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Kim H, Choi S, Lee E, Koh W, Lee CJ. Tonic NMDA Receptor Currents in the Brain: Regulation and Cognitive Functions. Biol Psychiatry 2024:S0006-3223(24)01147-8. [PMID: 38490367 DOI: 10.1016/j.biopsych.2024.03.009] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/24/2023] [Revised: 02/20/2024] [Accepted: 03/04/2024] [Indexed: 03/17/2024]
Abstract
Synaptically localized NMDA receptors (NMDARs) play a crucial role in important cognitive functions by mediating synaptic transmission and plasticity. In contrast, a tonic NMDAR current, thought to be mediated by extrasynaptic NMDARs, has a less clear function. This review provides a comprehensive overview of tonic NMDAR currents, focusing on their roles in synaptic transmission/plasticity and their impact on cognitive functions and psychiatric disorders. We discuss the roles of 3 endogenous ligands (i.e., glutamate, glycine, and D-serine) and receptors in mediating tonic NMDAR currents and explore the diverse mechanisms that regulate tonic NMDAR currents. In light of recent controversies surrounding the source of D-serine, we highlight the recent findings suggesting that astrocytes release D-serine to modulate tonic NMDAR currents and control cognitive flexibility. Furthermore, we propose distinct roles of neuronal and astrocytic D-serine in different locations and their implications for synaptic regulation and cognitive functions. The potential roles of tonic NMDAR currents in various psychiatric disorders, such as schizophrenia and autism spectrum disorder, are discussed in the context of the NMDAR hypofunction hypothesis. By presenting the mechanisms by which various cells, particularly astrocytes, regulate tonic NMDAR currents, we aim to stimulate future research in NMDAR hypofunction- or hyperfunction-related psychiatric disorders. This review not only provides a better understanding of the complex interplay between tonic NMDAR currents and cognitive functions but also sheds light on its potential therapeutic target for the treatment of various psychiatric disorders.
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Affiliation(s)
- Hayoung Kim
- Center for Cognition and Sociality, Life Science Institute, Institute for Basic Science, Daejeon, South Korea
| | - Sunyeong Choi
- Center for Cognition and Sociality, Life Science Institute, Institute for Basic Science, Daejeon, South Korea
| | - Euisun Lee
- Center for Cognition and Sociality, Life Science Institute, Institute for Basic Science, Daejeon, South Korea
| | - Wuhyun Koh
- Center for Cognition and Sociality, Life Science Institute, Institute for Basic Science, Daejeon, South Korea.
| | - C Justin Lee
- Center for Cognition and Sociality, Life Science Institute, Institute for Basic Science, Daejeon, South Korea.
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Perdikaris P, Prouska P, Dermon CR. Social withdrawal and anxiety-like behavior have an impact on zebrafish adult neurogenesis. Front Behav Neurosci 2023; 17:1244075. [PMID: 37908201 PMCID: PMC10614005 DOI: 10.3389/fnbeh.2023.1244075] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2023] [Accepted: 09/29/2023] [Indexed: 11/02/2023] Open
Abstract
Introduction Accumulating evidence highlights the key role of adult neurogenesis events in environmental challenges, cognitive functions and mood regulation. Abnormal hippocampal neurogenesis has been implicated in anxiety-like behaviors and social impairments, but the possible mechanisms remain elusive. Methods The present study questioned the contribution of altered excitation/inhibition as well as excessive neuroinflammation in regulating the neurogenic processes within the Social Decision-Making (SDM) network, using an adult zebrafish model displaying NMDA receptor hypofunction after sub-chronic MK-801 administration. For this, the alterations in cell proliferation and newborn cell densities were evaluated using quantitative 5-Bromo-2'-Deoxyuridine (BrdU) methodology. Results In short-term survival experiments. MK-801-treated zebrafish displayed decreased cell proliferation pattern within distinct neurogenic zones of telencephalic and preoptic SDM nodes, in parallel to the social withdrawal and anxiety-like comorbidity. BrdU+ cells co-expressed the pro-inflammatory marker IL-1β solely in MK-801-treated zebrafish, indicating a role of inflammation. Following the cessation of drug treatment, significant increases in the BrdU+ cell densities were accompanied by the normalization of the social and anxiety-like phenotype. Importantly, most labeled cells in neurogenic zones showed a radial glial phenotype while a population of newborn cells expressed the early neuronal marker TOAD or mGLuR5, the latter suggesting the possible involvement of metabotropic glutamate receptor 5 in neurogenic events. Discussion Overall, our results indicate the role of radial glial cell proliferation in the overlapping pathologies of anxiety and social disorders, observed in many neuropsychiatric disorders and possibly represent potential novel targets for amelioration of these symptoms.
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Affiliation(s)
| | | | - Catherine R. Dermon
- Laboratory of Human and Animal Physiology, Department of Biology, University of Patras, Patras, Greece
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Perdikaris P, Dermon CR. Altered GABAergic, glutamatergic and endocannabinoid signaling is accompanied by neuroinflammatory response in a zebrafish model of social withdrawal behavior. Front Mol Neurosci 2023; 16:1120993. [PMID: 37284463 PMCID: PMC10239971 DOI: 10.3389/fnmol.2023.1120993] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2022] [Accepted: 04/27/2023] [Indexed: 06/08/2023] Open
Abstract
Introduction Deficits in social communication are in the core of clinical symptoms characterizing many neuropsychiatric disorders such as schizophrenia and autism spectrum disorder. The occurrence of anxiety-related behavior, a common co-morbid condition in individuals with impairments in social domain, suggests the presence of overlapping neurobiological mechanisms between these two pathologies. Dysregulated excitation/inhibition balance and excessive neuroinflammation, in specific neural circuits, are proposed as common etiological mechanisms implicated in both pathologies. Methods and Results In the present study we evaluated changes in glutamatergic/GABAergic neurotransmission as well as the presence of neuroinflammation within the regions of the Social Decision-Making Network (SDMN) using a zebrafish model of NMDA receptor hypofunction, following sub-chronic MK-801 administration. MK-801-treated zebrafish are characterized by impaired social communication together with increased anxiety levels. At the molecular level, the behavioral phenotype was accompanied by increased mGluR5 and GAD67 but decreased PSD-95 protein expression levels in telencephalon and midbrain. In parallel, MK-801-treated zebrafish exhibited altered endocannabinoid signaling as indicated by the upregulation of cannabinoid receptor 1 (CB1R) in the telencephalon. Interestingly, glutamatergic dysfunction was positively correlated with social withdrawal behavior whereas defective GABAergic and endocannabinoid activity were positively associated with anxiety-like behavior. Moreover, neuronal and astrocytic IL-1β expression was increased in regions of the SDMN, supporting the role of neuroinflammatory responses in the manifestation of MK-801 behavioral phenotype. Colocalization of interleukin-1β (IL-1β) with β2-adrenergic receptors (β2-ARs) underlies the possible influence of noradrenergic neurotransmission to increased IL-1β expression in comorbidity between social deficits and elevated anxiety comorbidity. Discussion Overall, our results indicate the contribution of altered excitatory and inhibitory synaptic transmission as well as excessive neuroinflammatory responses in the manifestation of social deficits and anxiety-like behavior of MK-801-treated fish, identifying possible novel targets for amelioration of these symptoms.
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Sultana R, Lee CC. Expression of Behavioral Phenotypes in Genetic and Environmental Mouse Models of Schizophrenia. Front Behav Neurosci 2020; 14:29. [PMID: 32184711 PMCID: PMC7058961 DOI: 10.3389/fnbeh.2020.00029] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2019] [Accepted: 02/07/2020] [Indexed: 02/04/2023] Open
Abstract
Schizophrenia is a neuropsychiatric disorder characterized by multifactorial etiology involving complex interactions among genetic and environmental factors. "Multiple-hit" models of the disorder can explain its variable incidence and prevalence in related individuals. Hence, there is a dire need to understand these interactions in the emergence of schizophrenia. To test these factors in the emergence of schizophrenia-like behaviors, we employed a genetic mouse model of the disorder (harboring the DISC1 mutation) along with various environmental insults, such as early life stress (maternal separation of pups) and/or pharmacological interventions (ketamine injections). When assessed on a battery of behavioral tests, we found that environmental interventions affect the severity of behavioral phenotypes in terms of increased negative behavior, as shown by reduced mobility in the forced swim and tail suspension tests, and changes to positive and cognitive symptoms, such as increased locomotion and disrupted PPI along with reduced working memory, respectively. Among the various interventions, the genetic mutation had the most profound effect on behavioral aberrations, followed by an environmental intervention by ketamine injections and ketamine-injected animals that were maternally separated during early postnatal days. We conclude that although environmental factors increased the prevalence of aberrant behavioral phenotypes, genetic background is still the predominant influence on phenotypic alterations in these mouse models of schizophrenia.
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Affiliation(s)
- Razia Sultana
- Neural Systems Laboratory, Department of Comparative Biomedical Sciences, Louisiana State University School of Veterinary Medicine, Baton Rouge, LA, United States
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Bodkin JA, Coleman MJ, Godfrey LJ, Carvalho CM, Morgan CJ, Suckow RF, Anderson T, Ongur D, Kaufman MJ, Lewandowski KE, Siegel AJ, Waldstreicher E, Grochowski CM, Javitt DC, Rujescu D, Hebbring S, Weinshilboum R, Rodriguez SB, Kirchhoff C, Visscher T, Vuckovic A, Fialkowski A, McCarthy S, Malhotra D, Sebat J, Goff DC, Hudson JI, Lupski JR, Coyle JT, Rudolph U, Levy DL. Targeted Treatment of Individuals With Psychosis Carrying a Copy Number Variant Containing a Genomic Triplication of the Glycine Decarboxylase Gene. Biol Psychiatry 2019; 86:523-535. [PMID: 31279534 PMCID: PMC6745274 DOI: 10.1016/j.biopsych.2019.04.031] [Citation(s) in RCA: 26] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/21/2018] [Revised: 04/17/2019] [Accepted: 04/17/2019] [Indexed: 02/08/2023]
Abstract
BACKGROUND The increased mutational burden for rare structural genomic variants in schizophrenia and other neurodevelopmental disorders has so far not yielded therapies targeting the biological effects of specific mutations. We identified two carriers (mother and son) of a triplication of the gene encoding glycine decarboxylase, GLDC, presumably resulting in reduced availability of the N-methyl-D-aspartate receptor coagonists glycine and D-serine and N-methyl-D-aspartate receptor hypofunction. Both carriers had a diagnosis of a psychotic disorder. METHODS We carried out two double-blind, placebo-controlled clinical trials of N-methyl-D-aspartate receptor augmentation of psychotropic drug treatment in these two individuals. Glycine was used in the first clinical trial, and D-cycloserine was used in the second one. RESULTS Glycine or D-cycloserine augmentation of psychotropic drug treatment each improved psychotic and mood symptoms in placebo-controlled trials. CONCLUSIONS These results provide two independent proof-of-principle demonstrations of symptom relief by targeting a specific genotype and explicitly link an individual mutation to the pathophysiology of psychosis and treatment response.
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Affiliation(s)
| | | | | | | | | | | | | | - Dost Ongur
- McLean Hospital, Belmont, MA.,Harvard Medical School, Boston, MA
| | - Marc J. Kaufman
- McLean Hospital, Belmont, MA.,Harvard Medical School, Boston, MA
| | | | - Arthur J. Siegel
- McLean Hospital, Belmont, MA.,Harvard Medical School, Boston, MA
| | | | | | - Daniel C. Javitt
- Columbia University Medical Center, New York, NY.,Nathan Kline Institute, Orangeburg, NY
| | - Dan Rujescu
- Department of Psychiatry, Psychotherapy, and Psychosomatics, Martin Luther University of Halle-Wittenberg, Halle, Germany
| | - Scott Hebbring
- Center for Human Genetics, Marshfield Clinic Research Institute, Marshfield, WI
| | | | | | | | | | | | | | | | | | | | - Donald C. Goff
- Nathan Kline Institute, Orangeburg, NY.,Department of Psychiatry, New York University Langone Medical Center, New York, NY
| | - James I. Hudson
- McLean Hospital, Belmont, MA.,Harvard Medical School, Boston, MA
| | | | - Joseph T. Coyle
- McLean Hospital, Belmont, MA.,Harvard Medical School, Boston, MA
| | - Uwe Rudolph
- McLean Hospital, Belmont, MA.,Harvard Medical School, Boston, MA
| | - Deborah L. Levy
- McLean Hospital, Belmont, MA.,Harvard Medical School, Boston, MA
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Pei JC, Hung WL, Lin BX, Shih MH, Lu LY, Luo DZ, Tai HC, Studer V, Min MY, Lai WS. Therapeutic potential and underlying mechanism of sarcosine (N-methylglycine) in N-methyl-D-aspartate (NMDA) receptor hypofunction models of schizophrenia. J Psychopharmacol 2019; 33:1288-1302. [PMID: 31294644 DOI: 10.1177/0269881119856558] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
BACKGROUND Compelling animal and clinical studies support the N-methyl-D-aspartate receptor (NMDAR) hypofunction hypothesis of schizophrenia and suggest promising pharmacological agents to ameliorate negative and cognitive symptoms of schizophrenia, including sarcosine, a glycine transporter-1 inhibitor. AIMS AND METHODS It is imperative to evaluate the therapeutic potential of sarcosine in animal models, which provide indispensable tools for testing drug effects in detail and elucidating the underlying mechanisms. In this study, a series of seven experiments was conducted to investigate the effect of sarcosine in ameliorating behavioral deficits and the underlying mechanism in pharmacological (i.e., MK-801-induced) and genetic (i.e., serine racemase-null mutant (SR-/-) mice) NMDAR hypofunction models. RESULTS In Experiment 1, the acute administration of 500/1000 mg/kg sarcosine (i.p.) had no adverse effects on motor function and serum biochemical responses. In Experiments 2-4, sarcosine significantly alleviated MK-801-induced (0.2 mg/kg) brain abnormalities and behavioral deficits in MK-801-induced and SR-/- mouse models. In Experiment 5, the injection of sarcosine enhanced CSF levels of glycine and serine in rat brain. In Experiments 6-7, we show for the first time that sarcosine facilitated NMDAR-mediated hippocampal field excitatory postsynaptic potentials and influenced the movement of surface NMDARs at extrasynaptic sites. CONCLUSIONS Sarcosine effectively regulated the surface trafficking of NMDARs, NMDAR-evoked electrophysiological activity, brain glycine levels and MK-801-induced abnormalities in the brain, which contributed to the amelioration of behavioral deficits in mouse models of NMDAR hypofunction.
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Affiliation(s)
- Ju-Chun Pei
- Department of Psychology, National Taiwan University, Taipei, Taiwan
| | - Wei-Li Hung
- Department of Psychology, National Taiwan University, Taipei, Taiwan
| | - Bei-Xuan Lin
- Institute of Zoology, National Taiwan University, Taipei, Taiwan
| | - Min-Han Shih
- Department of Chemistry, National Taiwan University, Taipei, Taiwan
| | - Liang-Yin Lu
- Department of Psychology, National Taiwan University, Taipei, Taiwan
| | - Da-Zhong Luo
- Department of Psychology, National Taiwan University, Taipei, Taiwan
| | - Hwan-Ching Tai
- Department of Chemistry, National Taiwan University, Taipei, Taiwan
| | - Vincent Studer
- Interdisciplinary Institute for Neuroscience, University of Bordeaux, Bordeaux, France.,French National Center for Scientific Research (CNRS), Bordeaux, France
| | - Ming-Yuan Min
- Institute of Zoology, National Taiwan University, Taipei, Taiwan.,Graduate Institute of Brain and Mind Sciences, National Taiwan University, Taipei, Taiwan.,Neurobiology and Cognitive Science Center, National Taiwan University, Taipei, Taiwan
| | - Wen-Sung Lai
- Department of Psychology, National Taiwan University, Taipei, Taiwan.,Graduate Institute of Brain and Mind Sciences, National Taiwan University, Taipei, Taiwan.,Neurobiology and Cognitive Science Center, National Taiwan University, Taipei, Taiwan
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Abstract
The N-methyl-d-aspartate receptor (NMDAR) hypofunction hypothesis has been proposed to help understand the etiology and pathophysiology of schizophrenia. This hypothesis was based on early observations that NMDAR antagonists could induce a full range of symptoms of schizophrenia in normal human subjects. Accumulating evidence in humans and animal studies points to NMDAR hypofunctionality as a convergence point for various symptoms of schizophrenia. Here we review animal models of NMDAR hypofunction generated by pharmacological and genetic approaches, and how they relate to the pathophysiology of schizophrenia. In addition, we discuss the limitations of animal models of NMDAR hypofunction and their potential utility for therapeutic applications.
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Affiliation(s)
| | - Yi Zhou
- Department of Biomedical Sciences, Florida State University College of Medicine, Tallahassee, FL, United States
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Hamilton HK, D’Souza DC, Ford JM, Roach BJ, Kort NS, Ahn KH, Bhakta S, Ranganathan M, Mathalon DH. Interactive effects of an N-methyl-d-aspartate receptor antagonist and a nicotinic acetylcholine receptor agonist on mismatch negativity: Implications for schizophrenia. Schizophr Res 2018; 191:87-94. [PMID: 28711472 PMCID: PMC5745273 DOI: 10.1016/j.schres.2017.06.040] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/28/2017] [Revised: 06/18/2017] [Accepted: 06/21/2017] [Indexed: 11/29/2022]
Abstract
N-methyl-d-aspartate glutamate receptor (NMDAR) hypofunction has been implicated in the pathophysiology of schizophrenia, including auditory processing abnormalities reflected by the mismatch negativity (MMN) event-related potential component. Evidence suggesting cognitive benefits from nicotine administration, together with the high rate of cigarette use in patients with schizophrenia, has stimulated interest in whether nicotine modulates NMDAR hypofunction. We examined the interactive effects of ketamine, an NMDAR antagonist that produces transient schizophrenia-like neurophysiological effects, and nicotine, a nicotinic acetylcholine receptor (nAChR) agonist, in 30 healthy volunteers to determine whether nicotine prevents or attenuates MMN abnormalities. Secondary analyses compared the profile of ketamine and schizophrenia effects on MMN using previously reported data from 24 schizophrenia patients (Hay et al. 2015). Healthy volunteers completed four test days, during which they received ketamine/placebo and nicotine/placebo in a double-blind, counterbalanced design. MMN to intensity, frequency, duration, and frequency+duration double deviant sounds was assessed each day. Ketamine decreased intensity, frequency, and double deviant MMN amplitudes, whereas nicotine increased intensity and double deviant MMN amplitudes. A ketamine×nicotine interaction indicated, however, that nicotine failed to attenuate the decrease in MMN associated with ketamine. Although the present dose of ketamine produced smaller decrements in MMN than those associated with schizophrenia, the profile of effects across deviant types did not differ between ketamine and schizophrenia. Results suggest that while ketamine and schizophrenia produce similar profiles of MMN effects across deviant types, nicotinic agonists may have limited potential to improve these putative NMDAR hypofunction-mediated impairments in schizophrenia.
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Affiliation(s)
- Holly K. Hamilton
- San Francisco VA Health Care System, 4150 Clement St 116D, San Francisco, CA 94121 USA,University of California, San Francisco, 401 Parnassus Ave, San Francisco, CA, 94143 USA
| | - Deepak C. D’Souza
- Veterans Affairs Connecticut Health Care System, 950 Campbell Ave, 116A, West Haven, CT 06516 USA,Yale University, 300 George St, Suite 901, New Haven, CT 06511 USA
| | - Judith M. Ford
- San Francisco VA Health Care System, 4150 Clement St 116D, San Francisco, CA 94121 USA,University of California, San Francisco, 401 Parnassus Ave, San Francisco, CA, 94143 USA
| | - Brian J. Roach
- Northern California Institute for Research and Education, 4150 Clement St, San Francisco, CA 94121 USA
| | - Naomi S. Kort
- University of California, San Francisco, 401 Parnassus Ave, San Francisco, CA, 94143 USA
| | - Kyung-Heup Ahn
- Veterans Affairs Connecticut Health Care System, 950 Campbell Ave, 116A, West Haven, CT 06516 USA,Yale University, 300 George St, Suite 901, New Haven, CT 06511 USA
| | - Savita Bhakta
- Yale University, 300 George St, Suite 901, New Haven, CT 06511 USA
| | | | - Daniel H. Mathalon
- San Francisco VA Health Care System, 4150 Clement St 116D, San Francisco, CA 94121 USA,University of California, San Francisco, 401 Parnassus Ave, San Francisco, CA, 94143 USA
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Richard EA, Khlestova E, Nanu R, Lisman JE. Potential synergistic action of 19 schizophrenia risk genes in the thalamus. Schizophr Res 2017; 180:64-9. [PMID: 27645107 DOI: 10.1016/j.schres.2016.09.008] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/17/2016] [Revised: 08/31/2016] [Accepted: 09/03/2016] [Indexed: 11/22/2022]
Abstract
A goal of current schizophrenia (SZ) research is to understand how multiple risk genes work together with environmental factors to produce the disease. In schizophrenia, there is elevated delta frequency EEG power in the awake state, an elevation that can be mimicked in rodents by N-methyl-d-aspartate receptor (NMDAR) antagonist action in the thalamus. This thalamic delta can be blocked by dopamine D2 receptor antagonists, agents known to be therapeutic in SZ. Experiments suggest that these oscillations can interfere with brain function and may thus be causal in producing psychosis. Here we evaluate the question of whether well-established schizophrenia risk genes may interact to affect the delta generation process. We identify 19 risk genes that can plausibly work in a synergistic fashion to generate delta oscillations.
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Lee J, Green MF. Social Preference and Glutamatergic Dysfunction: Underappreciated Prerequisites for Social Dysfunction in Schizophrenia. Trends Neurosci 2016; 39:587-96. [PMID: 27477199 DOI: 10.1016/j.tins.2016.06.005] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2016] [Revised: 05/17/2016] [Accepted: 06/13/2016] [Indexed: 12/21/2022]
Abstract
Impaired social functioning is pervasive in schizophrenia. Unfortunately, existing treatments have limited efficacy, and possible psychological or neurobiological mechanisms underlying social dysfunction in this disorder remain obscure. Here, we evaluate whether social preference, one key aspect of social processing that has been largely overlooked in schizophrenia research, and N-methyl-d-aspartate receptor (NMDAR) dysfunction can provide insights into the mechanism underlying social dysfunction in schizophrenia. Based on evidence from developmental psychology, and behavioral and clinical neuroscience, we propose a heuristic model in which reduced NMDAR function may induce disrupted social preference that can subsequently lead to social cognitive impairment and social disability. We discuss its implications in terms of the pathophysiology of schizophrenia, other disorders with marked social disability, and potential treatments.
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Murray JD, Anticevic A, Gancsos M, Ichinose M, Corlett PR, Krystal JH, Wang XJ. Linking microcircuit dysfunction to cognitive impairment: effects of disinhibition associated with schizophrenia in a cortical working memory model. Cereb Cortex 2012. [PMID: 23203979 DOI: 10.1093/cercor/bhs370] [Citation(s) in RCA: 163] [Impact Index Per Article: 13.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
Excitation-inhibition balance (E/I balance) is a fundamental property of cortical microcircuitry. Disruption of E/I balance in prefrontal cortex is hypothesized to underlie cognitive deficits observed in neuropsychiatric illnesses such as schizophrenia. To elucidate the link between these phenomena, we incorporated synaptic disinhibition, via N-methyl-D-aspartate receptor perturbation on interneurons, into a network model of spatial working memory (WM). At the neural level, disinhibition broadens the tuning of WM-related, stimulus-selective persistent activity patterns. The model predicts that this change at the neural level leads to 2 primary behavioral deficits: 1) increased behavioral variability that degrades the precision of stored information and 2) decreased ability to filter out distractors during WM maintenance. We specifically tested the main model prediction, broadened WM representation under disinhibition, using behavioral data from human subjects performing a spatial WM task combined with ketamine infusion, a pharmacological model of schizophrenia hypothesized to induce disinhibition. Ketamine increased errors in a pattern predicted by the model. Finally, as proof-of-principle, we demonstrate that WM deteriorations in the model can be ameliorated by compensations that restore E/I balance. Our findings identify specific ways by which cortical disinhibition affects WM, suggesting new experimental designs for probing the brain mechanisms of WM deficits in schizophrenia.
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Affiliation(s)
- John D Murray
- Department of Physics, Yale University, New Haven, CT 06520, USA
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