101
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Hasan A, Mitchell A, Schneider A, Halene T, Akbarian S. Epigenetic dysregulation in schizophrenia: molecular and clinical aspects of histone deacetylase inhibitors. Eur Arch Psychiatry Clin Neurosci 2013; 263:273-84. [PMID: 23381549 DOI: 10.1007/s00406-013-0395-2] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/15/2012] [Accepted: 01/18/2013] [Indexed: 12/22/2022]
Abstract
Notwithstanding the considerable advances in the treatment options for schizophrenia, the cognitive symptoms in particular are not receptive to antipsychotic treatment and considered one of the main predictors for poor social and functional outcome of the disease. Recent findings in preclinical model systems indicate that epigenetic modulation might emerge as a promising target for the treatment of cognitive disorders. The aim of this review is to introduce some of the principles of chromatin biology to the reader and to discuss a possible role in the neurobiology and pathophysiology of schizophrenia. We will discuss potential epigenetic targets for drug therapy, including histone deacetylase inhibitors (HDACi). In a second part, conceptual and practical challenges associated with clinical trials of chromatin-modifying drugs in psychiatric patient populations are discussed, including safety profiles, the potential for adverse effects and general issues revolving around pharmacokinetics and pharmacodynamics. Additional investigations are required in order to fully evaluate the potential of HDACi and similar "epigenetic therapies" as novel treatment options for schizophrenia and other psychotic disease.
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Affiliation(s)
- Alkomiet Hasan
- Deparment of Psychiatry and Psychotherapy, Ludwig-Maximilians-University, Nussbaumstr. 7, 80336 Munich, Germany.
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102
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Blot K, Bai J, Otani S. The effect of non-competitive NMDA receptor antagonist MK-801 on neuronal activity in rodent prefrontal cortex: an animal model for cognitive symptoms of schizophrenia. ACTA ACUST UNITED AC 2013; 107:448-51. [PMID: 23603055 DOI: 10.1016/j.jphysparis.2013.04.003] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2013] [Revised: 04/09/2013] [Accepted: 04/11/2013] [Indexed: 11/29/2022]
Abstract
Schizophrenia affects about 1% of the world population and is a major socio-economical problem in ours societies. Cognitive symptoms are particularly resistant to current treatments and are believed to be closely related to an altered function of prefrontal cortex (PFC). Particularly, abnormalities in the plasticity processes in the PFC are a candidate mechanism underlying cognitive symptoms, and the recent evidences in patients are in line with this hypothesis. Animal pharmacological models of cognitive symptoms, notably with non-competitive NMDA receptor antagonists such as MK-801, are commonly used to investigate the underlying cellular and molecular mechanisms of schizophrenia. However, it is still unknown whether in these animal models, impairments in plasticity of PFC neurons are present. In this article, we briefly summarize the current knowledge on the effect of non-competitive NMDA receptor antagonist MK-801 on medial PFC (mPFC) neuronal activity and then introduce a form of plasticity found after acute exposure to MK-801, which was accompanied by cognitive deficits. These observations suggest a potential correlation between cognitive deficits and the aberrant plasticity in the mPFC in the animal model of schizophrenia.
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Affiliation(s)
- Kevin Blot
- INSERM U952/CNRS UMR 7224, Université Pierre et Marie Curie, 9 quai Saint Bernard, 75252 Paris cedex 05, France.
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103
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Hasan A, Misewitsch K, Nitsche MA, Gruber O, Padberg F, Falkai P, Wobrock T. Impaired motor cortex responses in non-psychotic first-degree relatives of schizophrenia patients: a cathodal tDCS pilot study. Brain Stimul 2013; 6:821-9. [PMID: 23545473 DOI: 10.1016/j.brs.2013.03.001] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2012] [Revised: 01/09/2013] [Accepted: 03/03/2013] [Indexed: 12/22/2022] Open
Abstract
BACKGROUND Schizophrenia has recently been described as a disorder of impaired plasticity and dysconnectivity. Several lines of evidence suggest that alterations in glutamatergic neurotransmission underlie different symptom domains of schizophrenia. Little is known about the impact of genetic liability on cortical plasticity and connectivity in schizophrenia. OBJECTIVE To compare N-methyl-d-aspartate receptor (NMDAR)-dependent cortical plasticity and connectivity in schizophrenia patients and unaffected first-degree relatives to that in healthy subjects. METHODS Cortical plasticity can be induced in the motor cortex with cathodal transcranial direct current stimulation (tDCS). Animal and human research indicates that this long-term depression-like plasticity (LTD-like) is NMDAR dependent, and that these plasticity shifts can last for several hours. tDCS-induced plasticity was assessed by measuring motor-evoked potentials (MEPs) generated by applying transcranial magnetic stimulation (TMS) to both hemispheres in healthy controls, chronically ill schizophrenia patients and unaffected first-degree relatives. RESULTS Compared to healthy controls, both first-degree relatives and schizophrenia patients showed abolished motor-cortical LTD-like plasticity of the stimulated hemisphere. On the non-stimulated hemisphere, plasticity was again abolished in schizophrenia patients, whereas first-degree relatives had a reversed plasticity. CONCLUSIONS Non-psychotic and clinically unaffected first-degree relatives showed an alteration and a reversal of LTD-like cortical plasticity, indicating functional alterations of glutamatergic transmission as a result of a genetic liability for developing schizophrenia. These results provide new evidence for the association between plasticity dysregulation and functional cortical connectivity, and the importance of these networks in the pathophysiology of schizophrenia.
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Affiliation(s)
- Alkomiet Hasan
- Department of Psychiatry and Psychotherapy, Ludwig-Maximilians-University, Munich, Germany; Department of Psychiatry and Psychotherapy, Georg-August University, Goettingen, Germany.
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104
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Rajji TK, Rogasch NC, Daskalakis ZJ, Fitzgerald PB. Neuroplasticity-based brain stimulation interventions in the study and treatment of schizophrenia: a review. CANADIAN JOURNAL OF PSYCHIATRY. REVUE CANADIENNE DE PSYCHIATRIE 2013; 58:93-8. [PMID: 23442896 DOI: 10.1177/070674371305800206] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
We reviewed novel brain stimulation approaches that modify neuroplasticity and are used in the treatment and study of schizophrenia. We searched PubMed and Scholars Portal using search terms related to schizophrenia, brain stimulation, and neuroplasticity. Various brain stimulation approaches simulating a range of experimental protocols that induce synaptic long-term potentiation or depression have been developed. By far, repetitive transcranial magnetic stimulation (rTMS) has been the most widely used in the field of schizophrenia. Its application has been associated with mixed results in treating treatment-resistant symptoms and cognitive deficits associated with schizophrenia. Compared to the other approaches, rTMS is probably the least similar to plasticity-inducing cellular paradigms. Other approaches, such as paired associative stimulation, theta-burst stimulation, and transcranial direct current stimulation, are in their incipient stages in the study and treatment of schizophrenia, with promising early results. Numerous brain stimulation approaches have been developed to treat resistant dimensions of schizophrenia. Notwithstanding some promising reports, optimization of the methods and large randomized controlled trials are still needed.
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Affiliation(s)
- Tarek K Rajji
- Department of Psychiatry, University of Toronto, Toronto, Ontario, Canada.
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105
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Silverstein SM, Wang Y, Keane BP. Cognitive and neuroplasticity mechanisms by which congenital or early blindness may confer a protective effect against schizophrenia. Front Psychol 2013; 3:624. [PMID: 23349646 PMCID: PMC3552473 DOI: 10.3389/fpsyg.2012.00624] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2012] [Accepted: 12/31/2012] [Indexed: 12/12/2022] Open
Abstract
Several authors have noted that there are no reported cases of people with schizophrenia who were born blind or who developed blindness shortly after birth, suggesting that congenital or early (C/E) blindness may serve as a protective factor against schizophrenia. By what mechanisms might this effect operate? Here, we hypothesize that C/E blindness offers protection by strengthening cognitive functions whose impairment characterizes schizophrenia, and by constraining cognitive processes that exhibit excessive flexibility in schizophrenia. After briefly summarizing evidence that schizophrenia is fundamentally a cognitive disorder, we review areas of perceptual and cognitive function that are both impaired in the illness and augmented in C/E blindness, as compared to healthy sighted individuals. We next discuss: (1) the role of neuroplasticity in driving these cognitive changes in C/E blindness; (2) evidence that C/E blindness does not confer protective effects against other mental disorders; and (3) evidence that other forms of C/E sensory loss (e.g., deafness) do not reduce the risk of schizophrenia. We conclude by discussing implications of these data for designing cognitive training interventions to reduce schizophrenia-related cognitive impairment, and perhaps to reduce the likelihood of the development of the disorder itself.
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Affiliation(s)
- Steven M. Silverstein
- University Behavioral HealthCare, University of Medicine and Dentistry of New JerseyPiscataway, NJ, USA
- Department of Psychiatry, University of Medicine and Dentistry of New Jersey, Robert Wood Johnson Medical SchoolPiscataway, NJ, USA
| | - Yushi Wang
- University Behavioral HealthCare, University of Medicine and Dentistry of New JerseyPiscataway, NJ, USA
| | - Brian P. Keane
- University Behavioral HealthCare, University of Medicine and Dentistry of New JerseyPiscataway, NJ, USA
- Department of Psychiatry, University of Medicine and Dentistry of New Jersey, Robert Wood Johnson Medical SchoolPiscataway, NJ, USA
- Rutgers University Center for Cognitive SciencePiscataway, NJ, USA
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106
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Magnetic stimulation modulates structural synaptic plasticity and regulates BDNF–TrkB signal pathway in cultured hippocampal neurons. Neurochem Int 2013. [DOI: 10.1016/j.neuint.2012.11.010] [Citation(s) in RCA: 75] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
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107
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Hasan A, Bergener T, Nitsche MA, Strube W, Bunse T, Falkai P, Wobrock T. Impairments of motor-cortex responses to unilateral and bilateral direct current stimulation in schizophrenia. Front Psychiatry 2013; 4:121. [PMID: 24109457 PMCID: PMC3790105 DOI: 10.3389/fpsyt.2013.00121] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/23/2013] [Accepted: 09/16/2013] [Indexed: 12/27/2022] Open
Abstract
Transcranial direct current stimulation (tDCS) is a non-invasive stimulation technique that can be applied to modulate cortical activity through induction of cortical plasticity. Since various neuropsychiatric disorders are characterized by fluctuations in cortical activity levels (e.g., schizophrenia), tDCS is increasingly investigated as a treatment tool. Several studies have shown that the induction of cortical plasticity following classical, unilateral tDCS is reduced or impaired in the stimulated and non-stimulated primary motor cortices (M1) of patients with schizophrenia. Moreover, an alternative, bilateral tDCS setup has recently been shown to modulate cortical plasticity in both hemispheres in healthy subjects, highlighting another potential treatment approach. Here we present the first study comparing the efficacy of unilateral tDCS (cathode left M1, anode right supraorbital) with simultaneous bilateral tDCS (cathode left M1, anode right M1) in patients with schizophrenia. tDCS-induced cortical plasticity was monitored by investigating motor-evoked potentials induced by single-pulse transcranial magnetic stimulation applied to both hemispheres. Healthy subjects showed a reduction of left M1 excitability following unilateral tDCS on the stimulated left hemisphere and an increase in right M1 excitability following bilateral tDCS. In schizophrenia, no plasticity was induced following both stimulation paradigms. The pattern of these results indicates a complex interplay between plasticity and connectivity that is impaired in patients with schizophrenia. Further studies are needed to clarify the biological underpinnings and clinical impact of these findings.
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Affiliation(s)
- Alkomiet Hasan
- Department of Psychiatry and Psychotherapy, Ludwig-Maximilians-University Munich , Munich , Germany
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108
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Deficient inhibitory cortical networks in antipsychotic-naive subjects at risk of developing first-episode psychosis and first-episode schizophrenia patients: a cross-sectional study. Biol Psychiatry 2012; 72:744-51. [PMID: 22502988 DOI: 10.1016/j.biopsych.2012.03.005] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/12/2011] [Revised: 02/29/2012] [Accepted: 03/06/2012] [Indexed: 12/28/2022]
Abstract
BACKGROUND Impaired cortical inhibition is a well-established finding in schizophrenia patients and has been linked to dysfunctional gamma-aminobutyric acid (GABA)ergic transmission. However, there have been no previous studies investigating cortical excitability with particular regard to intracortical inhibitory networks in antipsychotic-naive subjects at risk of developing first-episode psychosis. METHODS A total of 18 subjects at risk, 18 first-episode schizophrenia patients, and 18 healthy control subjects were included in this study. Transcranial magnetic stimulation over the left primary motor cortex was used to determine short-latency intracortical inhibition, intracortical facilitation, and the contralateral silent period (CSP). Short-latency intracortical inhibition can be considered as a parameter of GABA type A (GABA(A))-mediated inhibition and it has been proposed that CSP can test GABA type B (GABA(B))-mediated inhibitory intracortical networks. RESULTS Subjects at risk and first-episode patients showed a reduced short-latency intracortical inhibition compared with healthy control subjects, suggesting reduced GABA(A)-mediated inhibition. First-episode patients had a prolonged CSP duration compared with the other two groups, implying a GABA(B) imbalance only in patients with full-blown psychosis. Analyses did not reveal group differences for intracortical facilitation. CONCLUSIONS These results indicate specific alterations in inhibitory cortical networks in subjects at risk and in first-episode patients. It appears that there is already a cortical inhibitory deficit in at-risk individuals. These results suggest a possible GABA(A) dysfunction early in the disease course, whereas alterations in GABA(B) functionality seem to occur later in the disease's progression. Future longitudinal studies will be needed to clarify this inhibitory deficit and its relation to the transition to psychosis.
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109
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Nitsche MA, Müller-Dahlhaus F, Paulus W, Ziemann U. The pharmacology of neuroplasticity induced by non-invasive brain stimulation: building models for the clinical use of CNS active drugs. J Physiol 2012; 590:4641-62. [PMID: 22869014 DOI: 10.1113/jphysiol.2012.232975] [Citation(s) in RCA: 124] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
The term neuroplasticity encompasses structural and functional modifications of neuronal connectivity. Abnormal neuroplasticity is involved in various neuropsychiatric diseases, such as dystonia, epilepsy, migraine, Alzheimer's disease, fronto-temporal degeneration, schizophrenia, and post cerebral stroke. Drugs affecting neuroplasticity are increasingly used as therapeutics in these conditions. Neuroplasticity was first discovered and explored in animal experimentation. However, non-invasive brain stimulation (NIBS) has enabled researchers recently to induce and study similar processes in the intact human brain. Plasticity induced by NIBS can be modulated by pharmacological interventions, targeting ion channels, or neurotransmitters. Importantly, abnormalities of plasticity as studied by NIBS are directly related to clinical symptoms in neuropsychiatric diseases. Therefore, a core theme of this review is the hypothesis that NIBS-induced plasticity can explore and potentially predict the therapeutic efficacy of CNS-acting drugs in neuropsychiatric diseases. We will (a) review the basics of neuroplasticity, as explored in animal experimentation, and relate these to our knowledge about neuroplasticity induced in humans by NIBS techniques. We will then (b) discuss pharmacological modulation of plasticity in animals and humans. Finally, we will (c) review abnormalities of plasticity in neuropsychiatric diseases, and discuss how the combination of NIBS with pharmacological intervention may improve our understanding of the pathophysiology of abnormal plasticity in these diseases and their purposeful pharmacological treatment.
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Affiliation(s)
- Michael A Nitsche
- M. A. Nitsche: Georg-August-University, University Medical Centre, Dept Clinical Neurophysiology, Robert-Koch-Str. 40, 37099 Göttingen, Germany.
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110
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Teo JT, Edwards MJ, Bhatia K. Tardive dyskinesia is caused by maladaptive synaptic plasticity: A hypothesis. Mov Disord 2012; 27:1205-15. [DOI: 10.1002/mds.25107] [Citation(s) in RCA: 93] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2011] [Revised: 05/22/2012] [Accepted: 06/11/2012] [Indexed: 12/19/2022] Open
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Pilato F, Profice P, Ranieri F, Capone F, Di Iorio R, Florio L, Di Lazzaro V. Synaptic plasticity in neurodegenerative diseases evaluated and modulated by in vivo neurophysiological techniques. Mol Neurobiol 2012; 46:563-71. [PMID: 22821187 DOI: 10.1007/s12035-012-8302-9] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2012] [Accepted: 07/09/2012] [Indexed: 12/12/2022]
Abstract
Several studies demonstrated in experimental models and in humans synaptic plasticity impairment in some neurodegenerative and neuropsychiatric diseases such as Parkinson's disease, Alzheimer's disease, Huntington's disease, and schizophrenia. Recently new neurophysiological tools, such as repetitive transcranial magnetic stimulation and transcranial direct current stimulation, have been introduced in experimental and clinical settings for studying physiology of the brain and modulating cortical activity. These techniques use noninvasive transcranial electrical or magnetic stimulation to modulate neurons activity in the human brain. Cortical stimulation might enhance or inhibit the activity of cortico-subcortical networks, depending on stimulus frequency and intensity, current polarity, and other stimulation parameters such as the configuration of the induced electric field and stimulation protocols. On this basis, in the last two decades, these techniques have rapidly become valuable tools to investigate physiology of the human brain and have been applied to treat drug-resistant neurological and psychiatric diseases. Here we describe these techniques and discuss the mechanisms that may explain these effects.
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Affiliation(s)
- F Pilato
- Department of Neurosciences, Università Cattolica del Sacro Cuore, Largo A. Gemelli 8, 00168 Rome, Italy.
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112
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Popov T, Rockstroh B, Weisz N, Elbert T, Miller GA. Adjusting brain dynamics in schizophrenia by means of perceptual and cognitive training. PLoS One 2012; 7:e39051. [PMID: 22815697 PMCID: PMC3399837 DOI: 10.1371/journal.pone.0039051] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2011] [Accepted: 05/14/2012] [Indexed: 01/17/2023] Open
Abstract
BACKGROUND In a previous report we showed that cognitive training fostering auditory-verbal discrimination and working memory normalized magnetoencephalographic (MEG) M50 gating ratio in schizophrenia patients. The present analysis addressed whether training effects on M50 ratio and task performance are mediated by changes in brain oscillatory activity. Such evidence should improve understanding of the role of oscillatory activity in phenomena such as M50 ratio, the role of dysfunctional oscillatory activity in processing abnormalities in schizophrenia, and mechanisms of action of cognitive training. METHODOLOGY/PRINCIPAL FINDINGS Time-locked and non-time-locked oscillatory activity was measured together with M50 ratio in a paired-click design before and after a 4-week training of 36 patients randomly assigned to specific cognitive exercises (CE) or standard (comparison) cognitive training (CP). Patient data were compared to those of 15 healthy controls who participated in two MEG measurements 4 weeks apart without training. Training led to more time-locked gamma-band response and more non-time-locked alpha-band desynchronization, moreso after CE than after CP. Only after CE, increased alpha desynchronization was associated with normalized M50 ratio and with improved verbal memory performance. Thus, both types of cognitive training normalized gamma activity, associated with improved stimulus encoding. More targeted training of auditory-verbal discrimination and memory additionally normalized alpha desynchronization, associated with improved elaborative processing. The latter presumably contributes to improved auditory gating and cognitive function. CONCLUSIONS/SIGNIFICANCE Results suggest that dysfunctional interplay of ocillatory activity that may contribute to auditory processing disruption in schizophrenia can be modified by targeted training.
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Affiliation(s)
- Tzvetan Popov
- Department of Psychology, University of Konstanz, Konstanz, Germany.
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113
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Villamar MF, Santos Portilla A, Fregni F, Zafonte R. Noninvasive brain stimulation to modulate neuroplasticity in traumatic brain injury. Neuromodulation 2012; 15:326-38. [PMID: 22882244 DOI: 10.1111/j.1525-1403.2012.00474.x] [Citation(s) in RCA: 71] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
Abstract
OBJECTIVE To review the use of noninvasive brain stimulation (NBS) as a therapeutic tool to enhance neuroplasticity following traumatic brain injury (TBI). MATERIALS AND METHODS Based on a literature search, we describe the pathophysiological events following TBI and the rationale for the use of transcranial magnetic stimulation (TMS) and transcranial direct current stimulation (tDCS) in this setting. RESULTS The pathophysiological mechanisms occurring after TBI vary across time and therefore require differential interventions. Theoretically, given the neurophysiological effects of both TMS and tDCS, these tools may: 1) decrease cortical hyperexcitability acutely after TBI; 2) modulate long-term synaptic plasticity as to avoid maladaptive consequences; and 3) combined with physical and behavioral therapy, facilitate cortical reorganization and consolidation of learning in specific neural networks. All of these interventions may help decrease the burden of disabling sequelae after brain injury. CONCLUSIONS Evidence from animal and human studies reveals the potential benefit of NBS in decreasing the extent of injury and enhancing plastic changes to facilitate learning and recovery of function in lesioned neural tissue. However, this evidence is mainly theoretical at this point. Given safety constraints, studies in TBI patients are necessary to address the role of NBS in this condition as well as to further elucidate its therapeutic effects and define optimal stimulation parameters.
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Affiliation(s)
- Mauricio Fernando Villamar
- Laboratory of Neuromodulation, Department of Physical Medicine & Rehabilitation, Spaulding Rehabilitation Hospital and Massachusetts General Hospital, Harvard Medical School, Boston, MA 02114, USA
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114
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Redrobe JP, Elster L, Frederiksen K, Bundgaard C, de Jong IEM, Smith GP, Bruun AT, Larsen PH, Didriksen M. Negative modulation of GABAA α5 receptors by RO4938581 attenuates discrete sub-chronic and early postnatal phencyclidine (PCP)-induced cognitive deficits in rats. Psychopharmacology (Berl) 2012; 221:451-68. [PMID: 22124672 DOI: 10.1007/s00213-011-2593-9] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/14/2011] [Accepted: 11/15/2011] [Indexed: 11/29/2022]
Abstract
RATIONALE A growing body of evidence suggests that negative modulation of γ-aminobutyric acid (GABA) GABA(A) α5 receptors may be a promising strategy for the treatment of certain facets of cognitive impairment; however, selective modulators of GABA(A) α5 receptors have not yet been tested in "schizophrenia-relevant" cognitive assay/model systems in animals. OBJECTIVES The objectives of this study were to investigate the potential of RO4938581, a negative modulator of GABA(A) α5 receptors, and to attenuate cognitive impairments induced following sub-chronic (sub-PCP) and early postnatal PCP (neo-PCP) administration in the novel object recognition (NOR) and intra-extradimensional shift (ID/ED) paradigms in rats. Complementary in vitro, ex vivo and in vivo studies were performed to confirm negative modulatory activity of RO4938581 and to investigate animal model validity, concept validity and potential side effect issues, respectively. RESULTS In vitro studies confirmed the reported negative modulatory activity of RO4938581, whilst immunohistochemical analyses revealed significantly reduced parvalbumin-positive cells in the prefrontal cortex of sub-PCP- and neo-PCP-treated rats. RO4938581 (1 mg/kg) ameliorated both sub-PCP- and neo-PCP-induced cognitive deficits in NOR and ID/ED performance, respectively. In contrast, QH-II-066 (1 and 3 mg/kg), a GABA(A) α5 receptor positive modulator, impaired cognitive performance in the NOR task when administered to vehicle-treated animals. Additional studies revealed that both RO4938581 (1 mg/kg) and QH-II-066 (1 and 3 mg/kg) attenuated amphetamine-induced hyperactivity in rats. CONCLUSIONS Taken together, these novel findings suggest that negative modulation of GABA(A) α5 receptors may represent an attractive treatment option for the cognitive impairments, and potentially positive symptoms, associated with schizophrenia.
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Affiliation(s)
- John P Redrobe
- Synaptic Transmission I, Neuroscience Research DK, H Lundbeck A/S, Ottiliavej 9, 2500 Valby, Denmark.
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115
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Current world literature. Curr Opin Psychiatry 2012; 25:155-62. [PMID: 22297717 DOI: 10.1097/yco.0b013e3283514a53] [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: 11/26/2022]
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116
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Spivey A. Decoding neurodevelopment: findings on environmental exposures and synaptic plasticity. ENVIRONMENTAL HEALTH PERSPECTIVES 2012; 120:a70-a75. [PMID: 22296776 PMCID: PMC3279465 DOI: 10.1289/ehp.120-a70] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
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117
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Medeiros LF, de Souza ICC, Vidor LP, de Souza A, Deitos A, Volz MS, Fregni F, Caumo W, Torres ILS. Neurobiological effects of transcranial direct current stimulation: a review. Front Psychiatry 2012; 3:110. [PMID: 23293607 PMCID: PMC3531595 DOI: 10.3389/fpsyt.2012.00110] [Citation(s) in RCA: 167] [Impact Index Per Article: 13.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/05/2012] [Accepted: 12/04/2012] [Indexed: 12/20/2022] Open
Abstract
Transcranial Direct Current Stimulation (tDCS) is a non-invasive brain stimulation technique that is affordable and easy to operate compared to other neuromodulation techniques. Anodal stimulation increases cortical excitability, while the cathodal stimulation decreases it. Although tDCS is a promising treatment approach for chronic pain as well as for neuropsychiatric diseases and other neurological disorders, several complex neurobiological mechanisms that are not well understood are involved in its effect. The purpose of this systematic review is to summarize the current knowledge regarding the neurobiological mechanisms involved in the effects of tDCS. The initial search resulted in 171 articles. After applying inclusion and exclusion criteria, we screened 32 full-text articles to extract findings about the neurobiology of tDCS effects including investigation of cortical excitability parameters. Overall, these findings show that tDCS involves a cascade of events at the cellular and molecular levels. Moreover, tDCS is associated with glutamatergic, GABAergic, dopaminergic, serotonergic, and cholinergic activity modulation. Though these studies provide important advancements toward the understanding of mechanisms underlying tDCS effects, further studies are needed to integrate these mechanisms as to optimize clinical development of tDCS.
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Affiliation(s)
- Liciane Fernandes Medeiros
- Post-Graduate Program in Biological Sciences, Department of Physiology, Universidade Federal do Rio Grande do Sul Porto Alegre, Brazil ; Pharmacology Department, Institute of Basic Health Science, Universidade Federal do Rio Grande do Sul Porto Alegre, Brazil ; Laboratory of Pain and Neuromodulation, Hospital de Clínicas de Porto Alegre Porto Alegre, Brazil
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118
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Schmitt A, Hasan A, Gruber O, Falkai P. Schizophrenia as a disorder of disconnectivity. Eur Arch Psychiatry Clin Neurosci 2011; 261 Suppl 2:S150-4. [PMID: 21866371 PMCID: PMC3207137 DOI: 10.1007/s00406-011-0242-2] [Citation(s) in RCA: 170] [Impact Index Per Article: 13.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/20/2011] [Accepted: 08/01/2011] [Indexed: 01/17/2023]
Abstract
Schizophrenia is considered as a neurodevelopmental disorder with genetic and environmental factors playing a role. Animal models show that developmental hippocampal lesions are causing disconnectivity of the prefrontal cortex. Magnetic resonance imaging and postmortem investigations revealed deficits in the temporoprefrontal neuronal circuit. Decreased oligodendrocyte numbers and expression of oligodendrocyte genes and synaptic proteins may contribute to disturbances of micro- and macro-circuitry in the pathophysiology of the disease. Functional connectivity between cortical areas can be investigated with high temporal resolution using transcranial magnetic stimulation (TMS), electroencephalography (EEG), and magnetoencephalography (MEG). In this review, disconnectivity between different cortical areas in schizophrenia patients is described. The specificity and the neurobiological origin of these connectivity deficits and the relation to the symptom complex of schizophrenia and the glutamatergic and GABAergic system are discussed.
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Affiliation(s)
- Andrea Schmitt
- Department of Psychiatry and Psychotherapy, University of Göttingen, Von-Siebold-Str. 5, 37075 Göttingen, Germany.
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