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Landek-Salgado MA, Faust TE, Sawa A. Molecular substrates of schizophrenia: homeostatic signaling to connectivity. Mol Psychiatry 2016; 21:10-28. [PMID: 26390828 PMCID: PMC4684728 DOI: 10.1038/mp.2015.141] [Citation(s) in RCA: 73] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/26/2014] [Revised: 06/24/2015] [Accepted: 06/25/2015] [Indexed: 02/06/2023]
Abstract
Schizophrenia (SZ) is a devastating psychiatric condition affecting numerous brain systems. Recent studies have identified genetic factors that confer an increased risk of SZ and participate in the disease etiopathogenesis. In parallel to such bottom-up approaches, other studies have extensively reported biological changes in patients by brain imaging, neurochemical and pharmacological approaches. This review highlights the molecular substrates identified through studies with SZ patients, namely those using top-down approaches, while also referring to the fruitful outcomes of recent genetic studies. We have subclassified the molecular substrates by system, focusing on elements of neurotransmission, targets in white matter-associated connectivity, immune/inflammatory and oxidative stress-related substrates, and molecules in endocrine and metabolic cascades. We further touch on cross-talk among these systems and comment on the utility of animal models in charting the developmental progression and interaction of these substrates. Based on this comprehensive information, we propose a framework for SZ research based on the hypothesis of an imbalance in homeostatic signaling from immune/inflammatory, oxidative stress, endocrine and metabolic cascades that, at least in part, underlies deficits in neural connectivity relevant to SZ. Thus, this review aims to provide information that is translationally useful and complementary to pathogenic hypotheses that have emerged from genetic studies. Based on such advances in SZ research, it is highly expected that we will discover biomarkers that may help in the early intervention, diagnosis or treatment of SZ.
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Affiliation(s)
- M A Landek-Salgado
- Department of Psychiatry, John Hopkins University School of Medicine, Baltimore, MD, USA
| | - T E Faust
- Department of Psychiatry, John Hopkins University School of Medicine, Baltimore, MD, USA.,Department of Neuroscience, John Hopkins University School of Medicine, Baltimore, MD, USA
| | - A Sawa
- Department of Psychiatry, John Hopkins University School of Medicine, Baltimore, MD, USA
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Cui LB, Liu J, Wang LX, Li C, Xi YB, Guo F, Wang HN, Zhang LC, Liu WM, He H, Tian P, Yin H, Lu H. Anterior cingulate cortex-related connectivity in first-episode schizophrenia: a spectral dynamic causal modeling study with functional magnetic resonance imaging. Front Hum Neurosci 2015; 9:589. [PMID: 26578933 PMCID: PMC4630283 DOI: 10.3389/fnhum.2015.00589] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2015] [Accepted: 10/12/2015] [Indexed: 11/13/2022] Open
Abstract
Understanding the neural basis of schizophrenia (SZ) is important for shedding light on the neurobiological mechanisms underlying this mental disorder. Structural and functional alterations in the anterior cingulate cortex (ACC), dorsolateral prefrontal cortex (DLPFC), hippocampus, and medial prefrontal cortex (MPFC) have been implicated in the neurobiology of SZ. However, the effective connectivity among them in SZ remains unclear. The current study investigated how neuronal pathways involving these regions were affected in first-episode SZ using functional magnetic resonance imaging (fMRI). Forty-nine patients with a first-episode of psychosis and diagnosis of SZ-according to the Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition, Text Revision-were studied. Fifty healthy controls (HCs) were included for comparison. All subjects underwent resting state fMRI. We used spectral dynamic causal modeling (DCM) to estimate directed connections among the bilateral ACC, DLPFC, hippocampus, and MPFC. We characterized the differences using Bayesian parameter averaging (BPA) in addition to classical inference (t-test). In addition to common effective connectivity in these two groups, HCs displayed widespread significant connections predominantly involved in ACC not detected in SZ patients, but SZ showed few connections. Based on BPA results, SZ patients exhibited anterior cingulate cortico-prefrontal-hippocampal hyperconnectivity, as well as ACC-related and hippocampal-dorsolateral prefrontal-medial prefrontal hypoconnectivity. In summary, spectral DCM revealed the pattern of effective connectivity involving ACC in patients with first-episode SZ. This study provides a potential link between SZ and dysfunction of ACC, creating an ideal situation to associate mechanisms behind SZ with aberrant connectivity among these cognition and emotion-related regions.
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Affiliation(s)
- Long-Biao Cui
- Department of Radiology, Xijing Hospital, The Fourth Military Medical University Xi'an, China
| | - Jian Liu
- Network Center, The Fourth Military Medical University Xi'an, China
| | - Liu-Xian Wang
- Department of Radiology, Xijing Hospital, The Fourth Military Medical University Xi'an, China
| | - Chen Li
- Department of Radiology, Xijing Hospital, The Fourth Military Medical University Xi'an, China
| | - Yi-Bin Xi
- Department of Radiology, Xijing Hospital, The Fourth Military Medical University Xi'an, China
| | - Fan Guo
- Department of Radiology, Xijing Hospital, The Fourth Military Medical University Xi'an, China
| | - Hua-Ning Wang
- Department of Psychiatry, Xijing Hospital, The Fourth Military Medical University Xi'an, China
| | - Lin-Chuan Zhang
- School of Biomedical Engineering, The Fourth Military Medical University Xi'an, China
| | - Wen-Ming Liu
- Department of Psychiatry, Xijing Hospital, The Fourth Military Medical University Xi'an, China
| | - Hong He
- Department of Psychiatry, Xijing Hospital, The Fourth Military Medical University Xi'an, China
| | - Ping Tian
- Department of Radiology, Xijing Hospital, The Fourth Military Medical University Xi'an, China
| | - Hong Yin
- Department of Radiology, Xijing Hospital, The Fourth Military Medical University Xi'an, China
| | - Hongbing Lu
- School of Biomedical Engineering, The Fourth Military Medical University Xi'an, China
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Samudra N, Ivleva EI, Hubbard NA, Rypma B, Sweeney JA, Clementz BA, Keshavan MS, Pearlson GD, Tamminga CA. Alterations in hippocampal connectivity across the psychosis dimension. Psychiatry Res 2015; 233:148-57. [PMID: 26123450 PMCID: PMC4784701 DOI: 10.1016/j.pscychresns.2015.06.004] [Citation(s) in RCA: 45] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/22/2015] [Revised: 04/24/2015] [Accepted: 06/08/2015] [Indexed: 01/13/2023]
Abstract
Recent evidence demonstrates that hippocampal hyperactivity helps mediate psychosis. Using resting state functional magnetic resonance imaging (rsfMRI), we examined hippocampal connectivity alterations in individuals with psychosis (PS) versus healthy controls (HC). Because of its putative greater involvement in psychiatric disorders, we hypothesized that the anterior hippocampus network would show greater dysconnectivity in psychosis. We tested rsfMRI connectivity in 88 PS (including 21 with schizophrenia; 40 with schizoaffective disorder; 27 with psychotic bipolar I disorder) and 65 HC. Seed-based voxel-wise connectivity analyses were carried out using whole, anterior, and posterior hippocampal seeds. No significant differences in functional hippocampal connectivity were found across the three conventional diagnoses. PS were then contrasted with HC, showing strong reductions in anterior hippocampal connectivity to anterior neocortical regions, including medial frontal and anterior cingulate cortices, as well as superior temporal gyrus, precuneus, thalamus and cerebellum. Posterior hippocampal seeds also demonstrated decreased connectivity in PS, with fewer dysconnected regions and a posterior/cerebellar distribution. Whole hippocampal outcomes were consistent with anterior/posterior hippocampal connectivity changes. Connectivity alterations did not correlate with cognition, clinical symptoms, or medication effect variables. Our results suggest a psychosis network of decreased hippocampal connectivity with limbic and frontal contributions, independent of diagnostic categories.
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Affiliation(s)
- Niyatee Samudra
- Department of Psychiatry, University of Texas Southwestern Medical Center, Dallas, TX, United States.
| | - Elena I Ivleva
- Department of Psychiatry, University of Texas Southwestern Medical Center, Dallas, TX, United States
| | | | - Bart Rypma
- Department of Psychiatry, University of Texas Southwestern Medical Center, Dallas, TX, United States; Center for Brain Health, UT Dallas, Dallas, TX, United States
| | - John A Sweeney
- Department of Psychiatry, University of Texas Southwestern Medical Center, Dallas, TX, United States
| | - Brett A Clementz
- Department of Psychology, University of Georgia, Athens, GA, United States
| | - Matcheri S Keshavan
- Department of Psychiatry, Beth Israel Deaconess Hospital, Harvard Medical School, Boston, MA, United States
| | - Godfrey D Pearlson
- Department of Psychiatry, Institute of Living/Hartford Hospital, Yale School of Medicine, New Haven, CT, United States
| | - Carol A Tamminga
- Department of Psychiatry, University of Texas Southwestern Medical Center, Dallas, TX, United States
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Tamminga CA, Zukin RS. Schizophrenia: Evidence implicating hippocampal GluN2B protein and REST epigenetics in psychosis pathophysiology. Neuroscience 2015. [PMID: 26211447 DOI: 10.1016/j.neuroscience.2015.07.038] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
The hippocampus is strongly implicated in the psychotic symptoms of schizophrenia. Functionally, basal hippocampal activity (perfusion) is elevated in schizophrenic psychosis, as measured with positron emission tomography (PET) and with magnetic resonance (MR) perfusion techniques, while hippocampal activation to memory tasks is reduced. Subfield-specific hippocampal molecular pathology exists in human psychosis tissue which could underlie this neuronal hyperactivity, including increased GluN2B-containing NMDA receptors in hippocampal CA3, along with increased postsynaptic density protein-95 (PSD-95) along with augmented dendritic spines on the pyramidal neuron apical dendrites. We interpret these observations to implicate a reduction in the influence of a ubiquitous gene repressor, repressor element-1 silencing transcription factor (REST) in psychosis; REST is involved in the age-related maturation of the NMDA receptor from GluN2B- to GluN2A-containing NMDA receptors through epigenetic remodeling. These CA3 changes in psychosis leave the hippocampus liable to pathological increases in neuronal activity, feedforward excitation and false memory formation, sometimes with psychotic content.
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Affiliation(s)
- C A Tamminga
- UT Southwestern Medical School, Dallas, TX, United States.
| | - R S Zukin
- Albert Einstein School of Medicine, New York, NY, United States
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Contribution of substantia nigra glutamate to prediction error signals in schizophrenia: a combined magnetic resonance spectroscopy/functional imaging study. NPJ SCHIZOPHRENIA 2015; 1:14001. [PMID: 26878032 PMCID: PMC4752128 DOI: 10.1038/npjschz.2014.1] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Background: Because dopamine neurons signal a mismatch between expected and actual reward called prediction error (PE), aberrant PE signals in schizophrenia have been attributed to known dopaminergic abnormalities. However, dysfunction of N-methyl-D-aspartate receptors on cortical γ-aminobutyric acid neurons, as hypothesized in schizophrenia, could lead to excess glutamate release in the substantia nigra (SN) and affect reward processing. Aims: The aim of this study was to investigate the contribution of SN glutamate to PE signals in healthy controls (HC) and patients with schizophrenia (SZ). Methods: We recruited 22 medicated SZ and 19 HC. We obtained (1) functional magnetic resonance imaging during a probabilistic monetary reward task to assess PE-related blood oxygen level-dependent (BOLD) signal and (2) magnetic resonance spectroscopy to measure Glx (glutamate+glutamine) in the SN. To identify group differences in regions where the BOLD signal varies as a function of PE, we analyzed PEs generated during the task as parametric modulators of reward delivery. Finally, we examined the correlation of PE-related BOLD signal and SN Glx in each group. Results: Relative to HC, PE-related BOLD signals in SZ were significantly different in the midbrain/SN and ventral striatum. In SZ, SN Glx was significantly elevated. In HC, but not in SZ, PE-related BOLD signal in SN was positively correlated with SN Glx. Conclusions: These results suggest a role of glutamate in the neural coding of PE in controls. They indicate that glutamatergic dysfunction might contribute to abnormal PE coding in schizophrenia, suggesting the use of glutamate-targeted approaches to improve these deficits.
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Modinos G, Allen P, Grace AA, McGuire P. Translating the MAM model of psychosis to humans. Trends Neurosci 2014; 38:129-38. [PMID: 25554679 DOI: 10.1016/j.tins.2014.12.005] [Citation(s) in RCA: 117] [Impact Index Per Article: 11.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2014] [Revised: 11/12/2014] [Accepted: 12/02/2014] [Indexed: 12/13/2022]
Abstract
Elevated dopamine function and alterations in medial temporal lobe (MTL) structure and function are two of the most robust findings in schizophrenia, but how interactions between these abnormalities underlie the onset of psychosis is unclear. The methylazoxymethanol acetate (MAM) rodent model proposes that psychosis develops as a result of a perturbation of MTL function, leading to elevated striatal dopamine dysfunction. Here, we review several recent neuroimaging studies that examine components of the putative model in humans with an ultra high risk (UHR) of the psychosis. While data from these studies are broadly consistent with the MAM model, caution is required when comparing data across animal and human studies.
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Affiliation(s)
- Gemma Modinos
- Department of Psychosis Studies, Institute of Psychiatry, Psychology and Neuroscience, King's College London, London, UK.
| | - Paul Allen
- Department of Psychosis Studies, Institute of Psychiatry, Psychology and Neuroscience, King's College London, London, UK
| | - Anthony A Grace
- Departments of Neuroscience, Psychiatry, and Psychology, University of Pittsburgh, Pittsburgh, PA, USA
| | - Philip McGuire
- Department of Psychosis Studies, Institute of Psychiatry, Psychology and Neuroscience, King's College London, London, UK
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Wesseling H, Rahmoune H, Tricklebank M, Guest PC, Bahn S. A Targeted Multiplexed Proteomic Investigation Identifies Ketamine-Induced Changes in Immune Markers in Rat Serum and Expression Changes in Protein Kinases/Phosphatases in Rat Brain. J Proteome Res 2014; 14:411-21. [DOI: 10.1021/pr5009493] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Affiliation(s)
- Hendrik Wesseling
- Department
of Chemical Engineering and Biotechnology, University of Cambridge, Cambridge CB2 1QT, United Kingdom
| | - Hassan Rahmoune
- Department
of Chemical Engineering and Biotechnology, University of Cambridge, Cambridge CB2 1QT, United Kingdom
| | - Mark Tricklebank
- Ely Lilly
and
Co. Ltd, Erl Wood Manor, Sunninghill
Road, Windelesham, Surrey GU20 6PH, United Kingdom
| | - Paul C. Guest
- Department
of Chemical Engineering and Biotechnology, University of Cambridge, Cambridge CB2 1QT, United Kingdom
| | - Sabine Bahn
- Department
of Chemical Engineering and Biotechnology, University of Cambridge, Cambridge CB2 1QT, United Kingdom
- Department
of Neuroscience, Erasmus Medical Center Rotterdam, 3000 CA, The Netherlands
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58
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Das T, Ivleva EI, Wagner AD, Stark CE, Tamminga CA. Loss of pattern separation performance in schizophrenia suggests dentate gyrus dysfunction. Schizophr Res 2014; 159:193-7. [PMID: 25176349 PMCID: PMC4177293 DOI: 10.1016/j.schres.2014.05.006] [Citation(s) in RCA: 79] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/24/2014] [Revised: 05/05/2014] [Accepted: 05/09/2014] [Indexed: 02/04/2023]
Abstract
Motivated by evidence that the dentate gyrus differentially mediates the pattern separation (PS) component of declarative memory function and that dentate gyrus harbors molecular and cellular pathologies in schizophrenia, we examined whether PS performance is altered in volunteers with schizophrenia (SZV) relative to healthy volunteers (HV). In groups of well-characterized SZV (n=14) and HV (n=15), we contrasted performance on the Behavioral Pattern Separation (BPS) Task, acquiring two outcome measures, a PS parameter and a Recognition Memory (RM) parameter, as well as specific recognition data by stimulus type. The SZVs showed a significant decrement in PS performance relative to HV (mean ± SEM, SZV: 3.1 ± 2.7%; HV: 17.1 ± 5.8%; p=0.039, d'=0.86); whereas SZV and HV did not significantly differ in RM performance (SZV: 50.1 ± 8.1%; HV: 59.3 ± 5.5%; p=0.350, d'=0.36). Moreover, the SZVs showed a selective defect in correctly identifying similar lure items (SZV: 24.0 ± 3.7%; HV: 41.2 ± 4.6%; p<0.05), but demonstrated no impairment in identifying targets and novel foils. These data suggest that the dentate gyrus is dysfunctional in schizophrenia, a feature that could contribute to declarative memory impairment in the disorder and possibly to psychosis, a conclusion consistent with the considerable molecular pathology in the dentate gyrus in schizophrenia.
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Affiliation(s)
- Tanusree Das
- Department of Psychiatry, UT Southwestern Medical School, Dallas, TX
| | - Elena I. Ivleva
- Department of Psychiatry, UT Southwestern Medical School, Dallas, TX
| | - Anthony D. Wagner
- Department of Psychology and Neurosciences Program, Stanford University, Stanford, CA
| | | | - Carol A. Tamminga
- Department of Psychiatry, UT Southwestern Medical School, Dallas, TX
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