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Pál B. On the functions of astrocyte-mediated neuronal slow inward currents. Neural Regen Res 2024; 19:2602-2612. [PMID: 38595279 PMCID: PMC11168512 DOI: 10.4103/nrr.nrr-d-23-01723] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2023] [Revised: 12/25/2023] [Accepted: 01/24/2024] [Indexed: 04/11/2024] Open
Abstract
Slow inward currents are known as neuronal excitatory currents mediated by glutamate release and activation of neuronal extrasynaptic N-methyl-D-aspartate receptors with the contribution of astrocytes. These events are significantly slower than the excitatory postsynaptic currents. Parameters of slow inward currents are determined by several factors including the mechanisms of astrocytic activation and glutamate release, as well as the diffusion pathways from the release site towards the extrasynaptic receptors. Astrocytes are stimulated by neuronal network activity, which in turn excite neurons, forming an astrocyte-neuron feedback loop. Mostly as a consequence of brain edema, astrocytic swelling can also induce slow inward currents under pathological conditions. There is a growing body of evidence on the roles of slow inward currents on a single neuron or local network level. These events often occur in synchrony on neurons located in the same astrocytic domain. Besides synchronization of neuronal excitability, slow inward currents also set synaptic strength via eliciting timing-dependent synaptic plasticity. In addition, slow inward currents are also subject to non-synaptic plasticity triggered by long-lasting stimulation of the excitatory inputs. Of note, there might be important region-specific differences in the roles and actions triggering slow inward currents. In greater networks, the pathophysiological roles of slow inward currents can be better understood than physiological ones. Slow inward currents are identified in the pathophysiological background of autism, as slow inward currents drive early hypersynchrony of the neural networks. Slow inward currents are significant contributors to paroxysmal depolarizational shifts/interictal spikes. These events are related to epilepsy, but also found in Alzheimer's disease, Parkinson's disease, and stroke, leading to the decline of cognitive functions. Events with features overlapping with slow inward currents (excitatory, N-methyl-D-aspartate-receptor mediated currents with astrocytic contribution) as ischemic currents and spreading depolarization also have a well-known pathophysiological role in worsening consequences of stroke, traumatic brain injury, or epilepsy. One might assume that slow inward currents occurring with low frequency under physiological conditions might contribute to synaptic plasticity and memory formation. However, to state this, more experimental evidence from greater neuronal networks or the level of the individual is needed. In this review, I aimed to summarize findings on slow inward currents and to speculate on the potential functions of it.
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Affiliation(s)
- Balázs Pál
- Department of Physiology, Faculty of Medicine, University of Debrecen, Debrecen, Hungary
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2
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Luppi AI, Girn M, Rosas FE, Timmermann C, Roseman L, Erritzoe D, Nutt DJ, Stamatakis EA, Spreng RN, Xing L, Huttner WB, Carhart-Harris RL. A role for the serotonin 2A receptor in the expansion and functioning of human transmodal cortex. Brain 2024; 147:56-80. [PMID: 37703310 DOI: 10.1093/brain/awad311] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2023] [Revised: 08/14/2023] [Accepted: 08/18/2023] [Indexed: 09/15/2023] Open
Abstract
Integrating independent but converging lines of research on brain function and neurodevelopment across scales, this article proposes that serotonin 2A receptor (5-HT2AR) signalling is an evolutionary and developmental driver and potent modulator of the macroscale functional organization of the human cerebral cortex. A wealth of evidence indicates that the anatomical and functional organization of the cortex follows a unimodal-to-transmodal gradient. Situated at the apex of this processing hierarchy-where it plays a central role in the integrative processes underpinning complex, human-defining cognition-the transmodal cortex has disproportionately expanded across human development and evolution. Notably, the adult human transmodal cortex is especially rich in 5-HT2AR expression and recent evidence suggests that, during early brain development, 5-HT2AR signalling on neural progenitor cells stimulates their proliferation-a critical process for evolutionarily-relevant cortical expansion. Drawing on multimodal neuroimaging and cross-species investigations, we argue that, by contributing to the expansion of the human cortex and being prevalent at the apex of its hierarchy in the adult brain, 5-HT2AR signalling plays a major role in both human cortical expansion and functioning. Owing to its unique excitatory and downstream cellular effects, neuronal 5-HT2AR agonism promotes neuroplasticity, learning and cognitive and psychological flexibility in a context-(hyper)sensitive manner with therapeutic potential. Overall, we delineate a dual role of 5-HT2ARs in enabling both the expansion and modulation of the human transmodal cortex.
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Affiliation(s)
- Andrea I Luppi
- Department of Clinical Neurosciences and Division of Anaesthesia, University of Cambridge, Cambridge, CB2 0QQ, UK
- Leverhulme Centre for the Future of Intelligence, University of Cambridge, Cambridge, CB2 1SB, UK
- The Alan Turing Institute, London, NW1 2DB, UK
| | - Manesh Girn
- Montreal Neurological Institute, Department of Neurology and Neurosurgery, McGill University, Montreal, H3A 2B4, Canada
- Psychedelics Division-Neuroscape, Department of Neurology, University of California SanFrancisco, San Francisco, CA 94158, USA
| | - Fernando E Rosas
- Centre for Psychedelic Research, Department of Brain Sciences, Faculty of Medicine, Imperial College London, London, SW7 2AZ, UK
- Data Science Institute, Imperial College London, London, SW7 2AZ, UK
- Centre for Complexity Science, Imperial College London, London, SW7 2AZ, UK
| | - Christopher Timmermann
- Centre for Psychedelic Research, Department of Brain Sciences, Faculty of Medicine, Imperial College London, London, SW7 2AZ, UK
| | - Leor Roseman
- Centre for Psychedelic Research, Department of Brain Sciences, Faculty of Medicine, Imperial College London, London, SW7 2AZ, UK
| | - David Erritzoe
- Centre for Psychedelic Research, Department of Brain Sciences, Faculty of Medicine, Imperial College London, London, SW7 2AZ, UK
| | - David J Nutt
- Centre for Psychedelic Research, Department of Brain Sciences, Faculty of Medicine, Imperial College London, London, SW7 2AZ, UK
| | - Emmanuel A Stamatakis
- Department of Clinical Neurosciences and Division of Anaesthesia, University of Cambridge, Cambridge, CB2 0QQ, UK
| | - R Nathan Spreng
- Montreal Neurological Institute, Department of Neurology and Neurosurgery, McGill University, Montreal, H3A 2B4, Canada
| | - Lei Xing
- Max Planck Institute of Molecular Cell Biology and Genetics, Dresden, 01307, Germany
| | - Wieland B Huttner
- Max Planck Institute of Molecular Cell Biology and Genetics, Dresden, 01307, Germany
| | - Robin L Carhart-Harris
- Psychedelics Division-Neuroscape, Department of Neurology, University of California SanFrancisco, San Francisco, CA 94158, USA
- Centre for Psychedelic Research, Department of Brain Sciences, Faculty of Medicine, Imperial College London, London, SW7 2AZ, UK
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Stoliker D, Egan GF, Friston KJ, Razi A. Neural Mechanisms and Psychology of Psychedelic Ego Dissolution. Pharmacol Rev 2022; 74:876-917. [PMID: 36786290 DOI: 10.1124/pharmrev.121.000508] [Citation(s) in RCA: 13] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2021] [Revised: 06/26/2022] [Accepted: 06/29/2022] [Indexed: 11/22/2022] Open
Abstract
Neuroimaging studies of psychedelics have advanced our understanding of hierarchical brain organization and the mechanisms underlying their subjective and therapeutic effects. The primary mechanism of action of classic psychedelics is binding to serotonergic 5-HT2A receptors. Agonist activity at these receptors leads to neuromodulatory changes in synaptic efficacy that can have a profound effect on hierarchical message-passing in the brain. Here, we review the cognitive and neuroimaging evidence for the effects of psychedelics: in particular, their influence on selfhood and subject-object boundaries-known as ego dissolution-surmised to underwrite their subjective and therapeutic effects. Agonism of 5-HT2A receptors, located at the apex of the cortical hierarchy, may have a particularly powerful effect on sentience and consciousness. These effects can endure well after the pharmacological half-life, suggesting that psychedelics may have effects on neural plasticity that may play a role in their therapeutic efficacy. Psychologically, this may be accompanied by a disarming of ego resistance that increases the repertoire of perceptual hypotheses and affords alternate pathways for thought and behavior, including those that undergird selfhood. We consider the interaction between serotonergic neuromodulation and sentience through the lens of hierarchical predictive coding, which speaks to the value of psychedelics in understanding how we make sense of the world and specific predictions about effective connectivity in cortical hierarchies that can be tested using functional neuroimaging. SIGNIFICANCE STATEMENT: Classic psychedelics bind to serotonergic 5-HT2A receptors. Their agonist activity at these receptors leads to neuromodulatory changes in synaptic efficacy, resulting in a profound effect on information processing in the brain. Here, we synthesize an abundance of brain imaging research with pharmacological and psychological interpretations informed by the framework of predictive coding. Moreover, predictive coding is suggested to offer more sophisticated interpretations of neuroimaging findings by bridging the role between the 5-HT2A receptors and large-scale brain networks.
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Affiliation(s)
- Devon Stoliker
- Turner Institute for Brain and Mental Health (D.S., G.F.E., A.R.) and Monash Biomedical Imaging (G.F.E., A.R.), Monash University, Clayton, Victoria, Australia; Wellcome Centre for Human Neuroimaging, UCL, London, United Kingdom (K.J.F., A.R.); and CIFAR Azrieli Global Scholar, CIFAR, Toronto, Canada (A.R.)
| | - Gary F Egan
- Turner Institute for Brain and Mental Health (D.S., G.F.E., A.R.) and Monash Biomedical Imaging (G.F.E., A.R.), Monash University, Clayton, Victoria, Australia; Wellcome Centre for Human Neuroimaging, UCL, London, United Kingdom (K.J.F., A.R.); and CIFAR Azrieli Global Scholar, CIFAR, Toronto, Canada (A.R.)
| | - Karl J Friston
- Turner Institute for Brain and Mental Health (D.S., G.F.E., A.R.) and Monash Biomedical Imaging (G.F.E., A.R.), Monash University, Clayton, Victoria, Australia; Wellcome Centre for Human Neuroimaging, UCL, London, United Kingdom (K.J.F., A.R.); and CIFAR Azrieli Global Scholar, CIFAR, Toronto, Canada (A.R.)
| | - Adeel Razi
- Turner Institute for Brain and Mental Health (D.S., G.F.E., A.R.) and Monash Biomedical Imaging (G.F.E., A.R.), Monash University, Clayton, Victoria, Australia; Wellcome Centre for Human Neuroimaging, UCL, London, United Kingdom (K.J.F., A.R.); and CIFAR Azrieli Global Scholar, CIFAR, Toronto, Canada (A.R.)
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Cortical influences of serotonin and glutamate on layer V pyramidal neurons. PROGRESS IN BRAIN RESEARCH 2021; 261:341-378. [PMID: 33785135 DOI: 10.1016/bs.pbr.2020.11.002] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Layer V pyramidal neurons constitute principle output neurons of the medial prefrontal cortex (mPFC)/neocortex to subcortical regions including the intralaminar/midline thalamic nuclei, amygdala, basal ganglia, brainstem nuclei and the spinal cord. The effects of 5-hydroxytryptamine (5-HT) on layer V pyramidal cells primarily reflect a range of excitatory influences through 5-HT2A receptors and inhibitory influences through non-5-HT2A receptors, including 5-HT1A receptors. While the 5-HT2A receptor is primarily a postsynaptic receptor on throughout the apical dendritic field of 5-HT2A receptors, activation of a minority of 5-HT2A receptors also appears to increase spontaneous excitatory postsynaptic currents/potentials (EPSCs/EPSPs) via a presynaptic effect on thalamocortical terminals arising from the midline and intralaminar thalamic nuclei. Activation of 5-HT2A receptors by the phenethylamine hallucinogen also appears to increase asynchronous release of glutamate upon the layer V pyramidal dendritic field, an effect that is suppressed by 5-HT itself through non-5-HT2A receptors. Serotonergic hallucinogens acting on 5-HT2A receptors also appears to increase gene expression of immediate early genes (iEG) and other receptors appearing to induce an iEG-like response like BDNF. Psychedelic hallucinogens acting on 5-HT2A receptors also induce head twitches in rodents that appear related to induction of glutamate release. These electrophysiological, biochemical and behavioral effects of serotonergic hallucinogens appear to be related to modulating glutamatergic thalamocortical neurotransmission and/or shifting the balance toward 5-HT2A receptor activation and away from non-5-HT2A receptor activation. These 5-HT2A receptor induced responses are modulated by feedback homeostatic mechanisms through mGlu2, mGlu4, and mGlu8 presynaptic receptors on thalamocortical terminals. These 5-HT2A receptor and glutamatergic interactions also appear to play a role on higher cortical functions of the mPFC such as motoric impulsivity and antidepressant-like behavioral responses on the differential-reinforcement-of low rate 72-s (DRL 72-s schedule). These mutually opposing effects between 5-HT2A receptor and mGlu autoreceptor activation (e.g., blocking 5-HT2A receptors and enhancing activity at mGlu2 receptors) may play a clinical role with respect to currently prescribed or novel antidepressant drugs. Thus, there is an important balance between 5-HT2A receptor activation and activation of mGlu autoreceptors on prefrontal cortical layer V pyramidal cells with respect to the electrophysiological, biochemical and behavioral effects serotonergic hallucinogenic drugs.
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Inserra A, De Gregorio D, Gobbi G. Psychedelics in Psychiatry: Neuroplastic, Immunomodulatory, and Neurotransmitter Mechanisms. Pharmacol Rev 2020; 73:202-277. [PMID: 33328244 DOI: 10.1124/pharmrev.120.000056] [Citation(s) in RCA: 93] [Impact Index Per Article: 23.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Mounting evidence suggests safety and efficacy of psychedelic compounds as potential novel therapeutics in psychiatry. Ketamine has been approved by the Food and Drug Administration in a new class of antidepressants, and 3,4-methylenedioxymethamphetamine (MDMA) is undergoing phase III clinical trials for post-traumatic stress disorder. Psilocybin and lysergic acid diethylamide (LSD) are being investigated in several phase II and phase I clinical trials. Hence, the concept of psychedelics as therapeutics may be incorporated into modern society. Here, we discuss the main known neurobiological therapeutic mechanisms of psychedelics, which are thought to be mediated by the effects of these compounds on the serotonergic (via 5-HT2A and 5-HT1A receptors) and glutamatergic [via N-methyl-d-aspartate (NMDA) and α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) receptors] systems. We focus on 1) neuroplasticity mediated by the modulation of mammalian target of rapamycin-, brain-derived neurotrophic factor-, and early growth response-related pathways; 2) immunomodulation via effects on the hypothalamic-pituitary-adrenal axis, nuclear factor ĸB, and cytokines such as tumor necrosis factor-α and interleukin 1, 6, and 10 production and release; and 3) modulation of serotonergic, dopaminergic, glutamatergic, GABAergic, and norepinephrinergic receptors, transporters, and turnover systems. We discuss arising concerns and ways to assess potential neurobiological changes, dependence, and immunosuppression. Although larger cohorts are required to corroborate preliminary findings, the results obtained so far are promising and represent a critical opportunity for improvement of pharmacotherapies in psychiatry, an area that has seen limited therapeutic advancement in the last 20 years. Studies are underway that are trying to decouple the psychedelic effects from the therapeutic effects of these compounds. SIGNIFICANCE STATEMENT: Psychedelic compounds are emerging as potential novel therapeutics in psychiatry. However, understanding of molecular mechanisms mediating improvement remains limited. This paper reviews the available evidence concerning the effects of psychedelic compounds on pathways that modulate neuroplasticity, immunity, and neurotransmitter systems. This work aims to be a reference for psychiatrists who may soon be faced with the possibility of prescribing psychedelic compounds as medications, helping them assess which compound(s) and regimen could be most useful for decreasing specific psychiatric symptoms.
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Affiliation(s)
- Antonio Inserra
- Neurobiological Psychiatry Unit, Department of Psychiatry, McGill University, Montreal, Quebec, Canada
| | - Danilo De Gregorio
- Neurobiological Psychiatry Unit, Department of Psychiatry, McGill University, Montreal, Quebec, Canada
| | - Gabriella Gobbi
- Neurobiological Psychiatry Unit, Department of Psychiatry, McGill University, Montreal, Quebec, Canada
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6
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Azizi SA. Monoamines: Dopamine, Norepinephrine, and Serotonin, Beyond Modulation, "Switches" That Alter the State of Target Networks. Neuroscientist 2020; 28:121-143. [PMID: 33292070 DOI: 10.1177/1073858420974336] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
How do monoamines influence the perceptual and behavioral aspects of brain function? A library of information regarding the genetic, molecular, cellular, and function of monoamines in the nervous system and other organs has accumulated. We briefly review monoamines' anatomy and physiology and discuss their effects on the target neurons and circuits. Monoaminergic cells in the brain stem receive inputs from sensory, limbic, and prefrontal areas and project extensively to the forebrain and hindbrain. We review selected studies on molecular, cellular, and electrophysiological effects of monoamines on the brain's target areas. The idea is that monoamines, by reversibly modulating the "primary" information processing circuits, regulate and switch the functions of brain networks and can reversibly alter the "brain states," such as consciousness, emotions, and movements. Monoamines, as the drivers of normal motor and sensory brain operations, including housekeeping, play essential roles in pathogenesis of neuropsychiatric diseases.
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Affiliation(s)
- Sayed Ausim Azizi
- Department of Neurology, Global Neuroscience Institute, Chester, PA, USA
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7
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Marek GJ, Salek AA. Extending the Specificity of DRL 72-s Behavior for Screening Antidepressant-Like Effects of Glutamatergic Clinically Validated Anxiolytic or Antidepressant Drugs in Rats. J Pharmacol Exp Ther 2020; 374:200-210. [PMID: 32265323 DOI: 10.1124/jpet.119.264069] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2019] [Accepted: 03/13/2020] [Indexed: 12/26/2022] Open
Abstract
Both an agonist and its associated prodrug for metabotropic glutamate2/3 (mGlu2/3) receptors demonstrated anxiolytic efficacy in large, randomized, multicenter, double-blind, placebo-controlled trials studying patients with generalized anxiety disorder (GAD). These mGlu2/3 receptor agonists produced robust preclinical anxiolytic-like effects in rodent models. Several different metabotropic glutamate2 receptor positive allosteric modulators have been found to produce antidepressant-like effects on several preclinical screening paradigms, including differential-reinforcement-of-low-rate 72-second (DRL 72-s) behavior [increased reinforcers, decreased response rate, and cohesive rightward shifts in inter-response time distributions]. Although mGlu2/3 receptor agonists have not been tested formally for therapeutic effects in treating patients with major depressive disorder, these compounds generally fail to exert antidepressant-like effects in preclinical screening paradigms and did not improve depressive symptoms in GAD trials. Thus, the present studies were designed to test the potential antidepressant-like effects of the mGlu2/3 receptor agonist 1S,2S,5R,6S-2-aminobicyclo[3.1.0]hexane-2,6-bicarboxylate monohydrate (LY354740) on the DRL 72-s schedule. LY354740 did not test similarly to clinically validated antidepressant drugs when administered alone or when coadministered with the selective serotonin reuptake inhibitor fluoxetine in rats. Another glutamate-based antidepressant drug, the uncompetitive N-methyl-D-aspartate channel blocker racemic ketamine, exerted antidepressant-like effects when administered at subanesthetic doses in rats. The findings further support the specificity of rat DRL 72-s behavior when screening for anxiolytic versus antidepressant drugs and extend testing of compounds with glutamatergic mechanisms of action. SIGNIFICANCE STATEMENT: The metabotropic glutamate2/3 receptor agonist and clinically validated anxiolytic drug 1S,2S,5R,6S-2-aminobicyclo[3.1.0]hexane-2,6-bicarboxylate monohydrate did not test similar to antidepressant drugs (increased reinforcers, decreased response rate, and cohesive rightward shifts in the inter-response time distribution) when tested on differential-reinforcement-of-low-rate 72-second (DRL 72-s) behavior and also did not enhance the antidepressant-like effects of the serotonin reuptake inhibitor fluoxetine. The uncompetitive N-methyl-D-aspartate receptor antagonist ketamine increased the reinforcement rate, decreased the response rate, and induced a rightward shift in the inter-response time distribution similar to antidepressant drugs; these results confirm the utility of DRL 72-s schedule of reinforcement when testing clinically validated anxiolytic versus antidepressant glutamatergic drugs.
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Affiliation(s)
- Gerard J Marek
- Yale School of Medicine Department of Psychiatry, Ribicoff Research Facilities of the Connecticut Mental Health Center, New Haven, Connecticut
| | - Allyson A Salek
- Yale School of Medicine Department of Psychiatry, Ribicoff Research Facilities of the Connecticut Mental Health Center, New Haven, Connecticut
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8
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Tarasov VV, Svistunov AA, Chubarev VN, Sologova SS, Mukhortova P, Levushkin D, Somasundaram SG, Kirkland CE, Bachurin SO, Aliev G. Alterations of Astrocytes in the Context of Schizophrenic Dementia. Front Pharmacol 2020; 10:1612. [PMID: 32116664 PMCID: PMC7020441 DOI: 10.3389/fphar.2019.01612] [Citation(s) in RCA: 45] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2019] [Accepted: 12/10/2019] [Indexed: 12/19/2022] Open
Abstract
The levels of the astrocyte markers (GFAP, S100B) were increased unevenly in patients with schizophrenia. Reactive astrogliosis was found in approximately 70% of patients with schizophrenia. The astrocytes play a major role in etiology and pathogenesis of schizophrenia. Astrocytes produce the components that altered in schizophrenia extracellular matrix system which are involved in inflammation, functioning of interneurons, glio-, and neurotransmitter system, especially glutamate system. Astrocytes activate the interneurons through glutamate release and ATP. Decreased expression of astrocyte glutamate transporters was observed in patients with schizophrenia. Astrocytes influence on N-methyl-d-aspartate (NMDA) receptors via D-serine, an agonist of the glycine-binding site of NMDA receptors, and kynurenic acid, an endogenous antagonist. NMDA receptors, on its turn, control the impulses of dopamine neurons. Therefore following theories of schizophrenia are proposed. They are a) activation of astrocytes for neuroinflammation, b) glutamate and dopamine theory, as astrocyte products control the activity of NMDA receptors, which influence on the dopamine neurons.
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Affiliation(s)
- Vadim V Tarasov
- I.M. Sechenov First Moscow State Medical University (Sechenov University), Moscow, Russia
| | - Andrey A Svistunov
- I.M. Sechenov First Moscow State Medical University (Sechenov University), Moscow, Russia
| | - Vladimir N Chubarev
- I.M. Sechenov First Moscow State Medical University (Sechenov University), Moscow, Russia
| | - Susanna S Sologova
- I.M. Sechenov First Moscow State Medical University (Sechenov University), Moscow, Russia
| | - Polina Mukhortova
- I.M. Sechenov First Moscow State Medical University (Sechenov University), Moscow, Russia
| | - Dmitrii Levushkin
- I.M. Sechenov First Moscow State Medical University (Sechenov University), Moscow, Russia
| | - Siva G Somasundaram
- Department of Biological Sciences, Salem University, Salem, WV, United States
| | - Cecil E Kirkland
- Department of Biological Sciences, Salem University, Salem, WV, United States
| | - Sergey O Bachurin
- Institute of Physiologically Active Compounds Russian Academy of Sciences, Chernogolovka, Russia
| | - Gjumrakch Aliev
- I.M. Sechenov First Moscow State Medical University (Sechenov University), Moscow, Russia.,Institute of Physiologically Active Compounds Russian Academy of Sciences, Chernogolovka, Russia.,Federal State Budgetary Institution, Research Institute of Human Morphology, Russian Federation, Moscow, Russia.,GALLY International Research Institute, San Antonio, TX, United States
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Kato T, Duman RS. Rapastinel, a novel glutamatergic agent with ketamine-like antidepressant actions: Convergent mechanisms. Pharmacol Biochem Behav 2019; 188:172827. [PMID: 31733218 DOI: 10.1016/j.pbb.2019.172827] [Citation(s) in RCA: 30] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/03/2019] [Revised: 11/08/2019] [Accepted: 11/12/2019] [Indexed: 12/22/2022]
Abstract
Conventional antidepressant medications, which act on monoaminergic systems, have significant limitations, including a time lag of weeks to months and low rates of therapeutic efficacy. Recently, clinical findings demonstrate that ketamine, a dissociative anesthetic that blocks N-methyl-d-aspartate (NMDA) receptor channel activity, causes rapid (within hours) and long-lasting (7 to 10 days) antidepressant effects. Rapastinel is a novel glutamatergic compound that acts as an NMDAR postive allosteric modulator and produces rapid antidepressant actions in depressed patients and in preclinical rodent models. In addition, rapastinel has no ketamine-like side effect such as cognitive impairment and psychotomimetic symptoms. Despite recent negative clinical trials, it remains possible that rapastinel could prove effective as an alternative rapid agent with reduced side effects. In this review, we discuss the pharmacological profile of rapastinel and the molecular and cellular mechanisms underlying the rapid and sustained antidepressant actions of this novel agent.
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Affiliation(s)
- Taro Kato
- Department of Psychiatry, Yale University School of Medicine, 34 Park Street, New Haven, CT 06520, United States of America; Pharmacology Research Unit, Sumitomo Dainippon Pharma, 3-1-98 Kasugade-naka, Konohana-ku, Osaka 554-0022, Japan; Department of Neurosciences, Yale University School of Medicine, 34 Park Street, New Haven, CT 06520, United States of America
| | - Ronald S Duman
- Department of Psychiatry, Yale University School of Medicine, 34 Park Street, New Haven, CT 06520, United States of America; Department of Neurosciences, Yale University School of Medicine, 34 Park Street, New Haven, CT 06520, United States of America.
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10
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Carhart-Harris RL, Friston KJ. REBUS and the Anarchic Brain: Toward a Unified Model of the Brain Action of Psychedelics. Pharmacol Rev 2019; 71:316-344. [PMID: 31221820 PMCID: PMC6588209 DOI: 10.1124/pr.118.017160] [Citation(s) in RCA: 342] [Impact Index Per Article: 68.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
This paper formulates the action of psychedelics by integrating the free-energy principle and entropic brain hypothesis. We call this formulation relaxed beliefs under psychedelics (REBUS) and the anarchic brain, founded on the principle that-via their entropic effect on spontaneous cortical activity-psychedelics work to relax the precision of high-level priors or beliefs, thereby liberating bottom-up information flow, particularly via intrinsic sources such as the limbic system. We assemble evidence for this model and show how it can explain a broad range of phenomena associated with the psychedelic experience. With regard to their potential therapeutic use, we propose that psychedelics work to relax the precision weighting of pathologically overweighted priors underpinning various expressions of mental illness. We propose that this process entails an increased sensitization of high-level priors to bottom-up signaling (stemming from intrinsic sources), and that this heightened sensitivity enables the potential revision and deweighting of overweighted priors. We end by discussing further implications of the model, such as that psychedelics can bring about the revision of other heavily weighted high-level priors, not directly related to mental health, such as those underlying partisan and/or overly-confident political, religious, and/or philosophical perspectives. SIGNIFICANCE STATEMENT: Psychedelics are capturing interest, with efforts underway to bring psilocybin therapy to marketing authorisation and legal access within a decade, spearheaded by the findings of a series of phase 2 trials. In this climate, a compelling unified model of how psychedelics alter brain function to alter consciousness would have appeal. Towards this end, we have sought to integrate a leading model of global brain function, hierarchical predictive coding, with an often-cited model of the acute action of psychedelics, the entropic brain hypothesis. The resulting synthesis states that psychedelics work to relax high-level priors, sensitising them to liberated bottom-up information flow, which, with the right intention, care provision and context, can help guide and cultivate the revision of entrenched pathological priors.
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Affiliation(s)
- R L Carhart-Harris
- Centre for Psychedelic Research, Division of Brain Sciences, Imperial College London, London, United Kingdom (R.L.C.-H.); and Institute of Neurology, Wellcome Trust Centre for Neuroimaging, University College London, London, United Kingdom (K.J.F.)
| | - K J Friston
- Centre for Psychedelic Research, Division of Brain Sciences, Imperial College London, London, United Kingdom (R.L.C.-H.); and Institute of Neurology, Wellcome Trust Centre for Neuroimaging, University College London, London, United Kingdom (K.J.F.)
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11
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Marek GJ. Interactions of Hallucinogens with the Glutamatergic System: Permissive Network Effects Mediated Through Cortical Layer V Pyramidal Neurons. Curr Top Behav Neurosci 2018; 36:107-135. [PMID: 28831734 DOI: 10.1007/7854_2017_480] [Citation(s) in RCA: 32] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Recordings made from layer V (L5) pyramidal cells of the prefrontal cortex (PFC) and neocortex in rodent slice preparations have shown that serotonin (5-hydroxytryptamine, 5-HT) and serotonergic hallucinogens induce an increase in the frequency of spontaneous excitatory postsynaptic currents (EPSCs) in the apical dendritic field by activating 5-HT2A receptors. Serotonergic hallucinogens induce late EPSCs and increase recurrent network activity when subcortical or mid-cortical regions are stimulated at low frequencies (e.g., 0.1 Hz). A range of agonists or positive allosteric modulators (PAMs) for mostly Gi/o-coupled receptors, including metabotropic glutamate2 (mGlu2), adenosine A1, or μ-opioid receptors, suppress these effects of 5-HT2A receptor stimulation. Furthermore, a range of mostly Gq/11-coupled receptors (including orexin2 [OX2]; α1-adrenergic, and mGlu5 receptors) similarly induce glutamate (Glu) release onto L5 pyramidal cells. Evidence implicates a number of brain regions in mediating these effects of serotonergic hallucinogens and Gq/11-coupled receptors including the midline and intralaminar thalamic nuclei, claustrum, and neurons in deep PFC. These effects on 5-HT2A receptors and related GPCRs appear to play a major role in the behavioral effects of serotonergic hallucinogens, such as head twitches in rodents and higher order behaviors such as rodent lever pressing on the differential-reinforcement-of-low rate 72-s (DRL 72-s) schedule. This implies that the effects of 5-HT2A receptor activation on the activity of L5 pyramidal cells may be responsible for mediating a range of behaviors linked to limbic circuitry with connectivity between the PFC, striatum, thalamus, claustrum, striatum, amygdala, and the hippocampal formation.
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Affiliation(s)
- Gerard J Marek
- Global Medical Science, CNS and Pain, Astellas Pharma Global Development, 1 Astellas Way, Northbrook, IL, 60062, USA.
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Marek GJ, Ramos BP. β 2-Adrenergic Receptor Activation Suppresses the Rat Phenethylamine Hallucinogen-Induced Head Twitch Response: Hallucinogen-Induced Excitatory Post-synaptic Potentials as a Potential Substrate. Front Pharmacol 2018; 9:89. [PMID: 29472863 PMCID: PMC5809958 DOI: 10.3389/fphar.2018.00089] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2017] [Accepted: 01/26/2018] [Indexed: 12/20/2022] Open
Abstract
5-Hydroxytryptamine2A (5-HT2A) receptors are enriched in layers I and Va of the rat prefrontal cortex and neocortex and their activation increases the frequency of glutamatergic excitatory post-synaptic potentials/currents (EPSP/Cs) onto layer V pyramidal cells. A number of other G-protein coupled receptors (GPCRs) are also enriched in cortical layers I and Va and either induce (α1-adrenergic and orexin2) or suppress (metabotropic glutamate2 [mGlu2], adenosine A1, μ-opioid) both 5-HT-induced EPSCs and head twitches or head shakes induced by the phenethylamine hallucinogen 2,5-dimethoxy-4-iodoamphetamine (DOI). Another neurotransmitter receptor also localized to apparent thalamocortical afferents to layers I and Va of the rat prefrontal cortex and neocortex is the β2-adrenergic receptor. Therefore, we conducted preliminary electrophysiological experiments with rat brain slices examining the effects of epinephrine on electrically-evoked EPSPs following bath application of DOI (3 μM). Epinephrine (0.3-10 μM) suppressed the late EPSPs produced by electrical stimulation and DOI. The selective β2-adrenergic receptor antagonist ICI-118,551 (300 nM) resulted in a rightward shift of the epinephrine concentration-response relationship. We also tested the selective β2-adrenergic receptor agonist clenbuterol and the antagonist ICI-118,551 on DOI-induced head twitches. Clenbuterol (0.3-3 mg/kg, i.p.) suppressed DOI (1.25 mg/kg, i.p.)-induced head twitches. This clenbuterol effect appeared to be at least partially reversed by the selective β2-adrenergic receptor antagonist ICI-118,553 (0.01-1 mg/kg, i.p.), with significant reversal at doses of 0.1 and 1 mg/kg. Thus, β2-adrenergic receptor activation reverses the effects of phenethylamine hallucinogens in the rat prefrontal cortex. While Gi/Go-coupled GPCRs have previously been shown to suppress both the electrophysiological and behavioral effects of 5-HT2A receptor activation in the mPFC, the present work appears to extend this suppressant action to a Gs-coupled GPCR. Furthermore, the modulation of 5-HT2A receptor activation-induced glutamate release onto mPFC layer V pyramidal neurons apical dendrites by a range GPCRs in rat brain slices appears to results in behaviorally salient effects of relevance when screening for novel CNS therapeutic drugs.
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Affiliation(s)
- Gerard J. Marek
- Department of Psychiatry, School of Medicine, Ribicoff Research Facilities of the Connecticut Mental Health Center, Yale University, New Haven, CT, United States
- Astellas Pharma Global Development, Inc., Global Medical Science, CNS and Pain, Northbrook, IL, United States
| | - Brian P. Ramos
- Department of Neurobiology, School of Medicine, Yale University, New Haven, CT, United States
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Kometer M, Vollenweider FX. Serotonergic Hallucinogen-Induced Visual Perceptual Alterations. Curr Top Behav Neurosci 2018; 36:257-282. [PMID: 27900674 DOI: 10.1007/7854_2016_461] [Citation(s) in RCA: 44] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
Serotonergic hallucinogens, such as lysergic acid diethylamide (LSD), psilocybin, and N,N-dimethyltryptamine (DMT), are famous for their capacity to temporally and profoundly alter an individual's visual experiences. These visual alterations show consistent attributes despite large inter- and intra-individual variances. Many reports document a common perception of colors as more saturated, with increased brightness and contrast in the environment ("Visual Intensifications"). Environmental objects might be altered in size ("Visual illusions") or take on a modified and special meaning for the subject ("Altered self-reference"). Subjects may perceive light flashes or geometrical figures containing recurrent patterns ("Elementary imagery and hallucinations") influenced by auditory stimuli ("Audiovisual synesthesia"), or they may envision images of people, animals, or landscapes ("Complex imagery and hallucinations") without any physical stimuli supporting their percepts. This wide assortment of visual phenomena suggests that one single neuropsychopharmacological mechanism is unlikely to explain such vast phenomenological diversity. Starting with mechanisms that act at the cellular level, the key role of 5-HT2A receptor activation and the subsequent increased cortical excitation will be considered. Next, it will be shown that area specific anatomical and dynamical features link increased excitation to the specific visual contents of hallucinations. The decrease of alpha oscillations by hallucinogens will then be introduced as a systemic mechanism for amplifying internal-driven excitation that overwhelms stimulus-induced excitations. Finally, the hallucinogen-induced parallel decrease of the N170 visual evoked potential and increased medial P1 potential will be discussed as key mechanisms for inducing a dysbalance between global integration and early visual gain that may explain several hallucinogen-induced visual experiences, including visual hallucinations, illusions, and intensifications.
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Affiliation(s)
- Michael Kometer
- Neuropsychopharmacology and Brain Imaging Research Unit, Heffter Research Center Zurich, Department of Psychiatry, Psychotherapy and Psychosomatics, Psychiatric University Hospital, University of Zurich, Lenggstrasse 31, 8032, Zurich, Switzerland.
| | - Franz X Vollenweider
- Neuropsychopharmacology and Brain Imaging Research Unit, Heffter Research Center Zurich, Department of Psychiatry, Psychotherapy and Psychosomatics, Psychiatric University Hospital, University of Zurich, Lenggstrasse 31, 8032, Zurich, Switzerland
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GLYX-13 Produces Rapid Antidepressant Responses with Key Synaptic and Behavioral Effects Distinct from Ketamine. Neuropsychopharmacology 2017; 42:1231-1242. [PMID: 27634355 PMCID: PMC5437877 DOI: 10.1038/npp.2016.202] [Citation(s) in RCA: 82] [Impact Index Per Article: 11.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/25/2016] [Revised: 08/18/2016] [Accepted: 08/29/2016] [Indexed: 12/28/2022]
Abstract
GLYX-13 is a putative NMDA receptor modulator with glycine-site partial agonist properties that produces rapid antidepressant effects, but without the psychotomimetic side effects of ketamine. Studies were conducted to examine the molecular, cellular, and behavioral actions of GLYX-13 to further characterize the mechanisms underlying the antidepressant actions of this agent. The results demonstrate that a single dose of GLYX-13 rapidly activates the mTORC1 pathway in the prefrontal cortex (PFC), and that infusion of the selective mTORC1 inhibitor rapamycin into the medial PFC (mPFC) blocks the antidepressant behavioral actions of GLYX-13, indicating a requirement for mTORC1 similar to ketamine. The results also demonstrate that GLYX-13 rapidly increases the number and function of spine synapses in the apical dendritic tuft of layer V pyramidal neurons in the mPFC. Notably, GLYX-13 significantly increased the synaptic responses to hypocretin, a measure of thalamocortical synapses, compared with its effects on 5-HT responses, a measure of cortical-cortical responses mediated by the 5-HT2A receptor. Behavioral studies further demonstrate that GLYX-13 does not influence 5-HT2 receptor induced head twitch response or impulsivity in a serial reaction time task (SRTT), whereas ketamine increased responses in both tests. In contrast, both GLYX-13 and ketamine increased attention in the SRTT task, which is linked to hypocretin-thalamocortical responses. The differences in the 5-HT2 receptor synaptic and behavioral responses may be related to the lack of psychotomimetic side effects of GLYX-13 compared with ketamine, whereas regulation of the hypocretin responses may contribute to the therapeutic benefits of both rapid acting antidepressants.
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Abstract
The neuropsychological effects of naturally occurring psychoactive chemicals have been recognized for millennia. Hallucinogens, which include naturally occurring chemicals such as mescaline and psilocybin, as well as synthetic compounds, such as lysergic acid diethylamide (LSD), induce profound alterations of human consciousness, emotion, and cognition. The discovery of the hallucinogenic effects of LSD and the observations that LSD and the endogenous ligand serotonin share chemical and pharmacological profiles led to the suggestion that biogenic amines like serotonin were involved in the psychosis of mental disorders such as schizophrenia. Although they bind other G protein-coupled receptor (GPCR) subtypes, studies indicate that several effects of hallucinogens involve agonist activity at the serotonin 5-HT2A receptor. In this chapter, we review recent advances in understanding hallucinogen drug action through characterization of structure, neuroanatomical location, and function of the 5-HT2A receptor.
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Martin DA, Nichols CD. Psychedelics Recruit Multiple Cellular Types and Produce Complex Transcriptional Responses Within the Brain. EBioMedicine 2016; 11:262-277. [PMID: 27649637 PMCID: PMC5050000 DOI: 10.1016/j.ebiom.2016.08.049] [Citation(s) in RCA: 43] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2016] [Revised: 08/24/2016] [Accepted: 08/31/2016] [Indexed: 11/22/2022] Open
Abstract
There has recently been a resurgence of interest in psychedelics, substances that profoundly alter perception and cognition and have recently demonstrated therapeutic efficacy to treat anxiety, depression, and addiction in the clinic. The receptor mechanisms that drive their molecular and behavioral effects involve activation of cortical serotonin 5-HT2A receptors, but the responses of specific cellular populations remain unknown. Here, we provide evidence that a small subset of 5-HT2A-expressing excitatory neurons is directly activated by psychedelics and subsequently recruits other select cell types including subpopulations of inhibitory somatostatin and parvalbumin GABAergic interneurons, as well as astrocytes, to produce distinct and regional responses. To gather data regarding the response of specific neuronal populations, we developed methodology for fluorescence-activated cell sorting (FACS) to segregate and enrich specific cellular subtypes in the brain. These methods allow for robust neuronal sorting based on cytoplasmic epitopes followed by downstream nucleic acid analysis, expanding the utility of FACS in neuroscience research. Psychedelics activate distinct transcription across cell types, including excitatory neurons, inhibitory neurons, and astrocytes Psychedelics induce internalization of 5-HT2A receptors throughout the cortex and claustrum FACS can separate neuronal subpopulations that require non-nuclear markers
Psychedelic drugs are known to act through the 5-HT2A receptor to produce many of their effects, however, the precise cellular populations in the brain which respond to this class of drugs remain unknown. We use flow cytometric analyses, immunohistochemistry, and gene expression analyses to identify small populations of specific cells in the brain that are activated by the psychedelic drug, (R)-DOI. The methodology used in these studies will be useful to determine the molecular effects of any manipulation or disease on particular brain cells.
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Affiliation(s)
- David A Martin
- Department of Pharmacology and Experimental Therapeutics, Louisiana State University Health Sciences Center, New Orleans, LA 70112, USA
| | - Charles D Nichols
- Department of Pharmacology and Experimental Therapeutics, Louisiana State University Health Sciences Center, New Orleans, LA 70112, USA.
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Lavreysen H, Langlois X, Donck LV, Nuñez JMC, Pype S, Lütjens R, Megens A. Preclinical evaluation of the antipsychotic potential of the mGlu2-positive allosteric modulator JNJ-40411813. Pharmacol Res Perspect 2015; 3:e00097. [PMID: 25692027 PMCID: PMC4324682 DOI: 10.1002/prp2.97] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2014] [Accepted: 09/08/2014] [Indexed: 01/25/2023] Open
Abstract
JNJ-40411813/ADX71149 (1-butyl-3-chloro-4-(4-phenylpiperidin-1-yl) pyridin-2(1H)-one) is a positive allosteric modulator (PAM) of the mGlu2 receptor, which also displays 5-Hydroxytryptamine (5HT2A) antagonism after administration in rodents due to a rodent-specific metabolite. JNJ-40411813 was compared with the orthosteric mGlu2/3 agonist LY404039 (4-amino-2-thiabicyclo [3.1.0] hexane-4,6-dicarboxylic acid 2,2-dioxide), the selective mGlu2 PAM JNJ-42153605 (3-(cyclopropylmethyl)-7-(4-phenylpiperidin-1-yl)-8-(trifluoromethyl)[1,2,4]triazolo[4,3-a]pyridine) and the 5HT2A antagonist ritanserin in rodent models for antipsychotic activity and potential side effects, attempting to differentiate between the various compounds and mechanisms of action. In mice, JNJ-40411813, JNJ-42153605, and LY404039 inhibited spontaneous locomotion and phencyclidine- and scopolamine-induced but not d-amphetamine-induced hyperlocomotion; the 5HT2A antagonist ritanserin inhibited only spontaneous locomotion and phencyclidine-induced hyperlocomotion. As measured by 2-deoxyglucose uptake, all compounds reversed memantine-induced brain activation in mice. The two mGlu2 PAMs and LY404039, but not ritanserin, inhibited conditioned avoidance behavior in rats. Like ritanserin, the mGlu2 ligands antagonized 2,5-dimethoxy-4-methylamphetamine-induced head twitches in rats. LY404039 but not the mGlu2 PAMs impaired rotarod performance in rats and increased the acoustic startle response in mice. Our results show that although 5HT2A antagonism has effect in some models, mGlu2 receptor activation is sufficient for activity in several animal models of antipsychotic activity. The mGlu2 PAMs mimicked the in vivo pharmacodynamic effects observed with LY404039 except for effects on the rotarod and acoustic startle, suggesting that they produce a primary activity profile similar to that of the mGlu2/3 receptor agonist while they can be differentiated based on their secondary activity profile. The results are discussed in light of clinical data available for some of these molecules, in particular JNJ-40411813.
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Affiliation(s)
- Hilde Lavreysen
- Janssen Research & Development, Janssen Pharmaceutica NVBeerse, Belgium
| | - Xavier Langlois
- Janssen Research & Development, Janssen Pharmaceutica NVBeerse, Belgium
| | - Luc Ver Donck
- Janssen Research & Development, Janssen Pharmaceutica NVBeerse, Belgium
| | | | - Stefan Pype
- Janssen Research & Development, Janssen Pharmaceutica NVBeerse, Belgium
| | | | - Anton Megens
- Janssen Research & Development, Janssen Pharmaceutica NVBeerse, Belgium
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Abstract
One of the main obstacles faced by translational neuroscience is the development of animal models of psychiatric disorders. Behavioural pharmacology studies indicate that psychedelic drugs, such as lysergic acid diethylamide (LSD) and dissociative drugs, such as phencyclidine (PCP), induce in healthy human volunteers psychotic and cognitive symptoms that resemble some of those observed in schizophrenia patients. Serotonin 5-HT2A and metabotropic glutamate 2 receptors have been involved in the mechanism of action of psychedelic and dissociative drugs. Here we review recent advances using LSD-like and PCP-like drugs in rodent models that implicate these receptors in the neurobiology of schizophrenia and its treatment.
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Hanks JB, González-Maeso J. Animal models of serotonergic psychedelics. ACS Chem Neurosci 2013; 4:33-42. [PMID: 23336043 DOI: 10.1021/cn300138m] [Citation(s) in RCA: 98] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2012] [Accepted: 09/24/2012] [Indexed: 11/30/2022] Open
Abstract
The serotonin 5-HT(2A) receptor is the major target of psychedelic drugs such as lysergic acid diethylamide (LSD), mescaline, and psilocybin. Serotonergic psychedelics induce profound effects on cognition, emotion, and sensory processing that often seem uniquely human. This raises questions about the validity of animal models of psychedelic drug action. Nonetheless, recent findings suggest behavioral abnormalities elicited by psychedelics in rodents that predict such effects in humans. Here we review the behavioral effects induced by psychedelic drugs in rodent models, discuss the translational potential of these findings, and define areas where further research is needed to better understand the molecular mechanisms and neuronal circuits underlying their neuropsychological effects.
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Affiliation(s)
- James B. Hanks
- Departments of Psychiatry and ‡Neurology, §Friedman Brain Institute, Mount Sinai School of Medicine, New York, New York 10029, United States
| | - Javier González-Maeso
- Departments of Psychiatry and ‡Neurology, §Friedman Brain Institute, Mount Sinai School of Medicine, New York, New York 10029, United States
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Moreno JL, Muguruza C, Umali A, Mortillo S, Holloway T, Pilar-Cuéllar F, Mocci G, Seto J, Callado LF, Neve RL, Milligan G, Sealfon SC, López-Giménez JF, Meana JJ, Benson DL, González-Maeso J. Identification of three residues essential for 5-hydroxytryptamine 2A-metabotropic glutamate 2 (5-HT2A·mGlu2) receptor heteromerization and its psychoactive behavioral function. J Biol Chem 2012; 287:44301-19. [PMID: 23129762 DOI: 10.1074/jbc.m112.413161] [Citation(s) in RCA: 93] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Serotonin and glutamate G protein-coupled receptor (GPCR) neurotransmission affects cognition and perception in humans and rodents. GPCRs are capable of forming heteromeric complexes that differentially alter cell signaling, but the role of this structural arrangement in modulating behavior remains unknown. Here, we identified three residues located at the intracellular end of transmembrane domain four that are necessary for the metabotropic glutamate 2 (mGlu2) receptor to be assembled as a GPCR heteromer with the serotonin 5-hydroxytryptamine 2A (5-HT(2A)) receptor in the mouse frontal cortex. Substitution of these residues (Ala-677(4.40), Ala-681(4.44), and Ala-685(4.48)) leads to absence of 5-HT(2A)·mGlu2 receptor complex formation, an effect that is associated with a decrease in their heteromeric ligand binding interaction. Disruption of heteromeric expression with mGlu2 attenuates the psychosis-like effects induced in mice by hallucinogenic 5-HT(2A) agonists. Furthermore, the ligand binding interaction between the components of the 5-HT(2A)·mGlu2 receptor heterocomplex is up-regulated in the frontal cortex of schizophrenic subjects as compared with controls. Together, these findings provide structural evidence for the unique behavioral function of a GPCR heteromer.
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Affiliation(s)
- José L Moreno
- Department of Psychiatry, Mount Sinai School of Medicine, New York, New York 10029, USA
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González-Maeso J, Sealfon SC. Functional selectivity in GPCR heterocomplexes. Mini Rev Med Chem 2012; 12:851-5. [PMID: 22681249 DOI: 10.2174/138955712800959152] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2011] [Revised: 09/06/2011] [Accepted: 09/09/2011] [Indexed: 01/15/2023]
Abstract
G protein-coupled receptors (GPCRs) can couple to more than one signaling pathway. Biophysical studies and pharmacological theory indicate that they exist in different active conformations that differ in their capacity to activate specific signaling pathways. Individual agonists stabilize particular active conformations and thereby can differ in their relative activation of different signaling pathways coupled to the same receptor, a phenomenon referred to as functional selectivity. Many pairs of GPCRs have been shown to interact and form heterocomplexes in vitro and in vivo. Recent studies implicate these complexes in the responses to some therapeutic drugs and drugs of abuse, and raise the possibility that they may be involved in mediating functional selectivity.
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Affiliation(s)
- J González-Maeso
- Department Psychiatry, Mount Sinai School of Medicine, New York, New York, USA
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Kurita M, Holloway T, García-Bea A, Kozlenkov A, Friedman AK, Moreno JL, Heshmati M, Golden SA, Kennedy PJ, Takahashi N, Dietz DM, Mocci G, Gabilondo AM, Hanks J, Umali A, Callado LF, Gallitano AL, Neve RL, Shen L, Buxbaum JD, Han MH, Nestler EJ, Meana JJ, Russo SJ, González-Maeso J. HDAC2 regulates atypical antipsychotic responses through the modulation of mGlu2 promoter activity. Nat Neurosci 2012; 15:1245-54. [PMID: 22864611 PMCID: PMC3431440 DOI: 10.1038/nn.3181] [Citation(s) in RCA: 197] [Impact Index Per Article: 16.4] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2012] [Accepted: 07/05/2012] [Indexed: 02/08/2023]
Abstract
Histone deacetylases (HDACs) compact chromatin structure and repress gene transcription. In schizophrenia, clinical studies demonstrate that HDAC inhibitors are efficacious when given in combination with atypical antipsychotics. However, the molecular mechanism that integrates a better response to antipsychotics with changes in chromatin structure remains unknown. Here we found that chronic atypical antipsychotics downregulated the transcription of metabotropic glutamate 2 receptor (mGlu2, also known as Grm2), an effect that was associated with decreased histone acetylation at its promoter in mouse and human frontal cortex. This epigenetic change occurred in concert with a serotonin 5-HT(2A) receptor-dependent upregulation and increased binding of HDAC2 to the mGlu2 promoter. Virally mediated overexpression of HDAC2 in frontal cortex decreased mGlu2 transcription and its electrophysiological properties, thereby increasing psychosis-like behavior. Conversely, HDAC inhibitors prevented the repressive histone modifications induced at the mGlu2 promoter by atypical antipsychotics, and augmented their therapeutic-like effects. These observations support the view of HDAC2 as a promising new target for schizophrenia treatment.
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Affiliation(s)
- Mitsumasa Kurita
- Department of Psychiatry, Mount Sinai School of Medicine, New York, New York, USA
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Peña-Ortega F. Tonic neuromodulation of the inspiratory rhythm generator. Front Physiol 2012; 3:253. [PMID: 22934010 PMCID: PMC3429030 DOI: 10.3389/fphys.2012.00253] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2012] [Accepted: 06/19/2012] [Indexed: 12/15/2022] Open
Abstract
The generation of neural network dynamics relies on the interactions between the intrinsic and synaptic properties of their neural components. Moreover, neuromodulators allow networks to change these properties and adjust their activity to specific challenges. Endogenous continuous (“tonic”) neuromodulation can regulate and sometimes be indispensible for networks to produce basal activity. This seems to be the case for the inspiratory rhythm generator located in the pre-Bötzinger complex (preBötC). This neural network is necessary and sufficient for generating inspiratory rhythms. The preBötC produces normal respiratory activity (eupnea) as well as sighs under normoxic conditions, and it generates gasping under hypoxic conditions after a reconfiguration process. The reconfiguration leading to gasping generation involves changes of synaptic and intrinsic properties that can be mediated by several neuromodulators. Over the past years, it has been shown that endogenous continuous neuromodulation of the preBötC may involve the continuous action of amines and peptides on extrasynaptic receptors. I will summarize the findings supporting the role of endogenous continuous neuromodulation in the generation and regulation of different inspiratory rhythms, exploring the possibility that these neuromodulatory actions involve extrasynaptic receptors along with evidence of glial modulation of preBötC activity.
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Affiliation(s)
- Fernando Peña-Ortega
- Departamento de Neurobiología del Desarrollo y Neurofisiología, Instituto de Neurobiología, UNAM-Campus Juriquilla Querétaro, Mexico
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Auditory steady state responses in a schizophrenia rat model probed by excitatory/inhibitory receptor manipulation. Int J Psychophysiol 2012; 86:136-42. [PMID: 22504207 DOI: 10.1016/j.ijpsycho.2012.04.002] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2011] [Revised: 03/23/2012] [Accepted: 04/05/2012] [Indexed: 11/21/2022]
Abstract
Alterations in neural synchrony and oscillations may contribute to the pathophysiology of schizophrenia and reflect aberrations in cortical glutamatergic and GABAergic neurotransmission. We tested the effects of a GABA agonist and an NMDA antagonist on auditory steady state responses (ASSRs) in awake rats with neonatal ventral hippocampal lesions (NVHLs) as a neurodevelopmental model of schizophrenia. NVHL vs. SHAM lesioned rats were injected with saline then either ketamine (NMDA antagonist) or muscimol (GABA(A) agonist). Time-frequency analyses examined alterations in phase locking (consistency) across trials and changes in total power (magnitude). ASSRs were compared at five stimulation frequencies (10, 20, 30, 40, and 50 Hz). In SHAM rats, phase locking and power generally increased with stimulation frequency. Both ketamine and muscimol also increased phase locking and power in SHAM rats, but mostly in the 20 to 40 Hz range. NVHL and ketamine altered the frequency dependence of phase locking, while only ketamine changed power frequency dependence. Muscimol affected power, but not phase locking, in the NVHL rats. NVHL and ketamine models of schizophrenia produce similar independent effects on ASSR, potentially representing similar forms of cortical network/glutamatergic dysfunction, albeit the effects of ketamine were more robust. Muscimol produced NVHL-dependent reductions in ASSR measures, suggesting that cortical networks in this model are intolerant to post-synaptic GABAergic stimulation. These findings suggest the utility of combining lesion, pharmacological, and ASSR approaches in understanding neural mechanisms underlying disturbed synchrony in schizophrenia.
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Moreno JL, Holloway T, Albizu L, Sealfon SC, González-Maeso J. Metabotropic glutamate mGlu2 receptor is necessary for the pharmacological and behavioral effects induced by hallucinogenic 5-HT2A receptor agonists. Neurosci Lett 2011; 493:76-9. [PMID: 21276828 DOI: 10.1016/j.neulet.2011.01.046] [Citation(s) in RCA: 167] [Impact Index Per Article: 12.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2010] [Revised: 01/11/2011] [Accepted: 01/20/2011] [Indexed: 01/18/2023]
Abstract
Hallucinogenic drugs, including mescaline, psilocybin and lysergic acid diethylamide (LSD), act at serotonin 5-HT2A receptors (5-HT2ARs). Metabotropic glutamate receptor 2/3 (mGluR2/3) ligands show efficacy in modulating the responses induced by activation of 5-HT2ARs. The formation of a 5-HT2AR-mGluR2 complex suggests a functional interaction that affects the hallucinogen-regulated cellular signaling pathways. Here, we tested the cellular and behavioral effects of hallucinogenic 5-HT2AR agonists in mGluR2 knockout (mGluR2-KO) mice. Mice were intraperitoneally injected with the hallucinogens DOI (2 mg/kg) and LSD (0.24 mg/kg), or vehicle. Head-twitch behavioral response, expression of c-fos, which is induced by all 5-HT2AR agonists, and expression of egr-2, which is hallucinogen-specific, were determined in wild type and mGluR2-KO mice. [(3)H]Ketanserin binding displacement curves by DOI were performed in mouse frontal cortex membrane preparations. Head twitch behavior was abolished in mGluR2-KO mice. The high-affinity binding site of DOI was undetected in mGluR2-KO mice. The hallucinogen DOI induced c-fos in both wild type and mGluR2-KO mice. However, the induction of egr-2 by DOI was eliminated in mGlu2-KO mice. These findings suggest that the 5-HT2AR-mGluR2 complex is necessary for the neuropsychological responses induced by hallucinogens.
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Affiliation(s)
- José L Moreno
- Department of Psychiatry, Mount Sinai School of Medicine, 1425 Madison Avenue, Box 1229, New York, NY 10029, United States
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Corlett PR, Honey GD, Krystal JH, Fletcher PC. Glutamatergic model psychoses: prediction error, learning, and inference. Neuropsychopharmacology 2011; 36:294-315. [PMID: 20861831 PMCID: PMC3055519 DOI: 10.1038/npp.2010.163] [Citation(s) in RCA: 156] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/18/2010] [Revised: 08/16/2010] [Accepted: 08/18/2010] [Indexed: 01/01/2023]
Abstract
Modulating glutamatergic neurotransmission induces alterations in conscious experience that mimic the symptoms of early psychotic illness. We review studies that use intravenous administration of ketamine, focusing on interindividual variability in the profundity of the ketamine experience. We will consider this individual variability within a hypothetical model of brain and cognitive function centered upon learning and inference. Within this model, the brains, neural systems, and even single neurons specify expectations about their inputs and responding to violations of those expectations with new learning that renders future inputs more predictable. We argue that ketamine temporarily deranges this ability by perturbing both the ways in which prior expectations are specified and the ways in which expectancy violations are signaled. We suggest that the former effect is predominantly mediated by NMDA blockade and the latter by augmented and inappropriate feedforward glutamatergic signaling. We suggest that the observed interindividual variability emerges from individual differences in neural circuits that normally underpin the learning and inference processes described. The exact source for that variability is uncertain, although it is likely to arise not only from genetic variation but also from subjects' previous experiences and prior learning. Furthermore, we argue that chronic, unlike acute, NMDA blockade alters the specification of expectancies more profoundly and permanently. Scrutinizing individual differences in the effects of acute and chronic ketamine administration in the context of the Bayesian brain model may generate new insights about the symptoms of psychosis; their underlying cognitive processes and neurocircuitry.
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Affiliation(s)
- Philip R Corlett
- Department of Psychiatry, Yale University School of Medicine, New Haven, CT 06519, USA.
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Baggott MJ, Siegrist JD, Galloway GP, Robertson LC, Coyle JR, Mendelson JE. Investigating the mechanisms of hallucinogen-induced visions using 3,4-methylenedioxyamphetamine (MDA): a randomized controlled trial in humans. PLoS One 2010; 5:e14074. [PMID: 21152030 PMCID: PMC2996283 DOI: 10.1371/journal.pone.0014074] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2010] [Accepted: 10/20/2010] [Indexed: 11/19/2022] Open
Abstract
BACKGROUND The mechanisms of drug-induced visions are poorly understood. Very few serotonergic hallucinogens have been studied in humans in decades, despite widespread use of these drugs and potential relevance of their mechanisms to hallucinations occurring in psychiatric and neurological disorders. METHODOLOGY/PRINCIPAL FINDINGS We investigated the mechanisms of hallucinogen-induced visions by measuring the visual and perceptual effects of the hallucinogenic serotonin 5-HT2AR receptor agonist and monoamine releaser, 3,4-methylenedioxyamphetamine (MDA), in a double-blind placebo-controlled study. We found that MDA increased self-report measures of mystical-type experience and other hallucinogen-like effects, including reported visual alterations. MDA produced a significant increase in closed-eye visions (CEVs), with considerable individual variation. Magnitude of CEVs after MDA was associated with lower performance on measures of contour integration and object recognition. CONCLUSIONS/SIGNIFICANCE Drug-induced visions may have greater intensity in people with poor sensory or perceptual processing, suggesting common mechanisms with other hallucinatory syndromes. MDA is a potential tool to investigate mystical experiences and visual perception. TRIAL REGISTRATION Clinicaltrials.gov NCT00823407.
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Affiliation(s)
- Matthew J Baggott
- Addiction and Pharmacology Research Laboratory, California Pacific Medical Center Research Institute, St Luke's Hospital, San Francisco, California, United States of America.
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Vollenweider FX, Kometer M. The neurobiology of psychedelic drugs: implications for the treatment of mood disorders. Nat Rev Neurosci 2010; 11:642-51. [DOI: 10.1038/nrn2884] [Citation(s) in RCA: 398] [Impact Index Per Article: 28.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
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Metabotropic glutamate2/3 (mGlu2/3) receptors, schizophrenia and cognition. Eur J Pharmacol 2010; 639:81-90. [PMID: 20371229 DOI: 10.1016/j.ejphar.2010.02.058] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2009] [Revised: 01/19/2010] [Accepted: 02/04/2010] [Indexed: 10/19/2022]
Abstract
Recently, a metabotropic glutamate(2/3) (mGlu(2/3)) receptor agonist prodrug was found to improve both the positive and negative symptoms of schizophrenic patients. Thus far, however, definitive data directly describing the effects of mGlu(2/3) receptor agonists on cognition in schizophrenic patients is lacking. In this review, we will first describe the location of mGlu(2) and mGlu(3) receptors with respect to cellular compartments in cortical circuits of both the prefrontal cortex and the hippocampal formation. We will then address the function of mGlu(2) and mGlu(3) receptors in both macrocircuits and microcircuits involving the prefrontal cortex and hippocampal formation. Imbalance within and between macrocircuits, including the re-entrant cortico-striatal-thalamic loops; the trisynaptic organization of the hippocampal formation; and the ascending reticular activating system/monoaminergic brainstem nuclei projecting throughout the neural axis, appear central to understanding both the pathophysiology and therapeutic approaches for treating the pervasive cognitive dysfunction associated with schizophrenia. Understanding the function of mGlu(2) and mGlu(3) receptors in these macrocircuits also may provide answers to currently conflicting data between some preclinical studies and the clinical studies seemingly predicting impairment and improvement in cognitive function with activation of mGlu(2) and mGlu(3) receptors.
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Haider B, McCormick DA. Rapid neocortical dynamics: cellular and network mechanisms. Neuron 2009; 62:171-89. [PMID: 19409263 PMCID: PMC3132648 DOI: 10.1016/j.neuron.2009.04.008] [Citation(s) in RCA: 321] [Impact Index Per Article: 21.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2008] [Revised: 04/12/2009] [Accepted: 04/13/2009] [Indexed: 01/07/2023]
Abstract
The highly interconnected local and large-scale networks of the neocortical sheet rapidly and dynamically modulate their functional connectivity according to behavioral demands. This basic operating principle of the neocortex is mediated by the continuously changing flow of excitatory and inhibitory synaptic barrages that not only control participation of neurons in networks but also define the networks themselves. The rapid control of neuronal responsiveness via synaptic bombardment is a fundamental property of cortical dynamics that may provide the basis of diverse behaviors, including sensory perception, motor integration, working memory, and attention.
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Affiliation(s)
- Bilal Haider
- Department of Neurobiology, Kavli Institute for Neuroscience, Yale University School of Medicine, 333 Cedar Street, New Haven, CT 06510, USA
| | - David A. McCormick
- Department of Neurobiology, Kavli Institute for Neuroscience, Yale University School of Medicine, 333 Cedar Street, New Haven, CT 06510, USA
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