251
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Klingaman EA, Palmer-Bacon J, Bennett ME, Rowland LM. Sleep Disorders Among People With Schizophrenia: Emerging Research. Curr Psychiatry Rep 2015; 17:79. [PMID: 26279058 DOI: 10.1007/s11920-015-0616-7] [Citation(s) in RCA: 43] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
Up to 80 % of individuals with schizophrenia spectrum disorders experience sleep disturbances, which impact physical and mental health, as well as quality of life. In this paper, we review and integrate emerging literature, published between 2012 and 2014, regarding approaches to diagnosis and treatment of major sleep disorders for people with schizophrenia spectrum disorders, including insomnia, obstructive sleep apnea (OSA), circadian rhythm dysfunction, and restless legs syndrome (RLS). We advocate for (1) the need to evaluate the utility of nonpharmacological approaches in people with schizophrenia spectrum disorders; (2) documentation of guidelines to assist providers in clinically tailoring such interventions when their clients experience positive, negative, and/or cognitive symptoms; (3) research on the best ways providers can capitalize on clients' self-identified needs and motivation to engage in sleep treatments through shared decision making; and (4) the importance of investigating whether and how mental health and sleep treatment services should be better connected to facilitate access for people with schizophrenia spectrum disorders. Assessment and tailored treatment of sleep disorders within mental health treatment settings has the potential to reduce sleep problems and improve functioning, quality of life, and recovery of this population.
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Affiliation(s)
- Elizabeth A Klingaman
- Mental Illness Research, Education, and Clinical Center (MIRECC), VA Capitol Health Care Network (VISN 5), 10 North Greene Street (Annex Suite 720), Baltimore, MD, 21201, USA,
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252
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Ray LB, Sockeel S, Soon M, Bore A, Myhr A, Stojanoski B, Cusack R, Owen AM, Doyon J, Fogel SM. Expert and crowd-sourced validation of an individualized sleep spindle detection method employing complex demodulation and individualized normalization. Front Hum Neurosci 2015; 9:507. [PMID: 26441604 PMCID: PMC4585171 DOI: 10.3389/fnhum.2015.00507] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2015] [Accepted: 08/31/2015] [Indexed: 11/16/2022] Open
Abstract
A spindle detection method was developed that: (1) extracts the signal of interest (i.e., spindle-related phasic changes in sigma) relative to ongoing "background" sigma activity using complex demodulation, (2) accounts for variations of spindle characteristics across the night, scalp derivations and between individuals, and (3) employs a minimum number of sometimes arbitrary, user-defined parameters. Complex demodulation was used to extract instantaneous power in the spindle band. To account for intra- and inter-individual differences, the signal was z-score transformed using a 60 s sliding window, per channel, over the course of the recording. Spindle events were detected with a z-score threshold corresponding to a low probability (e.g., 99th percentile). Spindle characteristics, such as amplitude, duration and oscillatory frequency, were derived for each individual spindle following detection, which permits spindles to be subsequently and flexibly categorized as slow or fast spindles from a single detection pass. Spindles were automatically detected in 15 young healthy subjects. Two experts manually identified spindles from C3 during Stage 2 sleep, from each recording; one employing conventional guidelines, and the other, identifying spindles with the aid of a sigma (11-16 Hz) filtered channel. These spindles were then compared between raters and to the automated detection to identify the presence of true positives, true negatives, false positives and false negatives. This method of automated spindle detection resolves or avoids many of the limitations that complicate automated spindle detection, and performs well compared to a group of non-experts, and importantly, has good external validity with respect to the extant literature in terms of the characteristics of automatically detected spindles.
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Affiliation(s)
- Laura B. Ray
- Brain and Mind Institute, Western UniversityLondon, ON, Canada
| | - Stéphane Sockeel
- Functional Neuroimaging Unit, Centre de Recherche de l'Institut Universitaire de Gériatrie de MontréalMontreal, QC, Canada
| | - Melissa Soon
- Brain and Mind Institute, Western UniversityLondon, ON, Canada
- Department of Psychology, Western UniversityLondon, ON, Canada
| | - Arnaud Bore
- Functional Neuroimaging Unit, Centre de Recherche de l'Institut Universitaire de Gériatrie de MontréalMontreal, QC, Canada
| | - Ayako Myhr
- Brain and Mind Institute, Western UniversityLondon, ON, Canada
| | | | - Rhodri Cusack
- Brain and Mind Institute, Western UniversityLondon, ON, Canada
- Department of Psychology, Western UniversityLondon, ON, Canada
| | - Adrian M. Owen
- Brain and Mind Institute, Western UniversityLondon, ON, Canada
- Department of Psychology, Western UniversityLondon, ON, Canada
| | - Julien Doyon
- Functional Neuroimaging Unit, Centre de Recherche de l'Institut Universitaire de Gériatrie de MontréalMontreal, QC, Canada
- Department of Psychology, University of MontrealMontreal, QC, Canada
| | - Stuart M. Fogel
- Brain and Mind Institute, Western UniversityLondon, ON, Canada
- Functional Neuroimaging Unit, Centre de Recherche de l'Institut Universitaire de Gériatrie de MontréalMontreal, QC, Canada
- Department of Psychology, Western UniversityLondon, ON, Canada
- Department of Psychology, University of MontrealMontreal, QC, Canada
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253
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Cellini N, Goodbourn PT, McDevitt EA, Martini P, Holcombe AO, Mednick SC. Sleep after practice reduces the attentional blink. Atten Percept Psychophys 2015; 77:1945-54. [PMID: 25911156 PMCID: PMC4704698 DOI: 10.3758/s13414-015-0912-7] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
The attentional blink (AB) is an impairment in detecting the second of two targets that appear in close temporal succession. We investigated the effect of practice and a nap on the magnitude of the AB deficit. We found evidence that sleep boosts practice-dependent reduction of the AB. Participants reported two target letters embedded in a rapid serial visual presentation display. After two morning sessions, half the participants took a polysomnographically recorded nap, while the others remained awake. Comparing two afternoon sessions to the two morning sessions, we observed a decreased AB only within the group who napped. The improvement was due to increased efficacy of the attentional selection of T2 (the probability of reporting a T2-relevant item). There was no change in selection's latency or temporal precision. The magnitude of improvement was positively associated with the duration of N2 sleep and the number of N2 sleep spindles. Our results suggest that sleep, particularly N2 sleep and sleep spindles, improves attentional selection in time.
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Affiliation(s)
- Nicola Cellini
- Department of General Psychology, University of Padova, Via Venezia 8, Padova 35131, Italy
| | - Patrick T. Goodbourn
- School of Psychology, University of Sydney, Brennan MacCallum Building (A18), Sydney 2006, New South Wales, Australia
| | - Elizabeth A. McDevitt
- Department of Psychology, University of California Riverside, 900 University Avenue, Riverside, CA 92521, USA
| | - Paolo Martini
- Department of Psychology, Harvard University, 52 Oxford Street, Cambridge 02138, MA, USA
| | - Alex O. Holcombe
- School of Psychology, University of Sydney, Brennan MacCallum Building (A18), Sydney 2006, New South Wales, Australia
| | - Sara C. Mednick
- Department of Psychology, University of California Riverside, 900 University Avenue, Riverside, CA 92521, USA
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254
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Tesler N, Gerstenberg M, Franscini M, Jenni OG, Walitza S, Huber R. Reduced sleep spindle density in early onset schizophrenia: a preliminary finding. Schizophr Res 2015; 166:355-7. [PMID: 25999041 DOI: 10.1016/j.schres.2015.04.042] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/21/2014] [Revised: 04/28/2015] [Accepted: 04/30/2015] [Indexed: 11/30/2022]
Affiliation(s)
- Noemi Tesler
- Child Development Center, University Children's Hospital Zurich, Switzerland; Neuroscience Center Zurich, University of Zurich, Switzerland
| | - Miriam Gerstenberg
- University Clinics for Child and Adolescent Psychiatry, University of Zurich, Switzerland
| | - Maurizia Franscini
- University Clinics for Child and Adolescent Psychiatry, University of Zurich, Switzerland
| | - Oskar G Jenni
- Child Development Center, University Children's Hospital Zurich, Switzerland; Zurich Center for Integrative Human Physiology, University of Zurich, Switzerland
| | - Susanne Walitza
- Neuroscience Center Zurich, University of Zurich, Switzerland; University Clinics for Child and Adolescent Psychiatry, University of Zurich, Switzerland; Zurich Center for Integrative Human Physiology, University of Zurich, Switzerland
| | - Reto Huber
- Child Development Center, University Children's Hospital Zurich, Switzerland; Neuroscience Center Zurich, University of Zurich, Switzerland; University Clinics for Child and Adolescent Psychiatry, University of Zurich, Switzerland; Zurich Center for Integrative Human Physiology, University of Zurich, Switzerland.
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255
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O'Reilly C, Nielsen T. Automatic sleep spindle detection: benchmarking with fine temporal resolution using open science tools. Front Hum Neurosci 2015; 9:353. [PMID: 26157375 PMCID: PMC4478395 DOI: 10.3389/fnhum.2015.00353] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2015] [Accepted: 06/01/2015] [Indexed: 11/13/2022] Open
Abstract
Sleep spindle properties index cognitive faculties such as memory consolidation and diseases such as major depression. For this reason, scoring sleep spindle properties in polysomnographic recordings has become an important activity in both research and clinical settings. The tediousness of this manual task has motivated efforts for its automation. Although some progress has been made, increasing the temporal accuracy of spindle scoring and improving the performance assessment methodology are two aspects needing more attention. In this paper, four open-access automated spindle detectors with fine temporal resolution are proposed and tested against expert scoring of two proprietary and two open-access databases. Results highlight several findings: (1) that expert scoring and polysomnographic databases are important confounders when comparing the performance of spindle detectors tested using different databases or scorings; (2) because spindles are sparse events, specificity estimates are potentially misleading for assessing automated detector performance; (3) reporting the performance of spindle detectors exclusively with sensitivity and specificity estimates, as is often seen in the literature, is insufficient; including sensitivity, precision and a more comprehensive statistic such as Matthew's correlation coefficient, F1-score, or Cohen's κ is necessary for adequate evaluation; (4) reporting statistics for some reasonable range of decision thresholds provides a much more complete and useful benchmarking; (5) performance differences between tested automated detectors were found to be similar to those between available expert scorings; (6) much more development is needed to effectively compare the performance of spindle detectors developed by different research teams. Finally, this work clarifies a long-standing but only seldomly posed question regarding whether expert scoring truly is a reliable gold standard for sleep spindle assessment.
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Affiliation(s)
- Christian O'Reilly
- MEG Laboratory, McConnell Brain Imaging Centre, Montreal Neurological Institute, McGill UniversityMontreal, QC, Canada
- Dream and Nightmare Laboratory, Center for Advanced Research in Sleep Medicine, Hôpital du Sacré-Coeur de MontréalMontreal, QC, Canada
- Département de Psychiatrie, Université de MontréalMontreal, QC, Canada
| | - Tore Nielsen
- Dream and Nightmare Laboratory, Center for Advanced Research in Sleep Medicine, Hôpital du Sacré-Coeur de MontréalMontreal, QC, Canada
- Département de Psychiatrie, Université de MontréalMontreal, QC, Canada
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256
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Pittman-Polletta BR, Kocsis B, Vijayan S, Whittington MA, Kopell NJ. Brain rhythms connect impaired inhibition to altered cognition in schizophrenia. Biol Psychiatry 2015; 77:1020-30. [PMID: 25850619 PMCID: PMC4444389 DOI: 10.1016/j.biopsych.2015.02.005] [Citation(s) in RCA: 56] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/11/2014] [Revised: 01/23/2015] [Accepted: 02/07/2015] [Indexed: 01/06/2023]
Abstract
In recent years, schizophrenia research has focused on inhibitory interneuron dysfunction at the level of neurobiology and on cognitive impairments at the psychological level. Reviewing both experimental and computational findings, we show how the temporal structure of the activity of neuronal populations, exemplified by brain rhythms, can begin to bridge these levels of complexity. Oscillations in neuronal activity tie the pathophysiology of schizophrenia to alterations in local processing and large-scale coordination, and these alterations in turn can lead to the cognitive and perceptual disturbances observed in schizophrenia.
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Affiliation(s)
- Benjamin R. Pittman-Polletta
- Cognitive Rhythms Collaborative, Boston, MA,Department of Mathematics & Statistics, Boston University, Boston MA,Corresponding author. Please send correspondence to: 111 Cummington Mall, Boston MA 02215. Phone: 617-353-2560. Fax: 617-353-8100., (Benjamin R. Pittman-Polletta)
| | - Bernat Kocsis
- Cognitive Rhythms Collaborative, Boston, MA,Department of Psychiatry, Beth Israel Medical Center, Harvard Medical School, Boston MA
| | - Sujith Vijayan
- Cognitive Rhythms Collaborative, Boston, MA,Department of Mathematics & Statistics, Boston University, Boston MA
| | - Miles A. Whittington
- Cognitive Rhythms Collaborative, Boston, MA,Department of Neuroscience, Hull York Medical School, York University, UK
| | - Nancy J. Kopell
- Cognitive Rhythms Collaborative, Boston, MA,Department of Mathematics & Statistics, Boston University, Boston MA
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257
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Parekh A, Selesnick IW, Rapoport DM, Ayappa I. Detection of K-complexes and sleep spindles (DETOKS) using sparse optimization. J Neurosci Methods 2015; 251:37-46. [PMID: 25956566 DOI: 10.1016/j.jneumeth.2015.04.006] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2015] [Revised: 04/03/2015] [Accepted: 04/07/2015] [Indexed: 01/09/2023]
Abstract
BACKGROUND This paper addresses the problem of detecting sleep spindles and K-complexes in human sleep EEG. Sleep spindles and K-complexes aid in classifying stage 2 NREM human sleep. NEW METHOD We propose a non-linear model for the EEG, consisting of a transient, low-frequency, and an oscillatory component. The transient component captures the non-oscillatory transients in the EEG. The oscillatory component admits a sparse time-frequency representation. Using a convex objective function, this paper presents a fast non-linear optimization algorithm to estimate the components in the proposed signal model. The low-frequency and oscillatory components are used to detect K-complexes and sleep spindles respectively. RESULTS AND COMPARISON WITH OTHER METHODS The performance of the proposed method is evaluated using an online EEG database. The F1 scores for the spindle detection averaged 0.70 ± 0.03 and the F1 scores for the K-complex detection averaged 0.57 ± 0.02. The Matthews Correlation Coefficient and Cohen's Kappa values were in a range similar to the F1 scores for both the sleep spindle and K-complex detection. The F1 scores for the proposed method are higher than existing detection algorithms. CONCLUSIONS Comparable run-times and better detection results than traditional detection algorithms suggests that the proposed method is promising for the practical detection of sleep spindles and K-complexes.
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Affiliation(s)
- Ankit Parekh
- Department of Mathematics, School of Engineering, New York University, USA.
| | - Ivan W Selesnick
- Department of Electrical and Computer Engineering, School of Engineering, New York University, USA
| | - David M Rapoport
- Department of Medicine, Division of Pulmonary, Critical Care and Sleep Medicine, School of Medicine, New York University, USA
| | - Indu Ayappa
- Department of Medicine, Division of Pulmonary, Critical Care and Sleep Medicine, School of Medicine, New York University, USA
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258
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Palliyali AJ, Ahmed MN, Ahmed B. Using a quadratic parameter sinusoid model to characterize the structure of EEG sleep spindles. Front Hum Neurosci 2015; 9:206. [PMID: 25999833 PMCID: PMC4419846 DOI: 10.3389/fnhum.2015.00206] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2014] [Accepted: 03/28/2015] [Indexed: 11/28/2022] Open
Abstract
Sleep spindles are essentially non-stationary signals that display time and frequency-varying characteristics within their envelope, which makes it difficult to accurately identify its instantaneous frequency and amplitude. To allow a better parameterization of the structure of spindle, we propose modeling spindles using a Quadratic Parameter Sinusoid (QPS). The QPS is well suited to model spindle activity as it utilizes a quadratic representation to capture the inherent duration and frequency variations within spindles. The effectiveness of our proposed model and estimation technique was quantitatively evaluated in parameter determination experiments using simulated spindle-like signals and real spindles in the presence of background EEG. We used the QPS parameters to predict the energy and frequency of spindles with a mean accuracy of 92.34 and 97.73% respectively. We also show that the QPS parameters provide a quantification of the amplitude and frequency variations occurring within sleep spindles that can be observed visually and related to their characteristic "waxing and waning" shape. We analyze the variations in the parameters values to present how they can be used to understand the inter- and intra-participant variations in spindle structure. Finally, we present a comparison of the QPS parameters of spindles and non-spindles, which shows a substantial difference in parameter values between the two classes.
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Affiliation(s)
| | | | - Beena Ahmed
- Electrical and Computer Engineering Program, Texas A&M University at QatarDoha, Qatar
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259
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Keshavan MS, Mehta UM, Padmanabhan JL, Shah JL. Dysplasticity, metaplasticity, and schizophrenia: Implications for risk, illness, and novel interventions. Dev Psychopathol 2015; 27:615-35. [PMID: 25997775 PMCID: PMC6283269 DOI: 10.1017/s095457941500019x] [Citation(s) in RCA: 54] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
In this paper, we review the history of the concept of neuroplasticity as it relates to the understanding of neuropsychiatric disorders, using schizophrenia as a case in point. We briefly review the myriad meanings of the term neuroplasticity, and its neuroscientific basis. We then review the evidence for aberrant neuroplasticity and metaplasticity associated with schizophrenia as well as the risk for developing this illness, and discuss the implications of such understanding for prevention and therapeutic interventions. We argue that the failure and/or altered timing of plasticity of critical brain circuits might underlie cognitive and deficit symptoms, and may also lead to aberrant plastic reorganization in other circuits, leading to affective dysregulation and eventually psychosis. This "dysplastic" model of schizophrenia can suggest testable etiology and treatment-relevant questions for the future.
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Affiliation(s)
- Matcheri S. Keshavan
- Department of Psychiatry, Beth Israel Deaconess Medical Center and Harvard Medical School, Boston, Massachusetts, United States
| | - Urvakhsh Meherwan Mehta
- Department of Psychiatry, Beth Israel Deaconess Medical Center and Harvard Medical School, Boston, Massachusetts, United States
- Department of Psychiatry, National Institute of Mental Health and Neurosciences, Bangalore, India
| | - Jaya L. Padmanabhan
- Department of Psychiatry, Beth Israel Deaconess Medical Center and Harvard Medical School, Boston, Massachusetts, United States
| | - Jai L. Shah
- Douglas Hospital Research Center and Department of Psychiatry, McGill University, Montreal, Quebec, Canada
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260
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Christensen JAE, Nikolic M, Warby SC, Koch H, Zoetmulder M, Frandsen R, Moghadam KK, Sorensen HBD, Mignot E, Jennum PJ. Sleep spindle alterations in patients with Parkinson's disease. Front Hum Neurosci 2015; 9:233. [PMID: 25983685 PMCID: PMC4416460 DOI: 10.3389/fnhum.2015.00233] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2014] [Accepted: 04/11/2015] [Indexed: 01/04/2023] Open
Abstract
The aim of this study was to identify changes of sleep spindles (SS) in the EEG of patients with Parkinson's disease (PD). Five sleep experts manually identified SS at a central scalp location (C3-A2) in 15 PD and 15 age- and sex-matched control subjects. Each SS was given a confidence score, and by using a group consensus rule, 901 SS were identified and characterized by their (1) duration, (2) oscillation frequency, (3) maximum peak-to-peak amplitude, (4) percent-to-peak amplitude, and (5) density. Between-group comparisons were made for all SS characteristics computed, and significant changes for PD patients vs. control subjects were found for duration, oscillation frequency, maximum peak-to-peak amplitude and density. Specifically, SS density was lower, duration was longer, oscillation frequency slower and maximum peak-to-peak amplitude higher in patients vs. controls. We also computed inter-expert reliability in SS scoring and found a significantly lower reliability in scoring definite SS in patients when compared to controls. How neurodegeneration in PD could influence SS characteristics is discussed. We also note that the SS morphological changes observed here may affect automatic detection of SS in patients with PD or other neurodegenerative disorders (NDDs).
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Affiliation(s)
- Julie A E Christensen
- Biomedical Engineering, Department of Electrical Engineering, Technical University of Denmark Kongens Lyngby, Denmark ; Danish Center for Sleep Medicine, Department of Clinical Neurophysiology, Glostrup University Hospital Glostrup, Denmark ; Stanford Center for Sleep Sciences and Medicine, Psychiatry and Behavioral Sciences, Stanford University Palo Alto, CA, USA
| | - Miki Nikolic
- Danish Center for Sleep Medicine, Department of Clinical Neurophysiology, Glostrup University Hospital Glostrup, Denmark
| | - Simon C Warby
- Center for Advanced Research in Sleep Medicine, Sacré-Coeur Hospital of Montréal, University of Montréal Montréal, QC, Canada
| | - Henriette Koch
- Biomedical Engineering, Department of Electrical Engineering, Technical University of Denmark Kongens Lyngby, Denmark ; Danish Center for Sleep Medicine, Department of Clinical Neurophysiology, Glostrup University Hospital Glostrup, Denmark ; Stanford Center for Sleep Sciences and Medicine, Psychiatry and Behavioral Sciences, Stanford University Palo Alto, CA, USA
| | - Marielle Zoetmulder
- Danish Center for Sleep Medicine, Department of Clinical Neurophysiology, Glostrup University Hospital Glostrup, Denmark ; Department of Neurology, Bispebjerg Hospital Copenhagen, Denmark
| | - Rune Frandsen
- Danish Center for Sleep Medicine, Department of Clinical Neurophysiology, Glostrup University Hospital Glostrup, Denmark
| | - Keivan K Moghadam
- Department of Biomedical and Neuromotor Sciences (DIBINEM), University of Bologna Bologna, Italy
| | - Helge B D Sorensen
- Biomedical Engineering, Department of Electrical Engineering, Technical University of Denmark Kongens Lyngby, Denmark
| | - Emmanuel Mignot
- Stanford Center for Sleep Sciences and Medicine, Psychiatry and Behavioral Sciences, Stanford University Palo Alto, CA, USA
| | - Poul J Jennum
- Danish Center for Sleep Medicine, Department of Clinical Neurophysiology, Glostrup University Hospital Glostrup, Denmark ; Center for Healthy Ageing, University of Copenhagen Copenhagen, Denmark
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261
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Slow-oscillatory Transcranial Direct Current Stimulation Modulates Memory in Temporal Lobe Epilepsy by Altering Sleep Spindle Generators: A Possible Rehabilitation Tool. Brain Stimul 2015; 8:567-73. [DOI: 10.1016/j.brs.2015.01.410] [Citation(s) in RCA: 47] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2014] [Revised: 01/07/2015] [Accepted: 01/12/2015] [Indexed: 11/23/2022] Open
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262
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Tsanas A, Clifford GD. Stage-independent, single lead EEG sleep spindle detection using the continuous wavelet transform and local weighted smoothing. Front Hum Neurosci 2015; 9:181. [PMID: 25926784 PMCID: PMC4396195 DOI: 10.3389/fnhum.2015.00181] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2014] [Accepted: 03/17/2015] [Indexed: 12/05/2022] Open
Abstract
Sleep spindles are critical in characterizing sleep and have been associated with cognitive function and pathophysiological assessment. Typically, their detection relies on the subjective and time-consuming visual examination of electroencephalogram (EEG) signal(s) by experts, and has led to large inter-rater variability as a result of poor definition of sleep spindle characteristics. Hitherto, many algorithmic spindle detectors inherently make signal stationarity assumptions (e.g., Fourier transform-based approaches) which are inappropriate for EEG signals, and frequently rely on additional information which may not be readily available in many practical settings (e.g., more than one EEG channels, or prior hypnogram assessment). This study proposes a novel signal processing methodology relying solely on a single EEG channel, and provides objective, accurate means toward probabilistically assessing the presence of sleep spindles in EEG signals. We use the intuitively appealing continuous wavelet transform (CWT) with a Morlet basis function, identifying regions of interest where the power of the CWT coefficients corresponding to the frequencies of spindles (11-16 Hz) is large. The potential for assessing the signal segment as a spindle is refined using local weighted smoothing techniques. We evaluate our findings on two databases: the MASS database comprising 19 healthy controls and the DREAMS sleep spindle database comprising eight participants diagnosed with various sleep pathologies. We demonstrate that we can replicate the experts' sleep spindles assessment accurately in both databases (MASS database: sensitivity: 84%, specificity: 90%, false discovery rate 83%, DREAMS database: sensitivity: 76%, specificity: 92%, false discovery rate: 67%), outperforming six competing automatic sleep spindle detection algorithms in terms of correctly replicating the experts' assessment of detected spindles.
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Affiliation(s)
- Athanasios Tsanas
- Department of Engineering Science, Institute of Biomedical Engineering, University of OxfordOxford, UK
- Wolfson Centre for Mathematical Biology, Mathematical Institute, University of OxfordOxford, UK
- Nuffield Department of Medicine, Sleep and Circadian Neuroscience Institute, University of OxfordUK
| | - Gari D. Clifford
- Nuffield Department of Medicine, Sleep and Circadian Neuroscience Institute, University of OxfordUK
- Department of Biomedical Informatics, Emory UniversityAtlanta, GA, USA
- Department of Biomedical Engineering, Georgia Institute of TechnologyAtlanta, GA, USA
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263
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Göder R, Graf A, Ballhausen F, Weinhold S, Baier PC, Junghanns K, Prehn-Kristensen A. Impairment of sleep-related memory consolidation in schizophrenia: relevance of sleep spindles? Sleep Med 2015; 16:564-9. [PMID: 25912599 DOI: 10.1016/j.sleep.2014.12.022] [Citation(s) in RCA: 88] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/15/2014] [Revised: 11/21/2014] [Accepted: 12/04/2014] [Indexed: 11/30/2022]
Abstract
OBJECTIVES Deficits in declarative memory performance are among the most severe neuropsychological impairments in schizophrenia and contribute to poor clinical outcomes. The importance of sleep for brain plasticity and memory consolidation is widely accepted, and sleep spindles seem to play an important role in these processes. The aim of this study was to test the associations of sleep spindles and picture memory consolidation in patients with schizophrenia and healthy controls. METHODS We studied 16 patients with schizophrenia on stable antipsychotic medication (mean age ± standard deviation, 29.4 ± 6.4 years) and 16 healthy controls matched for age and educational level. Sleep was recorded and scored according to American Academy of Sleep Medicine (AASM) standard criteria. We performed a picture recognition paradigm and compared recognition performance for neutral and emotional pictures in sleep and wake conditions. RESULTS Recognition accuracy was better in healthy controls than in patients with schizophrenia in the sleep and wake conditions. However, the memory-promoting effect of sleep was significantly lower in schizophrenia patients than in controls. Sleep spindle activity was reduced in patients, and sleep spindle density was correlated with sleep-associated facilitation of recognition accuracy for neutral pictures. CONCLUSION Reduced sleep spindles seem to play an important role as a possible mechanism or biomarker for impaired sleep-related memory consolidation in patients with schizophrenia, and are a new target for treatment to improve memory functions and clinical outcomes in these patients.
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Affiliation(s)
- Robert Göder
- Department of Psychiatry and Psychotherapy, University Hospital Schleswig-Holstein, Kiel, Germany.
| | - Anna Graf
- Department of Psychiatry and Psychotherapy, University Hospital Schleswig-Holstein, Kiel, Germany
| | - Felix Ballhausen
- Department of Psychiatry and Psychotherapy, University Hospital Schleswig-Holstein, Kiel, Germany
| | - Sara Weinhold
- Department of Psychiatry and Psychotherapy, University Hospital Schleswig-Holstein, Kiel, Germany
| | - Paul Christian Baier
- Department of Psychiatry and Psychotherapy, University Hospital Schleswig-Holstein, Kiel, Germany
| | - Klaus Junghanns
- Department of Psychiatry and Psychotherapy, University Hospital Schleswig-Holstein, Lübeck, Germany
| | - Alexander Prehn-Kristensen
- Department of Adolescent and Child Psychiatry and Psychotherapy, University Hospital Schleswig-Holstein, Kiel, Germany
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264
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Lustenberger C, O’Gorman RL, Pugin F, Tüshaus L, Wehrle F, Achermann P, Huber R. Sleep spindles are related to schizotypal personality traits and thalamic glutamine/glutamate in healthy subjects. Schizophr Bull 2015; 41:522-31. [PMID: 25074975 PMCID: PMC4332948 DOI: 10.1093/schbul/sbu109] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
BACKGROUND Schizophrenia is a severe mental disorder affecting approximately 1% of the worldwide population. Yet, schizophrenia-like experiences (schizotypy) are very common in the healthy population, indicating a continuum between normal mental functioning and the psychosis found in schizophrenic patients. A continuum between schizotypy and schizophrenia would be supported if they share the same neurobiological origin. Two such neurobiological markers of schizophrenia are: (1) a reduction of sleep spindles (12-15 Hz oscillations during nonrapid eye movement sleep), likely reflecting deficits in thalamo-cortical circuits and (2) increased glutamine and glutamate (Glx) levels in the thalamus. Thus, this study aimed to investigate whether sleep spindles and Glx levels are related to schizotypal personality traits in healthy subjects. METHODS Twenty young male subjects underwent 2 all-night sleep electroencephalography recordings (128 electrodes). Sleep spindles were detected automatically. After those 2 nights, thalamic Glx levels were measured by magnetic resonance spectroscopy. Subjects completed a magical ideation scale to assess schizotypy. RESULTS Sleep spindle density was negatively correlated with magical ideation (r = -.64, P < .01) and thalamic Glx levels (r = -.70, P < .005). No correlation was found between Glx levels in the thalamus and magical ideation (r = .12, P > .1). CONCLUSIONS The common relationship of sleep spindle density with schizotypy and thalamic Glx levels indicates a neurobiological overlap between nonclinical schizotypy and schizophrenia. Thus, sleep spindle density and magical ideation may reflect the anatomy and efficiency of the thalamo-cortical system that shows pronounced impairment in patients with schizophrenia.
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Affiliation(s)
- Caroline Lustenberger
- Child Development Center, University Children’s Hospital Zurich, Zurich, Switzerland;,Neuroscience Center Zurich, University and ETH Zurich, Zurich, Switzerland
| | - Ruth L. O’Gorman
- Children Research Center, University Children’s Hospital Zurich, Zurich, Switzerland;,MR Center, University Children’s Hospital Zurich, Zurich, Switzerland;,Zurich Center for Integrative Human Physiology, University of Zurich, Zurich, Switzerland
| | - Fiona Pugin
- Child Development Center, University Children’s Hospital Zurich, Zurich, Switzerland;,Zurich Center for Integrative Human Physiology, University of Zurich, Zurich, Switzerland
| | - Laura Tüshaus
- Neuroscience Center Zurich, University and ETH Zurich, Zurich, Switzerland;,Institute of Pharmacology and Toxicology, University of Zurich, Zurich, Switzerland
| | - Flavia Wehrle
- Zurich Center for Integrative Human Physiology, University of Zurich, Zurich, Switzerland;,Division of Neonatology, University Hospital Zurich, Zurich, Switzerland
| | - Peter Achermann
- Neuroscience Center Zurich, University and ETH Zurich, Zurich, Switzerland;,Zurich Center for Integrative Human Physiology, University of Zurich, Zurich, Switzerland;,Institute of Pharmacology and Toxicology, University of Zurich, Zurich, Switzerland
| | - Reto Huber
- Child Development Center, University Children's Hospital Zurich, Zurich, Switzerland; Neuroscience Center Zurich, University and ETH Zurich, Zurich, Switzerland; Children Research Center, University Children's Hospital Zurich, Zurich, Switzerland; Zurich Center for Integrative Human Physiology, University of Zurich, Zurich, Switzerland; University Clinics for Child and Adolescent Psychiatry, Zurich, Switzerland
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265
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Djonlagic I, Guo M, Matteis P, Carusona A, Stickgold R, Malhotra A. First night of CPAP: impact on memory consolidation attention and subjective experience. Sleep Med 2015; 16:697-702. [PMID: 25953301 DOI: 10.1016/j.sleep.2015.01.017] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/02/2014] [Revised: 12/23/2014] [Accepted: 01/23/2015] [Indexed: 11/29/2022]
Abstract
OBJECTIVE Neurocognitive deficits are common and serious consequences of obstructive sleep apnea (OSA). Currently, the gold standard treatment is continuous positive air pressure (CPAP) therapy, although the clinical responses to this intervention can be variable. This study examined the effect of one night of CPAP therapy on sleep-dependent memory consolidation, attention, and vigilance as well as subjective experience. METHODS Fifteen healthy controls and 29 patients with obstructive sleep apnea of whom 14 underwent a full-night CPAP titration completed the psychomotor vigilance test (PVT) and motor sequence learning task (MST) in the evening and the morning after undergoing overnight polysomnography. All participants also completed subjective evaluations of sleep quality. RESULTS Participants with OSA showed significantly less overnight improvement on the MST compared to controls without OSA, independent of whether or not they had received CPAP treatment, while there was no significant difference between the untreated OSA and CPAP-treated patients. Within the OSA group, only those receiving CPAP exhibited faster reaction times on the PVT in the morning. Compared to untreated OSA patients, they also felt subjectively more rested and reported that they slept better. CONCLUSION Our results demonstrate an instant augmentation of subjective experience and, based on PVT results, attention and vigilance after one night of CPAP, but a lack of an effect on offline sleep-dependent motor memory consolidation. This dissociation may be explained by different brain structures underlying these processes, some of which might require longer continued adherence to CPAP to generate an effect.
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Affiliation(s)
- Ina Djonlagic
- Department of Neurology, Beth Israel Deaconess Medical Center, Boston, MA, USA; Center for Sleep and Cognition, Department of Psychiatry, Beth Israel Deaconess Medical Center, Boston, MA, USA; Division of Sleep Medicine, Sleep Disorders Program Brigham & Women's Hospital and Harvard Medical School, Boston, MA, USA.
| | - Mengshuang Guo
- Center for Sleep and Cognition, Department of Psychiatry, Beth Israel Deaconess Medical Center, Boston, MA, USA; Division of Sleep Medicine, Sleep Disorders Program Brigham & Women's Hospital and Harvard Medical School, Boston, MA, USA
| | - Paul Matteis
- Center for Sleep and Cognition, Department of Psychiatry, Beth Israel Deaconess Medical Center, Boston, MA, USA; Division of Sleep Medicine, Sleep Disorders Program Brigham & Women's Hospital and Harvard Medical School, Boston, MA, USA
| | - Andrea Carusona
- Division of Sleep Medicine, Sleep Disorders Program Brigham & Women's Hospital and Harvard Medical School, Boston, MA, USA
| | - Robert Stickgold
- Center for Sleep and Cognition, Department of Psychiatry, Beth Israel Deaconess Medical Center, Boston, MA, USA
| | - Atul Malhotra
- Division of Sleep Medicine, Sleep Disorders Program Brigham & Women's Hospital and Harvard Medical School, Boston, MA, USA; Division of Pulmonary and Critical Care, University of California San Diego, La Jolla, CA, USA
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266
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Pratt JA, Morris BJ. The thalamic reticular nucleus: a functional hub for thalamocortical network dysfunction in schizophrenia and a target for drug discovery. J Psychopharmacol 2015; 29:127-37. [PMID: 25586397 DOI: 10.1177/0269881114565805] [Citation(s) in RCA: 62] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
The thalamus (comprising many distinct nuclei) plays a key role in facilitating sensory discrimination and cognitive processes through connections with the cortex. Impaired thalamocortical processing has long been considered to be involved in schizophrenia. In this review we focus on the thalamic reticular nucleus (TRN) providing evidence for it being an important communication hub between the thalamus and cortex and how it may play a key role in the pathophysiology of schizophrenia. We first highlight the functional neuroanatomy, neurotransmitter localisation and physiology of the TRN. We then present evidence of the physiological roles of the TRN in relation to oscillatory activity, cognition and behaviour. Next we discuss the role of the TRN in rodent models of risk factors for schizophrenia (genetic and pharmacological) and provide evidence for TRN deficits in schizophrenia. Finally we discuss new drug targets for schizophrenia in relation to restoring TRN circuitry dysfunction.
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Affiliation(s)
- Judith A Pratt
- Strathclyde Institute of Pharmacy and Biomedical Sciences, University of Strathclyde, Glasgow, UK Psychiatric Research Institute of Neuroscience in Glasgow (PsyRING), University of Glasgow and University of Strathclyde, Glasgow, UK
| | - Brian J Morris
- Psychiatric Research Institute of Neuroscience in Glasgow (PsyRING), University of Glasgow and University of Strathclyde, Glasgow, UK Institute of Neuroscience and Psychology, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow, UK
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267
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Phillips KG, Uhlhaas PJ. Neural oscillations as a translational tool in schizophrenia research: rationale, paradigms and challenges. J Psychopharmacol 2015; 29:155-68. [PMID: 25567552 DOI: 10.1177/0269881114562093] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
Neural oscillations have received recently a great deal of interest in schizophrenia research because of the possibility to integrate findings from non-invasive electro/magnetoencephalographical recordings with pre-clinical research, which could potentially lead to the identification of pathophysiological mechanisms and novel treatment targets. In the current paper, we review the potential as well as the challenges of this approach by summarizing findings on alterations in rhythmic activity from both animal models and human data which have implicated dysfunctional neural oscillations in the explanation of cognitive deficits and certain clinical symptoms of schizophrenia. Specifically, we will focus on findings that have examined neural oscillations during 1) perceptual processing, 2) working memory and executive processes and 3) spontaneous activity. The importance of the development of paradigms suitable for human and animal models is discussed as well as the search for mechanistic explanation for oscillatory dysfunctions.
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Affiliation(s)
- Keith G Phillips
- Lilly Centre for Cognitive Neuroscience, Eli Lilly and Company, Windlesham, UK
| | - Peter J Uhlhaas
- Institute of Neuroscience and Psychology, University of Glasgow, Glasgow, UK
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268
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Affiliation(s)
- Dara S Manoach
- Department of Psychiatry, Massachusetts General Hospital, Boston, MA; Athinoula A. Martinos Center for Biomedical Imaging, Charlestown, MA; Harvard Medical School, Boston, MA.
| | - Robert Stickgold
- Department of Psychiatry, Beth Israel Deaconess Medical Center, Boston, MA; Harvard Medical School, Boston, MA
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269
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Genzel L, Dresler M, Cornu M, Jäger E, Konrad B, Adamczyk M, Friess E, Steiger A, Czisch M, Goya-Maldonado R. Medial prefrontal-hippocampal connectivity and motor memory consolidation in depression and schizophrenia. Biol Psychiatry 2015; 77:177-86. [PMID: 25037555 DOI: 10.1016/j.biopsych.2014.06.004] [Citation(s) in RCA: 95] [Impact Index Per Article: 10.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/24/2014] [Revised: 06/01/2014] [Accepted: 06/02/2014] [Indexed: 12/24/2022]
Abstract
BACKGROUND Overnight memory consolidation is disturbed in both depression and schizophrenia, creating an ideal situation to investigate the mechanisms underlying sleep-related consolidation and to distinguish disease-specific processes from common elements in their pathophysiology. METHODS We investigated patients with depression and schizophrenia, as well as healthy control subjects (each n = 16), under a motor memory consolidation protocol with functional magnetic resonance imaging and polysomnography. RESULTS In a sequential finger-tapping task associated with the degree of hippocampal-prefrontal cortex functional connectivity during the task, significantly less overnight improvement was identified as a common deficit in both patient groups. A task-related overnight decrease in activation of the basal ganglia was observed in control subjects and schizophrenia patients; in contrast, patients with depression showed an increase. During the task, schizophrenia patients, in comparison with control subjects, additionally recruited adjacent cortical areas, which showed a decrease in functional magnetic resonance imaging activation overnight and were related to disease severity. Effective connectivity analyses revealed that the hippocampus was functionally connected to the motor task network, and the cerebellum decoupled from this network overnight. CONCLUSIONS While both patient groups showed similar deficits in consolidation associated with hippocampal-prefrontal cortex connectivity, other activity patterns more specific for disease pathology differed.
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Affiliation(s)
- Lisa Genzel
- Max Planck Institute of Psychiatry, Munich, Germany; Centre for Cognitive and Neural Systems, University of Edinburgh, Edinburgh, United Kingdom.
| | | | - Marion Cornu
- Max Planck Institute of Psychiatry, Munich, Germany
| | - Eugen Jäger
- Max Planck Institute of Psychiatry, Munich, Germany
| | - Boris Konrad
- Max Planck Institute of Psychiatry, Munich, Germany
| | | | | | - Axel Steiger
- Max Planck Institute of Psychiatry, Munich, Germany
| | | | - Roberto Goya-Maldonado
- Max Planck Institute of Psychiatry, Munich, Germany; Centre for Translational Research in Systems Neuroscience and Psychiatry, Department of Psychiatry and Psychotherapy, Georg August University, Göttingen, Germany
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270
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Schizophrenia and Psychosis. Sleep Med 2015. [DOI: 10.1007/978-1-4939-2089-1_39] [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: 11/27/2022]
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271
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Sprecher KE, Ferrarelli F, Benca RM. Sleep and plasticity in schizophrenia. Curr Top Behav Neurosci 2015; 25:433-58. [PMID: 25608723 DOI: 10.1007/7854_2014_366] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Schizophrenia is a devastating mental illness with a worldwide prevalence of approximately 1%. Although the clinical features of the disorder were described over one hundred years ago, its neurobiology is still largely elusive despite several decades of research. Schizophrenia is associated with marked sleep disturbances and memory impairment. Above and beyond altered sleep architecture, sleep rhythms including slow waves and spindles are disrupted in schizophrenia. In the healthy brain, these rhythms reflect and participate in plastic processes during sleep. This chapter discusses evidence that schizophrenia patients exhibit dysfunction of sleep-mediated plasticity on a behavioral, cellular, and molecular level and offers suggestions on how the study of sleeping brain activity can shed light on the pathophysiological mechanisms of the disorder.
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Affiliation(s)
- Kate E Sprecher
- Department of Psychiatry, Neuroscience Training Program, University of Wisconsin, Madison, WI, USA
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272
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Fröhlich F, Sellers KK, Cordle AL. Targeting the neurophysiology of cognitive systems with transcranial alternating current stimulation. Expert Rev Neurother 2014; 15:145-67. [PMID: 25547149 DOI: 10.1586/14737175.2015.992782] [Citation(s) in RCA: 62] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Cognitive impairment represents one of the most debilitating and most difficult symptom to treat of many psychiatric illnesses. Human neurophysiology studies have suggested that specific pathologies of cortical network activity correlate with cognitive impairment. However, we lack demonstration of causal relationships between specific network activity patterns and cognitive capabilities and treatment modalities that directly target impaired network dynamics of cognition. Transcranial alternating current stimulation (tACS), a novel non-invasive brain stimulation approach, may provide a crucial tool to tackle these challenges. Here, we propose that tACS can be used to elucidate the causal role of cortical synchronization in cognition and, eventually, to enhance pathologically weakened synchrony that may underlie cognitive deficits. To accelerate such development of tACS as a treatment for cognitive deficits, we discuss studies on tACS and cognition performed in healthy participants, according to the Research Domain Criteria of the National Institute of Mental Health.
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Affiliation(s)
- Flavio Fröhlich
- Department of Psychiatry, University of North Carolina at Chapel Hill, Chapel Hill NC 27599, USA
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273
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Abstract
Schizophrenia patients often show irregularities in sleep and circadian rhythms and deficits in recognition memory. Similar phenotypes are seen in schizophrenia-relevant genetic mouse models, such as synaptosomal associated protein of 25 kDa (Snap-25) point mutant mice, vasoactive intestinal peptide receptor 2 (Vipr2) knockout mice, and neuregulin 1 (Nrg1)-deficient mice. Sleep and circadian abnormalities and impaired recognition memory may be causally related in both schizophrenia patients and schizophrenia-relevant mouse models, since sleep deprivation, abnormal photic input, and the manipulation of core clock genes (cryptochrome 1/2) can all disrupt object recognition memory in rodent models. The recognition deficits observed in patients and mouse models (both schizophrenia-related and -unrelated) are discussed here in terms of the dual-process theory of recognition, which postulates that there are two recognition mechanisms-recollection versus familiarity-that can be selectively impaired by brain lesions, neuropsychiatric conditions, and putatively, sleep and circadian rhythm disruption. However, based on this view, the findings from patient studies and studies using genetic mouse models (Nrg1 deficiency) seem to be inconsistent with each other. Schizophrenia patients are impaired at recollection (and to a lesser extent, familiarity judgments), but Nrg1-deficient mice are impaired at familiarity-based object recognition, raising concerns regarding the validity of using these genetically modified mice to model recognition phenotypes observed in patients. This issue can be resolved in future animal studies by examining performance in different variants of the spontaneous recognition task-the standard, perirhinal cortex-dependent, object recognition task versus the hippocampus-dependent object-place recognition task-in order to see which of the two recognition mechanisms is more disrupted.
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274
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Flint J, Timpson N, Munafò M. Assessing the utility of intermediate phenotypes for genetic mapping of psychiatric disease. Trends Neurosci 2014; 37:733-41. [PMID: 25216981 PMCID: PMC4961231 DOI: 10.1016/j.tins.2014.08.007] [Citation(s) in RCA: 63] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2014] [Revised: 08/19/2014] [Accepted: 08/21/2014] [Indexed: 01/19/2023]
Abstract
Intermediate phenotypes are traits positioned somewhere between genetic variation and disease. They represent a target for attempts to find disease-associated genetic variants and elucidation of mechanisms. Psychiatry has been particularly enamoured with intermediate phenotypes, due to uncertainty about disease aetiology, inconclusive results in early psychiatric genetic studies, and their appeal relative to traditional diagnostic categories. In this review, we argue that new genetic findings are relevant to the question of the utility of these constructs. In particular, results from genome-wide association studies of psychiatric disorders now allow an assessment of the potential role of particular intermediate phenotypes. Based on such an analysis, as well as other recent results, we conclude that intermediate phenotypes are likely to be most valuable in understanding mechanism.
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Affiliation(s)
- Jonathan Flint
- Wellcome Trust Centre for Human Genetics, Oxford OX3 7BN, UK.
| | - Nicholas Timpson
- MRC Integrative Epidemiology Unit, University of Bristol, Bristol BS8 2BN, UK
| | - Marcus Munafò
- MRC Integrative Epidemiology Unit, University of Bristol, Bristol BS8 2BN, UK; UK Centre for Tobacco and Alcohol Studies and School of Experimental Psychology, University of Bristol, Bristol BS8 1TU, UK
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275
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Wendt SL, Welinder P, Sorensen HBD, Peppard PE, Jennum P, Perona P, Mignot E, Warby SC. Inter-expert and intra-expert reliability in sleep spindle scoring. Clin Neurophysiol 2014; 126:1548-56. [PMID: 25434753 DOI: 10.1016/j.clinph.2014.10.158] [Citation(s) in RCA: 43] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2014] [Revised: 09/20/2014] [Accepted: 10/29/2014] [Indexed: 01/13/2023]
Abstract
OBJECTIVES To measure the inter-expert and intra-expert agreement in sleep spindle scoring, and to quantify how many experts are needed to build a reliable dataset of sleep spindle scorings. METHODS The EEG dataset was comprised of 400 randomly selected 115s segments of stage 2 sleep from 110 sleeping subjects in the general population (57±8, range: 42-72 years). To assess expert agreement, a total of 24 Registered Polysomnographic Technologists (RPSGTs) scored spindles in a subset of the EEG dataset at a single electrode location (C3-M2). Intra-expert and inter-expert agreements were calculated as F1-scores, Cohen's kappa (κ), and intra-class correlation coefficient (ICC). RESULTS We found an average intra-expert F1-score agreement of 72±7% (κ: 0.66±0.07). The average inter-expert agreement was 61±6% (κ: 0.52±0.07). Amplitude and frequency of discrete spindles were calculated with higher reliability than the estimation of spindle duration. Reliability of sleep spindle scoring can be improved by using qualitative confidence scores, rather than a dichotomous yes/no scoring system. CONCLUSIONS We estimate that 2-3 experts are needed to build a spindle scoring dataset with 'substantial' reliability (κ: 0.61-0.8), and 4 or more experts are needed to build a dataset with 'almost perfect' reliability (κ: 0.81-1). SIGNIFICANCE Spindle scoring is a critical part of sleep staging, and spindles are believed to play an important role in development, aging, and diseases of the nervous system.
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Affiliation(s)
- Sabrina L Wendt
- Center for Sleep Science and Medicine, Stanford University, Palo Alto, CA, United States; Danish Center for Sleep Medicine, Glostrup University Hospital, DK-2600 Glostrup, Denmark
| | - Peter Welinder
- Computational Vision Laboratory, California Institute of Technology, Pasadena, CA, United States
| | - Helge B D Sorensen
- Dept. of Electrical Engineering, Technical University of Denmark, DK-2800 Kongens Lyngby, Denmark
| | - Paul E Peppard
- Department of Population Health Sciences, University of Wisconsin - Madison, Madison, WI, United States
| | - Poul Jennum
- Danish Center for Sleep Medicine, Glostrup University Hospital, DK-2600 Glostrup, Denmark
| | - Pietro Perona
- Computational Vision Laboratory, California Institute of Technology, Pasadena, CA, United States
| | - Emmanuel Mignot
- Center for Sleep Science and Medicine, Stanford University, Palo Alto, CA, United States
| | - Simon C Warby
- Center for Sleep Science and Medicine, Stanford University, Palo Alto, CA, United States; Center for Advanced Research in Sleep Medicine, Hôpital du Sacré-Coeur de Montréal, Department of Psychiatry, Université de Montréal, Montréal, Canada.
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276
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Manoach DS, Demanuele C, Wamsley EJ, Vangel M, Montrose DM, Miewald J, Kupfer D, Buysse D, Stickgold R, Keshavan MS. Sleep spindle deficits in antipsychotic-naïve early course schizophrenia and in non-psychotic first-degree relatives. Front Hum Neurosci 2014; 8:762. [PMID: 25339881 PMCID: PMC4188028 DOI: 10.3389/fnhum.2014.00762] [Citation(s) in RCA: 107] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2014] [Accepted: 09/09/2014] [Indexed: 12/31/2022] Open
Abstract
INTRODUCTION Chronic medicated patients with schizophrenia have marked reductions in sleep spindle activity and a correlated deficit in sleep-dependent memory consolidation. Using archival data, we investigated whether antipsychotic-naïve early course patients with schizophrenia and young non-psychotic first-degree relatives of patients with schizophrenia also show reduced sleep spindle activity and whether spindle activity correlates with cognitive function and symptoms. METHOD Sleep spindles during Stage 2 sleep were compared in antipsychotic-naïve adults newly diagnosed with psychosis, young non-psychotic first-degree relatives of schizophrenia patients and two samples of healthy controls matched to the patients and relatives. The relations of spindle parameters with cognitive measures and symptom ratings were examined. RESULTS Early course schizophrenia patients showed significantly reduced spindle activity relative to healthy controls and to early course patients with other psychotic disorders. Relatives of schizophrenia patients also showed reduced spindle activity compared with controls. Reduced spindle activity correlated with measures of executive function in early course patients, positive symptoms in schizophrenia and IQ estimates across groups. CONCLUSIONS Like chronic medicated schizophrenia patients, antipsychotic-naïve early course schizophrenia patients and young non-psychotic relatives of individuals with schizophrenia have reduced sleep spindle activity. These findings indicate that the spindle deficit is not an antipsychotic side-effect or a general feature of psychosis. Instead, the spindle deficit may predate the onset of schizophrenia, persist throughout its course and be an endophenotype that contributes to cognitive dysfunction.
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Affiliation(s)
- Dara S. Manoach
- Department of Psychiatry, Massachusetts General HospitalCharlestown, MA, USA
- Athinoula A. Martinos Center for Biomedical ImagingCharlestown, MA, USA
- Harvard Medical SchoolBoston, MA, USA
| | - Charmaine Demanuele
- Department of Psychiatry, Massachusetts General HospitalCharlestown, MA, USA
- Athinoula A. Martinos Center for Biomedical ImagingCharlestown, MA, USA
- Harvard Medical SchoolBoston, MA, USA
| | - Erin J. Wamsley
- Harvard Medical SchoolBoston, MA, USA
- Department of Psychiatry, Beth Israel Deaconess Medical CenterBoston, MA, USA
| | - Mark Vangel
- Athinoula A. Martinos Center for Biomedical ImagingCharlestown, MA, USA
- Harvard Medical SchoolBoston, MA, USA
| | - Debra M. Montrose
- Department of Psychiatry, Western Psychiatric Institute and Clinic, University of Pittsburgh School of MedicinePittsburgh, PA, USA
| | - Jean Miewald
- Department of Psychiatry, Western Psychiatric Institute and Clinic, University of Pittsburgh School of MedicinePittsburgh, PA, USA
| | - David Kupfer
- Department of Psychiatry, Western Psychiatric Institute and Clinic, University of Pittsburgh School of MedicinePittsburgh, PA, USA
| | - Daniel Buysse
- Department of Psychiatry, Western Psychiatric Institute and Clinic, University of Pittsburgh School of MedicinePittsburgh, PA, USA
| | - Robert Stickgold
- Harvard Medical SchoolBoston, MA, USA
- Department of Psychiatry, Beth Israel Deaconess Medical CenterBoston, MA, USA
| | - Matcheri S. Keshavan
- Harvard Medical SchoolBoston, MA, USA
- Department of Psychiatry, Beth Israel Deaconess Medical CenterBoston, MA, USA
- Department of Psychiatry, Western Psychiatric Institute and Clinic, University of Pittsburgh School of MedicinePittsburgh, PA, USA
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277
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Impaired off-line motor skills consolidation in young primary insomniacs. Neurobiol Learn Mem 2014; 114:141-7. [DOI: 10.1016/j.nlm.2014.06.006] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/26/2013] [Revised: 06/04/2014] [Accepted: 06/11/2014] [Indexed: 11/22/2022]
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278
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Buchmann A, Dentico D, Peterson MJ, Riedner BA, Sarasso S, Massimini M, Tononi G, Ferrarelli F. Reduced mediodorsal thalamic volume and prefrontal cortical spindle activity in schizophrenia. Neuroimage 2014; 102 Pt 2:540-7. [PMID: 25139002 DOI: 10.1016/j.neuroimage.2014.08.017] [Citation(s) in RCA: 59] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2014] [Revised: 07/29/2014] [Accepted: 08/09/2014] [Indexed: 01/11/2023] Open
Abstract
BACKGROUND We recently found marked deficits in sleep spindles, non-rapid eye movement (NREM) sleep oscillations that are generated within the thalamus and then amplified and sustained in the cortex, in patients with schizophrenia compared to both healthy and psychiatric controls. Here, we investigated the thalamic and cortical contributions to these sleep spindle deficits. METHODS Anatomical volume of interest analysis (i.e., thalamic volumes) and electroencephalogram (EEG) source modeling (i.e., spindle-related cortical currents) were performed in patients with schizophrenia and healthy comparison subjects. FINDINGS Schizophrenia patients had reduced mediodorsal (MD) thalamic volumes, especially on the left side, compared to healthy controls, whereas whole thalami and lateral geniculate nuclei did not differ between groups. Furthermore, left MD volumes were strongly correlated with the number of scalp-recorded spindles in an anterior frontal region, and cortical currents underlying these anterior frontal spindles were localized in the prefrontal cortex, in Brodmann area (BA) 10. Finally, prefrontal currents at the peak of spindle activity were significantly reduced in schizophrenia patients and correlated with their performance in an abstraction/working memory task. CONCLUSION Altogether, these findings point to deficits in a specific thalamo-cortical circuitry in schizophrenia, which is associated with some cognitive deficits commonly reported in those patients.
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Affiliation(s)
| | | | | | | | - Simone Sarasso
- Department of Psychiatry, University of WI-Madison, USA; Department of Clinical Sciences, University of Milan, Italy
| | - Marcello Massimini
- Department of Psychiatry, University of WI-Madison, USA; Department of Clinical Sciences, University of Milan, Italy
| | - Giulio Tononi
- Department of Psychiatry, University of WI-Madison, USA
| | - Fabio Ferrarelli
- Department of Psychiatry, University of WI-Madison, USA; Department of Clinical Sciences, University of Milan, Italy.
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279
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Landry S, Anderson C, Andrewartha P, Sasse A, Conduit R. The impact of obstructive sleep apnea on motor skill acquisition and consolidation. J Clin Sleep Med 2014; 10:491-6. [PMID: 24910549 DOI: 10.5664/jcsm.3692] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
STUDY OBJECTIVE Recent investigations suggest that motor skill learning is impaired in patients with obstructive sleep apnea (OSA) syndrome; however, it is not fully understood at what stages of learning this impairment occurs. The current study aimed to compare motor learning and memory across both daytime acquisition and overnight consolidation. METHODS Twelve OSA patients and twelve control participants, matched for age and education, were recruited and completed the Karolinska Sleepiness Scale and the sequential finger-tapping task (SFTT), a motor skill learning task, both before and after polysomnographic recorded sleep. RESULTS During the evening acquisition phase both groups showed significant and equitable improvement in the number of correctly typed sequences across trials. On retesting the following morning, the control patients showed significantly greater improvement overnight (15.35%) compared to OSA patients (1.78%). The post sleep improvement in controls, but lacking in OSA patients, was typical of a sleep dependent enhancement effect. The magnitude of improvement overnight for either group was not significantly correlated with any of the recorded sleep variables. CONCLUSIONS These results suggest daytime/practice related acquisition of motor skill is largely intact in OSA patients; however, marked impairment in the consolidation phase is evident following a sleep period. This particular pattern of dysfunction may remain unnoticed following single-day learning/memory assessments.
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Affiliation(s)
- Shane Landry
- School of Psychological Sciences, Faculty of Medicine, Nursing & Health Sciences, Monash University, Melbourne, Victoria, Australia
| | - Clare Anderson
- School of Psychological Sciences, Faculty of Medicine, Nursing & Health Sciences, Monash University, Melbourne, Victoria, Australia
| | - Peter Andrewartha
- School of Psychological Sciences, Faculty of Medicine, Nursing & Health Sciences, Monash University, Melbourne, Victoria, Australia
| | | | - Russell Conduit
- School of Psychological Sciences, Faculty of Medicine, Nursing & Health Sciences, Monash University, Melbourne, Victoria, Australia
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280
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Abstract
Despite the ubiquity of sleep across phylogeny, its function remains elusive. In this review, we consider one compelling candidate: brain plasticity associated with memory processing. Focusing largely on hippocampus-dependent memory in rodents and humans, we describe molecular, cellular, network, whole-brain and behavioral evidence establishing a role for sleep both in preparation for initial memory encoding, and in the subsequent offline consolidation of memory. Sleep and sleep deprivation bidirectionally alter molecular signaling pathways that regulate synaptic strength and control plasticity-related gene transcription and protein translation. At the cellular level, sleep deprivation impairs cellular excitability necessary for inducing synaptic potentiation and accelerates the decay of long-lasting forms of synaptic plasticity. In contrast, rapid eye movement (REM) and non-rapid eye movement (NREM) sleep enhance previously induced synaptic potentiation, although synaptic de-potentiation during sleep has also been observed. Beyond single cell dynamics, large-scale cell ensembles express coordinated replay of prior learning-related firing patterns during subsequent NREM sleep. At the whole-brain level, somewhat analogous learning-associated hippocampal (re)activation during NREM sleep has been reported in humans. Moreover, the same cortical NREM oscillations associated with replay in rodents also promote human hippocampal memory consolidation, and this process can be manipulated using exogenous reactivation cues during sleep. Mirroring molecular findings in rodents, specific NREM sleep oscillations before encoding refresh human hippocampal learning capacity, while deprivation of sleep conversely impairs subsequent hippocampal activity and associated encoding. Together, these cross-descriptive level findings demonstrate that the unique neurobiology of sleep exerts powerful effects on molecular, cellular and network mechanisms of plasticity that govern both initial learning and subsequent long-term memory consolidation.
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281
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Modeling combined schizophrenia-related behavioral and metabolic phenotypes in rodents. Behav Brain Res 2014; 276:130-42. [PMID: 24747658 DOI: 10.1016/j.bbr.2014.04.016] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2014] [Revised: 04/08/2014] [Accepted: 04/09/2014] [Indexed: 12/11/2022]
Abstract
Schizophrenia is a chronic, debilitating disorder with a complex behavioral and cognitive phenotype underlined by a similarly complex etiology involving an interaction between susceptibility genes and environmental factors during early development. Limited progress has been made in developing novel pharmacotherapy, partly due to a lack of valid animal models. The recent recognition of the potentially causal role of central and peripheral energy metabolism in the pathophysiology of schizophrenia raises the need of research on animal models that combine both behavioral and metabolic phenotypic domains, similar to what have been identified in humans. In this review we focus on selected genetic (DBA/2J mice, leptin receptor mutants, and PSD-93 knockout mice), early neurodevelopmental (maternal protein deprivation) and pharmacological (acute phencyclidine) animal models that capture the combined behavioral and metabolic abnormalities shown by schizophrenic patients. In reviewing behavioral phenotypes relevant to schizophrenia we apply the principles established by the Research Domain Criteria (RDoC) for better translation. We demonstrate that etiologically diverse manipulations such as specific breeding, deletion of genes that are primarily involved in metabolic regulation and in synaptic plasticity, as well as early metabolic deprivation and adult pharmacological challenge of the glutamate system can lead to schizophrenia-related behavioral and metabolic phenotypes, which suggest that these pathways might be interlinked. We propose that using animal models that combine different domains of schizophrenia can be used as a translationally valid approach to capture the system-level complex interplay between peripheral and central processes in the development of psychopathology.
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282
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Gardner RJ, Kersanté F, Jones MW, Bartsch U. Neural oscillations during non-rapid eye movement sleep as biomarkers of circuit dysfunction in schizophrenia. Eur J Neurosci 2014; 39:1091-106. [DOI: 10.1111/ejn.12533] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2013] [Revised: 01/06/2014] [Accepted: 01/29/2014] [Indexed: 12/25/2022]
Affiliation(s)
- Richard J. Gardner
- School of Physiology and Pharmacology; University of Bristol; Medical Sciences Building University Walk Bristol BS8 1TD UK
| | - Flavie Kersanté
- School of Physiology and Pharmacology; University of Bristol; Medical Sciences Building University Walk Bristol BS8 1TD UK
| | - Matthew W. Jones
- School of Physiology and Pharmacology; University of Bristol; Medical Sciences Building University Walk Bristol BS8 1TD UK
| | - Ullrich Bartsch
- School of Physiology and Pharmacology; University of Bristol; Medical Sciences Building University Walk Bristol BS8 1TD UK
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283
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Abstract
Several network patterns allow for information exchange between the neocortex and the entorhinal-hippocampal complex, including theta oscillations and sleep spindles. How neurons are organized in these respective patterns is not well understood. We examined the cellular-synaptic generation of sleep spindles and theta oscillations in the waking rat and during rapid eye movement (REM) sleep by simultaneously recording local field and spikes in the regions and layers of the hippocampus and entorhinal cortex (EC). We show the following: (1) current source density analysis reveals that similar anatomical substrates underlie spindles and theta in the hippocampus, although the hippocampal subregions are more synchronized during spindles than theta; (2) the spiking of putative principal cells and interneurons in the CA1, CA3, and dentate gyrus subregions of the hippocampus, as well as layers 2, 3, and 5 of medial EC, are significantly phase locked to spindles detected in CA1; (3) the relationship between local field potential (LFP) phase and unit spiking differs between spindles and theta; (4) individual hippocampal principal cells generally do not fire in a rhythmic manner during spindles; (5) power in gamma (30-90 Hz) and epsilon (>90 Hz) bands of hippocampal LFP is modulated by the phase of spindle oscillations; and (6) unit firing rates during spindles were not significantly affected by whether spindles occurred during non-REM or transitions between non-REM and REM sleep. Thus, despite the similar current generator inputs and macroscopic appearance of the LFP, the organization of neuronal firing patterns during spindles bears little resemblance to that of theta oscillations.
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284
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Cain CK, McCue M, Bello I, Creedon T, Tang DI, Laska E, Goff DC. d-Cycloserine augmentation of cognitive remediation in schizophrenia. Schizophr Res 2014; 153:177-83. [PMID: 24485587 PMCID: PMC4547356 DOI: 10.1016/j.schres.2014.01.016] [Citation(s) in RCA: 54] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/18/2013] [Revised: 01/11/2014] [Accepted: 01/13/2014] [Indexed: 12/21/2022]
Abstract
d-Cycloserine (DCS) has been shown to enhance memory and, in a previous trial, once-weekly DCS improved negative symptoms in schizophrenia subjects. We hypothesized that DCS combined with a cognitive remediation (CR) program would improve memory of a practiced auditory discrimination task and that gains would generalize to performance on unpracticed cognitive tasks. Stable, medicated adult schizophrenia outpatients participated in the Brain Fitness CR program 3-5 times per week for 8weeks. Subjects were randomly assigned to once-weekly adjunctive treatment with DCS (50mg) or placebo administered before the first session each week. Primary outcomes were performance on an auditory discrimination task, the MATRICS cognitive battery composite score and the Scale for the Assessment of Negative Symptoms (SANS) total score. 36 subjects received study drug and 32 completed the trial (average number of CR sessions=26.1). Performance on the practiced auditory discrimination task significantly improved in the DCS group compared to the placebo group. DCS was also associated with significantly greater negative symptom improvement for subjects symptomatic at baseline (SANS score ≥20). However, improvement on the MATRICS battery was observed only in the placebo group. Considered with previous results, these findings suggest that DCS augments CR and alleviates negative symptoms in schizophrenia patients. However, further work is needed to evaluate whether CR gains achieved with DCS can generalize to other unpracticed cognitive tasks.
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Affiliation(s)
- Christopher K. Cain
- Nathan Kline Institute for Psychiatric Research, 140 Old Orangeburg Road, Orangeburg, NY, USA, 10962,Child and Adolescent Psychiatry Department, NYU Langone Medical Center, One Park Avenue, New York City, NY, USA, 10016
| | - Margaret McCue
- Nathan Kline Institute for Psychiatric Research, 140 Old Orangeburg Road, Orangeburg, NY 10962, USA.
| | - Iruma Bello
- Psychiatry Department, NYU Langone Medical Center, 550 First Avenue, New York City, NY 10016, USA.
| | - Timothy Creedon
- Psychiatry Department, Harvard Medical School, 401 Park Drive, Boston, MA 02215, USA.
| | - Dei-in Tang
- Nathan Kline Institute for Psychiatric Research, 140 Old Orangeburg Road, Orangeburg, NY, USA, 10962
| | - Eugene Laska
- Nathan Kline Institute for Psychiatric Research, 140 Old Orangeburg Road, Orangeburg, NY 10962, USA.
| | - Donald C. Goff
- Psychiatry Department, NYU Langone Medical Center, 550 First Avenue, New York City, NY, USA, 10016,Nathan Kline Institute for Psychiatric Research, 140 Old Orangeburg Road, Orangeburg, NY, USA, 10962
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285
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Sleep-spindle detection: crowdsourcing and evaluating performance of experts, non-experts and automated methods. Nat Methods 2014; 11:385-92. [PMID: 24562424 PMCID: PMC3972193 DOI: 10.1038/nmeth.2855] [Citation(s) in RCA: 224] [Impact Index Per Article: 22.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2013] [Accepted: 01/31/2014] [Indexed: 11/19/2022]
Abstract
Sleep spindles are discrete, intermittent patterns of brain activity that arise as a result of interactions of several circuits in the brain. Increasingly, these oscillations are of biological and clinical interest because of their role in development, learning, and neurological disorders. We used an internet interface to ‘crowdsource’ spindle identification from human experts and non-experts, and compared performance with 6 automated detection algorithms in middle-to-older aged subjects from the general population. We also developed a method for forming group consensus, and refined methods of evaluating the performance of event detectors in physiological data such as polysomnography. Compared to the gold standard, the highest performance was by individual experts and the non-expert group consensus, followed by automated spindle detectors. Crowdsourcing the scoring of sleep data is an efficient method to collect large datasets, even for difficult tasks such as spindle identification. Further refinements to automated sleep spindle algorithms are needed for middle-to-older aged subjects.
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286
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Djonlagic I, Guo M, Matteis P, Carusona A, Stickgold R, Malhotra A. Untreated sleep-disordered breathing: links to aging-related decline in sleep-dependent memory consolidation. PLoS One 2014; 9:e85918. [PMID: 24489679 PMCID: PMC3906012 DOI: 10.1371/journal.pone.0085918] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2013] [Accepted: 12/06/2013] [Indexed: 11/18/2022] Open
Abstract
BACKGROUND Increasing age is associated with a decline in cognition and motor skills, while at the same time exacerbating one's risk of developing obstructive sleep apnea (OSA). OSA-related cognitive deficits are highly prevalent and can affect various memory systems including overnight memory consolidation on a motor sequence task. Thus, the aim of our study was to examine the effect of aging on sleep-dependent motor memory consolidation in patients with and without OSA. METHODS We studied 44 patients (19-68 years) who had been referred by a physician for a baseline polysomnography (PSG) evaluation. Based on their PSG, patients were assigned either to the OSA group (AHI>5/h), or control (Non-OSA) group (AHI<5/h). All subjects performed the Psychomotor Vigilance Task (PVT) and the Motor Sequence Learning Task (MST) in the evening and again in the morning after their PSG. RESULTS Despite similar learning in the evening, OSA subjects showed significantly less overnight improvement on the MST, both for immediate (OSA -2.7% ± 2.8% vs. controls 12.2% ± 3.5%; p = 0.002) and plateau improvement (OSA 4.9% ± 2.3% vs. controls 21.1%± 4.0%; p = 0.001). Within the OSA group, there was a significant negative correlation between overnight MST improvement and age (r(2) = 0.3; p = 0.01), an effect that was not observed in the Non-OSA group (r(2) = 0.08; p = 0.23). CONCLUSIONS Consistent with previous research, healthy sleepers demonstrated a higher degree of sleep-dependent overnight improvement on the MST, an effect not mitigated by increasing age. However, the presence of untreated obstructive sleep apnea is associated with an aging-related cognitive deficit, otherwise not present in individuals without OSA. As other research has linked the presence of OSA to a higher likelihood of developing dementia, future studies are necessary to examine if the inhibition of memory consolidation is tied to the onset of neurodegenerative disease.
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Affiliation(s)
- Ina Djonlagic
- Division of Sleep Medicine Sleep Disorders Research Program Brigham & Women's Hospital and Harvard Medical School, Boston, Massachusetts, United States of America
- Center for Sleep and Cognition, Department of Psychiatry, Beth Israel Hospital and Harvard Medical School, Boston, Massachusetts, United States of America
- * E-mail:
| | - Mengshuang Guo
- Division of Sleep Medicine Sleep Disorders Research Program Brigham & Women's Hospital and Harvard Medical School, Boston, Massachusetts, United States of America
- Center for Sleep and Cognition, Department of Psychiatry, Beth Israel Hospital and Harvard Medical School, Boston, Massachusetts, United States of America
| | - Paul Matteis
- Division of Sleep Medicine Sleep Disorders Research Program Brigham & Women's Hospital and Harvard Medical School, Boston, Massachusetts, United States of America
- Center for Sleep and Cognition, Department of Psychiatry, Beth Israel Hospital and Harvard Medical School, Boston, Massachusetts, United States of America
| | - Andrea Carusona
- Division of Sleep Medicine Sleep Disorders Research Program Brigham & Women's Hospital and Harvard Medical School, Boston, Massachusetts, United States of America
| | - Robert Stickgold
- Center for Sleep and Cognition, Department of Psychiatry, Beth Israel Hospital and Harvard Medical School, Boston, Massachusetts, United States of America
| | - Atul Malhotra
- Division of Sleep Medicine Sleep Disorders Research Program Brigham & Women's Hospital and Harvard Medical School, Boston, Massachusetts, United States of America
- Division of Pulmonary and Critical Care Medicine, University of California San Diego, La Jolla, California, United States of America
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287
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Göder R, Nissen C, Rasch B. [Sleep, learning and memory: relevance for psychiatry and psychotherapy]. DER NERVENARZT 2014; 85:50-6. [PMID: 24399500 DOI: 10.1007/s00115-013-3894-5] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Abstract
BACKGROUND Sleep has been identified as a state that optimizes the consolidation of newly acquired information in the memory. Sleep disturbances might essentially contribute to memory impairment in relevant psychiatric disorders, such as major depression and schizophrenia. METHODS This article provides a brief review of the latest research results on sleep and its association with memory consolidation. RESULTS AND CONCLUSION Specific disturbances of sleep structure are associated with particular memory deficits in psychiatric patients. Effective treatment of sleep disorders should not only improve signs of sleep but should also heal associated memory impairments.
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Affiliation(s)
- R Göder
- Klinik für Psychiatrie und Psychotherapie, Universitätsklinikum Schleswig-Holstein, Niemannsweg 147, 24105, Kiel, Deutschland,
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288
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A thalamo-cortical neural mass model for the simulation of brain rhythms during sleep. J Comput Neurosci 2014; 37:125-48. [PMID: 24402459 DOI: 10.1007/s10827-013-0493-1] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2013] [Revised: 09/30/2013] [Accepted: 12/26/2013] [Indexed: 10/25/2022]
Abstract
Cortico-thalamic interactions are known to play a pivotal role in many brain phenomena, including sleep, attention, memory consolidation and rhythm generation. Hence, simple mathematical models that can simulate the dialogue between the cortex and the thalamus, at a mesoscopic level, have a great cognitive value. In the present work we describe a neural mass model of a cortico-thalamic module, based on neurophysiological mechanisms. The model includes two thalamic populations (a thalamo-cortical relay cell population, TCR, and its related thalamic reticular nucleus, TRN), and a cortical column consisting of four connected populations (pyramidal neurons, excitatory interneurons, inhibitory interneurons with slow and fast kinetics). Moreover, thalamic neurons exhibit two firing modes: bursting and tonic. Finally, cortical synapses among pyramidal neurons incorporate a disfacilitation mechanism following prolonged activity. Simulations show that the model is able to mimic the different patterns of rhythmic activity in cortical and thalamic neurons (beta and alpha waves, spindles, delta waves, K-complexes, slow sleep waves) and their progressive changes from wakefulness to deep sleep, by just acting on modulatory inputs. Moreover, simulations performed by providing short sensory inputs to the TCR show that brain rhythms during sleep preserve the cortex from external perturbations, still allowing a high cortical activity necessary to drive synaptic plasticity and memory consolidation. In perspective, the present model may be used within larger cortico-thalamic networks, to gain a deeper understanding of mechanisms beneath synaptic changes during sleep, to investigate the specific role of brain rhythms, and to explore cortical synchronization achieved via thalamic influences.
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289
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Genzel L, Kroes MC, Dresler M, Battaglia FP. Light sleep versus slow wave sleep in memory consolidation: a question of global versus local processes? Trends Neurosci 2014; 37:10-9. [DOI: 10.1016/j.tins.2013.10.002] [Citation(s) in RCA: 136] [Impact Index Per Article: 13.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2013] [Revised: 10/07/2013] [Accepted: 10/08/2013] [Indexed: 01/06/2023]
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290
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M. Chambers A, D. Payne J. Neural Plasticity and Learning: The Consequences of Sleep. AIMS Neurosci 2014. [DOI: 10.3934/neuroscience.2014.2.163] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
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291
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Bang JW, Khalilzadeh O, Hämäläinen M, Watanabe T, Sasaki Y. Location specific sleep spindle activity in the early visual areas and perceptual learning. Vision Res 2013; 99:162-71. [PMID: 24380705 DOI: 10.1016/j.visres.2013.12.014] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2013] [Revised: 11/27/2013] [Accepted: 12/20/2013] [Indexed: 10/25/2022]
Abstract
Visual perceptual learning (VPL) is consolidated during sleep. However, the underlying neuronal mechanisms of consolidation are not yet fully understood. It has been suggested that the spontaneous brain oscillations that characterize sleep stages are indicative of the consolidation of learning and memory. We investigated whether sleep spindles and/or slow-waves are associated with consolidation of VPL during non-rapid eye movement (NREM) sleep during the first sleep cycle, using magnetoencephalography (MEG), magnetic resonance imaging (MRI), and polysomnography (PSG). We hypothesized that after training, early visual areas will show an increase in slow sigma, fast sigma and/or delta activity, corresponding to slow/fast sleep spindles and slow-waves, respectively. We found that during sleep stage 2, but not during slow-wave sleep, the slow sigma power within the trained region of early visual areas was larger after training compared to baseline, and that the increase was larger in the trained region than in the untrained region. However, neither fast sigma nor delta band power increased significantly after training in either sleep stage. Importantly, performance gains for the trained task were correlated with the difference of power increases in slow sigma activity between the trained and untrained regions. This finding suggests that slow sigma activity plays a critical role in the consolidation of VPL, at least in sleep stage 2 during the first sleep cycle.
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Affiliation(s)
- Ji Won Bang
- Laboratory for Cognitive and Perceptual Learning, Department of Cognitive, Linguistic & Psychological Sciences, Brown University, 190 Thayer St, Providence, RI 02912, USA.
| | - Omid Khalilzadeh
- Department of Radiology, Massachusetts General Hospital and Harvard Medical School, 55 Fruit St, Boston, MA 02114, USA.
| | - Matti Hämäläinen
- Athinoula A. Martinos Center for Biomedical Imaging, 149 13th St, Charlestown, MA 02129, USA.
| | - Takeo Watanabe
- Laboratory for Cognitive and Perceptual Learning, Department of Cognitive, Linguistic & Psychological Sciences, Brown University, 190 Thayer St, Providence, RI 02912, USA.
| | - Yuka Sasaki
- Laboratory for Cognitive and Perceptual Learning, Department of Cognitive, Linguistic & Psychological Sciences, Brown University, 190 Thayer St, Providence, RI 02912, USA.
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292
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Dickerson DD, Bilkey DK. Aberrant neural synchrony in the maternal immune activation model: using translatable measures to explore targeted interventions. Front Behav Neurosci 2013; 7:217. [PMID: 24409130 PMCID: PMC3873515 DOI: 10.3389/fnbeh.2013.00217] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2013] [Accepted: 12/16/2013] [Indexed: 01/01/2023] Open
Abstract
Maternal exposure to infection occurring mid-gestation produces a three-fold increase in the risk of schizophrenia in the offspring. The critical initiating factor appears to be the maternal immune activation (MIA) that follows infection. This process can be induced in rodents by exposure of pregnant dams to the viral mimic Poly I:C, which triggers an immune response that results in structural, functional, behavioral, and electrophysiological phenotypes in the adult offspring that model those seen in schizophrenia. We used this model to explore the role of synchronization in brain neural networks, a process thought to be dysfunctional in schizophrenia and previously associated with positive, negative, and cognitive symptoms of schizophrenia. Exposure of pregnant dams to Poly I:C on GD15 produced an impairment in long-range neural synchrony in adult offspring between two regions implicated in schizophrenia pathology; the hippocampus and the medial prefrontal cortex (mPFC). This reduction in synchrony was ameliorated by acute doses of the antipsychotic clozapine. MIA animals have previously been shown to have impaired pre-pulse inhibition (PPI), a gold-standard measure of schizophrenia-like deficits in animal models. Our data showed that deficits in synchrony were positively correlated with the impairments in PPI. Subsequent analysis of LFP activity during the PPI response also showed that reduced coupling between the mPFC and the hippocampus following processing of the pre-pulse was associated with reduced PPI. The ability of the MIA intervention to model neurodevelopmental aspects of schizophrenia pathology provides a useful platform from which to investigate the ontogeny of aberrant synchronous processes. Further, the way in which the model expresses translatable deficits such as aberrant synchrony and reduced PPI will allow researchers to explore novel intervention strategies targeted to these changes.
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Affiliation(s)
| | - David K Bilkey
- Department of Psychology, University of Otago Dunedin, New Zealand
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293
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Plante DT, Goldstein MR. Medroxyprogesterone acetate is associated with increased sleep spindles during non-rapid eye movement sleep in women referred for polysomnography. Psychoneuroendocrinology 2013; 38:3160-6. [PMID: 24054762 PMCID: PMC3844048 DOI: 10.1016/j.psyneuen.2013.08.012] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/27/2013] [Revised: 08/21/2013] [Accepted: 08/27/2013] [Indexed: 10/26/2022]
Abstract
Sleep spindles are characteristic electroencephalographic waveforms that may play functionally significant roles in sleep-dependent memory consolidation, cortical development, and neuropsychiatric disorders. Circumstantial evidence has connected endogenous progesterone and its metabolites to the production of sleep spindles; however, the effects of exogenous progestins on sleep spindles have not been described in women. We examined differences in sleep spindle frequency and morphology in a clinical sample of women (n=21) referred for polysomnography taking depot medroxyprogesterone acetate (MPA), relative to a matched comparison group. Consistent with our hypotheses, women taking MPA demonstrated significantly higher sleep spindle density and maximal amplitude relative to comparison patients. Our results suggest that progestins potentiate the generation of sleep spindles, which may have significant implications for research that examines the role of these waveforms in learning, development, and mental illness.
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Affiliation(s)
- David T. Plante
- Department of Psychiatry, University of Wisconsin School of Medicine and Public Health, Madison, WI, USA
| | - Michael R. Goldstein
- Department of Psychiatry, University of Wisconsin School of Medicine and Public Health, Madison, WI, USA,Department of Psychology, University of Arizona, Tucson, AZ, USA
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294
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Astori S, Wimmer RD, Lüthi A. Manipulating sleep spindles – expanding views on sleep, memory, and disease. Trends Neurosci 2013; 36:738-48. [DOI: 10.1016/j.tins.2013.10.001] [Citation(s) in RCA: 80] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2013] [Revised: 09/30/2013] [Accepted: 10/03/2013] [Indexed: 12/12/2022]
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295
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Zanini M, Castro J, Coelho FM, Bittencourt L, Bressan RA, Tufik S, Brietzke E. Do sleep abnormalities and misaligned sleep/circadian rhythm patterns represent early clinical characteristics for developing psychosis in high risk populations? Neurosci Biobehav Rev 2013; 37:2631-7. [PMID: 24096189 DOI: 10.1016/j.neubiorev.2013.08.012] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2013] [Revised: 08/24/2013] [Accepted: 08/28/2013] [Indexed: 02/04/2023]
Abstract
Sleep architecture changes, such as slow-wave sleep (SWS) percentage variations and reductions in latency and density of rapid eye movement (REM), are found in most patients with schizophrenia and are considered to be an important part of the pathophysiology of the disorder. In addition to these sleep parameters changes, disruptions in sleep homeostasis and the sleep/circadian rhythm also occur in these patients. Sleep/circadian rhythm abnormalities negatively affect neocortical plasticity and cognition and often precede the diagnosis of the illness. Thus, it has been suggested that the sleep/circadian rhythm might be involved in the pathophysiology of psychosis. Recent advances in the identification of individuals at a high risk for developing schizophrenia allow us to investigate several neurobiological processes involved in the development of psychosis. In this article, we review the current evidence of the effects of sleep parameter abnormalities, disruptions in sleep homeostasis and misalignments of sleep circadian rhythm on the early stages of schizophrenia. In addition, we discuss the preliminary evidence of sleep and circadian rhythm abnormalities during the prodromal stages of psychosis and propose that these abnormalities can be explored as potential predictors, as an adjunct to clinical diagnosis, of developing a psychotic disorder in at risk populations.
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Affiliation(s)
- Marcio Zanini
- Programa de Reconhecimento e Intervencao em Indivíduos em Estados Mentais de Risco (PRISMA), Departamento de Psiquiatria, Universidade Federal de Sao Paulo, Sao Paulo, Brazil.
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296
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Abstract
Despite the fact that midday naps are characteristic of early childhood, very little is understood about the structure and function of these sleep bouts. Given that sleep benefits memory in young adults, it is possible that naps serve a similar function for young children. However, children transition from biphasic to monophasic sleep patterns in early childhood, eliminating the nap from their daily sleep schedule. As such, naps may contain mostly light sleep stages and serve little function for learning and memory during this transitional age. Lacking scientific understanding of the function of naps in early childhood, policy makers may eliminate preschool classroom nap opportunities due to increasing curriculum demands. Here we show evidence that classroom naps support learning in preschool children by enhancing memories acquired earlier in the day compared with equivalent intervals spent awake. This nap benefit is greatest for children who nap habitually, regardless of age. Performance losses when nap-deprived are not recovered during subsequent overnight sleep. Physiological recordings of naps support a role of sleep spindles in memory performance. These results suggest that distributed sleep is critical in early learning; when short-term memory stores are limited, memory consolidation must take place frequently.
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Lunsford-Avery JR, Mittal VA. Sleep dysfunction prior to the onset of schizophrenia: A review and neurodevelopmental diathesis–stress conceptualization. ACTA ACUST UNITED AC 2013. [DOI: 10.1111/cpsp.12041] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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Wamsley EJ, Shinn AK, Tucker MA, Ono KE, McKinley SK, Ely AV, Goff DC, Stickgold R, Manoach DS. The effects of eszopiclone on sleep spindles and memory consolidation in schizophrenia: a randomized placebo-controlled trial. Sleep 2013; 36:1369-76. [PMID: 23997371 PMCID: PMC3738047 DOI: 10.5665/sleep.2968] [Citation(s) in RCA: 77] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022] Open
Abstract
STUDY OBJECTIVES In schizophrenia there is a dramatic reduction of sleep spindles that predicts deficient sleep-dependent memory consolidation. Eszopiclone (Lunesta), a non-benzodiazepine hypnotic, acts on γ-aminobutyric acid (GABA) neurons in the thalamic reticular nucleus where spindles are generated. We investigated whether eszopiclone could increase spindles and thereby improve memory consolidation in schizophrenia. DESIGN In a double-blind design, patients were randomly assigned to receive either placebo or 3 mg of eszopiclone. Patients completed Baseline and Treatment visits, each consisting of two consecutive nights of polysomnography. On the second night of each visit, patients were trained on the motor sequence task (MST) at bedtime and tested the following morning. SETTING Academic research center. PARTICIPANTS Twenty-one chronic, medicated schizophrenia outpatients. MEASUREMENTS AND RESULTS We compared the effects of two nights of eszopiclone vs. placebo on stage 2 sleep spindles and overnight changes in MST performance. Eszopiclone increased the number and density of spindles over baseline levels significantly more than placebo, but did not significantly enhance overnight MST improvement. In the combined eszopiclone and placebo groups, spindle number and density predicted overnight MST improvement. CONCLUSION Eszopiclone significantly increased sleep spindles, which correlated with overnight motor sequence task improvement. These findings provide partial support for the hypothesis that the spindle deficit in schizophrenia impairs sleep-dependent memory consolidation and may be ameliorated by eszopiclone. Larger samples may be needed to detect a significant effect on memory. Given the general role of sleep spindles in cognition, they offer a promising novel potential target for treating cognitive deficits in schizophrenia.
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Affiliation(s)
- Erin J. Wamsley
- Department of Psychiatry, Beth Israel Deaconess Medical Center, Boston, MA; Harvard Medical School, Boston, MA
| | - Ann K. Shinn
- Psychotic Disorders Division, McLean Hospital, Belmont, MA
| | - Matthew A. Tucker
- Department of Psychiatry, Beth Israel Deaconess Medical Center, Boston, MA; Harvard Medical School, Boston, MA
| | - Kim E. Ono
- Department of Psychiatry, Massachusetts General Hospital, Charlestown, MA
| | - Sophia K. McKinley
- Department of Psychiatry, Beth Israel Deaconess Medical Center, Boston, MA; Harvard Medical School, Boston, MA
| | - Alice V. Ely
- Department of Psychiatry, Beth Israel Deaconess Medical Center, Boston, MA; Harvard Medical School, Boston, MA
| | - Donald C. Goff
- Department of Psychiatry, Massachusetts General Hospital, Charlestown, MA
| | - Robert Stickgold
- Department of Psychiatry, Beth Israel Deaconess Medical Center, Boston, MA; Harvard Medical School, Boston, MA
| | - Dara S. Manoach
- Department of Psychiatry, Massachusetts General Hospital, Charlestown, MA
- Athinoula A. Martinos Center for Biomedical Imaging, Charlestown, MA
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O'Reilly C, Nielsen T. Assessing EEG sleep spindle propagation. Part 1: theory and proposed methodology. J Neurosci Methods 2013; 221:202-14. [PMID: 23999176 DOI: 10.1016/j.jneumeth.2013.08.013] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2013] [Revised: 07/27/2013] [Accepted: 08/13/2013] [Indexed: 10/26/2022]
Abstract
BACKGROUND A convergence of studies has revealed sleep spindles to be associated with sleep-related cognitive processing and even with fundamental waking state capacities such as intelligence. However, some spindle characteristics, such as propagation direction and delay, may play a decisive role but are only infrequently investigated because of technical complexities. NEW METHOD A new methodology for assessing sleep spindle propagation over the human scalp using noninvasive electroencephalography (EEG) is described. This approach is based on the alignment of time-frequency representations of spindle activity across recording channels. RESULTS This first of a two-part series concentrates on framing theoretical considerations related to EEG spindle propagation and on detailing the methodology. A short example application is provided that illustrates the repeatability of results obtained with the new propagation measure in a sample of 32 night recordings. A more comprehensive experimental investigation is presented in part two of the series. COMPARISON WITH EXISTING METHOD(S) Compared to existing methods, this approach is particularly well adapted for studying the propagation of sleep spindles because it estimates time delays rather than phase synchrony and it computes propagation properties for every individual spindle with windows adjusted to the specific spindle duration. CONCLUSIONS The proposed methodology is effective in tracking the propagation of spindles across the scalp and may thus help in elucidating the temporal aspects of sleep spindle dynamics, as well as other transient EEG and MEG events. A software implementation (the Spyndle Python package) is provided as open source software.
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Affiliation(s)
- Christian O'Reilly
- Dream and Nightmare Laboratory, Center for Advanced Research in Sleep Medicine, Hôpital du Sacré-Coeur de Montréal, 5400 boulevard Gouin Ouest Montréal, QC H4J 1C5, Canada.
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