1
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Lepow L, Morishita H, Yehuda R. Critical Period Plasticity as a Framework for Psychedelic-Assisted Psychotherapy. FOCUS (AMERICAN PSYCHIATRIC PUBLISHING) 2023; 21:329-336. [PMID: 37404962 PMCID: PMC10316207 DOI: 10.1176/appi.focus.23021012] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/06/2023]
Abstract
As psychedelic compounds gain traction in psychiatry, there is a need to consider the active mechanism to explain the effect observed in randomized clinical trials. Traditionally, biological psychiatry has asked how compounds affect the causal pathways of illness to reduce symptoms and therefore focus on analysis of the pharmacologic properties. In psychedelic-assisted psychotherapy (PAP), there is debate about whether ingestion of the psychedelic alone is thought to be responsible for the clinical outcome. A question arises how the medication and psychotherapeutic intervention together might lead to neurobiological changes that underlie recovery from illness such as post-traumatic stress disorder (PTSD). This paper offers a framework for investigating the neurobiological basis of PAP by extrapolating from models used to explain how a pharmacologic intervention might create an optimal brain state during which environmental input has enduring effects. Specifically, there are developmental "critical" periods (CP) with exquisite sensitivity to environmental input; the biological characteristics are largely unknown. We discuss a hypothesis that psychedelics may remove the brakes on adult neuroplasticity, inducing a state similar to that of neurodevelopment. In the visual system, progress has been made both in identifying the biological conditions which distinguishes the CP and in manipulating the active ingredients with the idea that we might pharmacologically reopen a critical period in adulthood. We highlight ocular dominance plasticity (ODP) in the visual system as a model for characterizing CP in limbic systems relevant to psychiatry. A CP framework may help to integrate the neuroscientific inquiry with the influence of the environment both in development and in PAP. Appeared originally in Front Neurosci 2021; 15:710004.
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Affiliation(s)
- Lauren Lepow
- Department of Psychiatry, Icahn School of Medicine Mount Sinai, New York, NY, United States (all authors). Department of Neuroscience, Icahn School of Medicine Mount Sinai, New York, NY, United States (Lepow, Morishita). Department of Ophthalmology, Icahn School of Medicine Mount Sinai, New York, NY, United States (Morishita). Department of Psychiatry, James J. Peters Veterans Affairs Medical Center, Bronx, NY, United States (Yehuda)
| | - Hirofumi Morishita
- Department of Psychiatry, Icahn School of Medicine Mount Sinai, New York, NY, United States (all authors). Department of Neuroscience, Icahn School of Medicine Mount Sinai, New York, NY, United States (Lepow, Morishita). Department of Ophthalmology, Icahn School of Medicine Mount Sinai, New York, NY, United States (Morishita). Department of Psychiatry, James J. Peters Veterans Affairs Medical Center, Bronx, NY, United States (Yehuda)
| | - Rachel Yehuda
- Department of Psychiatry, Icahn School of Medicine Mount Sinai, New York, NY, United States (all authors). Department of Neuroscience, Icahn School of Medicine Mount Sinai, New York, NY, United States (Lepow, Morishita). Department of Ophthalmology, Icahn School of Medicine Mount Sinai, New York, NY, United States (Morishita). Department of Psychiatry, James J. Peters Veterans Affairs Medical Center, Bronx, NY, United States (Yehuda)
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2
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O'Hagan ET, Wallwork SB, Callander E, Stanton TR, Mychasiuk R. The Foundations for Chronic Low Back Pain Management may Start in Early Life. Exploring the Role of Caregiver Parental Leave on Future Low Back Pain in the Offspring. THE JOURNAL OF PAIN 2023; 24:939-945. [PMID: 36646402 DOI: 10.1016/j.jpain.2023.01.008] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/14/2022] [Revised: 01/02/2023] [Accepted: 01/07/2023] [Indexed: 01/15/2023]
Abstract
Chronic low back pain is difficult to treat and despite increased spending on health services, clinical outcomes for people with low back pain have not improved. Innovative, large scale initiatives seem necessary to stem the cost of low back pain. Psychological health contributes to the development and persistence of chronic low back pain and psychological interventions are important in the management of low back pain. Given the contribution of psychological health to low back pain development and management, it raises the question; can we support psychological health in later life by bolstering emotional development in early life, and reduce the burden of this common condition? Positive early life experiences, including those induced by extended paid parental leave, could bolster emotional development and support the psychological health necessary to manage low back pain in later life. We present the current state of evidence demonstrating the potential value of increasing support for parent-child relationships in early life to reduce the burden of low back pain in future generations. The current evidence is limited to cross-sectional associations, but strong preclinical data clearly shows the potential negative impacts of maternal separation on rodent pup health that compels consideration in human populations. PERSPECTIVE: The benefits stemming from enhanced child development include stable emotional foundations, possibly improving psychological health and low back pain management in the future. This perspective raises questions for future studies - within the context of low back pain, what ingredients bolster stable psychological health? And are these ingredients influenced by parental leave?
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Affiliation(s)
- Edel T O'Hagan
- Westmead Applied Research Centre, Faculty of Medicine and Health, The University of Sydney, Sydney, NSW, Australia.
| | - Sarah B Wallwork
- IIMPACT in Health, Allied Health and Human Performance, University of South Australia, Sydney, NSW, Australia
| | - Emily Callander
- Monash Centre for Health Research and Implementation (MCHRI), School of Public Health and Preventative Medicine, Faculty of Medicine, Nursing and Health Sciences, Monash University, Clayton, VIC, Australia
| | - Tasha R Stanton
- IIMPACT in Health, Allied Health and Human Performance, University of South Australia, Sydney, NSW, Australia
| | - Richelle Mychasiuk
- Department of Neuroscience, Central Clinical School, Monash University, Clayton, VIC, Australia
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3
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All-or-none disconnection of pyramidal inputs onto parvalbumin-positive interneurons gates ocular dominance plasticity. Proc Natl Acad Sci U S A 2021; 118:2105388118. [PMID: 34508001 DOI: 10.1073/pnas.2105388118] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 08/07/2021] [Indexed: 12/16/2022] Open
Abstract
Disinhibition is an obligatory initial step in the remodeling of cortical circuits by sensory experience. Our investigation on disinhibitory mechanisms in the classical model of ocular dominance plasticity uncovered an unexpected form of experience-dependent circuit plasticity. In the layer 2/3 of mouse visual cortex, monocular deprivation triggers a complete, "all-or-none," elimination of connections from pyramidal cells onto nearby parvalbumin-positive interneurons (Pyr→PV). This binary form of circuit plasticity is unique, as it is transient, local, and discrete. It lasts only 1 d, and it does not manifest as widespread changes in synaptic strength; rather, only about half of local connections are lost, and the remaining ones are not affected in strength. Mechanistically, the deprivation-induced loss of Pyr→PV is contingent on a reduction of the protein neuropentraxin2. Functionally, the loss of Pyr→PV is absolutely necessary for ocular dominance plasticity, a canonical model of deprivation-induced model of cortical remodeling. We surmise, therefore, that this all-or-none loss of local Pyr→PV circuitry gates experience-dependent cortical plasticity.
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4
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Matsuda YT, Miyamoto H, Joho RH, Hensch TK. K v3.1 channels regulate the rate of critical period plasticity. Neurosci Res 2021; 167:3-10. [PMID: 33872635 DOI: 10.1016/j.neures.2021.04.003] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2021] [Revised: 04/12/2021] [Accepted: 04/13/2021] [Indexed: 11/18/2022]
Abstract
Experience-dependent plasticity within visual cortex is controlled by postnatal maturation of inhibitory circuits, which are both morphologically diverse and precisely connected. Gene-targeted disruption of the voltage-dependent potassium channel Kv3.1 broadens action potentials and reduces net inhibitory function of parvalbumin (PV)-positive GABA subtypes within the neocortex. In mice lacking Kv3.1, the rate of input loss from an eye deprived of vision was slowed two-fold, despite otherwise normal critical period timecourse and receptive field properties. Rapid ocular dominance plasticity was restored by local or systemic enhancement of GABAergic transmission with acute benzodiazepine infusion. Diazepam instead exacerbated a global suppression of slow-wave oscillations during sleep described previously in these mutant mice, which therefore did not account for the rescued plasticity. Rapid ocular dominance shifts closely reflected Kv3.1 gene dosage that prevented prolonged spike discharge of their target pyramidal cells in vivo or the spike amplitude decrement of fast-spiking cells during bouts of high-frequency firing in vitro. Late postnatal expression of this unique channel in fast-spiking interneurons thus subtly regulates the speed of critical period plasticity with implications for mental illnesses.
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Affiliation(s)
- Yoshi-Taka Matsuda
- Laboratory for Neuronal Circuit Development, RIKEN Brain Science Institute, 2-1 Hirosawa, Wako-shi, Saitama, 351-0198, Japan; Department of Child Studies, Shiraume Gakuen University, 1-830 Kodaira-shi, Tokyo, 187-8570 Japan
| | - Hiroyuki Miyamoto
- Laboratory for Neuronal Circuit Development, RIKEN Brain Science Institute, 2-1 Hirosawa, Wako-shi, Saitama, 351-0198, Japan; International Research Center for Neurointelligence, University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, 113-0033, Japan
| | - Rolf H Joho
- Center for Basic Neuroscience, Univ. Texas Southwestern Medical Center, Dallas, TX, 75390, USA
| | - Takao K Hensch
- Laboratory for Neuronal Circuit Development, RIKEN Brain Science Institute, 2-1 Hirosawa, Wako-shi, Saitama, 351-0198, Japan; International Research Center for Neurointelligence, University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, 113-0033, Japan; Center for Brain Science, Department of Molecular Cellular Biology, Harvard University, 52 Oxford Street, Cambridge, MA, 02138, USA.
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5
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Branchi I, Giuliani A. Shaping therapeutic trajectories in mental health: Instructive vs. permissive causality. Eur Neuropsychopharmacol 2021; 43:1-9. [PMID: 33384216 DOI: 10.1016/j.euroneuro.2020.12.001] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/14/2020] [Revised: 11/05/2020] [Accepted: 12/02/2020] [Indexed: 12/18/2022]
Abstract
We are currently facing the challenge of improving treatments for psychiatric disorders such as major depression. Notably, antidepressants have an incomplete efficacy, mostly due to our limited knowledge of their action. Here we present a theoretical framework that considers the distinction between instructive and permissive causality, which allows formalizing and disentangling the effects exerted by different therapeutic strategies commonly used in psychiatry. Instructive causality implies that an action determines a specific effect while permissive causality allows an action to take effect or not. We posit that therapeutic strategies able to improve the quality of the living environment or the ability to face it, including changes in lifestyle and psychotherapeutic interventions, rely mainly on instructive causality and thus shape the individual's ability to face the psychopathology and build resilience. By contrast, pharmacological treatments, such as selective serotonin reuptake inhibitors, act primarily through a permissive causality: they boost neural plasticity, i.e. the ability of the brain to change itself, and therefore allow for instructive interventions to produce beneficial effects or not. The combination of an instructive and a permissive action represents the most promising approach since the quality of the living environment can shape the path leading to mental health while drug treatment can increase the likelihood of achieving such a goal.
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Affiliation(s)
- Igor Branchi
- Center for Behavioral Sciences and Mental Health, Istituto Superiore di Sanità, Viale Regina Elena, 299, 00161 Roma, Italy.
| | - Alessandro Giuliani
- Department of Environment and Health, Istituto Superiore di Sanità, Rome, Italy
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6
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Lepow L, Morishita H, Yehuda R. Critical Period Plasticity as a Framework for Psychedelic-Assisted Psychotherapy. Front Neurosci 2021; 15:710004. [PMID: 34616272 PMCID: PMC8488335 DOI: 10.3389/fnins.2021.710004] [Citation(s) in RCA: 23] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2021] [Accepted: 08/17/2021] [Indexed: 12/28/2022] Open
Abstract
As psychedelic compounds gain traction in psychiatry, there is a need to consider the active mechanism to explain the effect observed in randomized clinical trials. Traditionally, biological psychiatry has asked how compounds affect the causal pathways of illness to reduce symptoms and therefore focus on analysis of the pharmacologic properties. In psychedelic-assisted psychotherapy (PAP), there is debate about whether ingestion of the psychedelic alone is thought to be responsible for the clinical outcome. A question arises how the medication and psychotherapeutic intervention together might lead to neurobiological changes that underlie recovery from illness such as post-traumatic stress disorder (PTSD). This paper offers a framework for investigating the neurobiological basis of PAP by extrapolating from models used to explain how a pharmacologic intervention might create an optimal brain state during which environmental input has enduring effects. Specifically, there are developmental "critical" periods (CP) with exquisite sensitivity to environmental input; the biological characteristics are largely unknown. We discuss a hypothesis that psychedelics may remove the brakes on adult neuroplasticity, inducing a state similar to that of neurodevelopment. In the visual system, progress has been made both in identifying the biological conditions which distinguishes the CP and in manipulating the active ingredients with the idea that we might pharmacologically reopen a critical period in adulthood. We highlight ocular dominance plasticity (ODP) in the visual system as a model for characterizing CP in limbic systems relevant to psychiatry. A CP framework may help to integrate the neuroscientific inquiry with the influence of the environment both in development and in PAP.
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Affiliation(s)
- Lauren Lepow
- Department of Psychiatry, Icahn School of Medicine Mount Sinai, New York, NY, United States.,Department of Neuroscience, Icahn School of Medicine Mount Sinai, New York, NY, United States
| | - Hirofumi Morishita
- Department of Psychiatry, Icahn School of Medicine Mount Sinai, New York, NY, United States.,Department of Neuroscience, Icahn School of Medicine Mount Sinai, New York, NY, United States.,Department of Ophthalmology, Icahn School of Medicine Mount Sinai, New York, NY, United States
| | - Rachel Yehuda
- Department of Psychiatry, Icahn School of Medicine Mount Sinai, New York, NY, United States.,Department of Psychiatry, James J. Peters Veterans Affairs Medical Center, Bronx, NY, United States
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7
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Brief localised monocular deprivation in adults alters binocular rivalry predominance retinotopically and reduces spatial inhibition. Sci Rep 2020; 10:18739. [PMID: 33127963 PMCID: PMC7603489 DOI: 10.1038/s41598-020-75252-w] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2020] [Accepted: 10/07/2020] [Indexed: 11/29/2022] Open
Abstract
Short-term deprivation (2.5 h) of an eye has been shown to boost its relative ocular dominance in young adults. Here, we show that a much shorter deprivation period (3–6 min) produces a similar paradoxical boost that is retinotopic and reduces spatial inhibition on neighbouring, non-deprived areas. Partial deprivation was conducted in the left hemifield, central vision or in an annular region, later assessed with a binocular rivalry tracking procedure. Post-deprivation, dominance of the deprived eye increased when rivalling images were within the deprived retinotopic region, but not within neighbouring, non-deprived areas where dominance was dependent on the correspondence between the orientation content of the stimuli presented in the deprived and that of the stimuli presented in non-deprived areas. Together, these results accord with other deprivation studies showing V1 activity changes and reduced GABAergic inhibition.
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8
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Severin D, Gallagher M, Kirkwood A. Afterhyperpolarization amplitude in CA1 pyramidal cells of aged Long-Evans rats characterized for individual differences. Neurobiol Aging 2020; 96:43-48. [PMID: 32932137 DOI: 10.1016/j.neurobiolaging.2020.07.022] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2020] [Revised: 07/06/2020] [Accepted: 07/25/2020] [Indexed: 11/18/2022]
Abstract
Altered neural excitability is considered a prominent contributing factor to cognitive decline during aging. A clear example is the excess neural activity observed in several temporal lobe structures of cognitively impaired older individuals in rodents and humans. At a cellular level, aging-related changes in mechanisms regulating intrinsic excitability have been well examined in pyramidal cells of the CA1 hippocampal subfield. Studies in the inbred Fisher 344 rat strain document an age-related increase in the slow afterhyperpolarization (AHP) that normally occurs after a burst of action potentials, and serves to reduce subsequent firing. We evaluated the status of the AHP in the outbred Long-Evans rat, a well-established model for studying individual differences in neurocognitive aging. In contrast to the findings reported in the Fisher 344 rats, in the Long-Evan rats we detected a selective reduction in AHP in cognitively impaired aged individuals. We discuss plausible scenarios to account for these differences and also discuss possible implications of these differences.
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Affiliation(s)
- Daniel Severin
- Department of Neurosciences, Mind/Brain Institute, Johns Hopkins University, Baltimore, MD, USA
| | - Michela Gallagher
- Department of Psychological and Brain Sciences, Johns Hopkins University, Baltimore, MD, USA
| | - Alfredo Kirkwood
- Department of Neurosciences, Mind/Brain Institute, Johns Hopkins University, Baltimore, MD, USA.
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9
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Hoseini MS, Rakela B, Flores-Ramirez Q, Hasenstaub AR, Alvarez-Buylla A, Stryker MP. Transplanted Cells Are Essential for the Induction But Not the Expression of Cortical Plasticity. J Neurosci 2019; 39:7529-7538. [PMID: 31391263 PMCID: PMC6750933 DOI: 10.1523/jneurosci.1430-19.2019] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2019] [Revised: 07/25/2019] [Accepted: 08/01/2019] [Indexed: 01/31/2023] Open
Abstract
Transplantation of even a small number of embryonic inhibitory neurons from the medial ganglionic eminence (MGE) into postnatal visual cortex makes it lose responsiveness to an eye deprived of vision when the transplanted neurons reach the age of the normal critical period of activity-dependent ocular dominance (OD) plasticity. The transplant might induce OD plasticity in the host circuitry or might instead construct a parallel circuit of its own to suppress cortical responses to the deprived eye. We transplanted MGE neurons expressing either archaerhodopsin or channelrhodopsin into the visual cortex of both male and female mice, closed one eyelid for 4-5 d, and, as expected, observed transplant-induced OD plasticity. This plasticity was evident even when the activity of the transplanted cells was suppressed or enhanced optogenetically, demonstrating that the plasticity was produced by changes in the host visual cortex.SIGNIFICANCE STATEMENT Interneuron transplantation into mouse V1 creates a window of heightened plasticity that is quantitatively and qualitatively similar to the normal critical period; that is, short-term occlusion of either eye markedly changes ocular dominance (OD). The underlying mechanism of this process is not known. Transplanted interneurons might either form a separate circuit to maintain the OD shift or might instead trigger changes in the host circuity. We designed experiments to distinguish the two hypotheses. Our findings suggest that while inhibition produced by the transplanted cells triggers this form of plasticity, the host circuity is entirely responsible for maintaining the OD shift.
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Affiliation(s)
- Mahmood S Hoseini
- Center for Integrative Neuroscience, University of California, San Francisco, California 94158,
- Department of Physiology, University of California, San Francisco, California 94143
| | - Benjamin Rakela
- Center for Integrative Neuroscience, University of California, San Francisco, California 94158
- Department of Physiology, University of California, San Francisco, California 94143
| | - Quetzal Flores-Ramirez
- Department of Neurological Surgery, University of California, San Francisco, California 94143
| | - Andrea R Hasenstaub
- Center for Integrative Neuroscience, University of California, San Francisco, California 94158
- Coleman Memorial Laboratory, University of California, San Francisco, California 94158
- Department of Otolaryngology-Head and Neck Surgery, University of California, San Francisco, California 94143, and
| | - Arturo Alvarez-Buylla
- Department of Neurological Surgery, University of California, San Francisco, California 94143
- The Eli and Edythe Broad Center of Regeneration Medicine and Stem Cell Research, University of California, San Francisco, California 94143
| | - Michael P Stryker
- Center for Integrative Neuroscience, University of California, San Francisco, California 94158,
- Department of Physiology, University of California, San Francisco, California 94143
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10
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A Hypothetical Model Concerning How Spike-Timing-Dependent Plasticity Contributes to Neural Circuit Formation and Initiation of the Critical Period in Barrel Cortex. J Neurosci 2019; 39:3784-3791. [PMID: 30877173 DOI: 10.1523/jneurosci.1684-18.2019] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2018] [Revised: 03/02/2019] [Accepted: 03/04/2019] [Indexed: 01/15/2023] Open
Abstract
Spike timing is an important factor in the modification of synaptic strength. Various forms of spike timing-dependent plasticity (STDP) occur in the brains of diverse species, from insects to humans. In unimodal STDP, only LTP or LTD occurs at the synapse, regardless of which neuron spikes first; the magnitude of potentiation or depression increases as the time between presynaptic and postsynaptic spikes decreases. This from of STDP may promote developmental strengthening or weakening of early projections. In bidirectional Hebbian STDP, the magnitude and the sign (potentiation or depression) of plasticity depend, respectively, on the timing and the order of presynaptic and postsynaptic spikes. In the rodent barrel cortex, multiple forms of STDP appear sequentially during development, and they contribute to network formation, retraction, or fine-scale functional reorganization. Hebbian STDP appears at L4-L2/3 synapses starting at postnatal day (P) 15; the synapses exhibit unimodal "all-LTP STDP" before that age. The appearance of Hebbian STDP at L4-L2/3 synapses coincides with the maturation of parvalbumin-containing GABA interneurons in L4, which contributes to the generation of L4-before-L2/3 spiking in response to thalamic input by producing fast feedforward suppression of both L4 and L2/3 cells. After P15, L4-L2/3 STDP mediates fine-scale circuit refinement, essential for the critical period in the barrel cortex. In this review, we first briefly describe the relevance of STDP to map plasticity in the barrel cortex, then look over roles of distinct forms of STDP during development. Finally, we propose a hypothesis that explains the transition from network formation to the initiation of the critical period in the barrel cortex.
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11
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Scheyltjens I, Vreysen S, Van den Haute C, Sabanov V, Balschun D, Baekelandt V, Arckens L. Transient and localized optogenetic activation of somatostatin-interneurons in mouse visual cortex abolishes long-term cortical plasticity due to vision loss. Brain Struct Funct 2018; 223:2073-2095. [PMID: 29372324 PMCID: PMC5968055 DOI: 10.1007/s00429-018-1611-7] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2017] [Accepted: 01/14/2018] [Indexed: 04/13/2023]
Abstract
Unilateral vision loss through monocular enucleation (ME) results in partial reallocation of visual cortical territory to another sense in adult mice. The functional recovery of the visual cortex occurs through a combination of spared-eye potentiation and cross-modal reactivation driven by whisker-related, somatosensory inputs. Brain region-specific intracortical inhibition was recently recognized as a crucial regulator of the cross-modal component, yet the contribution of specific inhibitory neuron subpopulations remains poorly understood. Somatostatin (SST)-interneurons are ideally located within the cortical circuit to modulate sensory integration. Here we demonstrate that optogenetic stimulation of visual cortex SST-interneurons prior to eye removal decreases ME-induced cross-modal recovery at the stimulation site. Our results suggest that SST-interneurons act as local hubs, which are able to control the influx and extent of cortical cross-modal inputs into the deprived cortex. These insights critically expand our understanding of SST-interneuron-specific regulation of cortical plasticity induced by sensory loss.
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Affiliation(s)
- Isabelle Scheyltjens
- Laboratory of Neuroplasticity and Neuroproteomics, KU Leuven, Naamsestraat 59, Box 2467, 3000, Leuven, Belgium.
| | - Samme Vreysen
- Laboratory of Neuroplasticity and Neuroproteomics, KU Leuven, Naamsestraat 59, Box 2467, 3000, Leuven, Belgium
| | - Chris Van den Haute
- Laboratory for Neurobiology and Gene Therapy, KU Leuven, 3000, Leuven, Belgium.,Leuven Viral Vector Core, KU Leuven, 3000, Leuven, Belgium
| | - Victor Sabanov
- Laboratory of Biological Psychology, KU Leuven, 3000, Leuven, Belgium
| | - Detlef Balschun
- Laboratory of Biological Psychology, KU Leuven, 3000, Leuven, Belgium
| | - Veerle Baekelandt
- Laboratory for Neurobiology and Gene Therapy, KU Leuven, 3000, Leuven, Belgium
| | - Lutgarde Arckens
- Laboratory of Neuroplasticity and Neuroproteomics, KU Leuven, Naamsestraat 59, Box 2467, 3000, Leuven, Belgium
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12
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Noble DJ, Martin K, Qin L, Britto P, O'sullivan M, Popkins J, Pouwels R, Scherpbier RW, Flowers R. What could cognitive capital mean for China's children? Psych J 2017; 6:153-160. [DOI: 10.1002/pchj.170] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2017] [Revised: 03/31/2017] [Accepted: 04/02/2017] [Indexed: 11/09/2022]
Affiliation(s)
| | | | - Lisa Qin
- United Nations Children's Fund (UNICEF); Beijing China
| | - Pia Britto
- United Nations Children's Fund (UNICEF); New York New York USA
| | | | | | - Ron Pouwels
- United Nations Children's Fund (UNICEF); Beijing China
| | | | - Rana Flowers
- United Nations Children's Fund (UNICEF); Beijing China
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13
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Scheyltjens I, Arckens L. The Current Status of Somatostatin-Interneurons in Inhibitory Control of Brain Function and Plasticity. Neural Plast 2016; 2016:8723623. [PMID: 27403348 PMCID: PMC4923604 DOI: 10.1155/2016/8723623] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2016] [Accepted: 05/12/2016] [Indexed: 12/05/2022] Open
Abstract
The mammalian neocortex contains many distinct inhibitory neuronal populations to balance excitatory neurotransmission. A correct excitation/inhibition equilibrium is crucial for normal brain development, functioning, and controlling lifelong cortical plasticity. Knowledge about how the inhibitory network contributes to brain plasticity however remains incomplete. Somatostatin- (SST-) interneurons constitute a large neocortical subpopulation of interneurons, next to parvalbumin- (PV-) and vasoactive intestinal peptide- (VIP-) interneurons. Unlike the extensively studied PV-interneurons, acknowledged as key components in guiding ocular dominance plasticity, the contribution of SST-interneurons is less understood. Nevertheless, SST-interneurons are ideally situated within cortical networks to integrate unimodal or cross-modal sensory information processing and therefore likely to be important mediators of experience-dependent plasticity. The lack of knowledge on SST-interneurons partially relates to the wide variety of distinct subpopulations present in the sensory neocortex. This review informs on those SST-subpopulations hitherto described based on anatomical, molecular, or electrophysiological characteristics and whose functional roles can be attributed based on specific cortical wiring patterns. A possible role for these subpopulations in experience-dependent plasticity will be discussed, emphasizing on learning-induced plasticity and on unimodal and cross-modal plasticity upon sensory loss. This knowledge will ultimately contribute to guide brain plasticity into well-defined directions to restore sensory function and promote lifelong learning.
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Affiliation(s)
- Isabelle Scheyltjens
- Laboratory of Neuroplasticity and Neuroproteomics, KU Leuven, 3000 Leuven, Belgium
| | - Lutgarde Arckens
- Laboratory of Neuroplasticity and Neuroproteomics, KU Leuven, 3000 Leuven, Belgium
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14
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Binocular input coincidence mediates critical period plasticity in the mouse primary visual cortex. J Neurosci 2014; 34:2940-55. [PMID: 24553935 DOI: 10.1523/jneurosci.2640-13.2014] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Classical studies on the development of ocular dominance (OD) organization in primary visual cortex (V1) have revealed a postnatal critical period (CP), during which visual inputs between the two eyes are most effective in shaping cortical circuits through synaptic competition. A brief closure of one eye during CP caused a pronounced shift of response preference of V1 neurons toward the open eye, a form of CP plasticity in the developing V1. However, it remains unclear what particular property of binocular inputs during CP is responsible for mediating this experience-dependent OD plasticity. Using whole-cell recording in mouse V1, we found that visually driven synaptic inputs from the two eyes to binocular cells in layers 2/3 and 4 became highly coincident during CP. Enhancing cortical GABAergic transmission activity by brain infusion with diazepam not only caused a precocious onset of the high coincidence of binocular inputs and OD plasticity in pre-CP mice, but rescued both of them in dark-reared mice, suggesting a tight link between coincident binocular inputs and CP plasticity. In Thy1-ChR2 mice, chronic disruption of this binocular input coincidence during CP by asynchronous optogenetic activation of retinal ganglion cells abolished the OD plasticity. Computational simulation using a feed-forward network model further suggests that the coincident inputs could mediate this CP plasticity through a homeostatic synaptic learning mechanism with synaptic competition. These results suggest that the high-level correlation of binocular inputs is a hallmark of the CP of developing V1 and serves as neural substrate for the induction of OD plasticity.
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do Monte-Silva KK, de Novaes Assis FL, Leal GMA, Guedes RCA. Nutrition-dependent influence of peripheral electrical stimulation during brain development on cortical spreading depression in weaned rats. Nutr Neurosci 2013; 10:187-94. [DOI: 10.1080/10284150701590316] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
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16
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Otx2 binding to perineuronal nets persistently regulates plasticity in the mature visual cortex. J Neurosci 2012; 32:9429-37. [PMID: 22764251 DOI: 10.1523/jneurosci.0394-12.2012] [Citation(s) in RCA: 270] [Impact Index Per Article: 22.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Specific transfer of (orthodenticle homeobox 2) Otx2 homeoprotein into GABAergic interneurons expressing parvalbumin (PV) is necessary and sufficient to open, then close, a critical period (CP) of plasticity in the developing mouse visual cortex. The accumulation of endogenous Otx2 in PV cells suggests the presence of specific Otx2 binding sites. Here, we find that perineuronal nets (PNNs) on the surfaces of PV cells permit the specific, constitutive capture of Otx2. We identify a 15 aa domain containing an arginine-lysine doublet (RK peptide) within Otx2, bearing prototypic traits of a glycosaminoglycan (GAG) binding sequence that mediates Otx2 binding to PNNs, and specifically to chondroitin sulfate D and E, with high affinity. Accordingly, PNN hydrolysis by chondroitinase ABC reduces the amount of endogenous Otx2 in PV cells. Direct infusion of RK peptide similarly disrupts endogenous Otx2 localization to PV cells, reduces PV and PNN expression, and reopens plasticity in adult mice. The closure of one eye during this transient window reduces cortical acuity and is specific to the RK motif, as an Alanine-Alanine variant or a scrambled peptide fails to reactivate plasticity. Conversely, this transient reopening of plasticity in the adult restores binocular vision in amblyopic mice. Thus, one function of PNNs is to facilitate the persistent internalization of Otx2 by PV cells to maintain CP closure. The pharmacological use of the Otx2 GAG binding domain offers a novel, potent therapeutic tool with which to restore cortical plasticity in the mature brain.
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Kunz PA, Burette AC, Weinberg RJ, Philpot BD. Glycine receptors support excitatory neurotransmitter release in developing mouse visual cortex. J Physiol 2012; 590:5749-64. [PMID: 22988142 DOI: 10.1113/jphysiol.2012.241299] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
Glycine receptors (GlyRs) are found in most areas of the brain, and their dysfunction can cause severe neurological disorders. While traditionally thought of as inhibitory receptors, presynaptic-acting GlyRs (preGlyRs) can also facilitate glutamate release under certain circumstances, although the underlying molecular mechanisms are unknown. In the current study, we sought to better understand the role of GlyRs in the facilitation of excitatory neurotransmitter release in mouse visual cortex. Using whole-cell recordings, we found that preGlyRs facilitate glutamate release in developing, but not adult, visual cortex. The glycinergic enhancement of neurotransmitter release in early development depends on the high intracellular to extracellular Cl(-) gradient maintained by the Na(+)-K(+)-2Cl(-) cotransporter and requires Ca(2+) entry through voltage-gated Ca(2+) channels. The glycine transporter 1, localized to glial cells, regulates extracellular glycine concentration and the activation of these preGlyRs. Our findings demonstrate a developmentally regulated mechanism for controlling excitatory neurotransmitter release in the neocortex.
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Affiliation(s)
- Portia A Kunz
- Department of Cell Biology and Physiology, University of North Carolina School of Medicine, Campus Box 7545, 115 Mason Farm Rd, Chapel Hill, NC 27599-7545, USA
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18
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Michels L, Lüchinger R, Koenig T, Martin E, Brandeis D. Developmental changes of BOLD signal correlations with global human EEG power and synchronization during working memory. PLoS One 2012; 7:e39447. [PMID: 22792176 PMCID: PMC3391196 DOI: 10.1371/journal.pone.0039447] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2011] [Accepted: 05/21/2012] [Indexed: 12/26/2022] Open
Abstract
In humans, theta band (5–7 Hz) power typically increases when performing cognitively demanding working memory (WM) tasks, and simultaneous EEG-fMRI recordings have revealed an inverse relationship between theta power and the BOLD (blood oxygen level dependent) signal in the default mode network during WM. However, synchronization also plays a fundamental role in cognitive processing, and the level of theta and higher frequency band synchronization is modulated during WM. Yet, little is known about the link between BOLD, EEG power, and EEG synchronization during WM, and how these measures develop with human brain maturation or relate to behavioral changes. We examined EEG-BOLD signal correlations from 18 young adults and 15 school-aged children for age-dependent effects during a load-modulated Sternberg WM task. Frontal load (in-)dependent EEG theta power was significantly enhanced in children compared to adults, while adults showed stronger fMRI load effects. Children demonstrated a stronger negative correlation between global theta power and the BOLD signal in the default mode network relative to adults. Therefore, we conclude that theta power mediates the suppression of a task-irrelevant network. We further conclude that children suppress this network even more than adults, probably from an increased level of task-preparedness to compensate for not fully mature cognitive functions, reflected in lower response accuracy and increased reaction time. In contrast to power, correlations between instantaneous theta global field synchronization and the BOLD signal were exclusively positive in both age groups but only significant in adults in the frontal-parietal and posterior cingulate cortices. Furthermore, theta synchronization was weaker in children and was –in contrast to EEG power– positively correlated with response accuracy in both age groups. In summary we conclude that theta EEG-BOLD signal correlations differ between spectral power and synchronization and that these opposite correlations with different distributions undergo similar and significant neuronal developments with brain maturation.
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Affiliation(s)
- Lars Michels
- Center for MR-Research, University Children's Hospital, Zurich, Switzerland.
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19
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Imbrosci B, Mittmann T. Functional consequences of the disturbances in the GABA-mediated inhibition induced by injuries in the cerebral cortex. Neural Plast 2011; 2011:614329. [PMID: 21766043 PMCID: PMC3135051 DOI: 10.1155/2011/614329] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2011] [Accepted: 04/05/2011] [Indexed: 11/18/2022] Open
Abstract
Cortical injuries are often reported to induce a suppression of the intracortical GABAergic inhibition in the surviving, neighbouring neuronal networks. Since GABAergic transmission provides the main source of inhibition in the mammalian brain, this condition may lead to hyperexcitability and epileptiform activity of cortical networks. However, inhibition plays also a crucial role in limiting the plastic properties of neuronal circuits, and as a consequence, interventions aiming to reestablish a normal level of inhibition might constrain the plastic capacity of the cortical tissue. A promising strategy to minimize the deleterious consequences of a modified inhibitory transmission without preventing the potential beneficial effects on cortical plasticity may be to unravel distinct GABAergic signaling pathways separately mediating these positive and negative events. Here, gathering data from several recent studies, we provide new insights to better face with this "double coin" condition in the attempt to optimize the functional recovery of patients.
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Affiliation(s)
- Barbara Imbrosci
- Institute of Physiology and Pathophysiology, Medical Center of the Johannes Gutenberg University, Duesbergweg 6, 55128 Mainz, Germany.
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20
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Zhang Z, Sun QQ. The balance between excitation and inhibition and functional sensory processing in the somatosensory cortex. INTERNATIONAL REVIEW OF NEUROBIOLOGY 2011; 97:305-33. [PMID: 21708316 DOI: 10.1016/b978-0-12-385198-7.00012-6] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
The balance between excitation and inhibition (E/I balance) is tightly regulated in adult cortices to maintain proper nervous system function. Disturbed E/I balance is associated with numerous neuropsychological disorders, such as autism, epilepsy and schizophrenia. The present review will discuss aspects of Hebbian and homeostatic mechanisms regulating excitatory and inhibitory balance related to sensory processing in somatosensory cortex of rodents. Additionally, changes in the E/I balance during sensory manipulation will be discussed.
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Affiliation(s)
- Zhi Zhang
- Department of Zoology and Physiology, University of Wyoming, Laramie, WY 82071, USA
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21
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Watt AJ, Desai NS. Homeostatic Plasticity and STDP: Keeping a Neuron's Cool in a Fluctuating World. Front Synaptic Neurosci 2010; 2:5. [PMID: 21423491 PMCID: PMC3059670 DOI: 10.3389/fnsyn.2010.00005] [Citation(s) in RCA: 98] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2010] [Accepted: 05/17/2010] [Indexed: 11/23/2022] Open
Abstract
Spike-timing-dependent plasticity (STDP) offers a powerful means of forming and modifying neural circuits. Experimental and theoretical studies have demonstrated its potential usefulness for functions as varied as cortical map development, sharpening of sensory receptive fields, working memory, and associative learning. Even so, it is unlikely that STDP works alone. Unless changes in synaptic strength are coordinated across multiple synapses and with other neuronal properties, it is difficult to maintain the stability and functionality of neural circuits. Moreover, there are certain features of early postnatal development (e.g., rapid changes in sensory input) that threaten neural circuit stability in ways that STDP may not be well placed to counter. These considerations have led researchers to investigate additional types of plasticity, complementary to STDP, that may serve to constrain synaptic weights and/or neuronal firing. These are collectively known as “homeostatic plasticity” and include schemes that control the total synaptic strength of a neuron, that modulate its intrinsic excitability as a function of average activity, or that make the ability of synapses to undergo Hebbian modification depend upon their history of use. In this article, we will review the experimental evidence for homeostatic forms of plasticity and consider how they might interact with STDP during development, and learning and memory.
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Affiliation(s)
- Alanna J Watt
- Wolfson Institute for Biomedical Research, University College London London, UK
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22
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Sale A, Berardi N, Spolidoro M, Baroncelli L, Maffei L. GABAergic inhibition in visual cortical plasticity. Front Cell Neurosci 2010; 4:10. [PMID: 20407586 PMCID: PMC2854574 DOI: 10.3389/fncel.2010.00010] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2010] [Accepted: 03/17/2010] [Indexed: 11/13/2022] Open
Abstract
Experience is required for the shaping and refinement of developing neural circuits during well defined periods of early postnatal development called critical periods. Many studies in the visual cortex have shown that intracortical GABAergic circuitry plays a crucial role in defining the time course of the critical period for ocular dominance plasticity. With the end of the critical period, neural plasticity wanes and recovery from the effects of visual defects on visual acuity (amblyopia) or binocularity is much reduced or absent. Recent results pointed out that intracortical inhibition is a fundamental limiting factor for adult cortical plasticity and that its reduction by means of different pharmacological and environmental strategies makes it possible to greatly enhance plasticity in the adult visual cortex, promoting ocular dominance plasticity and recovery from amblyopia. Here we focus on the role of intracortical GABAergic circuitry in controlling both developmental and adult cortical plasticity. We shall also discuss the potential clinical application of these findings to neurological disorders in which synaptic plasticity is compromised because of excessive intracortical inhibition.
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Affiliation(s)
- Alessandro Sale
- Institute of Neuroscience Consiglio Nazionale delle Ricerche Pisa, Italy
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23
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Reducing intracortical inhibition in the adult visual cortex promotes ocular dominance plasticity. J Neurosci 2010; 30:361-71. [PMID: 20053917 DOI: 10.1523/jneurosci.2233-09.2010] [Citation(s) in RCA: 243] [Impact Index Per Article: 17.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Experience-dependent plasticity in the cortex is often higher during short critical periods in postnatal development. The mechanisms limiting adult cortical plasticity are still unclear. Maturation of intracortical GABAergic inhibition is suggested to be crucial for the closure of the critical period for ocular dominance (OD) plasticity in the visual cortex. We find that reduction of GABAergic transmission in the adult rat visual cortex partially reactivates OD plasticity in response to monocular deprivation (MD). This is accompanied by an enhancement of activity-dependent potentiation of synaptic efficacy but not of activity-dependent depression. We also found a decrease in the expression of chondroitin sulfate proteoglycans in the visual cortex of MD animals with reduced inhibition, after the reactivation of OD plasticity. Thus, intracortical inhibition is a crucial limiting factor for the induction of experience-dependent plasticity in the adult visual cortex.
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Müller V, Gruber W, Klimesch W, Lindenberger U. Lifespan differences in cortical dynamics of auditory perception. Dev Sci 2009; 12:839-53. [DOI: 10.1111/j.1467-7687.2009.00834.x] [Citation(s) in RCA: 55] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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25
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Sun QQ. The missing piece in the 'use it or lose it' puzzle: is inhibition regulated by activity or does it act on its own accord? Rev Neurosci 2007; 18:295-310. [PMID: 18019611 DOI: 10.1515/revneuro.2007.18.3-4.295] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
We have gained enormous insight into the mechanisms underlying both activity-dependent and (to a lesser degree) -independent plasticity of excitatory synapses. Recently, cortical inhibition has been shown to play a vital role in the formation of critical periods for sensory plasticity. As such, sculpting of neuronal circuits by inhibition may be a common mechanism by which activity organizes or reorganizes brain circuits. Disturbances in the balance of excitation and inhibition in the neocortex provoke abnormal activities, such as epileptic seizures and abnormal cortical development. However, both the process of experience-dependent postnatal maturation of neocortical inhibitory networks and its underlying mechanisms remain elusive. Mechanisms that match excitation and inhibition are central to achieving balanced function at the level of individual circuits. The goal of this review is to reinforce our understanding of the mechanisms by which developing inhibitory networks are able to adapt to sensory inputs, and to maintain their balance with developing excitatory networks. Discussion is centered on the following questions related to experience-dependent plasticity of neocortical inhibitory networks: 1) What are the roles of GABAergic inhibition in the postnatal maturation of neocortical circuits? 2) Does the maturation of neocortical inhibitory circuits proceed in an activity-dependent manner or do they develop independently of sensory inputs? 3) Does activity regulate inhibitory networks in the same way it regulates excitatory networks? 4) What are the molecular and cellular mechanisms that underlie the activity-dependent maturation of inhibitory networks? 5) What are the functional advantages of experience-dependent plasticity of inhibitory networks to network processing in sensory cortices?
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Affiliation(s)
- Qian-Quan Sun
- Laboratory of Neural Development and Learning, Department of Zoology and Physiology and Neuroscience Program, University of Wyoming, Laramie, WY, USA.
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26
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Noreña AJ, Gourévitch B, Gourevich B, Aizawa N, Eggermont JJ. Spectrally enhanced acoustic environment disrupts frequency representation in cat auditory cortex. Nat Neurosci 2006; 9:932-9. [PMID: 16783369 DOI: 10.1038/nn1720] [Citation(s) in RCA: 116] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2006] [Accepted: 05/25/2006] [Indexed: 11/09/2022]
Abstract
Sensory environments are known to shape nervous system organization. Here we show that passive long-term exposure to a spectrally enhanced acoustic environment (EAE) causes reorganization of the tonotopic map in juvenile cat auditory cortex without inducing any hearing loss. The EAE consisted of tone pips of 32 different frequencies (5-20 kHz), presented in random order at an average rate of 96 Hz. The EAE caused a strong reduction of the representation of EAE frequencies and an over-representation of frequencies neighboring those of the EAE. This is in sharp contrast with earlier developmental studies showing an enlargement of the cortical representation of EAEs consisting of a narrow frequency band. We observed fewer than normal appropriately tuned short-latency responses to EAE frequencies, together with more common long-latency responses tuned to EAE-neighboring frequencies.
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Affiliation(s)
- Arnaud J Noreña
- Neurosciences and Sensory Systems Laboratory, UMR Centre National de la Recherche Scientifique 5020, Université Claude Bernard, Lyon, France
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Abstract
Neuronal circuits in the brain are shaped by experience during 'critical periods' in early postnatal life. In the primary visual cortex, this activity-dependent development is triggered by the functional maturation of local inhibitory connections and driven by a specific, late-developing subset of interneurons. Ultimately, the structural consolidation of competing sensory inputs is mediated by a proteolytic reorganization of the extracellular matrix that occurs only during the critical period. The reactivation of this process, and subsequent recovery of function in conditions such as amblyopia, can now be studied with realistic circuit models that might generalize across systems.
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Affiliation(s)
- Takao K Hensch
- RIKEN Brain Science Institute, 2-1 Hirosawa, Wako-shi, Saitama, 351-0198, Japan.
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28
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Jiang B, Huang ZJ, Morales B, Kirkwood A. Maturation of GABAergic transmission and the timing of plasticity in visual cortex. ACTA ACUST UNITED AC 2005; 50:126-33. [PMID: 16024085 DOI: 10.1016/j.brainresrev.2005.05.007] [Citation(s) in RCA: 83] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2004] [Revised: 04/27/2005] [Accepted: 05/05/2005] [Indexed: 11/19/2022]
Abstract
During a brief postnatal critical period, excitatory connections in visual cortex can be easily modified by alterations of visual experience. Recent studies conducted in rodents, and particularly in genetically altered mice, have implicated the maturation of cortical GABAergic inhibition in the timing of the critical period. In this paper we (1) review the postnatal changes in GABAergic transmission that can have consequences for visual cortex plasticity and (2) discuss possible mechanisms by which GABAergic circuits could regulate the onset and termination of the critical period for cortical plasticity.
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Affiliation(s)
- Bin Jiang
- Mind/Brain Institute 338 Krieger Hall, Johns Hopkins University, 3400 N. Charles Street, Baltimore, MD 21218, USA
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29
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Tao HW, Poo MM. Activity-dependent matching of excitatory and inhibitory inputs during refinement of visual receptive fields. Neuron 2005; 45:829-36. [PMID: 15797545 DOI: 10.1016/j.neuron.2005.01.046] [Citation(s) in RCA: 112] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2003] [Revised: 06/28/2004] [Accepted: 01/27/2005] [Indexed: 10/25/2022]
Abstract
The receptive field (RF) of single visual neurons undergoes progressive refinement during development. It remains largely unknown how the excitatory and inhibitory inputs on single developing neurons are refined in a coordinated manner to allow the formation of functionally correct circuits. Using whole-cell voltage-clamp recording from Xenopus tectal neurons, we found that RFs determined by excitatory and inhibitory inputs in more mature tectal neurons are spatially matched, with each spot stimulus evoking balanced synaptic excitation and inhibition. This emerges during development through a gradual reduction in the RF size and a transition from disparate to matched topography of excitatory and inhibitory inputs to the tectal neurons. Altering normal spiking activity of tectal neurons by either blocking or elevating GABA(A) receptor activity significantly impeded the developmental reduction and topographic matching of RFs. Thus, appropriate inhibitory activity is essential for the coordinated refinement of excitatory and inhibitory connections.
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Affiliation(s)
- Huizhong W Tao
- Division of Neurobiology, Department of Molecular and Cell Biology, University of California, CA 94720, USA
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Abstract
Binocular vision is shaped by experience during a critical period of early postnatal life. Loss of visual acuity following monocular deprivation is mediated by a shift of spiking output from the primary visual cortex. Both synaptic and network explanations have been offered for this heightened brain plasticity. Direct experimental control over its timing, duration, and closure has now been achieved through a consideration of balanced local circuit excitation-inhibition. Notably, canonical models of homosynaptic plasticity at excitatory synapses alone (LTP/LTD) fail to produce predictable manipulations of the critical period in vivo. Instead, a late functional maturation of intracortical inhibition is the driving force, with one subtype in particular standing out. Parvalbumin-positive large basket cells that innervate target cell bodies with synapses containing the alpha1-subunit of GABA(A) receptors appear to be critical. With age, these cells are preferentially enwrapped in peri-neuronal nets of extracellular matrix molecules, whose disruption by chondroitinase treatment reactivates ocular dominance plasticity in adulthood. In fact, critical period plasticity is best viewed as a continuum of local circuit computations ending in structural consolidation of inputs. Monocular deprivation induces an increase of endogenous proteolytic (tPA-plasmin) activity and consequently motility of spines followed by their pruning, then re-growth. These early morphological events faithfully reflect competition only during the critical period and lie downstream of excitatory-inhibitory balance on a timescale (of days) consistent with the physiological loss of deprived-eye responses in vivo. Ultimately, thalamic afferents retract or expand accordingly to hardwire the rapid functional changes in connectivity. Competition detected by local inhibitory circuits then implemented at an extracellular locus by proteases represents a novel, cellular understanding of the critical period mechanism. It is hoped that this paradigm shift will lead to novel therapies and training strategies for rehabilitation, recovery from injury, and lifelong learning in adulthood.
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Affiliation(s)
- Takao K Hensch
- Laboratory for Neuronal Circuit Development, RIKEN Brain Science Institute, Saitama, Japan
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31
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Hensch TK, Fagiolini M. Excitatory–inhibitory balance and critical period plasticity in developing visual cortex. PROGRESS IN BRAIN RESEARCH 2005; 147:115-24. [PMID: 15581701 DOI: 10.1016/s0079-6123(04)47009-5] [Citation(s) in RCA: 185] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/03/2022]
Affiliation(s)
- Takao K Hensch
- Laboratory for Neuronal Circuit Development, Critical Period Mechanisms Research Group, RIKEN Brain Science Institute, 2-1 Hirosawa, Wako-shi, Saitama 351-0198, Japan.
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Fagiolini M, Fritschy JM, Löw K, Möhler H, Rudolph U, Hensch TK. Specific GABAA circuits for visual cortical plasticity. Science 2004; 303:1681-3. [PMID: 15017002 DOI: 10.1126/science.1091032] [Citation(s) in RCA: 357] [Impact Index Per Article: 17.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
Weak inhibition within visual cortex early in life prevents experience-dependent plasticity. Loss of responsiveness to an eye deprived of vision can be initiated prematurely by enhancing gamma-aminobutyric acid (GABA)-mediated transmission with benzodiazepines. Here, we use a mouse "knockin" mutation to alpha subunits that renders individual GABA type A (GABA(A)) receptors insensitive to diazepam to show that a particular inhibitory network controls expression of the critical period. Only alpha1-containing circuits were found to drive cortical plasticity, whereas alpha2-enriched connections separately regulated neuronal firing. This dissociation carries implications for models of brain development and the safe design of benzodiazepines for use in infants.
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Affiliation(s)
- Michela Fagiolini
- Laboratory for Neuronal Circuit Development, RIKEN Brain Science Institute, 2-1 Hirosawa, Wako-shi, Saitama, 351-0198 Japan
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Mizoguchi Y, Kanematsu T, Hirata M, Nabekura J. A rapid increase in the total number of cell surface functional GABAA receptors induced by brain-derived neurotrophic factor in rat visual cortex. J Biol Chem 2003; 278:44097-102. [PMID: 12941963 DOI: 10.1074/jbc.m305872200] [Citation(s) in RCA: 55] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The number of postsynaptic gamma-aminobutyric acid type A (GABAA) receptors is a fundamental determinant of the variability of inhibitory synaptic responses in the central nervous system. In rat visual cortex, [3H]SR-95531 binding assays revealed that brain-derived neurotrophic factor (BDNF), one of the neurotrophins, induced a rapid increase in the total number of cell surface GABAA receptors, through the activation of Trk B receptor tyrosine kinases. We also demonstrated that BDNF rapidly induced a sustained potentiation of GABAA receptor-mediated currents, using nystatin-perforated patch clamp recordings, in visual cortical layer 5 pyramidal neurons freshly isolated from P14 rats. The potentiation was caused by the activation of Trk B receptor tyrosine kinase and phospholipase C-gamma. In addition, intracellular Ca2+ was important for the potentiation of GABAA responses induced by BDNF. The selective increase in mean miniature inhibitory postsynaptic (mIPSC) current amplitude without effects on mIPSC time courses supports the idea that BDNF rapidly induces an increase in the total number of cell surface functional GABAA receptors in visual cortical pyramidal neurons. These results suggest that BDNF could alter the number of cell surface GABAA receptors in a region-specific manner.
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Affiliation(s)
- Yoshito Mizoguchi
- Cellular and Systems Physiology, Graduate School of Medical Sciences, Kyushu University, Fukuoka 812-8582, Japan
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34
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Abstract
Mice lacking a synaptic isoform of glutamic acid decarboxylase (GAD65) do not exhibit ocular dominance plasticity unless an appropriate level of GABAergic transmission is restored by direct infusion of benzodiazepines into the brain. To better understand how intracortical inhibition triggers experience-dependent changes, we dissected the precise timing requirement for GABA function in the monocular deprivation (MD) paradigm. Diazepam (DZ) or vehicle solution was infused daily before and/or during 4 d of MD in GAD65 knock-out mice. Extracellular single-unit recordings from the binocular zone of visual cortex were performed at the end of deprivation. We found that a minimum treatment of 2 d near the beginning of MD was sufficient to fully activate plasticity but did not need to overlap the deprivation per se. Extended delay after DZ infusion eventually led to loss of plasticity accompanied by improved intrinsic inhibitory circuit function. Two day DZ treatment just after eye opening similarly closed the critical period prematurely in wild-type mice. Raising wild-type mice in complete darkness from birth delayed the peak sensitivity to MD as in other mammals. Interestingly, 2 d DZ infusion in the dark also closed the critical period, whereas equally brief light exposure during dark-rearing had no such effect. Thus, enhanced tonic signaling through GABA(A) receptors rapidly creates a milieu for plasticity within neocortex capable of triggering a critical period for ocular dominance independent of visual experience itself.
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Abstract
Neuronal circuits are shaped by experience during 'critical periods' of early postnatal life. The ability to control the timing, duration, and closure of these heightened levels of brain plasticity has recently become experimentally possible. Two seemingly opposed views of critical period mechanism have emerged: (1) plasticity may be functionally accessed throughout life by appropriately modified stimulation protocols, or (2) plasticity is rigidly limited to early postnatal life by structural modifications. This overview synthesizes both perspectives across a variety of brain regions and species. A deeper understanding of critical periods will form the basis for novel international efforts to "nurture the brain".
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Affiliation(s)
- Takao K Hensch
- Laboratory for Neuronal Circuit Development, RIKEN Brain Science Institute, 2-1 Hirosawa, Wako-shi, Saitama 351-0198, Japan.
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36
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Abstract
Neurons in mouse visual cortex have diverse receptive field properties and they respond selectively to specific features of visual stimuli. Owing to the lateral position of the eyes, only about a third of the visual cortex receives input from both eyes, but many cells in this region are binocular. Similar to higher mammals, closing one eye during a critical period shifts the responses of cells, such that they are better driven by the non-deprived eye. In this review I illustrate how the combination of transgenic mouse technology with single cell recording and modern imaging techniques might lead to a further understanding of the mechanisms that underlie the development, plasticity, and function of the mammalian visual cortex.
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Affiliation(s)
- Mark Hübener
- Max-Planck-Institut für Neurobiologie, Am Klopferspitz 18A, D-82152 Martinsried, Germany.
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37
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Abstract
Sensory experience is known to shape the maturation of cortical circuits during development. A paradigmatic example is the effect of monocular deprivation on ocular dominance of visual cortical neurons. Although visual cortical plasticity has been widely studied since its initial discovery by Hubel and Wiesel >40 years ago, the description of the underlying molecular mechanisms has lagged behind. Several new findings are now beginning to close this gap. Recent data deepen our knowledge of the factors involved in the intercellular communication and intracellular signaling that mediate experience-dependent plasticity in the developing visual cortex. In addition, new findings suggest a role for the extracellular matrix in inhibition of ocular-dominance plasticity in the adult visual cortex.
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Affiliation(s)
- Nicoletta Berardi
- Laboratory of Neurophysiology, Institute of Neuroscience, Pisa, Italy
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38
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Mishina M, Senda M, Kiyosawa M, Ishiwata K, De Volder AG, Nakano H, Toyama H, Oda KI, Kimura Y, Ishii K, Sasaki T, Ohyama M, Komaba Y, Kobayashi S, Kitamura S, Katayama Y. Increased regional cerebral blood flow but normal distribution of GABAA receptor in the visual cortex of subjects with early-onset blindness. Neuroimage 2003; 19:125-31. [PMID: 12781732 DOI: 10.1016/s1053-8119(03)00051-x] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
Before the completion of visual development, visual deprivation impairs synaptic elimination in the visual cortex. The purpose of this study was to determine whether the distribution of central benzodiazepine receptor (BZR) is also altered in the visual cortex in subjects with early-onset blindness. Positron emission tomography was carried out with [(15)O]water and [(11)C]flumazenil on six blind subjects and seven sighted controls at rest. We found that the CBF was significantly higher in the visual cortex for the early-onset blind subjects than for the sighted control subjects. However, there was no significant difference in the BZR distribution in the visual cortex for the subject with early-onset blindness than for the sighted control subjects. These results demonstrated that early visual deprivation does not affect the distribution of GABA(A) receptors in the visual cortex with the sensitivity of our measurements. Synaptic elimination may be independent of visual experience in the GABAergic system of the human visual cortex during visual development.
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Affiliation(s)
- Masahiro Mishina
- Department of Neurology, Neurological Institute, Nippon Medical School Chiba-Hokusoh Hospital, Inba, Japan.
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39
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Fagiolini M, Katagiri H, Miyamoto H, Mori H, Grant SGN, Mishina M, Hensch TK. Separable features of visual cortical plasticity revealed by N-methyl-D-aspartate receptor 2A signaling. Proc Natl Acad Sci U S A 2003; 100:2854-9. [PMID: 12591944 PMCID: PMC151430 DOI: 10.1073/pnas.0536089100] [Citation(s) in RCA: 151] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
How individual receptive field properties are formed in the maturing sensory neocortex remains largely unknown. The shortening of N-methyl-d-aspartate (NMDA) receptor currents by 2A subunit (NR2A) insertion has been proposed to delimit the critical period for experience-dependent refinement of circuits in visual cortex. In mice engineered to maintain prolonged NMDA responses by targeted deletion of NR2A, the sensitivity to monocular deprivation was surprisingly weakened but restricted to the typical critical period and delayed normally by dark rearing from birth. Orientation preference instead failed to mature, occluding further effects of dark rearing. Interestingly, a full ocular dominance plasticity (but not orientation bias) was selectively restored by enhanced inhibition, reflecting an imbalanced excitation in the absence of NR2A. Many of the downstream pathways involved in NMDA signaling are coupled to the receptor through a variety of protein-protein interactions and adaptor molecules. To further investigate a mechanistic dissociation of receptive field properties in the developing visual system, mice carrying a targeted disruption of the NR2A-associated 95-kDa postsynaptic density (PSD95) scaffolding protein were analyzed. Although the development and plasticity of ocular dominance was unaffected, orientation preference again failed to mature in these mice. Taken together, our results demonstrate that the cellular basis generating individual sensory response properties is separable in the developing neocortex.
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Affiliation(s)
- Michela Fagiolini
- Neuronal Circuit Development, Institute of Physical and Chemical Research, RIKEN, Brain Science Institute, 2-1 Hirosawa, Wako, Saitama 351-0198, Japan
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40
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Galarreta M, Hestrin S. Electrical and chemical synapses among parvalbumin fast-spiking GABAergic interneurons in adult mouse neocortex. Proc Natl Acad Sci U S A 2002; 99:12438-43. [PMID: 12213962 PMCID: PMC129463 DOI: 10.1073/pnas.192159599] [Citation(s) in RCA: 309] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2002] [Indexed: 12/26/2022] Open
Abstract
Networks of gamma-aminobutyric acid (GABA)ergic interneurons connected via electrical and chemical synapses are thought to play an important role in detecting and promoting synchronous activity in the cerebral cortex. Although the properties of electrical and chemical synaptic interactions among inhibitory interneurons are critical for their function as a network, they have only been studied systematically in juvenile animals. Here, we have used transgenic mice expressing the enhanced green fluorescent protein in cells containing parvalbumin (PV) to study the synaptic connectivity among fast-spiking (FS) cells in slices from adult animals (2-7 months old). We have recorded from pairs of PV-FS cells and found that the majority of them were electrically coupled (61%, 14 of 23 pairs). In addition, 78% of the pairs were connected via GABAergic chemical synapses, often reciprocally. The average coupling coefficient for step injections was 1.5% (n = 14), a smaller value than that reported in juvenile animals. GABA-mediated inhibitory postsynaptic currents and potentials decayed with exponential time constants of 2.6 and 5.9 ms, respectively, and exhibited paired-pulse depression (50-ms interval). The inhibitory synaptic responses in the adult were faster than those observed in young animals. Our results indicate that PV-FS cells are highly interconnected in the adult cerebral cortex by both electrical and chemical synapses, establishing networks that can have important implications for coordinating activity in cortical circuits.
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Affiliation(s)
- Mario Galarreta
- Department of Comparative Medicine, Stanford University School of Medicine, 300 Pasteur Drive, Edwards Building R102, Stanford, CA 94305-5330, USA.
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41
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Kaelin-Lang A, Luft AR, Sawaki L, Burstein AH, Sohn YH, Cohen LG. Modulation of human corticomotor excitability by somatosensory input. J Physiol 2002; 540:623-33. [PMID: 11956348 PMCID: PMC2290238 DOI: 10.1113/jphysiol.2001.012801] [Citation(s) in RCA: 287] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023] Open
Abstract
In humans, somatosensory stimulation results in increased corticomotoneuronal excitability to the stimulated body parts. The purpose of this study was to investigate the underlying mechanisms. We recorded motor evoked potentials (MEPs) to transcranial magnetic stimulation (TMS) from abductor pollicis brevis (APB), first dorsal interosseous (FDI), and abductor digiti minimi (ADM) muscles. MEP amplitudes, recruitment curves (RC), intracortical inhibition (ICI), intracortical facilitation (ICF), resting (rMT) and active motor thresholds (aMT) were recorded before and after a 2-h period of ulnar nerve electrical stimulation at the wrist. Somatosensory input was monitored by recording somatosensory evoked potentials. To differentiate excitability changes at cortical vs. subcortical sites, we recorded supramaximal peripheral M-responses and MEPs to brainstem electrical stimulation (BES). In order to investigate the involvement of GABAergic mechanisms, we studied the influence of lorazepam (LZ) (a GABA(A) receptor agonist) relative to that of dextromethorphan (DM) (an NMDA receptor antagonist) and placebo in a double-blind design. We found that somatosensory stimulation increased MEP amplitudes to TMS only in the ADM, confirming a previous report. This effect was blocked by LZ but not by either DM or placebo and lasted between 8 and 20 min in the absence of (i) changes in MEPs elicited by BES, (ii) amplitudes of early somatosensory-evoked potentials or (iii) M-responses. We conclude that somatosensory stimulation elicited a focal increase in corticomotoneuronal excitability that outlasts the stimulation period and probably occurs at cortical sites. The antagonistic effect of LZ supports the hypothesis of GABAergic involvement as an operating mechanism.
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Affiliation(s)
- Alain Kaelin-Lang
- Human Cortical Physiology Section, NINDS, National Institutes of Health, Bethesda, MD 20892, USA
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42
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Corner MA, van Pelt J, Wolters PS, Baker RE, Nuytinck RH. Physiological effects of sustained blockade of excitatory synaptic transmission on spontaneously active developing neuronal networks--an inquiry into the reciprocal linkage between intrinsic biorhythms and neuroplasticity in early ontogeny. Neurosci Biobehav Rev 2002; 26:127-85. [PMID: 11856557 DOI: 10.1016/s0149-7634(01)00062-8] [Citation(s) in RCA: 109] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Spontaneous bioelectric activity (SBA) taking the form of extracellularly recorded spike trains (SBA) has been quantitatively analyzed in organotypic neonatal rat visual cortex explants at different ages in vitro, and the effects investigated of both short- and long-term pharmacological suppression of glutamatergic synaptic transmission. In the presence of APV, a selective NMDA receptor blocker, 1-2- (but not 3-)week-old cultures recovered their previous SBA levels in a matter of hours, although in imitation of the acute effect of the GABAergic inhibitor picrotoxin (PTX), bursts of action potentials were abnormally short and intense. Cultures treated either overnight or chronically for 1-3 weeks with APV, the AMPA/kainate receptor blocker DNQX, or a combination of the two were found to display very different abnormalities in their firing patterns. NMDA receptor blockade for 3 weeks produced the most severe deviations from control SBA, consisting of greatly prolonged and intensified burst firing with a strong tendency to be broken up into trains of shorter spike clusters. This pattern was most closely approximated by acute GABAergic disinhibition in cultures of the same age, but this latter treatment also differed in several respects from the chronic-APV effect. In 2-week-old explants, in contrast, it was the APV+DNQX treated group which showed the most exaggerated spike bursts. Functional maturation of neocortical networks, therefore, may specifically require NMDA receptor activation (not merely a high level of neuronal firing) which initially is driven by endogenous rather than afferent evoked bioelectric activity. Putative cellular mechanisms are discussed in the context of a thorough review of the extensive but scattered literature relating activity-dependent brain development to spontaneous neuronal firing patterns.
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Affiliation(s)
- M A Corner
- Academic Medical Centre, Meibergdreef 33, Netherlands Institute for Brain Research, 1105 AZ Amsterdam, The Netherlands.
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43
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Sawaki L, Boroojerdi B, Kaelin-Lang A, Burstein AH, Bütefisch CM, Kopylev L, Davis B, Cohen LG. Cholinergic influences on use-dependent plasticity. J Neurophysiol 2002; 87:166-71. [PMID: 11784739 DOI: 10.1152/jn.00279.2001] [Citation(s) in RCA: 70] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Motor practice elicits use-dependent plasticity in humans as well as in animals. Given the influence of cholinergic neurotransmission on learning and memory processes, we evaluated the effects of scopolamine (a muscarinic receptor antagonist) on use-dependent plasticity and corticomotor excitability in a double-blind placebo-controlled randomized design study. Use-dependent plasticity was substantially attenuated by scopolamine in the absence of global changes in corticomotor excitability. These results identify a facilitatory role for cholinergic influences in use-dependent plasticity in the human motor system.
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Affiliation(s)
- L Sawaki
- Human Cortical Physiology Section, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, Maryland 20892, USA
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44
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Kral A, Hartmann R, Tillein J, Heid S, Klinke R. Delayed maturation and sensitive periods in the auditory cortex. Audiol Neurootol 2001; 6:346-62. [PMID: 11847463 DOI: 10.1159/000046845] [Citation(s) in RCA: 132] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
Behavioral data indicate the existence of sensitive periods in the development of audition and language. Neurophysiological data demonstrate deficits in the cerebral cortex of auditory-deprived animals, mainly in reduced cochleotopy and deficits in corticocortical and corticothalamic loops. In addition to current spread in the cochlea, reduced cochleotopy leads to channel interactions after cochlear implantation. Deficits in corticocortical and corticothalamic loops interfere with normal processing of auditory activity in cortical areas. Thus, the deprived auditory cortex cannot mature normally in congenital deafness. This maturation can be achieved using auditory experience through cochlear implants. However, implantation is necessary within the sensitive period of the auditory system. The functional role of long-term potentiation and long-term depression, inhibition, cholinergic modulation and neurotrophins in auditory development and sensitive periods are discussed.
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Affiliation(s)
- A Kral
- Physiologisches Institut II, J.W. Goethe-Universität, Frankfurt/Main, Germany.
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45
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Developmental inhibitory gate controls the relay of activity to the superficial layers of the visual cortex. J Neurosci 2001. [PMID: 11517267 DOI: 10.1523/jneurosci.21-17-06791.2001] [Citation(s) in RCA: 65] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
A developmental reduction in the radial transmission of synaptic activity has been proposed to underlie the end of the critical period for experience-dependent modification in layers II/III of the visual cortex. Using paired-pulse stimulation, we investigated in visual cortical slices how the propagation of synaptic activity to the superficial layers changes during development and how this process is affected by sensory experience. The results can be summarized as follows. (1) Layers II/III responses to repetitive stimulation of the white matter become increasingly depressed between the third and sixth week of postnatal development, a time course that parallels the end of the critical period. (2) Paired-pulse depression is reduced after dark rearing and also by blocking inhibitory synaptic transmission. (3) Paired-pulse depression and its regulation by age and sensory experience is more pronounced when stimulation is applied to the white matter than when applied to layer IV. Together, these results are consistent with the idea that the maturation of intracortical inhibition reduces the capability of the cortex to relay incoming high-frequency patterns of activity to the supragranular layers.
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46
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Gabaergic inhibition antagonizes adaptive adjustment of the owl's auditory space map during the initial phase of plasticity. J Neurosci 2001. [PMID: 11404421 DOI: 10.1523/jneurosci.21-12-04356.2001] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
We studied the influence of GABA-mediated inhibition on adaptive adjustment of the owl's auditory space map during the initial phase of plasticity. Plasticity of the auditory space map was induced by subjecting owls to a chronic prismatic displacement of the visual field. In the initial stages of plasticity, inhibition suppressed responses to behaviorally appropriate, newly functional excitatory inputs. As a result, adaptive changes in excitatory input were only partially expressed as postsynaptic spike activity. This masking effect of inhibition on map plasticity did not depend on the activity of NMDA receptors at the synapses that supported the newly learned responses. On the basis of these results, we propose that the pattern of feedforward inhibition is less dynamic than the pattern of feedforward excitation at the site of plasticity. As a result, initially in the adjustment process the preexisting pattern of feedforward GABAergic inhibition opposes changes in the auditory space map and tends to preserve the established response properties of the network. The implications of this novel role of inhibition for the functional plasticity of the brain are discussed.
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47
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Knudsen EI, Zheng W, DeBello WM. Traces of learning in the auditory localization pathway. Proc Natl Acad Sci U S A 2000; 97:11815-20. [PMID: 11050214 PMCID: PMC34354 DOI: 10.1073/pnas.97.22.11815] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
One of the fascinating properties of the central nervous system is its ability to learn: the ability to alter its functional properties adaptively as a consequence of the interactions of an animal with the environment. The auditory localization pathway provides an opportunity to observe such adaptive changes and to study the cellular mechanisms that underlie them. The midbrain localization pathway creates a multimodal map of space that represents the nervous system's associations of auditory cues with locations in visual space. Various manipulations of auditory or visual experience, especially during early life, that change the relationship between auditory cues and locations in space lead to adaptive changes in auditory localization behavior and to corresponding changes in the functional and anatomical properties of this pathway. Traces of this early learning persist into adulthood, enabling adults to reacquire patterns of connectivity that were learned initially during the juvenile period.
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Affiliation(s)
- E I Knudsen
- Department of Neurobiology, Stanford University School of Medicine, Stanford, CA 94305, USA
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