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Yates NJ, Robertson D, Rodger J, Martin-Iverson MT. Effects of Neonatal Dexamethasone Exposure on Adult Neuropsychiatric Traits in Rats. PLoS One 2016; 11:e0167220. [PMID: 27936175 PMCID: PMC5147874 DOI: 10.1371/journal.pone.0167220] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2016] [Accepted: 11/10/2016] [Indexed: 11/18/2022] Open
Abstract
The effects of early life stress in utero or in neonates has long-term consequences on hypothalamic-pituitary-adrenal (HPA) stress axis function and neurodevelopment. These effects extend into adulthood and may underpin a variety of mental illnesses and be related to various developmental and cognitive changes. We examined the potential role of neonatal HPA axis activation on adult psychopathology and dopamine sensitivity in the mature rat using neonatal exposure to the synthetic glucocorticoid receptor agonist and stress hormone, dexamethasone. We utilized a comprehensive battery of assessments for behaviour, brain function and gene expression to determine if elevated early life HPA activation is associated with adult-onset neuropsychiatric traits. Dexamethasone exposure increased startle reactivity under all conditions tested, but decreased sensitivity of sensorimotor gating to dopaminergic disruption–contrasting with what is observed in several neuropsychiatric diseases. Under certain conditions there also appeared to be mild long-term changes in stress and anxiety-related behaviours with neonatal dexamethasone exposure. Electrophysiology revealed that there were no consistent neuropsychiatric abnormalities in auditory processing or resting state brain function with dexamethasone exposure. However, neonatal dexamethasone altered auditory cortex glucocorticoid activation, and auditory cortex synchronization. Our results indicate that neonatal HPA axis activation by dexamethasone alters several aspects of adult brain function and behaviour and may induce long-term changes in emotional stress-reactivity. However, neonatal dexamethasone exposure is not specifically related to any particular neuropsychiatric disease.
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Affiliation(s)
- Nathanael J. Yates
- School of Animal Biology, Faculty of Science, The University of Western Australia, Crawley, Western Australia, Australia
- * E-mail:
| | - Donald Robertson
- School of Anatomy, Physiology, and Human Biology, Faculty of Science, The University of Western Australia, Crawley, Western Australia, Australia
| | - Jennifer Rodger
- School of Animal Biology, Faculty of Science, The University of Western Australia, Crawley, Western Australia, Australia
| | - Mathew T. Martin-Iverson
- School of Medicine and Pharmacology, Faculty of Medicine, Dentistry and Health Sciences, The University of Western Australia, Crawley, Western Australia, Australia
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Foxe JJ, Yeap S, Snyder AC, Kelly SP, Thakore JH, Molholm S. The N1 auditory evoked potential component as an endophenotype for schizophrenia: high-density electrical mapping in clinically unaffected first-degree relatives, first-episode, and chronic schizophrenia patients. Eur Arch Psychiatry Clin Neurosci 2011; 261:331-9. [PMID: 21153832 PMCID: PMC3119740 DOI: 10.1007/s00406-010-0176-0] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/20/2009] [Accepted: 11/23/2010] [Indexed: 12/19/2022]
Abstract
The N1 component of the auditory evoked potential (AEP) is a robust and easily recorded metric of auditory sensory-perceptual processing. In patients with schizophrenia, a diminution in the amplitude of this component is a near-ubiquitous finding. A pair of recent studies has also shown this N1 deficit in first-degree relatives of schizophrenia probands, suggesting that the deficit may be linked to the underlying genetic risk of the disease rather than to the disease state itself. However, in both these studies, a significant proportion of the relatives had other psychiatric conditions. As such, although the N1 deficit represents an intriguing candidate endophenotype for schizophrenia, it remains to be shown whether it is present in a group of clinically unaffected first-degree relatives. In addition to testing first-degree relatives, we also sought to replicate the N1 deficit in a group of first-episode patients and in a group of chronic schizophrenia probands. Subject groups consisted of 35 patients with schizophrenia, 30 unaffected first-degree relatives, 13 first-episode patients, and 22 healthy controls. Subjects sat in a dimly lit room and listened to a series of simple 1,000-Hz tones, indicating with a button press whenever they heard a deviant tone (1,500 Hz; 17% probability), while the AEP was recorded from 72 scalp electrodes. Both chronic and first-episode patients showed clear N1 amplitude decrements relative to healthy control subjects. Crucially, unaffected first-degree relatives also showed a clear N1 deficit. This study provides further support for the proposal that the auditory N1 deficit in schizophrenia is linked to the underlying genetic risk of developing this disorder. In light of recent studies, these results point to the N1 deficit as an endophenotypic marker for schizophrenia. The potential future utility of this metric as one element of a multivariate endophenotype is discussed.
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Affiliation(s)
- John J Foxe
- The Cognitive Neurophysiology Laboratory, Nathan S. Kline Institute for Psychiatric Research, Program in Cognitive Neuroscience and Schizophrenia, Orangeburg, NY 10962, USA.
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Kayser J, Tenke CE, Gil RB, Bruder GE. Stimulus- and response-locked neuronal generator patterns of auditory and visual word recognition memory in schizophrenia. Int J Psychophysiol 2009; 73:186-206. [PMID: 19275917 DOI: 10.1016/j.ijpsycho.2009.02.003] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2009] [Revised: 02/27/2009] [Accepted: 02/27/2009] [Indexed: 11/17/2022]
Abstract
Examining visual word recognition memory (WRM) with nose-referenced EEGs, we reported a preserved ERP 'old-new effect' (enhanced parietal positivity 300-800 ms to correctly-recognized repeated items) in schizophrenia ([Kayser, J., Bruder, G.E., Friedman, D., Tenke, C.E., Amador, X.F., Clark, S.C., Malaspina, D., Gorman, J.M., 1999. Brain event-related potentials (ERPs) in schizophrenia during a word recognition memory task. Int. J. Psychophysiol. 34(3), 249-265.]). However, patients showed reduced early negative potentials (N1, N2) and poorer WRM. Because group differences in neuronal generator patterns (i.e., sink-source orientation) may be masked by choice of EEG recording reference, the current study combined surface Laplacians and principal components analysis (PCA) to clarify ERP component topography and polarity and to disentangle stimulus- and response-related contributions. To investigate the impact of stimulus modality, 31-channel ERPs were recorded from 20 schizophrenic patients (15 male) and 20 age-, gender-, and handedness-matched healthy adults during parallel visual and auditory continuous WRM tasks. Stimulus- and response-locked reference-free current source densities (spherical splines) were submitted to unrestricted Varimax-PCA to identify and measure neuronal generator patterns underlying ERPs. Poorer (78.2+/-18.7% vs. 87.8+/-11.3% correct) and slower (958+/-226 vs. 773+/-206 ms) performance in patients was accompanied by reduced stimulus-related left-parietal P3 sources (150 ms pre-response) and vertex N2 sinks (both overall and old/new effects) but modality-specific N1 sinks were not significantly reduced. A distinct mid-frontal sink 50-ms post-response was markedly attenuated in patients. Reductions were more robust for auditory stimuli. However, patients showed increased lateral-frontotemporal sinks (T7 maximum) concurrent with auditory P3 sources. Electrophysiologic correlates of WRM deficits in schizophrenia suggest functional impairments of posterior cortex (stimulus representation) and anterior cingulate (stimulus categorization, response monitoring), primarily affecting memory for spoken words.
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Affiliation(s)
- Jürgen Kayser
- Department of Psychiatry, Columbia University College of Physicians and Surgeons, New York, NY, USA.
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Turetsky BI, Greenwood TA, Olincy A, Radant AD, Braff DL, Cadenhead KS, Dobie DJ, Freedman R, Green MF, Gur RE, Gur RC, Light GA, Mintz J, Nuechterlein KH, Schork NJ, Seidman LJ, Siever LJ, Silverman JM, Stone WS, Swerdlow NR, Tsuang DW, Tsuang MT, Calkins ME. Abnormal auditory N100 amplitude: a heritable endophenotype in first-degree relatives of schizophrenia probands. Biol Psychiatry 2008; 64:1051-9. [PMID: 18701089 PMCID: PMC2653714 DOI: 10.1016/j.biopsych.2008.06.018] [Citation(s) in RCA: 102] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/18/2008] [Revised: 06/05/2008] [Accepted: 06/30/2008] [Indexed: 01/31/2023]
Abstract
BACKGROUND N100 evoked potential amplitude and gating abnormalities have been widely observed in schizophrenia patients. However, previous studies have been inconclusive as to whether similar deficits are present in unaffected family members. The Consortium on the Genetics of Schizophrenia (COGS) is a multisite National Institute of Mental Health (NIMH) initiative examining neurocognitive and neurophysiological measures as endophenotypes for genetic studies of schizophrenia. We report initial results from the COGS dataset of auditory N100 amplitude and gating as candidate endophenotypes. METHODS Evoked potential data were acquired from 142 schizophrenia probands, 373 unaffected first-degree relatives, and 221 community comparison subjects (CCS), using an auditory paired-click stimulation paradigm. Amplitude of the N100 response to each click and the click 2/click 1 ratio were dependent variables. Heritability was estimated based on kinships using Solar v.2.1.2. Group differences were examined after subjects were categorized as either "broad" or "narrow," based on the presence (broad) or absence (narrow) of nonpsychotic psychiatric comorbidity. RESULTS Heritability estimates were .40 and .29 for click1 and click2 amplitudes and .22 for the ratio. Broad and narrow patients both had impaired click 1 amplitudes. Broad relatives, but not narrow relatives, exhibited similar impairments. There were no group differences for either click 2 amplitude or the gating ratio. CONCLUSIONS N100 amplitude is a heritable measure that is abnormal in patients and a subset of relatives for whom psychiatric comorbidity may be a genetically associated phenotype. Auditory N100 gating, although heritable, is less viable as a schizophrenia endophenotype.
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Affiliation(s)
- Bruce I. Turetsky
- Department of Psychiatry, University of Pennsylvania, Philadelphia, Pennsylvania, USA
| | - Tiffany A. Greenwood
- Department of Psychiatry, University of California San Diego, San Diego, California, USA
| | - Ann Olincy
- Department of Psychiatry, University of Colorado Health Sciences Center, Denver, Colorado, USA
| | - Allen D. Radant
- Department of Psychiatry and Behavioral Sciences, University of Washington, Seattle, Washington, and VA Puget Sound Health Care System, Seattle, Washington, USA
| | - David L. Braff
- Department of Psychiatry, University of California San Diego, San Diego, California, USA
| | - Kristin S. Cadenhead
- Department of Psychiatry, University of California San Diego, San Diego, California, USA
| | - Dorcas J. Dobie
- Department of Psychiatry and Behavioral Sciences, University of Washington, Seattle, Washington, and VA Puget Sound Health Care System, Seattle, Washington, USA
| | - Robert Freedman
- Department of Psychiatry, University of Colorado Health Sciences Center, Denver, Colorado, USA
| | - Michael F. Green
- Department of Psychiatry and Biobehavioral Sciences, Geffen School of Medicine at University of California Los Angeles, Los Angeles, California, USA.,VA Greater Los Angeles Healthcare System
| | - Raquel E. Gur
- Department of Psychiatry, University of Pennsylvania, Philadelphia, Pennsylvania, USA
| | - Ruben C. Gur
- Department of Psychiatry, University of Pennsylvania, Philadelphia, Pennsylvania, USA
| | - Gregory A. Light
- Department of Psychiatry, University of California San Diego, San Diego, California, USA
| | - James Mintz
- Department of Psychiatry and Biobehavioral Sciences, Geffen School of Medicine at University of California Los Angeles, Los Angeles, California, USA
| | - Keith H. Nuechterlein
- Department of Psychiatry and Biobehavioral Sciences, Geffen School of Medicine at University of California Los Angeles, Los Angeles, California, USA
| | - Nicholas J. Schork
- Scripps Genomic Medicine, La Jolla, CA, USA,Department of Molecular and Experimental Medicine, The Scripps Research Institute, La Jolla, CA, USA
| | - Larry J. Seidman
- Massachusetts Mental Health Center Public Psychiatry Division of the Beth Israel Deaconess Medical Center, Harvard Medical School Department of Psychiatry, Boston, Massachusetts, and Harvard Institute of Psychiatric Epidemiology and Genetics, Boston, Massachusetts, USA
| | - Larry J. Siever
- Department of Psychiatry, The Mount Sinai School of Medicine, New York, New York, USA.,James J. Peters VA Medical Center and VISN3 MIRECC
| | - Jeremy M. Silverman
- Department of Psychiatry, The Mount Sinai School of Medicine, New York, New York, USA
| | - William S. Stone
- Massachusetts Mental Health Center Public Psychiatry Division of the Beth Israel Deaconess Medical Center, Harvard Medical School Department of Psychiatry, Boston, Massachusetts, and Harvard Institute of Psychiatric Epidemiology and Genetics, Boston, Massachusetts, USA
| | - Neal R. Swerdlow
- Department of Psychiatry, University of California San Diego, San Diego, California, USA
| | - Debby W. Tsuang
- Department of Psychiatry and Behavioral Sciences, University of Washington, Seattle, Washington, and VA Puget Sound Health Care System, Seattle, Washington, USA
| | - Ming T. Tsuang
- Department of Psychiatry, University of California San Diego, San Diego, California, USA.,Massachusetts Mental Health Center Public Psychiatry Division of the Beth Israel Deaconess Medical Center, Harvard Medical School Department of Psychiatry, Boston, Massachusetts, and Harvard Institute of Psychiatric Epidemiology and Genetics, Boston, Massachusetts, USA
| | - Monica E. Calkins
- Department of Psychiatry, University of Pennsylvania, Philadelphia, Pennsylvania, USA
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Draganic DM, Catts SV, Carr VJ. Neuroscience Institute of Schizophrenia and Allied Disorders (NISAD): 10 years of Australia's first virtual research institute. Aust N Z J Psychiatry 2007; 41:78-88. [PMID: 17464685 DOI: 10.1080/00048670601057783] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
Abstract
OBJECTIVE To review the first 10 years of operation of the Neuroscience Institute of Schizophrenia and Allied Disorders (NISAD), Australia's first virtual research institute. METHOD Narrative description of the evolution of NISAD. RESULTS Since inception in 1996, NISAD has developed a wide range of activities to enhance existing efforts and develop new initiatives in schizophrenia research, initially throughout New South Wales, but increasingly on a national scale. This involved the initial development of critical research infrastructure to provide the foundation, with the subsequent focus on developing a multidisciplinary programme of schizophrenia research, across the basic to applied research spectrum. While the primary focus has been the scientific domain, NISAD has also played a leading role in increasing public awareness of schizophrenia as a disease amenable to scientific investigation. CONCLUSION NISAD has succeeded in building a framework to apply the latest developments in neuroscience to the study of schizophrenia and has formed a multidisciplinary network of clinicians and neuroscientists who are actively collaborating on a range of research initiatives. The 'virtual institute' structure of NISAD has proven cost-efficient and consistent with innovative thinking about research resource management.
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Affiliation(s)
- Daren M Draganic
- Neuroscience Institute of Schizophrenia and Allied Disorders, Darlinghurst, NSW 2010, Australia.
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