integrating sensory and cognitive information and may contribute to disease pathophysiology. In this study, we investigated the effects of 14-day consecutive administration of ketamine (30 mg/kg i.p.) vs. saline on alterations in amplitude and changes in the coupling of low-frequency (0-30 Hz) phase and high-frequency (30-115 Hz) amplitude in the CA1 hippocampus of Long Evans rats. Intracranial electrode recordings were conducted pre- and post-injection while the animals performed a foraging task on a four-arm rectangular maze. Permutation analysis of frequency band-specific change in amplitudes revealed between-group differences in theta (6-12 Hz) and slow gamma (25-50 Hz) but not fast gamma (65-100 Hz) bands at both slow and fast speeds. Chronic ketamine challenge resulted in decreased coupling (pre to post) at slow speeds but increased coupling at faster speeds, compared to either no or modest increased coupling in the saline group. These results demonstrate that chronic ketamine administration alters the interaction of low-frequency phase and high-frequency oscillations chronically and that such coupling varies as a function of locomotive speed. These findings provide evidence for the potential relevance of CFC to the pathophysiology of schizophrenia.
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Affiliation(s)
- Timothy I Michaels
- Psychological Sciences Department, University of Connecticut, 406 Babbidge Road, Unit 1020, Storrs, CT, 06269, USA
| | - Lauren L Long
- Psychological Sciences Department, University of Connecticut, 406 Babbidge Road, Unit 1020, Storrs, CT, 06269, USA
| | - Ian H Stevenson
- Psychological Sciences Department, University of Connecticut, 406 Babbidge Road, Unit 1020, Storrs, CT, 06269, USA
| | - James J Chrobak
- Psychological Sciences Department, University of Connecticut, 406 Babbidge Road, Unit 1020, Storrs, CT, 06269, USA
| | - Chi-Ming A Chen
- Psychological Sciences Department, University of Connecticut, 406 Babbidge Road, Unit 1020, Storrs, CT, 06269, USA
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105
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Lee M, Balla A, Sershen H, Sehatpour P, Lakatos P, Javitt DC. Rodent Mismatch Negativity/theta Neuro-Oscillatory Response as a Translational Neurophysiological Biomarker for N-Methyl-D-Aspartate Receptor-Based New Treatment Development in Schizophrenia. Neuropsychopharmacology 2018; 43:571-582. [PMID: 28816240 PMCID: PMC5770758 DOI: 10.1038/npp.2017.176] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/22/2017] [Revised: 08/04/2017] [Accepted: 08/09/2017] [Indexed: 12/25/2022]
Abstract
Deficits in the generation of auditory mismatch negativity (MMN) generation are among the most widely replicated neurophysiological abnormalities in schizophrenia and are linked to underlying dysfunction of N-methyl-D-aspartate receptor (NMDAR)-mediated neurotransmission. Here, we evaluate physiological properties of rodent MMN, along with sensitivity to NMDAR agonist and antagonist treatments, relative to known patterns of dysfunction in schizophrenia. Epidural neurophysiological responses to frequency and duration deviants, along with responses to standard stimuli, were obtained at baseline and following 2 and 4 weeks' treatment in rats treated with saline, phencyclidine (PCP, 15 mg/kg/d by osmotic minipump), or PCP+glycine (16% by weight diet) interventions. Responses were analyzed using both event-related potential (ERP) and neuro-oscillatory (evoked power) approaches. At baseline, rodent duration MMN was associated with increased theta (θ)-frequency response similar to that observed in humans. PCP significantly reduced rodent duration MMN (p<0.001) and θ-band (p<0.01) response. PCP effects were prevented by concurrent glycine treatment (p<0.01 vs PCP alone). Effects related to stimulus-specific adaptation (SSA) were observed primarily in the alpha (α) and beta (β) frequency ranges. PCP treatment also significantly reduced α-frequency response to standard stimuli while increasing θ-band response, reproducing the pattern of deficit observed in schizophrenia. Overall, we demonstrate that rodent duration MMN shows neuro-oscillatory signature similar to human MMN, along with sensitivity to the NMDAR antagonist and agonist administration. These findings reinforce recent human studies linking MMN deficits to θ-band neuro-oscillatory dysfunction and support utility of rodent duration MMN as a translational biomarker for investigation of mechanisms underlying impaired local circuit function in schizophrenia.
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Affiliation(s)
- Migyung Lee
- Division of Experimental Therapeutics, Department of Psychiatry, Columbia University Medical Center, New York, NY, USA,Program in Cognitive Neuroscience and Schizophrenia, Nathan Kline Institute, Orangeburg, NY, USA
| | - Andrea Balla
- Program in Cognitive Neuroscience and Schizophrenia, Nathan Kline Institute, Orangeburg, NY, USA
| | - Henry Sershen
- Program in Cognitive Neuroscience and Schizophrenia, Nathan Kline Institute, Orangeburg, NY, USA
| | - Pejman Sehatpour
- Division of Experimental Therapeutics, Department of Psychiatry, Columbia University Medical Center, New York, NY, USA,Program in Cognitive Neuroscience and Schizophrenia, Nathan Kline Institute, Orangeburg, NY, USA
| | - Peter Lakatos
- Program in Cognitive Neuroscience and Schizophrenia, Nathan Kline Institute, Orangeburg, NY, USA
| | - Daniel C Javitt
- Division of Experimental Therapeutics, Department of Psychiatry, Columbia University Medical Center, New York, NY, USA,Program in Cognitive Neuroscience and Schizophrenia, Nathan Kline Institute, Orangeburg, NY, USA,Division of Experimental Therapeutics, Department of Psychiatry, Columbia University Medical Center, 1051 Riverside Drive, Unit 21, New York, NY 10032, USA, Tel: +646 774-5404, E-mail:
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106
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Sherif MA, Cortes-Briones JA, Ranganathan M, Skosnik PD. Cannabinoid-glutamate interactions and neural oscillations: implications for psychosis. Eur J Neurosci 2018; 48:2890-2902. [PMID: 29247465 DOI: 10.1111/ejn.13800] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2017] [Revised: 12/06/2017] [Accepted: 12/07/2017] [Indexed: 12/13/2022]
Affiliation(s)
- Mohamed A. Sherif
- Department of Psychiatry; Yale University School of Medicine; VA Connecticut Healthcare System Building 5, Suite C-214 950 Campbell Avenue West Haven CT 06516 USA
| | - Jose A. Cortes-Briones
- Department of Psychiatry; Yale University School of Medicine; VA Connecticut Healthcare System Building 5, Suite C-214 950 Campbell Avenue West Haven CT 06516 USA
| | - Mohini Ranganathan
- Department of Psychiatry; Yale University School of Medicine; VA Connecticut Healthcare System Building 5, Suite C-214 950 Campbell Avenue West Haven CT 06516 USA
| | - Patrick D. Skosnik
- Department of Psychiatry; Yale University School of Medicine; VA Connecticut Healthcare System Building 5, Suite C-214 950 Campbell Avenue West Haven CT 06516 USA
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107
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Seshadri S, Klaus A, Winkowski DE, Kanold PO, Plenz D. Altered avalanche dynamics in a developmental NMDAR hypofunction model of cognitive impairment. Transl Psychiatry 2018; 8:3. [PMID: 29317600 PMCID: PMC5802445 DOI: 10.1038/s41398-017-0060-z] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/29/2017] [Revised: 08/29/2017] [Accepted: 09/13/2017] [Indexed: 12/25/2022] Open
Abstract
Disturbed activity patterns in cortical networks contribute to the pathophysiology of schizophrenia (SZ). Several lines of evidence implicate NMDA receptor hypofunction in SZ, and blocking NMDA receptor signaling during early neurodevelopment produces cognitive deficits in rodent models that resemble those seen in schizophrenic patients. However, the altered network dynamics underlying these cognitive impairments largely remain to be characterized, especially at the cellular level. Here, we use in vivo two-photon calcium imaging to describe pathological dynamics, occurring in parallel with cognitive dysfunction, in a developmental NMDA receptor hypofunction model. We observed increased synchrony and specific alterations in spatiotemporal activity propagation, which could be causally linked to a previously unidentified persistent bursting phenotype. This phenotype was rescued by acute treatment with the NMDA receptor co-agonist D-serine or the GABAB receptor agonist baclofen, which similarly rescued working memory performance. It was not reproduced by optogenetic inhibition of fast-spiking interneurons. These results provide novel insight into network-level abnormalities mediating the cognitive impairment induced by NMDA receptor hypofunction.
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Affiliation(s)
- Saurav Seshadri
- 0000 0004 0464 0574grid.416868.5Section on Critical Brain Dynamics, National Institute of Mental Health, Bethesda, MD USA
| | - Andreas Klaus
- 0000 0004 0464 0574grid.416868.5Section on Critical Brain Dynamics, National Institute of Mental Health, Bethesda, MD USA
| | - Daniel E. Winkowski
- 0000 0001 0941 7177grid.164295.dDepartment of Biology, Univ. of Maryland, College Park, MD USA
| | - Patrick O. Kanold
- 0000 0001 0941 7177grid.164295.dDepartment of Biology, Univ. of Maryland, College Park, MD USA
| | - Dietmar Plenz
- Section on Critical Brain Dynamics, National Institute of Mental Health, Bethesda, MD, USA.
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108
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Mitchell AC, Javidfar B, Pothula V, Ibi D, Shen EY, Peter CJ, Bicks L, Fehr T, Jiang Y, Brennand KJ, Neve RL, Gonzalez-Maeso J, Akbarian S. MEF2C transcription factor is associated with the genetic and epigenetic risk architecture of schizophrenia and improves cognition in mice. Mol Psychiatry 2018; 23:123-132. [PMID: 28115742 PMCID: PMC5966823 DOI: 10.1038/mp.2016.254] [Citation(s) in RCA: 55] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/21/2016] [Revised: 10/30/2016] [Accepted: 12/06/2016] [Indexed: 12/20/2022]
Abstract
Large-scale consortia mapping the genomic risk architectures of schizophrenia provide vast amounts of molecular information, with largely unexplored therapeutic potential. We harnessed publically available information from the Psychiatric Genomics Consortium, and report myocyte enhancer factor 2C (MEF2C) motif enrichment in sequences surrounding the top scoring single-nucleotide polymorphisms within risk loci contributing by individual small effect to disease heritability. Chromatin profiling at base-pair resolution in neuronal nucleosomes extracted from prefrontal cortex of 34 subjects, including 17 cases diagnosed with schizophrenia, revealed MEF2C motif enrichment within cis-regulatory sequences, including neuron-specific promoters and superenhancers, affected by histone H3K4 hypermethylation in disease cases. Vector-induced short- and long-term Mef2c upregulation in mouse prefrontal projection neurons consistently resulted in enhanced cognitive performance in working memory and object recognition paradigms at baseline and after psychotogenic drug challenge, in conjunction with remodeling of local connectivity. Neuronal genome tagging in vivo by Mef2c-Dam adenine methyltransferase fusion protein confirmed the link between cognitive enhancement and MEF2C occupancy at promoters harboring canonical and variant MEF2C motifs. The multilayered integrative approaches presented here provide a roadmap to uncover the therapeutic potential of transcriptional regulators for schizophrenia and related disorders.
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Affiliation(s)
- Amanda C. Mitchell
- Department of Psychiatry, Icahn School of Medicine at Mount Sinai, New York, NY 10029
- Department of Neuroscience, Icahn School of Medicine at Mount Sinai, New York, NY 10029
- Friedman Brain Institute, Icahn School of Medicine at Mount Sinai, New York, NY 10029
| | - Behnam Javidfar
- Department of Psychiatry, Icahn School of Medicine at Mount Sinai, New York, NY 10029
- Department of Neuroscience, Icahn School of Medicine at Mount Sinai, New York, NY 10029
- Friedman Brain Institute, Icahn School of Medicine at Mount Sinai, New York, NY 10029
| | - Venu Pothula
- Department of Psychiatry, Icahn School of Medicine at Mount Sinai, New York, NY 10029
- Department of Neuroscience, Icahn School of Medicine at Mount Sinai, New York, NY 10029
- Friedman Brain Institute, Icahn School of Medicine at Mount Sinai, New York, NY 10029
| | - Daisuke Ibi
- Department of Psychiatry, Icahn School of Medicine at Mount Sinai, New York, NY 10029
| | - Erica Y. Shen
- Department of Psychiatry, Icahn School of Medicine at Mount Sinai, New York, NY 10029
- Department of Neuroscience, Icahn School of Medicine at Mount Sinai, New York, NY 10029
- Friedman Brain Institute, Icahn School of Medicine at Mount Sinai, New York, NY 10029
| | - Cyril J. Peter
- Department of Psychiatry, Icahn School of Medicine at Mount Sinai, New York, NY 10029
- Department of Neuroscience, Icahn School of Medicine at Mount Sinai, New York, NY 10029
- Friedman Brain Institute, Icahn School of Medicine at Mount Sinai, New York, NY 10029
| | - Lucy Bicks
- Department of Psychiatry, Icahn School of Medicine at Mount Sinai, New York, NY 10029
- Department of Neuroscience, Icahn School of Medicine at Mount Sinai, New York, NY 10029
- Friedman Brain Institute, Icahn School of Medicine at Mount Sinai, New York, NY 10029
| | - Tristan Fehr
- Department of Psychiatry, Icahn School of Medicine at Mount Sinai, New York, NY 10029
- Department of Neuroscience, Icahn School of Medicine at Mount Sinai, New York, NY 10029
- Friedman Brain Institute, Icahn School of Medicine at Mount Sinai, New York, NY 10029
| | - Yan Jiang
- Department of Psychiatry, Icahn School of Medicine at Mount Sinai, New York, NY 10029
- Department of Neuroscience, Icahn School of Medicine at Mount Sinai, New York, NY 10029
- Friedman Brain Institute, Icahn School of Medicine at Mount Sinai, New York, NY 10029
| | - Kristen J. Brennand
- Department of Psychiatry, Icahn School of Medicine at Mount Sinai, New York, NY 10029
- Department of Neuroscience, Icahn School of Medicine at Mount Sinai, New York, NY 10029
- Friedman Brain Institute, Icahn School of Medicine at Mount Sinai, New York, NY 10029
| | - Rachael L. Neve
- McGovern Institute for Brain Research, Massachusetts Institute of Technology, Cambridge MA02139, USA
| | - Javier Gonzalez-Maeso
- Department of Physiology and Biophysics, Virginia Commonwealth University Medical School, Richmond, Virginia 23298, USA
| | - Schahram Akbarian
- Department of Psychiatry, Icahn School of Medicine at Mount Sinai, New York, NY 10029
- Department of Neuroscience, Icahn School of Medicine at Mount Sinai, New York, NY 10029
- Friedman Brain Institute, Icahn School of Medicine at Mount Sinai, New York, NY 10029
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109
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Joshi YB, Light GA. Using EEG-Guided Basket and Umbrella Trials in Psychiatry: A Precision Medicine Approach for Cognitive Impairment in Schizophrenia. Front Psychiatry 2018; 9:554. [PMID: 30510520 PMCID: PMC6252381 DOI: 10.3389/fpsyt.2018.00554] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/30/2018] [Accepted: 10/15/2018] [Indexed: 12/21/2022] Open
Abstract
Due to advances over the last several decades, many fields of medicine are moving toward a precision medicine approach where treatments are tailored to nuanced patient factors. While in some disciplines these innovations are commonplace leading to unique biomarker-guided experimental medicine trials, there are no such analogs in psychiatry. In this brief review, we will overview two unique biomarker-guided trial designs for future use in psychiatry: basket and umbrella trials. We will illustrate how such trials could be useful in psychiatry using schizophrenia as a candidate illness, the EEG measure mismatch negativity as the candidate biomarker, and cognitive impairment as the target disease dimension.
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Affiliation(s)
- Yash B Joshi
- Department of Psychiatry, University of California, San Diego, La Jolla, CA, United States
| | - Gregory A Light
- Department of Psychiatry, University of California, San Diego, La Jolla, CA, United States.,VISN-22 Mental Illness, Research, Education and Clinical Center (MIRECC), VA San Diego Health Care System, San Diego, CA, United States
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110
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Harms L, Fulham WR, Todd J, Meehan C, Schall U, Hodgson DM, Michie PT. Late deviance detection in rats is reduced, while early deviance detection is augmented by the NMDA receptor antagonist MK-801. Schizophr Res 2018; 191:43-50. [PMID: 28385587 DOI: 10.1016/j.schres.2017.03.042] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/31/2017] [Revised: 03/20/2017] [Accepted: 03/23/2017] [Indexed: 01/08/2023]
Abstract
One of the most robust electrophysiological features of schizophrenia is reduced mismatch negativity, a component of the event related potential (ERP) induced by rare and unexpected stimuli in an otherwise regular pattern. Emerging evidence suggests that mismatch negativity (MMN) is not the only ERP index of deviance detection in the mammalian brain and that sensitivity to deviant sounds in a regular background can be observed at earlier latencies in both the human and rodent brain. Pharmacological studies in humans and rodents have previously found that MMN reductions similar to those seen in schizophrenia can be elicited by N-methyl-d-aspartate (NMDA) receptor antagonism, an observation in agreement with the hypothesised role of NMDA receptor hypofunction in schizophrenia pathogenesis. However, it is not known how NMDA receptor antagonism affects early deviance detection responses. Here, we show that NMDA antagonism impacts both early and late deviance detection responses. By recording EEG in awake, freely-moving rats in a drug-free condition and after varying doses of NMDA receptor antagonist MK-801, we found the hypothesised reduction of deviance detection for a late, negative potential (N55). However, the amplitude of an early component, P13, as well as deviance detection evident in the same component, were increased by NMDA receptor antagonism. These findings indicate that late deviance detection in rats is similar to human MMN, but the surprising effect of MK-801 in increasing ERP amplitudes as well as deviance detection at earlier latencies suggests that future studies in humans should examine ERPs over early latencies in schizophrenia and after NMDA antagonism.
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Affiliation(s)
- L Harms
- School of Psychology, University of Newcastle, Callaghan, NSW, Australia; Priority Centre for Brain and Mental Health Research, Callaghan, NSW, Australia; Hunter Medical Research Institute, Newcastle, NSW, Australia; Schizophrenia Research Institute, Randwick, NSW, Australia.
| | - W R Fulham
- School of Psychology, University of Newcastle, Callaghan, NSW, Australia; Priority Centre for Brain and Mental Health Research, Callaghan, NSW, Australia; Hunter Medical Research Institute, Newcastle, NSW, Australia
| | - J Todd
- Priority Centre for Brain and Mental Health Research, Callaghan, NSW, Australia; Hunter Medical Research Institute, Newcastle, NSW, Australia; School of Medicine and Public Health, University of Newcastle, Callaghan, NSW, Australia
| | - C Meehan
- School of Psychology, University of Newcastle, Callaghan, NSW, Australia; Priority Centre for Brain and Mental Health Research, Callaghan, NSW, Australia
| | - U Schall
- Priority Centre for Brain and Mental Health Research, Callaghan, NSW, Australia; Hunter Medical Research Institute, Newcastle, NSW, Australia; Schizophrenia Research Institute, Randwick, NSW, Australia; School of Medicine and Public Health, University of Newcastle, Callaghan, NSW, Australia
| | - D M Hodgson
- School of Psychology, University of Newcastle, Callaghan, NSW, Australia; Priority Centre for Brain and Mental Health Research, Callaghan, NSW, Australia; Hunter Medical Research Institute, Newcastle, NSW, Australia; Schizophrenia Research Institute, Randwick, NSW, Australia
| | - P T Michie
- School of Psychology, University of Newcastle, Callaghan, NSW, Australia; Priority Centre for Brain and Mental Health Research, Callaghan, NSW, Australia; Hunter Medical Research Institute, Newcastle, NSW, Australia; Schizophrenia Research Institute, Randwick, NSW, Australia
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111
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Errico F, Nuzzo T, Carella M, Bertolino A, Usiello A. The Emerging Role of Altered d-Aspartate Metabolism in Schizophrenia: New Insights From Preclinical Models and Human Studies. Front Psychiatry 2018; 9:559. [PMID: 30459655 PMCID: PMC6232865 DOI: 10.3389/fpsyt.2018.00559] [Citation(s) in RCA: 30] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/20/2018] [Accepted: 10/17/2018] [Indexed: 01/08/2023] Open
Abstract
Besides d-serine, another d-amino acid with endogenous occurrence in the mammalian brain, d-aspartate, has been recently shown to influence NMDA receptor (NMDAR)-mediated transmission. d-aspartate is present in the brain at extracellular level in nanomolar concentrations, binds to the agonist site of NMDARs and activates this subclass of glutamate receptors. Along with its direct effect on NMDARs, d-aspartate can also evoke considerable l-glutamate release in specific brain areas through the presynaptic activation of NMDA, AMPA/kainate and mGlu5 receptors. d-aspartate is enriched in the embryonic brain of rodents and humans and its concentration strongly decreases after birth, due to the post-natal expression of the catabolising enzyme d-aspartate oxidase (DDO). Based on the hypothesis of NMDAR hypofunction in schizophrenia pathogenesis, recent preclinical and clinical studies suggested a relationship between perturbation of d-aspartate metabolism and this psychiatric disorder. Consistently, neurophysiological and behavioral characterization of Ddo knockout (Ddo -/-) and d-aspartate-treated mice highlighted that abnormally higher endogenous d-aspartate levels significantly increase NMDAR-mediated synaptic plasticity, neuronal spine density and memory. Remarkably, increased d-aspartate levels influence schizophrenia-like phenotypes in rodents, as indicated by improved fronto-hippocampal connectivity, attenuated prepulse inhibition deficits and reduced activation of neuronal circuitry induced by phencyclidine exposure. In healthy humans, a genetic polymorphism associated with reduced prefrontal DDO gene expression predicts changes in prefrontal phenotypes including greater gray matter volume and enhanced functional activity during working memory. Moreover, neurochemical detections in post-mortem brain of schizophrenia-affected patients have shown significantly reduced d-aspartate content in prefrontal regions, associated with increased DDO mRNA expression or DDO enzymatic activity. Overall, these findings suggest a possible involvement of dysregulated embryonic d-aspartate metabolism in schizophrenia pathophysiology and, in turn, highlight the potential use of free d-aspartate supplementation as a new add-on therapy for treating the cognitive symptoms of this mental illness.
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Affiliation(s)
- Francesco Errico
- Department of Agricultural Sciences, University of Naples "Federico II", Portici, Italy
| | - Tommaso Nuzzo
- Translational Neuroscience Unit, IRCCS Casa Sollievo Della Sofferenza, San Giovanni Rotondo, Italy
| | - Massimo Carella
- Translational Neuroscience Unit, IRCCS Casa Sollievo Della Sofferenza, San Giovanni Rotondo, Italy
| | - Alessandro Bertolino
- Group of Psychiatric Neuroscience, Department of Basic Medical Science, Neuroscience and Sense Organs, Aldo Moro University, Bari, Italy
| | - Alessandro Usiello
- Laboratory of Behavioural Neuroscience, Ceinge Biotecnologie Avanzate, Naples, Italy.,Department of Environmental, Biological and Pharmaceutical Sciences and Technologies, Università Degli Studi Della Campania "Luigi Vanvitelli", Caserta, Italy
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112
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Phase-Amplitude Coupling of the Electroencephalogram in the Auditory Cortex in Schizophrenia. BIOLOGICAL PSYCHIATRY: COGNITIVE NEUROSCIENCE AND NEUROIMAGING 2017; 3:69-76. [PMID: 29397081 DOI: 10.1016/j.bpsc.2017.09.001] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/16/2017] [Revised: 09/01/2017] [Accepted: 09/03/2017] [Indexed: 01/13/2023]
Abstract
BACKGROUND Cross-frequency interactions may coordinate neural circuits operating at different frequencies. While neural oscillations associated with particular circuits in schizophrenia (SZ) are impaired, few studies have examined cross-frequency interactions. Here we examined phase-amplitude coupling (PAC) in the electroencephalograms of individuals with SZ and healthy control subjects (HCs). We computed PAC during the baseline period of 40-Hz auditory steady-state stimulation and rest. We hypothesized that subjects with SZ would show abnormal theta/gamma coupling during stimulation, especially in the left auditory cortex, and coupling with high frequencies would be higher during stimulation than during rest. METHODS We reanalyzed data from 18 subjects with SZ and 18 HCs. Auditory cortex electroencephalogram activity was estimated using dipole source localization. PAC was computed using the debiased PAC measure, calculated with the generalized Morse wavelet transform. PAC clusters were identified using cluster-corrected permutation testing and interrogated in analyses of variance with correction for multiple tests. RESULTS Overall, coupling of high beta and gamma amplitude was higher during the auditory steady-state response, while alpha/beta PAC was higher during rest. Theta/alpha PAC was higher in subjects with SZ than in HCs. Theta/gamma PAC was lateralized to the left hemisphere in HCs but was not lateralized in subjects with SZ. CONCLUSIONS PAC involving high frequencies was state dependent and not abnormal in SZ. Increased theta/alpha PAC in subjects with SZ was consistent with other evidence of increased low-frequency activity. Hemispheric lateralization of theta/gamma PAC was reduced in subjects with SZ, consistent with evidence for left hemisphere auditory cortex abnormalities in subjects with SZ. PAC may reveal new insights into neural circuitry abnormalities in SZ and other neuropsychiatric disorders.
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113
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Phencyclidine-induced dysregulation of primary cilia in the rodent brain. Brain Res 2017; 1674:62-69. [PMID: 28842124 DOI: 10.1016/j.brainres.2017.08.022] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2016] [Revised: 08/17/2017] [Accepted: 08/18/2017] [Indexed: 11/22/2022]
Abstract
Significant roles of the primary cilia in the central nervous system have been reported in neural generation and cognitive functions. However, little is known about the possible pathological changes in brain primary cilia in neuropsychiatric disorders. To obtain an insight into the relationship between cilial dysregulation and schizophrenia, we presently investigated the effects of psychotomimetics, phencyclidine, MK-801 (dizocilpine), and methamphetamine, on morphological and molecular indices in the rodent brain. Using an immunohistochemical technique, we found that a subcutaneous injection of phencyclidine, an NMDA type glutamate receptor (NMDAR) antagonist, caused a reduction in the long axis length of a primary cilium in the CA1 region of the hippocampus without affecting that in the dentate gyrus and medial prefrontal cortex of rats and mice. The region-selective modulation of primary cilia was mimicked by another NMDAR antagonist, MK-801, but not by the indirect dopamine agonist methamphetamine. Furthermore, systemic administration of phencyclidine, but not methamphetamine, down-regulated mRNA expression of primary cilium morphology-related genes, including kif3a, 5-HTR6, RPGRIP1L, and TMEM67, and of genes composing the cilial Wnt/β-catenin signaling pathway, β-catenin, syn2 and Bcl-2, in the hippocampus, but not in the cerebral cortex of rats. These findings suggest that NMDAR hypofunction-induced dysregulation of CA1 primary cilia could be involved in the pathophysiology of dopamine transmission-independent symptoms of schizophrenia.
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114
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Dauvermann MR, Lee G, Dawson N. Glutamatergic regulation of cognition and functional brain connectivity: insights from pharmacological, genetic and translational schizophrenia research. Br J Pharmacol 2017. [PMID: 28626937 DOI: 10.1111/bph.13919] [Citation(s) in RCA: 53] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
The pharmacological modulation of glutamatergic neurotransmission to improve cognitive function has been a focus of intensive research, particularly in relation to the cognitive deficits seen in schizophrenia. Despite this effort, there has been little success in the clinical use of glutamatergic compounds as procognitive drugs. Here, we review a selection of the drugs used to modulate glutamatergic signalling and how they impact on cognitive function in rodents and humans. We highlight how glutamatergic dysfunction, and NMDA receptor hypofunction in particular, is a key mechanism contributing to the cognitive deficits observed in schizophrenia and outline some of the glutamatergic targets that have been tested as putative procognitive targets for this disorder. Using translational research in this area as a leading exemplar, namely, models of NMDA receptor hypofunction, we discuss how the study of functional brain network connectivity can provide new insight into how the glutamatergic system impacts on cognitive function. Future studies characterizing functional brain network connectivity will increase our understanding of how glutamatergic compounds regulate cognition and could contribute to the future success of glutamatergic drug validation. 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)
- Maria R Dauvermann
- School of Psychology, National University of Ireland, Galway, Ireland.,McGovern Institute for Brain Research, Massachusetts Institute of Technology, Cambridge, MA, USA
| | - Graham Lee
- McGovern Institute for Brain Research, Massachusetts Institute of Technology, Cambridge, MA, USA
| | - Neil Dawson
- Division of Biomedical and Life Sciences, Faculty of Health and Medicine, Lancaster University, Lancaster, UK
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115
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Lin CY, Liang SY, Chang YC, Ting SY, Kao CL, Wu YH, Tsai GE, Lane HY. Adjunctive sarcosine plus benzoate improved cognitive function in chronic schizophrenia patients with constant clinical symptoms: A randomised, double-blind, placebo-controlled trial. World J Biol Psychiatry 2017; 18:357-368. [PMID: 26691576 DOI: 10.3109/15622975.2015.1117654] [Citation(s) in RCA: 66] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Objectives Hypofunction of NMDA receptor is implicated in the pathophysiology, particularly cognitive impairment, of schizophrenia. Sarcosine, a glycine transporter I (GlyT-1) inhibitor, and sodium benzoate, a d-amino acid oxidase (DAAO) inhibitor, can both enhance NMDA receptor-mediated neurotransmission. We proposed simultaneously inhibiting DAAO and GlyT-1 may be more effective than inhibition of either in improving the cognitive and global functioning of schizophrenia patients. Methods This study compared add-on sarcosine (2 g/day) plus benzoate (1 g/day) vs. sarcosine (2 g/day) for the clinical symptoms, as well as the cognitive and global functioning, of chronic schizophrenia patients in a 12-week, double-blind, randomised, placebo-controlled trial. Participants were measured with the Positive and Negative Syndrome Scale and the Global Assessment of Functioning Scale every 3 weeks. Seven cognitive domains, recommended by the Measurement and Treatment Research to Improve Cognition in Schizophrenia Committee, were measured at weeks 0 and 12. Results Adjunctive sarcosine plus benzoate, but not sarcosine alone, improved the cognitive and global functioning of patients with schizophrenia, even when their clinical symptoms had not improved. Conclusions This finding suggests N-methyl-d-aspartate receptor-enhancement therapy can improve the cognitive function of patients with schizophrenia, further indicating this pro-cognitive effect can be primary without improvement in clinical symptoms.
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Affiliation(s)
- Chun-Yuan Lin
- a Graduate Institute of Clinical Medical Science, College of Medicine, China Medical University , Taichung , Taiwan.,b Tsaotun Psychiatric Center, Ministry of Health and Welfare , Nantou , Taiwan.,c National Changhua University of Education , Changhua , Taiwan
| | - Sun-Yuan Liang
- d Department of Psychiatry , Changhua Hospital, Ministry of Health and Welfare , Changhua , Taiwan
| | - Yue-Cune Chang
- e Department of Mathematics , Tamkang University , Taipei , Taiwan
| | - Shuo-Yen Ting
- d Department of Psychiatry , Changhua Hospital, Ministry of Health and Welfare , Changhua , Taiwan
| | - Ching-Ling Kao
- b Tsaotun Psychiatric Center, Ministry of Health and Welfare , Nantou , Taiwan
| | - Yu-Hsin Wu
- c National Changhua University of Education , Changhua , Taiwan.,f Feng-Yuan Hospital, Ministry of Health and Welfare , Taichung , Taiwan
| | - Guochuan E Tsai
- g Department of Psychiatry , Harbor-UCLA Medical Center , Torrance , CA , USA
| | - Hsien-Yuan Lane
- a Graduate Institute of Clinical Medical Science, College of Medicine, China Medical University , Taichung , Taiwan.,h Department of Psychiatry , China Medical University Hospital , Taichung , Taiwan
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The Role of GluN2C-Containing NMDA Receptors in Ketamine's Psychotogenic Action and in Schizophrenia Models. J Neurosci 2017; 36:11151-11157. [PMID: 27807157 DOI: 10.1523/jneurosci.1203-16.2016] [Citation(s) in RCA: 41] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2016] [Accepted: 09/14/2016] [Indexed: 11/21/2022] Open
Abstract
The NMDA receptor (NMDAR) hypofunction hypothesis of schizophrenia is supported by multiple lines of evidence. Notably, administration of the NMDAR antagonist, ketamine, to healthy human subjects has psychotogenic action, producing both positive and negative symptoms associated with schizophrenia. NMDARs have multiple subtypes, but the subtypes through which ketamine produces its psychotogenic effects are not known. Here we address this question using quantitative data that characterize ketamine's ability to block different NMDAR subtypes. Our calculations indicate that, at a concentration that has psychotogenic action in humans, ketamine blocks a substantial fraction of GluN2C subunit-containing receptors but has less effect on GluN2A-, GluN2B-, and GluN2D-containing receptors. Thus, GluN2C-containing receptors may have preferential involvement in psychotic states produced by ketamine. A separate line of experiments also points to a special role for GluN2C. That work demonstrates the ability of NMDAR antagonists to mimic the elevation in the awake-state δ frequency EEG power that occurs in schizophrenia. Physiological experiments in rodents show that NMDAR antagonists generate δ oscillations by their action on the GluN2C-containing NMDARs that are prevalent in the thalamus. Optogenetic experiments suggest that such oscillations could contribute to symptoms of schizophrenia.
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117
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Nagai T, Kirihara K, Tada M, Koshiyama D, Koike S, Suga M, Araki T, Hashimoto K, Kasai K. Reduced Mismatch Negativity is Associated with Increased Plasma Level of Glutamate in First-episode Psychosis. Sci Rep 2017; 7:2258. [PMID: 28536477 PMCID: PMC5442101 DOI: 10.1038/s41598-017-02267-1] [Citation(s) in RCA: 31] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2016] [Accepted: 04/10/2017] [Indexed: 01/17/2023] Open
Abstract
Reduced amplitude of mismatch negativity (MMN) is one of the more promising biological markers of schizophrenia. This finding holds true in both early and chronic phases of the disorder, and is compatible with the glutamatergic dysfunction hypothesis. To further establish MMN as a biomarker of aberrant glutamatergic neurotransmission, an exploration for an association with blood levels of glutamatergic amino acids is an important next step. Despite a large body of work investigating MMN in schizophrenia, no previous studies have undertaken this endeavor. Nineteen patients with first-episode psychosis (FEP), 21 ultra-high risk individuals (UHR), and 16 healthy controls (HC) participated in the study. The MMNs in response to duration change (dMMN) and frequency change (fMMN) were measured. The fasting plasma levels of glutamate, glutamine, glycine, D-serine, and L-serine were measured. dMMN amplitudes were significantly reduced in FEP and UHR, compared to HC. The plasma levels of glutamate of FEP were significantly higher than those of HC. Higher plasma levels of glutamate were associated with smaller dMMN amplitudes in the FEP and HC groups. These findings are compatible with the hypothesis that MMN is a useful biological marker of aberrant glutamatergic neurotransmission in the early stages of schizophrenia.
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Affiliation(s)
- Tatsuya Nagai
- Department of Psychiatry, Kawamuro Memorial Hospital 71-Ko, Ohaza, Kitashinpo, Joetsu-shi, Niigata-ken, 943-0109, Japan.,Department of Neuropsychiatry, Graduate School of Medicine, University of Tokyo7-3-1, Hongo, Bunkyo-ku, Tokyo, 113-8655, Japan
| | - Kenji Kirihara
- Department of Neuropsychiatry, Graduate School of Medicine, University of Tokyo7-3-1, Hongo, Bunkyo-ku, Tokyo, 113-8655, Japan
| | - Mariko Tada
- Department of Neuropsychiatry, Graduate School of Medicine, University of Tokyo7-3-1, Hongo, Bunkyo-ku, Tokyo, 113-8655, Japan
| | - Daisuke Koshiyama
- Department of Neuropsychiatry, Graduate School of Medicine, University of Tokyo7-3-1, Hongo, Bunkyo-ku, Tokyo, 113-8655, Japan
| | - Shinsuke Koike
- Office for Counseling and Support, Division for Mental Health Support, The University of Tokyo 7-3-1, Hongo, Bunkyo-ku, Tokyo, 113-8655, Japan
| | - Motomu Suga
- Department of Rehabilitation, Graduate School of Medicine, University of Tokyo 7-3-1, Hongo, Bunkyo-ku, Tokyo, 113-8655, Japan
| | - Tsuyoshi Araki
- Department of Youth Mental Health, Graduate School of Medicine, University of Tokyo 7-3-1, Hongo, Bunkyo-ku, Tokyo, 113-8655, Japan
| | - Kenji Hashimoto
- Division of Clinical Neuroscience, Chiba University Center for Forensic Mental Health 1-8-1, Inohana, Chuuoku-ku, Chiba-shi, Chiba-ken, 260-8670, Japan
| | - Kiyoto Kasai
- Department of Neuropsychiatry, Graduate School of Medicine, University of Tokyo7-3-1, Hongo, Bunkyo-ku, Tokyo, 113-8655, Japan.
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Millière R. Looking for the Self: Phenomenology, Neurophysiology and Philosophical Significance of Drug-induced Ego Dissolution. Front Hum Neurosci 2017; 11:245. [PMID: 28588463 PMCID: PMC5441112 DOI: 10.3389/fnhum.2017.00245] [Citation(s) in RCA: 86] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2016] [Accepted: 04/25/2017] [Indexed: 12/17/2022] Open
Abstract
There is converging evidence that high doses of hallucinogenic drugs can produce significant alterations of self-experience, described as the dissolution of the sense of self and the loss of boundaries between self and world. This article discusses the relevance of this phenomenon, known as “drug-induced ego dissolution (DIED)”, for cognitive neuroscience, psychology and philosophy of mind. Data from self-report questionnaires suggest that three neuropharmacological classes of drugs can induce ego dissolution: classical psychedelics, dissociative anesthetics and agonists of the kappa opioid receptor (KOR). While these substances act on different neurotransmitter receptors, they all produce strong subjective effects that can be compared to the symptoms of acute psychosis, including ego dissolution. It has been suggested that neuroimaging of DIED can indirectly shed light on the neural correlates of the self. While this line of inquiry is promising, its results must be interpreted with caution. First, neural correlates of ego dissolution might reveal the necessary neurophysiological conditions for the maintenance of the sense of self, but it is more doubtful that this method can reveal its minimally sufficient conditions. Second, it is necessary to define the relevant notion of self at play in the phenomenon of DIED. This article suggests that DIED consists in the disruption of subpersonal processes underlying the “minimal” or “embodied” self, i.e., the basic experience of being a self rooted in multimodal integration of self-related stimuli. This hypothesis is consistent with Bayesian models of phenomenal selfhood, according to which the subjective structure of conscious experience ultimately results from the optimization of predictions in perception and action. Finally, it is argued that DIED is also of particular interest for philosophy of mind. On the one hand, it challenges theories according to which consciousness always involves self-awareness. On the other hand, it suggests that ordinary conscious experience might involve a minimal kind of self-awareness rooted in multisensory processing, which is what appears to fade away during DIED.
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Affiliation(s)
- Raphaël Millière
- Faculty of Philosophy, University of OxfordOxford, United Kingdom
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119
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Impey D, de la Salle S, Baddeley A, Knott V. Effects of an NMDA antagonist on the auditory mismatch negativity response to transcranial direct current stimulation. J Psychopharmacol 2017; 31:614-624. [PMID: 27624152 DOI: 10.1177/0269881116665336] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Transcranial direct current stimulation (tDCS) is a non-invasive form of brain stimulation which uses a weak constant current to alter cortical excitability and activity temporarily. tDCS-induced increases in neuronal excitability and performance improvements have been observed following anodal stimulation of brain regions associated with visual and motor functions, but relatively little research has been conducted with respect to auditory processing. Recently, pilot study results indicate that anodal tDCS can increase auditory deviance detection, whereas cathodal tDCS decreases auditory processing, as measured by a brain-based event-related potential (ERP), mismatch negativity (MMN). As evidence has shown that tDCS lasting effects may be dependent on N-methyl-D-aspartate (NMDA) receptor activity, the current study investigated the use of dextromethorphan (DMO), an NMDA antagonist, to assess possible modulation of tDCS's effects on both MMN and working memory performance. The study, conducted in 12 healthy volunteers, involved four laboratory test sessions within a randomised, placebo and sham-controlled crossover design that compared pre- and post-anodal tDCS over the auditory cortex (2 mA for 20 minutes to excite cortical activity temporarily and locally) and sham stimulation (i.e. device is turned off) during both DMO (50 mL) and placebo administration. Anodal tDCS increased MMN amplitudes with placebo administration. Significant increases were not seen with sham stimulation or with anodal stimulation during DMO administration. With sham stimulation (i.e. no stimulation), DMO decreased MMN amplitudes. Findings from this study contribute to the understanding of underlying neurobiological mechanisms mediating tDCS sensory and memory improvements.
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Affiliation(s)
- Danielle Impey
- 1 Clinical Neuroelectrophysiology and Cognitive Research Laboratory, University of Ottawa Institute of Mental Health Research, Ottawa, Canada.,2 School of Psychology, University of Ottawa, Ottawa, Canada
| | - Sara de la Salle
- 1 Clinical Neuroelectrophysiology and Cognitive Research Laboratory, University of Ottawa Institute of Mental Health Research, Ottawa, Canada.,2 School of Psychology, University of Ottawa, Ottawa, Canada
| | - Ashley Baddeley
- 1 Clinical Neuroelectrophysiology and Cognitive Research Laboratory, University of Ottawa Institute of Mental Health Research, Ottawa, Canada
| | - Verner Knott
- 1 Clinical Neuroelectrophysiology and Cognitive Research Laboratory, University of Ottawa Institute of Mental Health Research, Ottawa, Canada.,2 School of Psychology, University of Ottawa, Ottawa, Canada
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120
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Rapado-Castro M, Dodd S, Bush AI, Malhi GS, Skvarc DR, On ZX, Berk M, Dean OM. Cognitive effects of adjunctive N-acetyl cysteine in psychosis. Psychol Med 2017; 47:866-876. [PMID: 27894373 DOI: 10.1017/s0033291716002932] [Citation(s) in RCA: 72] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
BACKGROUND Cognitive deficits are predictors of functional outcome in patients with psychosis. While conventional antipsychotics are relatively effective on positive symptoms, their impact on negative and cognitive symptoms is limited. Recent studies have established a link between oxidative stress and neurocognitive deficits in psychosis. N-acetylcysteine (NAC), a glutathione precursor with glutamatergic properties, has shown efficacy on negative symptoms and functioning in patients with schizophrenia and bipolar disorder, respectively. However, there are few evidence-based approaches for managing cognitive impairment in psychosis. The present study aims to examine the cognitive effects of adjunctive NAC treatment in a pooled subgroup of participants with psychosis who completed neuropsychological assessment in two trials of both schizophrenia and bipolar disorder. METHOD A sample of 58 participants were randomized in a double fashion to receive 2 g/day of NAC (n = 27) or placebo (n = 31) for 24 weeks. Attention, working memory and executive function domains were assessed. Differences between cognitive performance at baseline and end point were examined using Wilcoxon's test. The Mann-Whitney test was used to examine the differences between the NAC and placebo groups at the end point. RESULTS Participants treated with NAC had significantly higher working memory performance at week 24 compared with placebo (U = 98.5, p = 0.027). CONCLUSIONS NAC may have an impact on cognitive performance in psychosis, as a significant improvement in working memory was observed in the NAC-treated group compared with placebo; however, these preliminary data require replication. Glutamatergic compounds such as NAC may constitute a step towards the development of useful therapies for cognitive impairment in psychosis.
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Affiliation(s)
- M Rapado-Castro
- Child and Adolescent Psychiatry Department,Hospital General Universitario Gregorio Marañón,School of Medicine,Universidad Complutense,IiSGM,CIBERSAM,Madrid,Spain
| | - S Dodd
- Deakin University, IMPACT Strategic Research Centre, School of Medicine,Barwon Health,PO Box 291,Geelong,Victoria,Australia
| | - A I Bush
- Department of Psychiatry,University of Melbourne,Level 1 North,Main Block,Royal Melbourne Hospital,Parkville,Victoria,Australia
| | - G S Malhi
- Academic Department of Psychiatry,Kolling Institute,Northern Sydney Local Health District,St Leonards,NSW,Australia
| | - D R Skvarc
- Deakin University, IMPACT Strategic Research Centre, School of Medicine,Barwon Health,PO Box 291,Geelong,Victoria,Australia
| | - Z X On
- Melbourne School of Psychological Sciences,University of Melbourne,Level 12,Redmond Barry Building 115,Parkville,Victoria,Australia
| | - M Berk
- Orygen, The National Centre of Excellence in Youth Mental Health,Victoria,Australia
| | - O M Dean
- Deakin University, IMPACT Strategic Research Centre, School of Medicine,Barwon Health,PO Box 291,Geelong,Victoria,Australia
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121
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Role of N-Methyl-D-Aspartate Receptors in Action-Based Predictive Coding Deficits in Schizophrenia. Biol Psychiatry 2017; 81:514-524. [PMID: 27647218 PMCID: PMC5203970 DOI: 10.1016/j.biopsych.2016.06.019] [Citation(s) in RCA: 36] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/26/2016] [Revised: 06/24/2016] [Accepted: 06/27/2016] [Indexed: 01/25/2023]
Abstract
BACKGROUND Recent theoretical models of schizophrenia posit that dysfunction of the neural mechanisms subserving predictive coding contributes to symptoms and cognitive deficits, and this dysfunction is further posited to result from N-methyl-D-aspartate glutamate receptor (NMDAR) hypofunction. Previously, by examining auditory cortical responses to self-generated speech sounds, we demonstrated that predictive coding during vocalization is disrupted in schizophrenia. To test the hypothesized contribution of NMDAR hypofunction to this disruption, we examined the effects of the NMDAR antagonist, ketamine, on predictive coding during vocalization in healthy volunteers and compared them with the effects of schizophrenia. METHODS In two separate studies, the N1 component of the event-related potential elicited by speech sounds during vocalization (talk) and passive playback (listen) were compared to assess the degree of N1 suppression during vocalization, a putative measure of auditory predictive coding. In the crossover study, 31 healthy volunteers completed two randomly ordered test days, a saline day and a ketamine day. Event-related potentials during the talk/listen task were obtained before infusion and during infusion on both days, and N1 amplitudes were compared across days. In the case-control study, N1 amplitudes from 34 schizophrenia patients and 33 healthy control volunteers were compared. RESULTS N1 suppression to self-produced vocalizations was significantly and similarly diminished by ketamine (Cohen's d = 1.14) and schizophrenia (Cohen's d = .85). CONCLUSIONS Disruption of NMDARs causes dysfunction in predictive coding during vocalization in a manner similar to the dysfunction observed in schizophrenia patients, consistent with the theorized contribution of NMDAR hypofunction to predictive coding deficits in schizophrenia.
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123
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Atkinson RJ, Fulham WR, Michie PT, Ward PB, Todd J, Stain H, Langdon R, Thienel R, Paulik G, Cooper G, Schall U. Electrophysiological, cognitive and clinical profiles of at-risk mental state: The longitudinal Minds in Transition (MinT) study. PLoS One 2017; 12:e0171657. [PMID: 28187217 PMCID: PMC5302824 DOI: 10.1371/journal.pone.0171657] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2016] [Accepted: 01/24/2017] [Indexed: 12/22/2022] Open
Abstract
The onset of schizophrenia is typically preceded by a prodromal period lasting several years during which sub-threshold symptoms may be identified retrospectively. Clinical interviews are currently used to identify individuals who have an ultra-high risk (UHR) of developing a psychotic illness with a view to provision of interventions that prevent, delay or reduce severity of future mental health issues. The utility of bio-markers as an adjunct in the identification of UHR individuals is not yet established. Several event-related potential measures, especially mismatch-negativity (MMN), have been identified as potential biomarkers for schizophrenia. In this 12-month longitudinal study, demographic, clinical and neuropsychological data were acquired from 102 anti-psychotic naive UHR and 61 healthy controls, of whom 80 UHR and 58 controls provided valid EEG data during a passive auditory task at baseline. Despite widespread differences between UHR and controls on demographic, clinical and neuropsychological measures, MMN and P3a did not differ between these groups. Of 67 UHR at the 12-month follow-up, 7 (10%) had transitioned to a psychotic illness. The statistical power to detect differences between those who did or did not transition was limited by the lower than expected transition rate. ERPs did not predict transition, with trends in the opposite direction to that predicted. In exploratory analysis, the strongest predictors of transition were measures of verbal memory and subjective emotional disturbance.
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Affiliation(s)
- Rebbekah J. Atkinson
- Centre for Brain and Mental Health Research, University of Newcastle, Newcastle, New South Wales, Australia
- Hunter Medical Research Institute, Newcastle, New South Wales, Australia
- Schizophrenia Research Institute, Darlinghurst, New South Wales, Australia
| | - W. Ross Fulham
- Centre for Brain and Mental Health Research, University of Newcastle, Newcastle, New South Wales, Australia
- Hunter Medical Research Institute, Newcastle, New South Wales, Australia
- Schizophrenia Research Institute, Darlinghurst, New South Wales, Australia
- * E-mail:
| | - Patricia T. Michie
- Centre for Brain and Mental Health Research, University of Newcastle, Newcastle, New South Wales, Australia
- Hunter Medical Research Institute, Newcastle, New South Wales, Australia
- Schizophrenia Research Institute, Darlinghurst, New South Wales, Australia
- School of Psychology, University of Newcastle, Newcastle, New South Wales, Australia
| | - Philip B. Ward
- School of Medicine and Population Health, University of New South Wales, Sydney, New South Wales, Australia
- Schizophrenia Research Unit, South Western Sydney Local Health District, Sydney, New South Wales, Australia
| | - Juanita Todd
- Centre for Brain and Mental Health Research, University of Newcastle, Newcastle, New South Wales, Australia
- Schizophrenia Research Institute, Darlinghurst, New South Wales, Australia
- School of Psychology, University of Newcastle, Newcastle, New South Wales, Australia
| | - Helen Stain
- Centre for Rural and Remote Mental Health, Bloomfield Hospital, Orange, New South Wales, Australia
- School of Social and Health Sciences, Leeds Trinity University, Horsforth Leeds, United Kingdom
| | - Robyn Langdon
- Schizophrenia Research Institute, Darlinghurst, New South Wales, Australia
- ARC Centre of Excellence in Cognition and Its Disorders, Macquarie University, Sydney, New South Wales, Australia
- Department of Cognitive Science, Macquarie University, Sydney, New South Wales, Australia
| | - Renate Thienel
- Centre for Brain and Mental Health Research, University of Newcastle, Newcastle, New South Wales, Australia
- Hunter Medical Research Institute, Newcastle, New South Wales, Australia
- Schizophrenia Research Institute, Darlinghurst, New South Wales, Australia
- Hunter Institute for Mental Health, Newcastle, New South Wales, Australia
| | - Georgie Paulik
- Schizophrenia Research Institute, Darlinghurst, New South Wales, Australia
- School of Psychology, University of Western Australia, Nedlands, Western Australia, Australia
- School of Psychology and Exercise Science, Murdoch University, Murdoch, Western Australia, Australia
| | - Gavin Cooper
- Centre for Brain and Mental Health Research, University of Newcastle, Newcastle, New South Wales, Australia
- Schizophrenia Research Institute, Darlinghurst, New South Wales, Australia
| | | | - Ulrich Schall
- Centre for Brain and Mental Health Research, University of Newcastle, Newcastle, New South Wales, Australia
- Hunter Medical Research Institute, Newcastle, New South Wales, Australia
- Schizophrenia Research Institute, Darlinghurst, New South Wales, Australia
- Hunter New England Health, Newcastle, Australia
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Giraldo-Chica M, Woodward ND. Review of thalamocortical resting-state fMRI studies in schizophrenia. Schizophr Res 2017; 180:58-63. [PMID: 27531067 PMCID: PMC5297399 DOI: 10.1016/j.schres.2016.08.005] [Citation(s) in RCA: 140] [Impact Index Per Article: 20.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/02/2016] [Revised: 08/03/2016] [Accepted: 08/06/2016] [Indexed: 12/19/2022]
Abstract
Brain circuitry underlying cognition, emotion, and perception is abnormal in schizophrenia. There is considerable evidence that the neuropathology of schizophrenia includes the thalamus, a key hub of cortical-subcortical circuitry and an important regulator of cortical activity. However, the thalamus is a heterogeneous structure composed of several nuclei with distinct inputs and cortical connections. Limitations of conventional neuroimaging methods and conflicting findings from post-mortem investigations have made it difficult to determine if thalamic pathology in schizophrenia is widespread or limited to specific thalamocortical circuits. Resting-state fMRI has proven invaluable for understanding the large-scale functional organization of the brain and investigating neural circuitry relevant to psychiatric disorders. This article summarizes resting-state fMRI investigations of thalamocortical functional connectivity in schizophrenia. Particular attention is paid to the course, diagnostic specificity, and clinical correlates of thalamocortical network dysfunction.
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125
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Schnakenberg Martin AM, O’Donnell BF, Millward JB, Vohs JL, Leishman E, Bolbecker AR, Rass O, Morzorati SL. Acute Phencyclidine Alters Neural Oscillations Evoked by Tones in the Auditory Cortex of Rats. Neuropsychobiology 2017; 75:53-62. [PMID: 29065422 PMCID: PMC5752597 DOI: 10.1159/000480511] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/01/2016] [Accepted: 08/21/2017] [Indexed: 11/19/2022]
Abstract
BACKGROUND/AIMS The onset response to a single tone as measured by electroencephalography (EEG) is diminished in power and synchrony in schizophrenia. Because neural synchrony, particularly at gamma frequencies (30-80 Hz), is hypothesized to be supported by the N-methyl-D-aspartate receptor (NMDAr) system, we tested whether phencyclidine (PCP), an NMDAr antagonist, produced similar deficits to tone stimuli in rats. METHODS Experiment 1 tested the effect of a PCP dose (1.0, 2.5, and 4.5 mg/kg) on response to single tones on intracranial EEG recorded over the auditory cortex in rats. Experiment 2 evaluated the effect of PCP after acute administration of saline or PCP (5 mg/kg), after continuous subchronic administration of saline or PCP (5 mg/kg/day), and after a week of drug cessation. In both experiments, a time-frequency analysis quantified mean power (MP) and phase locking factor (PLF) between 1 and 80 Hz. Event-related potentials (ERPs) were also measured to tones, and EEG spectral power in the absence of auditory stimuli. RESULTS Acute PCP increased PLF and MP between 10 and 30 Hz, while decreasing MP and PLF between approximately 50 and 70 Hz. Acute PCP produced a dose-dependent broad-band increase in EEG power that extended into gamma range frequencies. There were no consistent effects of subchronic administration on gamma range activity. Acute PCP increased ERP amplitudes for the P16 and N70 components. CONCLUSIONS Findings suggest that acute PCP-induced NMDAr hypofunction has differential effects on neural power and synchrony which vary with dose, time course of administration and EEG frequency. EEG synchrony and power appear to be sensitive translational biomarkers for disrupted NMDAr function, which may contribute to the pathophysiology of schizophrenia and other neuropsychiatric disorders.
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Affiliation(s)
- Ashley M. Schnakenberg Martin
- Department of Psychological and Brain Sciences, Indiana University-Bloomington, 1101 E. 10 Street, Bloomington, Indiana 47405, United States of America,Larue D. Carter Memorial Hospital, 2601 Cold Springs Road, Indianapolis, Indiana 46222, United States of America,Corresponding author: Ashley M. Schnakenberg Martin, Department of Psychological and Brain Sciences, Indiana University-Bloomington, 1101 East 10 Street, Bloomington, Indiana 47405, United States of America, Phone: 812-856-4676,
| | - Brian F. O’Donnell
- Department of Psychological and Brain Sciences, Indiana University-Bloomington, 1101 E. 10 Street, Bloomington, Indiana 47405, United States of America,Department of Psychiatry, Indiana University School of Medicine, 340 West 10 Street, Suite 6200, Indianapolis, Indiana 46202, United States of America,Larue D. Carter Memorial Hospital, 2601 Cold Springs Road, Indianapolis, Indiana 46222, United States of America
| | - James B. Millward
- Department of Psychiatry, Indiana University School of Medicine, 340 West 10 Street, Suite 6200, Indianapolis, Indiana 46202, United States of America,Department of Psychiatry, Institute of Psychiatric Research, 791 Union Drive, Indianapolis, Indiana 46202
| | - Jenifer L. Vohs
- Department of Psychological and Brain Sciences, Indiana University-Bloomington, 1101 E. 10 Street, Bloomington, Indiana 47405, United States of America,Department of Psychiatry, Indiana University School of Medicine, 340 West 10 Street, Suite 6200, Indianapolis, Indiana 46202, United States of America,Larue D. Carter Memorial Hospital, 2601 Cold Springs Road, Indianapolis, Indiana 46222, United States of America
| | - Emma Leishman
- Department of Psychological and Brain Sciences, Indiana University-Bloomington, 1101 E. 10 Street, Bloomington, Indiana 47405, United States of America
| | - Amanda R. Bolbecker
- Department of Psychological and Brain Sciences, Indiana University-Bloomington, 1101 E. 10 Street, Bloomington, Indiana 47405, United States of America,Department of Psychiatry, Indiana University School of Medicine, 340 West 10 Street, Suite 6200, Indianapolis, Indiana 46202, United States of America,Larue D. Carter Memorial Hospital, 2601 Cold Springs Road, Indianapolis, Indiana 46222, United States of America
| | - Olga Rass
- Department of Psychological and Brain Sciences, Indiana University-Bloomington, 1101 E. 10 Street, Bloomington, Indiana 47405, United States of America
| | - Sandra L. Morzorati
- Department of Psychiatry, Indiana University School of Medicine, 340 West 10 Street, Suite 6200, Indianapolis, Indiana 46202, United States of America,Department of Psychiatry, Institute of Psychiatric Research, 791 Union Drive, Indianapolis, Indiana 46202
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126
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Dorner-Ciossek C, Kroker KS, Rosenbrock H. Role of PDE9 in Cognition. ADVANCES IN NEUROBIOLOGY 2017; 17:231-254. [DOI: 10.1007/978-3-319-58811-7_9] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
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127
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El-Tallawy HN, Saleem TH, El-Ebidi AM, Hassan MH, Gabra RH, Farghaly WM, Abo El-Maali N, Sherkawy HS. Clinical and biochemical study of d-serine metabolism among schizophrenia patients. Neuropsychiatr Dis Treat 2017; 13:1057-1063. [PMID: 28435276 PMCID: PMC5391825 DOI: 10.2147/ndt.s126979] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
BACKGROUND Schizophrenia is a typical N-methyl-d-aspartate receptor (NMDA-R) hypofunction disorder. Decreased d-serine (d-Ser) levels in the periphery occur in schizophrenia and may reflect decreased availability of d-Ser to activate NMDA-R in the brain. OBJECTIVE The objective of this study was to investigate the role of d-Ser metabolism in the pathogenesis of schizophrenia via biochemical assays and correlates, the serum level of d-Ser, d-serine racemase (SR) (responsible for its formation from l-serine [l-Ser]) and d-amino acid oxidase (DAAO) (responsible for its catabolism), among different clinical types of schizophrenia patients. PATIENTS AND METHODS This cross-sectional case-control study was carried out on 100 patients and 50 controls. They were recruited from the outpatients' psychiatric unit of the Neuropsychiatric Department of Assiut University Hospital, Upper Egypt. The type of schizophrenia was determined according to the Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition (DSM-IV), while the severity of schizophrenia was determined according to the Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition (DSM-5). Serum d-Ser levels were estimated using high-performance liquid chromatography (HPLC), while serum SR and DAAO were measured using commercially available enzyme-linked immunosorbent assay kits. RESULTS There were significantly lower mean serum levels of d-Ser and SR and significantly higher mean serum levels of DAAO (P-value <0.01 for each) among schizophrenia patients when compared with the control group. Paranoid schizophrenia had the highest frequency, with a significantly lower serum levels of d-Ser and SR in the residual type and significantly higher serum levels of DAAO in undifferentiated and catatonic types. Combined receiver-operating characteristic curve for serum d-Ser, SR and DAAO indicated that the best serum level cutoff points at which schizophrenia manifestations started to appear were ≤ 61.4 mg/L for d-Ser, ≤ 15.5 pg/mL for SR and >35.6 pg/mL for DAAO. CONCLUSION The present study confirms that disturbed d-Ser metabolism could be implicated in the pathogenesis of schizophrenia.
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Affiliation(s)
| | - Tahia H Saleem
- Department of Medical Biochemistry and Molecular Biology, Faculty of Medicine, Assiut University, Assiut
| | - Abdallah Maa El-Ebidi
- Department of Medical Biochemistry and Molecular Biology, Faculty of Medicine, Aswan University, Aswan
| | - Mohammed H Hassan
- Department of Medical Biochemistry and Molecular Biology, Qena Faculty of Medicine, South Valley University, Qena
| | | | | | - Nagwa Abo El-Maali
- Department of Chemistry, Faculty of Science, Assiut University, Assiut, Egypt
| | - Hoda S Sherkawy
- Department of Medical Biochemistry and Molecular Biology, Faculty of Medicine, Aswan University, Aswan
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128
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Taylor R, Osuch EA, Schaefer B, Rajakumar N, Neufeld RWJ, Théberge J, Williamson PC. Neurometabolic abnormalities in schizophrenia and depression observed with magnetic resonance spectroscopy at 7 T. BJPsych Open 2017; 3:6-11. [PMID: 28243459 PMCID: PMC5288640 DOI: 10.1192/bjpo.bp.116.003756] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/15/2016] [Revised: 11/26/2016] [Accepted: 01/05/2017] [Indexed: 01/01/2023] Open
Abstract
BACKGROUND Examining neurometabolic abnormalities in critical brain areas in schizophrenia and major depressive disorder (MDD) may help guide future pharmacological interventions including glutamate-modulating treatments. AIMS To measure metabolite concentrations within the anterior cingulate cortex (ACC) and thalamus of people with schizophrenia and people with MDD. METHODS Spectra were acquired from 16 volunteers with schizophrenia, 17 with MDD and 18 healthy controls using magnetic resonance spectroscopy on a 7 Tesla scanner. RESULTS In the thalamus, there were lower glycine concentrations in the schizophrenia group relative to control (P=0.017) and MDD groups (P=0.012), and higher glutamine concentrations relative to healthy controls (P=0.009). In the thalamus and the ACC, the MDD group had lower myo-inositol concentrations than the control (P=0.014, P=0.009, respectively) and schizophrenia (P=0.004, P=0.002, respectively) groups. CONCLUSION These results support the glutamatergic theory of schizophrenia and indicate a potential glycine deficiency in the thalamus. In addition, reduced myo-inositol concentrations in MDD suggest its involvement in the disorder. DECLARATION OF INTEREST None. COPYRIGHT AND USAGE © The Royal College of Psychiatrists 2017. This is an open access article distributed under the terms of the Creative Commons Non-Commercial, No Derivatives (CC BY-NC-ND) license.
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Affiliation(s)
- Reggie Taylor
- , PhD, Department of Medical Biophysics, University of Western Ontario, London, Ontario, Canada; Lawson Health Research Institute, London, Ontario, Canada
| | - Elizabeth A Osuch
- , MD, Department of Medical Biophysics; Department of Psychiatry, University of Western Ontario, London, Ontario, Canada
| | - Betsy Schaefer
- , BSc, Department of Psychiatry, University of Western Ontario, London, Ontario, Canada
| | - Nagalingam Rajakumar
- , PhD, Department of Anatomy and Cell Biology, University of Western Ontario, London, Ontario, Canada
| | - Richard W J Neufeld
- , PhD, Department of Psychology; Department of Neuroscience, University of Western Ontario, London, Ontario, Canada
| | - Jean Théberge
- , PhD, Department of Medical Biophysics, Department of Psychiatry, Department of Medical Imaging, University of Western Ontario, London, Ontario, Canada; Lawson Health Research Institute, London, Ontario, Canada; St. Joseph's Health Care, Department of Diagnostic Imaging, London, Ontario, Canada
| | - Peter C Williamson
- , MD, Department of Medical Biophysics, Department of Psychiatry, University of Western Ontario, London, Ontario, Canada; Lawson Health Research Institute, London, Ontario, Canada
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129
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Hansen KB, Yi F, Perszyk RE, Menniti FS, Traynelis SF. NMDA Receptors in the Central Nervous System. Methods Mol Biol 2017; 1677:1-80. [PMID: 28986865 DOI: 10.1007/978-1-4939-7321-7_1] [Citation(s) in RCA: 99] [Impact Index Per Article: 14.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
NMDA-type glutamate receptors are ligand-gated ion channels that mediate a major component of excitatory neurotransmission in the central nervous system (CNS). They are widely distributed at all stages of development and are critically involved in normal brain functions, including neuronal development and synaptic plasticity. NMDA receptors are also implicated in the pathophysiology of numerous neurological and psychiatric disorders, such as ischemic stroke, traumatic brain injury, Alzheimer's disease, epilepsy, mood disorders, and schizophrenia. For these reasons, NMDA receptors have been intensively studied in the past several decades to elucidate their physiological roles and to advance them as therapeutic targets. Seven NMDA receptor subunits exist that assemble into a diverse array of tetrameric receptor complexes, which are differently regulated, have distinct regional and developmental expression, and possess a wide range of functional and pharmacological properties. The diversity in subunit composition creates NMDA receptor subtypes with distinct physiological roles across neuronal cell types and brain regions, and enables precise tuning of synaptic transmission. Here, we will review the relationship between NMDA receptor structure and function, the diversity and significance of NMDA receptor subtypes in the CNS, as well as principles and rules by which NMDA receptors operate in the CNS under normal and pathological conditions.
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Affiliation(s)
- Kasper B Hansen
- Department of Biomedical and Pharmaceutical Sciences, University of Montana, Missoula, MT, USA. .,Center for Biomolecular Structure and Dynamics, University of Montana, Missoula, MT, USA.
| | - Feng Yi
- Department of Biomedical and Pharmaceutical Sciences, University of Montana, Missoula, MT, USA
| | - Riley E Perszyk
- Department of Pharmacology, Emory University School of Medicine, Atlanta, GA, USA
| | - Frank S Menniti
- MindImmune Therapeutics, Inc., George & Anne Ryan Institute for Neuroscience, Kingston, RI, USA
| | - Stephen F Traynelis
- Department of Pharmacology, Emory University School of Medicine, Atlanta, GA, USA
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130
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Al-Diwani A, Pollak TA, Langford AE, Lennox BR. Synaptic and Neuronal Autoantibody-Associated Psychiatric Syndromes: Controversies and Hypotheses. Front Psychiatry 2017; 8:13. [PMID: 28220082 PMCID: PMC5292436 DOI: 10.3389/fpsyt.2017.00013] [Citation(s) in RCA: 41] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/28/2016] [Accepted: 01/17/2017] [Indexed: 12/26/2022] Open
Abstract
Autoimmune encephalitis (AE) mediated by antibodies against synaptic and neuronal surface targets frequently presents with a psychiatric syndrome. In these patients, removal of autoantibodies treats the disease and outcomes are closely linked to early intervention. The discovery of these autoantibodies in isolated psychiatric syndromes has raised the possibility that these patients may derive similar benefits from immunotherapy, a potentially transformational approach to the treatment of mental illness. Although open-label case series suggest impressive therapeutic outcomes, the pathological relevance of these autoantibodies outside of canonical presentations is debated. The advent of diagnostic criteria for AE attempts to facilitate its prompt identification but risks prematurely neglecting the potential scientific and clinical significance of isolated syndromes that do not satisfy these criteria. Here, we propose using a syndrome-level taxonomy that has occasional, but not necessary, overlap with AE: synaptic and neuronal autoantibody-associated psychiatric syndromes or "SNAps". This will prevent confusion with AE and act heuristically to promote active investigation into this rare example of psychopathology defined on a molecular level. We suggest that this concept would have application in other autoantibody-associated syndromes including seizure, cognitive, and movement disorders, in which similar issues arise. We review putative direct and indirect mechanisms and outline experimentally testable hypotheses that would help to determine prospectively in whom autoantibody detection is relevant, and as important, in whom it is not. We summarize a pragmatic approach to autoantibody testing and management in severe mental illness in order to promptly diagnose AE and advocate a research-orientated experimental medicine paradigm for SNAps, where there is greater equipoise. We conclude that SNAps remains a nascent area of clinical neuroscience with great potential and in ongoing need of psychiatry-led basic and clinical research.
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Affiliation(s)
- Adam Al-Diwani
- Department of Psychiatry, University of Oxford, Warneford Hospital, Oxford, UK; Oxford Health NHS Foundation Trust, Oxford, Oxfordshire, UK
| | - Thomas A Pollak
- Department of Psychosis Studies, Institute of Psychiatry, Psychology and Neuroscience, King's Health Partners , London , UK
| | - Alexander E Langford
- Oxford Health NHS Foundation Trust, Oxford, Oxfordshire, UK; Department of Psychological Medicine, Oxford University Hospitals NHS Foundation Trust, John Radcliffe Hospital, Oxford, UK
| | - Belinda R Lennox
- Department of Psychiatry, University of Oxford, Warneford Hospital, Oxford, UK; Oxford Health NHS Foundation Trust, Oxford, Oxfordshire, UK
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131
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Kim M, Cho KIK, Yoon YB, Lee TY, Kwon JS. Aberrant temporal behavior of mismatch negativity generators in schizophrenia patients and subjects at clinical high risk for psychosis. Clin Neurophysiol 2016; 128:331-339. [PMID: 28056388 DOI: 10.1016/j.clinph.2016.11.027] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2016] [Revised: 11/23/2016] [Accepted: 11/26/2016] [Indexed: 12/21/2022]
Abstract
OBJECTIVE Although disconnection syndrome has been considered a core pathophysiologic mechanism of schizophrenia, little is known about the temporal behavior of mismatch negativity (MMN) generators in individuals with schizophrenia or clinical high risk (CHR) for psychosis. METHODS MMN was assessed in 29 schizophrenia patients, 40 CHR subjects, and 47 healthy controls (HCs). Individual realistic head models and the minimum L2 norm algorithm were used to generate a current source density (CSD) model of MMN. The strength and time course of MMN CSD activity were calculated separately for the frontal and temporal cortices and were compared across brain regions and groups. RESULTS Schizophrenia patients and CHR subjects displayed lower MMN CSD strength than HCs in both the temporal and frontal cortices. We found a significant time delay in MMN generator activity in the frontal cortex relative to that in the temporal cortex in HCs. However, the sequential temporo-frontal activities of MMN generators were disrupted in both the schizophrenia and CHR groups. CONCLUSIONS Impairments and altered temporal behavior of MMN multiple generators were observed even in individuals at risk for psychosis. SIGNIFICANCE These findings suggest that aberrant MMN generator activity might be helpful in revealing the pathophysiology of schizophrenia.
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Affiliation(s)
- Minah Kim
- Department of Psychiatry, Seoul National University College of Medicine, Seoul, Republic of Korea
| | - Kang Ik Kevin Cho
- Department of Brain and Cognitive Science, Seoul National University College of Natural Science, Seoul, Republic of Korea
| | - Youngwoo Bryan Yoon
- Department of Brain and Cognitive Science, Seoul National University College of Natural Science, Seoul, Republic of Korea
| | - Tae Young Lee
- Department of Neuropsychiatry, Seoul National University Hospital, Seoul, Republic of Korea
| | - Jun Soo Kwon
- Department of Psychiatry, Seoul National University College of Medicine, Seoul, Republic of Korea; Department of Brain and Cognitive Science, Seoul National University College of Natural Science, Seoul, Republic of Korea; Institute of Human Behavioral Medicine, SNU-MRC, Seoul, Republic of Korea.
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132
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Fujita Y, Ishima T, Hashimoto K. Supplementation with D-serine prevents the onset of cognitive deficits in adult offspring after maternal immune activation. Sci Rep 2016; 6:37261. [PMID: 27853241 PMCID: PMC5112512 DOI: 10.1038/srep37261] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2016] [Accepted: 10/26/2016] [Indexed: 12/26/2022] Open
Abstract
Prenatal maternal infection contributes to the etiology of schizophrenia, with D-serine, an endogenous co-agonist of the N-methyl-D-aspartate (NMDA) receptor, playing a role in the pathophysiology of this disease. We examined whether supplementation with D-serine during juvenile and adolescent stages could prevent the onset of cognitive deficits, prodromal and the core symptoms of schizophrenia in adult offspring after maternal immune activation (MIA). Juvenile offspring exposed prenatally to poly(I:C) showed reduced expression of NMDA receptor subunits in the hippocampus. Supplementing drinking water with D-serine (600 mg/L from P28 to P56) prevented the onset of cognitive deficits in adult offspring after MIA, in a significant manner. This study shows that supplementing offspring with D-serine during juvenile and adolescent stages could prevent the onset of psychosis in adulthood, after MIA. Therefore, early intervention with D-serine may prevent the occurrence of psychosis in high-risk subjects.
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Affiliation(s)
- Yuko Fujita
- Division of Clinical Neuroscience, Chiba University Center for Forensic Mental Health, Chiba 260-8670, Japan
| | - Tamaki Ishima
- Division of Clinical Neuroscience, Chiba University Center for Forensic Mental Health, Chiba 260-8670, Japan
| | - Kenji Hashimoto
- Division of Clinical Neuroscience, Chiba University Center for Forensic Mental Health, Chiba 260-8670, Japan
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Cunill V, Arboleya S, Jiménez MDLR, Campins A, Herbera P, Mestre LL, Clemente A, Barceló MI, Leyes M, Canellas F, Julià MR. Neuronal surface antibodies in HIV-infected patients with isolated psychosis. J Neuroimmunol 2016; 301:49-52. [PMID: 27836183 DOI: 10.1016/j.jneuroim.2016.10.008] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2016] [Revised: 10/24/2016] [Accepted: 10/31/2016] [Indexed: 12/13/2022]
Abstract
Neuronal surface antibodies (NSA) involved in autoimmune encephalitis (AE) have been related to relapses in HVS encephalitis. Their role in non-encephalitic psychosis is controversial. We previously reported an HIV-infected patient, NSA-positive, only presenting psychosis. Therefore, we determined the NSA prevalence in a prospective cohort of 22 HIV-positive patients with psychosis and we analyzed the frequency of HIV infection among NSA tested patients due to AE suspicion. We found no NSA in the prospective cohort. In the retrospective analysis, 22% of NSA-positive versus 4.6% of negative patients were HIV-positive. Wider studies are required to clarify the relationship between NSA and HIV infection.
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Affiliation(s)
- Vanessa Cunill
- Department of Immunology, Hospital Universitari Son Espases, Carretera de Valldemossa 79, 07120, Palma de Mallorca, Spain; Institut d'Investigacio Sanitaria de Palma (IdISPa), Spain
| | - Susana Arboleya
- Department of Psychiatry, Hospital Universitari Son Espases, Carretera de Valldemossa 79, 07120, Palma de Mallorca, Spain; Faculty of Medicine, Universitat de Barcelona, Carrer de Casanova 143, 08036 Barcelona, Spain
| | - Maria de Los Reyes Jiménez
- Department of Immunology, Hospital Universitari Son Espases, Carretera de Valldemossa 79, 07120, Palma de Mallorca, Spain; Institut d'Investigacio Sanitaria de Palma (IdISPa), Spain.
| | - Antoni Campins
- Institut d'Investigacio Sanitaria de Palma (IdISPa), Spain; Department of Internal Medicine, Hospital Universitari Son Espases, Carretera de Valldemossa 79, 07120, Palma de Mallorca, Spain
| | - Patricia Herbera
- Institut d'Investigacio Sanitaria de Palma (IdISPa), Spain; Department of Psychiatry, Hospital Universitari Son Espases, Carretera de Valldemossa 79, 07120, Palma de Mallorca, Spain
| | - LLuïsa Mestre
- Institut d'Investigacio Sanitaria de Palma (IdISPa), Spain; Department of Psychiatry, Hospital Universitari Son Espases, Carretera de Valldemossa 79, 07120, Palma de Mallorca, Spain
| | - Antonio Clemente
- Department of Immunology, Hospital Universitari Son Espases, Carretera de Valldemossa 79, 07120, Palma de Mallorca, Spain; Institut d'Investigacio Sanitaria de Palma (IdISPa), Spain
| | - Maria Inés Barceló
- Department of Neurology, Hospital Universitari Son Espases, Carretera de Valldemossa 79, 07120, Palma de Mallorca, Spain
| | - Maria Leyes
- Institut d'Investigacio Sanitaria de Palma (IdISPa), Spain; Department of Internal Medicine, Hospital Universitari Son Espases, Carretera de Valldemossa 79, 07120, Palma de Mallorca, Spain
| | - Francesca Canellas
- Institut d'Investigacio Sanitaria de Palma (IdISPa), Spain; Department of Psychiatry, Hospital Universitari Son Espases, Carretera de Valldemossa 79, 07120, Palma de Mallorca, Spain
| | - Maria Rosa Julià
- Department of Immunology, Hospital Universitari Son Espases, Carretera de Valldemossa 79, 07120, Palma de Mallorca, Spain; Institut d'Investigacio Sanitaria de Palma (IdISPa), Spain
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Steffens M, Becker B, Neumann C, Kasparbauer AM, Meyhöfer I, Weber B, Mehta MA, Hurlemann R, Ettinger U. Effects of ketamine on brain function during smooth pursuit eye movements. Hum Brain Mapp 2016; 37:4047-4060. [PMID: 27342447 PMCID: PMC6867533 DOI: 10.1002/hbm.23294] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2016] [Revised: 05/18/2016] [Accepted: 06/13/2016] [Indexed: 11/07/2022] Open
Abstract
The uncompetitive NMDA receptor antagonist ketamine has been proposed to model symptoms of psychosis. Smooth pursuit eye movements (SPEM) are an established biomarker of schizophrenia. SPEM performance has been shown to be impaired in the schizophrenia spectrum and during ketamine administration in healthy volunteers. However, the neural mechanisms mediating SPEM impairments during ketamine administration are unknown. In a counter-balanced, placebo-controlled, double-blind, within-subjects design, 27 healthy participants received intravenous racemic ketamine (100 ng/mL target plasma concentration) on one of two assessment days and placebo (intravenous saline) on the other. Participants performed a block-design SPEM task during functional magnetic resonance imaging (fMRI) at 3 Tesla field strength. Self-ratings of psychosis-like experiences were obtained using the Psychotomimetic States Inventory (PSI). Ketamine administration induced psychosis-like symptoms, during ketamine infusion, participants showed increased ratings on the PSI dimensions cognitive disorganization, delusional thinking, perceptual distortion and mania. Ketamine led to robust deficits in SPEM performance, which were accompanied by reduced blood oxygen level dependent (BOLD) signal in the SPEM network including primary visual cortex, area V5 and the right frontal eye field (FEF), compared to placebo. A measure of connectivity with V5 and FEF as seed regions, however, was not significantly affected by ketamine. These results are similar to the deviations found in schizophrenia patients. Our findings support the role of glutamate dysfunction in impaired smooth pursuit performance and the use of ketamine as a pharmacological model of psychosis, especially when combined with oculomotor biomarkers. Hum Brain Mapp 37:4047-4060, 2016. © 2016 Wiley Periodicals, Inc.
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Affiliation(s)
- M Steffens
- Department of Psychology, University of Bonn, Bonn, Germany
| | - B Becker
- Department of Psychiatry and Division of Medical Psychology, University of Bonn, Bonn, Germany
| | - C Neumann
- Department of Anesthesiology, University of Bonn, Bonn, Germany
| | | | - I Meyhöfer
- Department of Psychology, University of Bonn, Bonn, Germany
| | - B Weber
- Center for Economics and Neuroscience, University of Bonn, Bonn, Germany
- Department of Epileptology, University Hospital Bonn, Bonn, Germany
- Department of NeuroCognition/Imaging, Life&Brain Research Center, Bonn, Germany
| | - M A Mehta
- Department of Neuroimaging, Institute of Psychiatry, Psychology and Neuroscience, King's College London, London, United Kingdom
| | - R Hurlemann
- Department of Psychiatry and Division of Medical Psychology, University of Bonn, Bonn, Germany
| | - U Ettinger
- Department of Psychology, University of Bonn, Bonn, Germany.
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135
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Using model systems to understand errant plasticity mechanisms in psychiatric disorders. Nat Neurosci 2016; 19:1418-1425. [PMID: 27786180 DOI: 10.1038/nn.4413] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2016] [Accepted: 09/13/2016] [Indexed: 02/08/2023]
Abstract
In vivo model systems are a critical tool for gaining insight into the pathology underlying psychiatric disorders. Although modern functional imaging tools allow study of brain correlates of behavior in clinical groups and genome-wide association studies are beginning to uncover the complex genetic architecture of psychiatric disorders, there is less understanding of pathology at intervening levels of organization. Several psychiatric disorders derive from pathological neural plasticity, and studying the mechanisms that underlie these processes, including reinforcement learning and spike-timing-dependent plasticity, requires the use of animals. It will be particularly important to understand how individual differences in plasticity mechanisms at a cellular level confer resilience on some but lead to disease in others.
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136
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Tang WK, Liang H, Lin Y, Zhang C, Tang A, Chan F, Freeman TP, Ungvari GS. Psychiatric Co-morbidity in Ketamine and Methamphetamine Dependence: a Retrospective Chart Review. Int J Ment Health Addict 2016. [DOI: 10.1007/s11469-016-9681-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/20/2022] Open
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137
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Zandi MS. Autoimmune Encephalitis. FOCUS: JOURNAL OF LIFE LONG LEARNING IN PSYCHIATRY 2016; 14:432-436. [PMID: 31975823 DOI: 10.1176/appi.focus.20160019] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Antibodies to brain cell-surface proteins have recently been identified in patients whose symptoms cross the boundary between neurology and psychiatry and are associated with syndromes that are responsive to treatment with immunosuppression-based treatments. This has led to an expansion in the field of autoimmune encephalitis. The common syndromes, with particular relevance to psychiatry, are discussed, in particular the N-methyl-d-aspartate receptor antibody encephalitis syndrome, which is most often associated with a psychosis and cognitive prodrome resembling acute or first-episode psychosis. The recognition, clinical diagnosis and associations, and evidence for disease mechanisms are discussed in this brief review.
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Affiliation(s)
- Michael S Zandi
- Dr. Zandi is with the Institute of Neurology, University College London, London, United Kingdom, and with the National Institute for Health Research, University College London Hospitals Biomedical Research Centre. Address correspondence to Dr. Zandi at the UCL Institute of Neurology, Queen Square House, Queen Square, London, United Kingdom
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138
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Does cannabidiol have a role in the treatment of schizophrenia? Schizophr Res 2016; 176:281-290. [PMID: 27374322 DOI: 10.1016/j.schres.2016.06.022] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/23/2015] [Revised: 06/15/2016] [Accepted: 06/17/2016] [Indexed: 01/08/2023]
Abstract
Schizophrenia is a debilitating psychiatric disorder which places a significant emotional and economic strain on the individual and society-at-large. Unfortunately, currently available therapeutic strategies do not provide adequate relief and some patients are treatment-resistant. In this regard, cannabidiol (CBD), a non-psychoactive constituent of Cannabis sativa, has shown significant promise as a potential antipsychotic for the treatment of schizophrenia. However, there is still considerable uncertainty about the mechanism of action of CBD as well as the brain regions which are thought to mediate its putative antipsychotic effects. We argue that further research on CBD is required to fast-track its progress to the clinic and in doing so, we may generate novel insights into the neurobiology of schizophrenia.
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139
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de la Salle S, Choueiry J, Shah D, Bowers H, McIntosh J, Ilivitsky V, Knott V. Effects of Ketamine on Resting-State EEG Activity and Their Relationship to Perceptual/Dissociative Symptoms in Healthy Humans. Front Pharmacol 2016; 7:348. [PMID: 27729865 PMCID: PMC5037139 DOI: 10.3389/fphar.2016.00348] [Citation(s) in RCA: 67] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2016] [Accepted: 09/15/2016] [Indexed: 11/13/2022] Open
Abstract
N-methyl-D-aspartate (NMDA) receptor antagonists administered to healthy humans results in schizophrenia-like symptoms, which preclinical research suggests are due to glutamatergically altered brain oscillations. Here, we examined resting-state electroencephalographic activity in 21 healthy volunteers assessed in a placebo-controlled, double-blind, randomized study involving administration of either a saline infusion or a sub-anesthetic dose of ketamine, an NMDA receptor antagonist. Frequency-specific current source density (CSD) was assessed at sensor-level and source-level using eLORETA within regions of interest of a triple network model of schizophrenia (this model posits a dysfunctional switching between large-scale Default Mode and Central Executive networks by the monitor-controlling Salience Network). These CSDs were measured in each session along with subjective symptoms as indexed with the Clinician Administered Dissociative States Scale. Ketamine-induced CSD reductions in slow (delta/theta and alpha) and increases in fast (gamma) frequencies at scalp electrode sites were paralleled by frequency-specific CSD changes in the Default Mode, Central Executive, and Salience networks. Subjective symptoms scores were increased with ketamine and ratings of depersonalization in particular were associated with alpha CSD reductions in general and in specific regions of interest in each of the three networks. These results tentatively support the hypothesis that pathological brain oscillations associated with hypofunctional NMDA receptor activity may contribute to the emergence of the perceptual/dissociate symptoms of schizophrenia.
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Affiliation(s)
| | - Joelle Choueiry
- Department of Cellular and Molecular Medicine, University of Ottawa Ottawa, ON, Canada
| | - Dhrasti Shah
- School of Psychology, University of Ottawa Ottawa, ON, Canada
| | - Hayley Bowers
- Department of Psychology, University of Guelph Guelph, ON, Canada
| | - Judy McIntosh
- University of Ottawa Institute of Mental Health Research Ottawa, ON, Canada
| | - Vadim Ilivitsky
- Department of Psychiatry, University of OttawaOttawa, ON, Canada; Royal Ottawa Mental Health CentreOttawa, ON, Canada
| | - Verner Knott
- School of Psychology, University of OttawaOttawa, ON, Canada; Department of Cellular and Molecular Medicine, University of OttawaOttawa, ON, Canada; University of Ottawa Institute of Mental Health ResearchOttawa, ON, Canada; Department of Psychiatry, University of OttawaOttawa, ON, Canada
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140
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Longitudinal assessment of neuronal 3D genomes in mouse prefrontal cortex. Nat Commun 2016; 7:12743. [PMID: 27597321 PMCID: PMC5025847 DOI: 10.1038/ncomms12743] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2016] [Accepted: 07/28/2016] [Indexed: 12/15/2022] Open
Abstract
Neuronal epigenomes, including chromosomal loopings moving distal cis-regulatory elements into proximity of target genes, could serve as molecular proxy linking present-day-behaviour to past exposures. However, longitudinal assessment of chromatin state is challenging, because conventional chromosome conformation capture assays essentially provide single snapshots at a given time point, thus reflecting genome organization at the time of brain harvest and therefore are non-informative about the past. Here we introduce 'NeuroDam' to assess epigenome status retrospectively. Short-term expression of the bacterial DNA adenine methyltransferase Dam, tethered to the Gad1 gene promoter in mouse prefrontal cortex neurons, results in stable G(methyl)ATC tags at Gad1-bound chromosomal contacts. We show by NeuroDam that mice with defective cognition 4 months after pharmacological NMDA receptor blockade already were affected by disrupted chromosomal conformations shortly after drug exposure. Retrospective profiling of neuronal epigenomes is likely to illuminate epigenetic determinants of normal and diseased brain development in longitudinal context.
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141
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Kayser MS, Dalmau J. Anti-NMDA receptor encephalitis, autoimmunity, and psychosis. Schizophr Res 2016; 176:36-40. [PMID: 25458857 PMCID: PMC4409922 DOI: 10.1016/j.schres.2014.10.007] [Citation(s) in RCA: 136] [Impact Index Per Article: 17.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/16/2014] [Revised: 10/06/2014] [Accepted: 10/08/2014] [Indexed: 01/17/2023]
Abstract
Anti-N-methyl-d-aspartate receptor (NMDAR) encephalitis is a recently-discovered synaptic autoimmune disorder in which auto-antibodies target NMDARs in the brain, leading to their removal from the synapse. Patients manifest with prominent psychiatric symptoms - and in particular psychosis - early in the disease course. This presentation converges with long-standing evidence on multiple fronts supporting the glutamatergic model of schizophrenia. We review mechanisms underlying disease in anti-NMDAR encephalitis, and discuss its role in furthering our understanding of neural circuit dysfunction in schizophrenia.
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Affiliation(s)
- Matthew S Kayser
- Department of Psychiatry, Perelman School of Medicine, University of Pennsylvania, United States; Center for Sleep and Circadian Biology, Perelman School of Medicine, University of Pennsylvania, United States.
| | - Josep Dalmau
- Department of Neurology, Perelman School of Medicine, University of Pennsylvania, United States; Department of Neurology, Hospital Clinic, Barcelona, Spain
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142
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Hervig ME, Thomsen MS, Kalló I, Mikkelsen JD. Acute phencyclidine administration induces c-Fos-immunoreactivity in interneurons in cortical and subcortical regions. Neuroscience 2016; 334:13-25. [PMID: 27476436 DOI: 10.1016/j.neuroscience.2016.07.028] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2015] [Revised: 07/18/2016] [Accepted: 07/18/2016] [Indexed: 01/09/2023]
Abstract
Dysfunction of N-Methyl-d-aspartate receptors (NMDARs) is believed to underlie some of the symptoms in schizophrenia, and non-competitive NMDAR antagonists (including phencyclidine (PCP)) are widely used as pharmacological schizophrenia models. Furthermore, mounting evidence suggests that impaired γ-aminobutyric acid (GABA) neurotransmission contributes to the cognitive deficits in schizophrenia. Thus alterations in GABAergic interneurons have been observed in schizophrenia patients and animal models. Acute systemic administration of PCP increases levels of c-Fos in several cortical and subcortical areas, but whether such induction occurs in specific populations of GABAergic interneuron subtypes still remains to be established. We performed an immunohistochemical analysis of the PCP-induced c-Fos-immunoreactivity (IR) in parvalbumin (PV) and calbindin (CB) interneuron subtypes in the cortex and thalamus of rats. A single dose of PCP (10mg/kg, s.c.) significantly increased total number of c-Fos-IR in: (1) the prelimbic, infralimbic, anterior cingulate, ventrolateral orbital, motor, somatosensory and retrosplenial cortices as well as the nucleus accumbens (NAc), field CA1 of the hippocampus (CA1) field of hippocampus and mediodorsal thalamus (MD); (2) PV-IR cells in the ventrolateral orbitofrontal and retrosplenial cortices and CA1 field of hippocampus; and (3) CB-IR cells in the motor cortex. Overall, our data indicate that PCP activates a wide range of cortical and subcortical brain regions and that a substantial part of this activation is present in GABAergic interneurons in certain regions. This suggests that the psychotomimetic effect of PCP may be mediated via GABAergic interneurons.
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Affiliation(s)
- Mona E Hervig
- Neurobiology Research Unit, Copenhagen University Hospital, Rigshospitalet, Copenhagen, Denmark; Research Laboratory for Stereology and Neuroscience, Bispebjerg Hospital, Copenhagen, Denmark.
| | - Morten S Thomsen
- Neurobiology Research Unit, Copenhagen University Hospital, Rigshospitalet, Copenhagen, Denmark; Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, Denmark
| | - Imre Kalló
- Department of Endocrine Neurobiology, Institute of Experimental Medicine, Hungarian Academy of Sciences, Budapest, Hungary
| | - Jens D Mikkelsen
- Neurobiology Research Unit, Copenhagen University Hospital, Rigshospitalet, Copenhagen, Denmark
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143
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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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144
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Thibaut F, Boutros NN, Jarema M, Oranje B, Hasan A, Daskalakis ZJ, Wichniak A, Schmitt A, Riederer P, Falkai P. Consensus paper of the WFSBP Task Force on Biological Markers: Criteria for biomarkers and endophenotypes of schizophrenia part I: Neurophysiology. World J Biol Psychiatry 2016. [PMID: 26213111 DOI: 10.3109/15622975.2015.1050061] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
The neurophysiological components that have been proposed as biomarkers or as endophenotypes for schizophrenia can be measured through electroencephalography (EEG) and magnetoencephalography (MEG), transcranial magnetic stimulation (TMS), polysomnography (PSG), registration of event-related potentials (ERPs), assessment of smooth pursuit eye movements (SPEM) and antisaccade paradigms. Most of them demonstrate deficits in schizophrenia, show at least moderate stability over time and do not depend on clinical status, which means that they fulfil the criteria as valid endophenotypes for genetic studies. Deficits in cortical inhibition and plasticity measured using non-invasive brain stimulation techniques seem promising markers of outcome and prognosis. However the utility of these markers as biomarkers for predicting conversion to psychosis, response to treatments, or for tracking disease progression needs to be further studied.
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Affiliation(s)
- Florence Thibaut
- Department of Psychiatry, University Hospital Cochin (site Tarnier), University of Paris-Descartes, INSERM U 894 Centre Psychiatry and Neurosciences , Paris , France
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145
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Nagy D, Stoiljkovic M, Menniti FS, Hajós M. Differential Effects of an NR2B NAM and Ketamine on Synaptic Potentiation and Gamma Synchrony: Relevance to Rapid-Onset Antidepressant Efficacy. Neuropsychopharmacology 2016; 41:1486-94. [PMID: 26404843 PMCID: PMC4832008 DOI: 10.1038/npp.2015.298] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/08/2015] [Revised: 08/26/2015] [Accepted: 09/19/2015] [Indexed: 12/23/2022]
Abstract
Ketamine, a pan-NMDA receptor channel blocker, and CP-101,606, an NR2B-selective negative allosteric modulator, have antidepressant effects in humans that develop rapidly after the drugs are cleared from the body. It has been proposed that the antidepressant effect of ketamine results from delayed synaptic potentiation. To further investigate this hypothesis and potential mechanistic underpinnings we compared the effects of ketamine and CP-101,606 on neurophysiological biomarkers in rats immediately after drug administration and after the drugs had been eliminated. Local field and auditory-evoked potentials (AEPs) were recorded from primary auditory cortex and hippocampus in freely moving rats. Effects of different doses of ketamine or CP-101,606 were evaluated on amplitude of AEPs, auditory gating, and absolute power of delta and gamma oscillations 5-30 min (drug-on) and 5-6 h (drug-off) after systemic administration. Both ketamine and CP-101,606 significantly enhanced AEPs in cortex and hippocampus in the drug-off phase. In contrast, ketamine but not CP-101,606 disrupted auditory gating and increased gamma-band power during the drug-on period. Although both drugs affected delta power, these changes did not correlate with increase in AEPs in the drug-off phase. Our findings show that both ketamine and CP-101,606 augment AEPs after drug elimination, consistent with synaptic potentiation as a mechanism for antidepressant efficacy. However, these drugs had different acute effects on neurophysiological parameters. These results have implications for understanding the underlying mechanisms for the rapid-onset antidepressant effects of NMDA receptor inhibition and for the use of electrophysiological measures as translatable biomarkers.
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Affiliation(s)
- Dávid Nagy
- Laboratory of Translational Neuropharmacology, Section of Comparative Medicine, Yale School of Medicine, New Haven, CT, USA
| | - Milan Stoiljkovic
- Laboratory of Translational Neuropharmacology, Section of Comparative Medicine, Yale School of Medicine, New Haven, CT, USA
| | | | - Mihály Hajós
- Laboratory of Translational Neuropharmacology, Section of Comparative Medicine, Yale School of Medicine, New Haven, CT, USA,Laboratory of Translational Neuropharmacology, Section of Comparative Medicine, Yale School of Medicine, 310 Cedar St MBL 330, New Haven, CT 06520, USA, Tel: +1 203 737 7649, Fax: +1 203 785 7499, E-mail:
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146
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Atypical visual and somatosensory adaptation in schizophrenia-spectrum disorders. Transl Psychiatry 2016; 6:e804. [PMID: 27163205 PMCID: PMC5070065 DOI: 10.1038/tp.2016.63] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/28/2015] [Revised: 01/11/2016] [Accepted: 03/05/2016] [Indexed: 12/12/2022] Open
Abstract
Neurophysiological investigations in patients with schizophrenia consistently show early sensory processing deficits in the visual system. Importantly, comparable sensory deficits have also been established in healthy first-degree biological relatives of patients with schizophrenia and in first-episode drug-naive patients. The clear implication is that these measures are endophenotypic, related to the underlying genetic liability for schizophrenia. However, there is significant overlap between patient response distributions and those of healthy individuals without affected first-degree relatives. Here we sought to develop more sensitive measures of sensory dysfunction in this population, with an eye to establishing endophenotypic markers with better predictive capabilities. We used a sensory adaptation paradigm in which electrophysiological responses to basic visual and somatosensory stimuli presented at different rates (ranging from 250 to 2550 ms interstimulus intervals, in blocked presentations) were compared. Our main hypothesis was that adaptation would be substantially diminished in schizophrenia, and that this would be especially prevalent in the visual system. High-density event-related potential recordings showed amplitude reductions in sensory adaptation in patients with schizophrenia (N=15 Experiment 1, N=12 Experiment 2) compared with age-matched healthy controls (N=15 Experiment 1, N=12 Experiment 2), and this was seen for both sensory modalities. At the individual participant level, reduced adaptation was more robust for visual compared with somatosensory stimulation. These results point to significant impairments in short-term sensory plasticity across sensory modalities in schizophrenia. These simple-to-execute measures may prove valuable as candidate endophenotypes and will bear follow-up in future work.
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147
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Näätänen R, Todd J, Schall U. Mismatch negativity (MMN) as biomarker predicting psychosis in clinically at-risk individuals. Biol Psychol 2016; 116:36-40. [DOI: 10.1016/j.biopsycho.2015.10.010] [Citation(s) in RCA: 44] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2015] [Revised: 08/21/2015] [Accepted: 10/27/2015] [Indexed: 12/14/2022]
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148
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Harms L. Mismatch responses and deviance detection in N-methyl-D-aspartate (NMDA) receptor hypofunction and developmental models of schizophrenia. Biol Psychol 2016; 116:75-81. [DOI: 10.1016/j.biopsycho.2015.06.015] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2015] [Revised: 06/24/2015] [Accepted: 06/29/2015] [Indexed: 01/03/2023]
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149
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Halberstadt AL, Slepak N, Hyun J, Buell MR, Powell SB. The novel ketamine analog methoxetamine produces dissociative-like behavioral effects in rodents. Psychopharmacology (Berl) 2016; 233:1215-25. [PMID: 26758284 PMCID: PMC5403250 DOI: 10.1007/s00213-016-4203-3] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/22/2015] [Accepted: 12/31/2015] [Indexed: 01/20/2023]
Abstract
RATIONALE Methoxetamine (MXE) is a ketamine analog sold online that has been subject to widespread abuse for its dissociative and hallucinogenic effects. Previous studies have shown that MXE has high affinity for the phencyclidine (PCP) binding site located within the channel pore of the NMDA receptor (NMDAR), but little is known about its behavioral effects. Dissociative anesthetics such as ketamine and PCP produce a characteristic behavioral profile in rats that includes locomotor hyperactivity and disruption of prepulse inhibition (PPI) of acoustic startle. METHODS The goal of the present investigation was to determine whether MXE produces PCP-like effects in Sprague-Dawley rats using the PPI paradigm and the behavioral pattern monitor (BPM), which enables analyses of patterns of locomotor activity and investigatory behavior. PPI studies were conducted with several other uncompetitive NMDAR antagonists that produce dissociative effects in humans, including PCP, the S-(+) and R-(-) isomers of ketamine, and N-allylnormetazocine (NANM; SKF-10,047). RESULTS MXE disrupted PPI when administered at 3 and 10 mg/kg SC. The rank order of potency of MXE and the other test compounds in the PPI paradigm (PCP > MXE > S-(+)-ketamine > NANM > R-(-)-ketamine) parallels their affinities for the PCP binding site reported in the literature. When tested in the BPM, 10 mg/kg MXE induced locomotor hyperactivity, reduced the number of rearings, increased the roughness of locomotor paths, and produced perseverative patterns of locomotion. Administration of PCP (2.25 and 6.75 mg/kg, SC) produced a similar profile of effects in the BPM. CONCLUSIONS These results indicate that MXE produces a behavioral profile similar to that of other psychotomimetic uncompetitive NMDAR antagonists. Our findings support the classification of MXE as a dissociative drug and suggest that it likely has effects and abuse potential similar to that of PCP and ketamine.
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Affiliation(s)
- Adam L Halberstadt
- Department of Psychiatry, University of California San Diego, 9500 Gilman Drive, 92093-0804, La Jolla, CA, USA.
- Research Service, VA San Diego Healthcare System, San Diego, CA, USA.
| | - Natalia Slepak
- Department of Biology, University of California San Diego, La Jolla, CA, USA
| | - James Hyun
- Department of Psychiatry, University of California San Diego, 9500 Gilman Drive, 92093-0804, La Jolla, CA, USA
| | - Mahalah R Buell
- Department of Psychiatry, University of California San Diego, 9500 Gilman Drive, 92093-0804, La Jolla, CA, USA
| | - Susan B Powell
- Department of Psychiatry, University of California San Diego, 9500 Gilman Drive, 92093-0804, La Jolla, CA, USA
- Research Service, VA San Diego Healthcare System, San Diego, CA, USA
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Frost JD, Winkler I, Provost A, Todd J. Surprising sequential effects on MMN. Biol Psychol 2016; 116:47-56. [DOI: 10.1016/j.biopsycho.2015.10.005] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2015] [Revised: 08/21/2015] [Accepted: 10/14/2015] [Indexed: 12/01/2022]
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