101
|
BDNF signaling in the formation, maturation and plasticity of glutamatergic and GABAergic synapses. Exp Brain Res 2009; 199:203-34. [PMID: 19777221 DOI: 10.1007/s00221-009-1994-z] [Citation(s) in RCA: 226] [Impact Index Per Article: 15.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2009] [Accepted: 08/12/2009] [Indexed: 01/17/2023]
Abstract
In the past 15 years numerous reports provided strong evidence that brain-derived neurotrophic factor (BDNF) is one of the most important modulators of glutamatergic and GABAergic synapses. Remarkable progress regarding localization, kinetics, and molecular mechanisms of BDNF secretion has been achieved, and a large number of studies provided evidence that continuous extracellular supply of BDNF is important for the proper formation and functional maturation of glutamatergic and GABAergic synapses. BDNF can play a permissive role in shaping synaptic networks, making them more susceptible for the occurrence of plastic changes. In addition, BDNF appears to be also an instructive factor for activity-dependent long-term synaptic plasticity. BDNF release just in response to synaptic stimulation might be a molecular trigger to convert high-frequency synaptic activity into long-term synaptic memories. This review attempts to summarize the current knowledge in synaptic secretion and synaptic action of BDNF, including both permissive and instructive effects of BDNF in synaptic plasticity.
Collapse
|
102
|
Kanold PO. Subplate neurons: crucial regulators of cortical development and plasticity. Front Neuroanat 2009; 3:16. [PMID: 19738926 PMCID: PMC2737439 DOI: 10.3389/neuro.05.016.2009] [Citation(s) in RCA: 60] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2009] [Accepted: 08/03/2009] [Indexed: 01/14/2023] Open
Abstract
The developing cerebral cortex contains a distinct class of cells, subplate neurons, which form one of the first functional cortical circuits. Subplate neurons reside in the cortical white matter, receive thalamic inputs and project into the developing cortical plate, mostly to layer 4. Subplate neurons are present at key time points during development. Removal of subplate neurons profoundly affects cortical development. Subplate removal in visual cortex prevents the maturation of thalamocortical synapse, the maturation of inhibition in layer 4, the development of orientation selective responses in individual cortical neurons, and the formation of ocular dominance columns. In addition, monocular deprivation during development reveals that ocular dominance plasticity is paradoxical in the absence of subplate neurons. Because subplate neurons projecting to layer 4 are glutamatergic, these diverse deficits following subplate removal were hypothesized to be due to lack of feed-forward thalamic driven cortical excitation. A computational model of the developing thalamocortical pathway incorporating feed-forward excitatory subplate projections replicates both normal development and plasticity of ocular dominance as well as the effects of subplate removal. Therefore, we postulate that feed-forward excitatory projections from subplate neurons into the developing cortical plate enhance correlated activity between thalamus and layer 4 and, in concert with Hebbian learning rules in layer 4, allow maturational and plastic processes in layer 4 to commence. Thus subplate neurons are a crucial regulator of cortical development and plasticity, and damage to these neurons might play a role in the pathology of many neurodevelopmental disorders.
Collapse
Affiliation(s)
- Patrick O. Kanold
- Department of Biology, Institute for Systems Research, and Program in Neuroscience and Cognitive Science, University of MarylandCollege Park, MD, USA,*Correspondence: Patrick O. Kanold, Department of Biology, University of Maryland, 1116 Biosciences Research Building, College Park, MD 20742, USA. e-mail:
| |
Collapse
|
103
|
Yashiro K, Riday TT, Condon KH, Roberts AC, Bernardo DR, Prakash R, Weinberg RJ, Ehlers MD, Philpot BD. Ube3a is required for experience-dependent maturation of the neocortex. Nat Neurosci 2009; 12:777-83. [PMID: 19430469 PMCID: PMC2741303 DOI: 10.1038/nn.2327] [Citation(s) in RCA: 250] [Impact Index Per Article: 16.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2008] [Accepted: 03/24/2009] [Indexed: 02/06/2023]
Abstract
Experience-dependent maturation of neocortical circuits is required for normal sensory and cognitive abilities, which are distorted in neurodevelopmental disorders. We tested whether experience-dependent neocortical modifications require Ube3a, an E3 ubiquitin ligase whose dysregulation has been implicated in autism and Angelman syndrome. Using visual cortex as a model, we found that experience-dependent maturation of excitatory cortical circuits was severely impaired in Angelman syndrome model mice deficient in Ube3a. This developmental defect was associated with profound impairments in neocortical plasticity. Normal plasticity was preserved under conditions of sensory deprivation, but was rapidly lost by sensory experiences. The loss of neocortical plasticity is reversible, as late-onset visual deprivation restored normal synaptic plasticity. Furthermore, Ube3a-deficient mice lacked ocular dominance plasticity in vivo when challenged with monocular deprivation. We conclude that Ube3a is necessary for maintaining plasticity during experience-dependent neocortical development and suggest that the loss of neocortical plasticity contributes to deficits associated with Angelman syndrome.
Collapse
Affiliation(s)
- Koji Yashiro
- Department of Cell and Molecular Physiology, University of North Carolina, Chapel Hill, NC 27599, USA
- K.Y. present address: Urogenix Inc, Durham NC 27713, USA
| | - Thorfinn T. Riday
- Department of Cell and Molecular Physiology, University of North Carolina, Chapel Hill, NC 27599, USA
- Curriculum in Neurobiology, University of North Carolina, Chapel Hill, NC 27599, USA
| | - Kathryn H. Condon
- Department of Neurobiology Duke University Medical Center, Durham, NC 27710, USA
| | - Adam C. Roberts
- Department of Cell and Molecular Physiology, University of North Carolina, Chapel Hill, NC 27599, USA
- UNC Neuroscience Center, University of North Carolina, Chapel Hill, NC 27599, USA
- Neurodevelopmental Disorders Research Center, University of North Carolina, Chapel Hill, NC 27599, USA
| | - Danilo R. Bernardo
- Department of Cell and Molecular Physiology, University of North Carolina, Chapel Hill, NC 27599, USA
| | - Rohit Prakash
- Department of Cell and Molecular Physiology, University of North Carolina, Chapel Hill, NC 27599, USA
| | - Richard J. Weinberg
- UNC Neuroscience Center, University of North Carolina, Chapel Hill, NC 27599, USA
- Department of Cell and Developmental Biology, University of North Carolina, Chapel Hill, NC 27599, USA
| | - Michael D. Ehlers
- Department of Neurobiology Duke University Medical Center, Durham, NC 27710, USA
- Howard Hughes Medical Institute, Duke University Medical Center, Durham, NC 27710, USA
| | - Benjamin D. Philpot
- Department of Cell and Molecular Physiology, University of North Carolina, Chapel Hill, NC 27599, USA
- Curriculum in Neurobiology, University of North Carolina, Chapel Hill, NC 27599, USA
- UNC Neuroscience Center, University of North Carolina, Chapel Hill, NC 27599, USA
- Neurodevelopmental Disorders Research Center, University of North Carolina, Chapel Hill, NC 27599, USA
| |
Collapse
|
104
|
Visual deprivation decreases somatic GAD65 puncta number on layer 2/3 pyramidal neurons in mouse visual cortex. Neural Plast 2009; 2009:415135. [PMID: 19503840 PMCID: PMC2686200 DOI: 10.1155/2009/415135] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2009] [Accepted: 04/28/2009] [Indexed: 11/17/2022] Open
Abstract
Proper functioning of the visual system depends on maturation of both excitatory and inhibitory synapses within the visual cortex. Considering that perisomatic inhibition is one of the key factors that control the critical period in visual cortex, it is pertinent to understand its regulation by visual experience. To do this, we developed an immunohistochemical method that allows three-dimensional (3D) analysis of the glutamic acid decarboxylase (GAD) 65-positive inhibitory terminals in the visual cortex. Using this method on transgenic mice expressing yellow fluorescence protein (YFP) in a subset of neurons, we found that the number of somatic GAD65-puncta on individual layer 2/3 pyramidal neurons is reduced when mice are dark-reared from birth and reverted to normal levels by re-exposure to light. There was no change in GAD65-puncta volume or intensity. These results support the reorganization of inhibitory circuitry within layer 2/3 of visual cortex in response to changes in visual experience.
Collapse
|
105
|
Enrich the environment to empower the brain. Trends Neurosci 2009; 32:233-9. [DOI: 10.1016/j.tins.2008.12.004] [Citation(s) in RCA: 242] [Impact Index Per Article: 16.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2008] [Revised: 11/15/2008] [Accepted: 12/10/2008] [Indexed: 11/23/2022]
|
106
|
Abstract
Within primary visual cortex (V1), brain-derived neurotrophic factor (BDNF) signaling through its high-affinity receptor TrkB is important for normal development and experience-dependent plasticity. TrkB is expressed in several alternatively spliced isoforms, including full-length TrkB (TrkB.FL), and several truncated isoforms (TrkB.T1, TrkB.T2, and TrkB.T4) that lack the intracellular tyrosine kinase domain. These isoforms are important components of BDNF signaling, yet little is known about the developmental or experience-dependent regulation of their expression. Using immunohistochemistry, we found TrkB.FL and TrkB.T1 expressed in interneurons and pyramidal neurons within V1, but not in cortical astrocytes. We used real-time PCR to quantify the changes in mRNA expression of BDNF, the four TrkB isoforms, and the low-affinity receptor P75NTR during normal development, and in response to visual deprivation at two different ages. BDNF expression increased between postnatal days 10 (P10) and P30, and was rapidly down-regulated by 3 days of visual deprivation during both the pre-critical period (P14-P17) and the critical period (P18-P21). Over the same developmental period, expression of each TrkB isoform was regulated independently; TrkB.T1 increased, TrkB.FL and TrkB.T2 decreased, and TrkB.T4 showed transient changes. Neither brief visual deprivation nor prolonged dark-rearing induced changes in either TrkB.FL or TrkB.T1 expression. However, TrkB.T4 expression was reduced by brief visual deprivation, whereas TrkB.T4, TrkB.T2 and P75(NTR) were up-regulated by prolonged dark-rearing into the critical period. Our data indicate that TrkB isoform expression can be selectively regulated by visual experience, and may contribute to experience-dependent cortical plasticity.
Collapse
MESH Headings
- Age Factors
- Analysis of Variance
- Animals
- Animals, Newborn
- Brain-Derived Neurotrophic Factor/genetics
- Brain-Derived Neurotrophic Factor/metabolism
- Dark Adaptation/physiology
- Functional Laterality
- Gene Expression Regulation, Developmental/physiology
- Nerve Tissue Proteins/metabolism
- Neurons/classification
- Neurons/metabolism
- Parvalbumins/metabolism
- Protein Isoforms/genetics
- Protein Isoforms/metabolism
- RNA, Messenger/metabolism
- Rats
- Rats, Long-Evans
- Receptor, trkB/genetics
- Receptor, trkB/metabolism
- Receptors, Growth Factor
- Receptors, Nerve Growth Factor/genetics
- Receptors, Nerve Growth Factor/metabolism
- Sensory Deprivation/physiology
- Vision, Binocular/physiology
- Vision, Monocular/physiology
- Visual Cortex/cytology
- Visual Cortex/metabolism
Collapse
Affiliation(s)
- Bethany K. Bracken
- Dept. of Biology and Center for Behavioral Genomics Brandeis University, Waltham MA 02454
| | - Gina G. Turrigiano
- Dept. of Biology and Center for Behavioral Genomics Brandeis University, Waltham MA 02454
| |
Collapse
|
107
|
Tropea D, Van Wart A, Sur M. Molecular mechanisms of experience-dependent plasticity in visual cortex. Philos Trans R Soc Lond B Biol Sci 2009; 364:341-55. [PMID: 18977729 PMCID: PMC2674480 DOI: 10.1098/rstb.2008.0269] [Citation(s) in RCA: 89] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
A remarkable amount of our current knowledge of mechanisms underlying experience-dependent plasticity during cortical development comes from study of the mammalian visual cortex. Recent advances in high-resolution cellular imaging, combined with genetic manipulations in mice, novel fluorescent recombinant probes, and large-scale screens of gene expression, have revealed multiple molecular mechanisms that underlie structural and functional plasticity in visual cortex. We situate these mechanisms in the context of a new conceptual framework of feed-forward and feedback regulation for understanding how neurons of the visual cortex reorganize their connections in response to changes in sensory inputs. Such conceptual advances have important implications for understanding not only normal development but also pathological conditions that afflict the central nervous system.
Collapse
Affiliation(s)
- Daniela Tropea
- Picower Institute for Learning and Memory and Department of Brain and Cognitive Sciences, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | | | | |
Collapse
|
108
|
Mainardi M, Landi S, Berardi N, Maffei L, Pizzorusso T. Reduced responsiveness to long-term monocular deprivation of parvalbumin neurons assessed by c-Fos staining in rat visual cortex. PLoS One 2009; 4:e4342. [PMID: 19194492 PMCID: PMC2632740 DOI: 10.1371/journal.pone.0004342] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2008] [Accepted: 12/23/2008] [Indexed: 11/18/2022] Open
Abstract
Background It is generally assumed that visual cortical cells homogeneously shift their ocular dominance (OD) in response to monocular deprivation (MD), however little experimental evidence directly supports this notion. By using immunohistochemistry for the activity-dependent markers c-Fos and Arc, coupled with staining for markers of inhibitory cortical sub-populations, we studied whether long-term MD initiated at P21 differentially affects visual response of inhibitory neurons in rat binocular primary visual cortex. Methodology/Principal Findings The inhibitory markers GAD67, parvalbumin (PV), calbindin (CB) and calretinin (CR) were used. Visually activated Arc did not colocalize with PV and was discarded from further studies. MD decreased visually induced c-Fos activation in GAD67 and CR positive neurons. The CB population responded to MD with a decrease of CB expression, while PV cells did not show any effect of MD on c-Fos expression. The persistence of c-Fos expression induced by deprived eye stimulation in PV cells is not likely to be due to a particularly low threshold for activity-dependent c-Fos induction. Indeed, c-Fos induction by increasing concentrations of the GABAA antagonist picrotoxin in visual cortical slices was similar between PV cells and the other cortical neurons. Conclusion These data indicate that PV cells are particularly refractory to MD, suggesting that different cortical subpopulation may show different response to MD.
Collapse
Affiliation(s)
- Marco Mainardi
- Laboratory of Neurobiology, Scuola Normale Superiore, Pisa, Italy
| | - Silvia Landi
- Laboratory of Neurobiology, Scuola Normale Superiore, Pisa, Italy
| | - Nicoletta Berardi
- Department of Psychology, University of Florence, Florence, Italy
- Institute of Neuroscience, CNR, Pisa, Italy
| | - Lamberto Maffei
- Laboratory of Neurobiology, Scuola Normale Superiore, Pisa, Italy
- Institute of Neuroscience, CNR, Pisa, Italy
| | - Tommaso Pizzorusso
- Department of Psychology, University of Florence, Florence, Italy
- Institute of Neuroscience, CNR, Pisa, Italy
- * E-mail:
| |
Collapse
|
109
|
Siu TL, Morley JW. Suppression of visual cortical evoked responses following deprivation of pattern vision in adult mice. Eur J Neurosci 2008; 28:484-90. [PMID: 18702720 DOI: 10.1111/j.1460-9568.2008.06342.x] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The effect of visual loss on the adult neocortex can have significant impact on the success of a visual implant. Recent research has shown that the adult neocortex retains substantial plasticity following a disruption to its afferent input. The result of these changes may hamper the development of a visual prosthesis if visual sensation cannot be effectively restored by stimulation of the surviving elements of the visual pathway. In order to evaluate further the visual performance of the mammalian adult brain following visual loss, especially the dominant form of blindness in humans, namely loss of pattern vision, we examined the cortical evoked potential of adult mice following 7, 30 and 120 days of visual deprivation via bilateral eyelid suture. Cortical potentials were elicited with a flash visual stimulus or by electrical stimulation of the retina. We found that after 7 days deprivation there was a potentiation of the evoked response while at 30 and 120 days deprivation the visual evoked responses were significantly reduced. Increasing the visual stimulus intensity reduced the effects. The electrical evoked potential demonstrated a corresponding reduction in stimulus threshold at 7 days and a corresponding rise (40-50%) after 30 and 120 days. These findings suggest that the adult brain exhibited significant experience-dependent modifications following visual loss, and the impact depended on the duration of deprivation. Such reduction in visual responsiveness, especially with electrical activation, will need to be taken into account in the development of a visual implant.
Collapse
Affiliation(s)
- Timothy L Siu
- School of Medical Sciences, University of New South Wales, Sydney, NSW, Australia.
| | | |
Collapse
|
110
|
Gene expression patterns in visual cortex during the critical period: synaptic stabilization and reversal by visual deprivation. Proc Natl Acad Sci U S A 2008; 105:9409-14. [PMID: 18606990 DOI: 10.1073/pnas.0710172105] [Citation(s) in RCA: 59] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
The mapping of eye-specific, geniculocortical inputs to primary visual cortex (V1) is highly sensitive to the balance of correlated activity between the two eyes during a restricted postnatal critical period for ocular dominance plasticity. This critical period is likely to have amplified expression of genes and proteins that mediate synaptic plasticity. DNA microarray analysis of transcription in mouse V1 before, during, and after the critical period identified 31 genes that were up-regulated and 22 that were down-regulated during the critical period. The highest-ranked up-regulated gene, cardiac troponin C, codes for a neuronal calcium-binding protein that regulates actin binding and whose expression is activity-dependent and relatively selective for layer-4 star pyramidal neurons. The highest-ranked down-regulated gene, synCAM, also has actin-based function. Actin-binding function, G protein signaling, transcription, and myelination are prominently represented in the critical period transcriptome. Monocular deprivation during the critical period reverses the expression of nearly all critical period genes. The profile of regulated genes suggests that synaptic stability is a principle driver of critical period gene expression and that alteration in visual activity drives homeostatic restoration of stability.
Collapse
|
111
|
Bengoetxea H, Argandoña EG, Lafuente JV. Effects of visual experience on vascular endothelial growth factor expression during the postnatal development of the rat visual cortex. Cereb Cortex 2008; 18:1630-9. [PMID: 17986606 PMCID: PMC2430152 DOI: 10.1093/cercor/bhm190] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023] Open
Abstract
The development of the cortical vascular network depends on functional maturation. External inputs are an essential requirement in the modeling of the visual cortex, mainly during the critical period, when the functional and structural properties of visual cortical neurons are particularly susceptible to alterations. Vascular endothelial growth factor (VEGF) is the major angiogenic factor, a key signal in the induction of vessel growth. Our study focused on the role of visual stimuli on the development of the vascular pattern correlated with VEGF levels. Vascular density and the expression of VEGF were examined in the primary visual cortex of rats reared under different visual environments (dark rearing, dark-rearing in conditions of enriched environment, enriched environment, and laboratory standard conditions) during postnatal development (before, during, and after the critical period). Our results show a restricted VEGF cellular expression to astroglial cells. Quantitative differences appeared during the critical period: higher vascular density and VEGF protein levels were found in the enriched environment group; both dark-reared groups showed lower vascular density and VEGF levels, which means that enriched environment without the physical exercise component does not exert effects in dark-reared rats.
Collapse
Affiliation(s)
- Harkaitz Bengoetxea
- Laboratory of Clinical and Experimental Neuroscience (LaNCE), Department of Neuroscience, Faculty of Medicine and Odontology, Basque Country University, Barrio Sarriena, 48940 Leioa, Spain.
| | | | | |
Collapse
|
112
|
Abidin I, Eysel UT, Lessmann V, Mittmann T. Impaired GABAergic inhibition in the visual cortex of brain-derived neurotrophic factor heterozygous knockout mice. J Physiol 2008; 586:1885-901. [PMID: 18238806 DOI: 10.1113/jphysiol.2007.148627] [Citation(s) in RCA: 61] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023] Open
Abstract
Brain derived neurotrophic factor (BDNF) promotes the formation, maturation and stabilization of inhibitory synapses in the central nervous system. In addition, BDNF has been suggested to regulate the critical period for ocular dominance plasticity in the visual system. Here we further evaluated the role of BDNF in the visual cortex by studying the GABAergic synaptic transmission under conditions of chronically reduced levels of BDNF. Whole-cell patch-clamp recordings were performed from pyramidal neurons located in layers II/III of visual cortical slices in heterozygous BDNF knockout mice (BDNF (+/-)) and their wild-type littermates at the age of 21-25 days. The BDNF (+/-) mice showed a decreased frequency and amplitude of miniature inhibitory postsynaptic currents (mIPSCs) as well as a reduced amplitude and prolonged decay time constant of evoked IPSCs. Further analyses indicated an impaired presynaptic GABAergic function in BDNF (+/-) mice, as shown by the decreased release probability, steady-state release and synchronous release of GABA. However, the number of functional release sites remained unchanged. In line with these observations, an impaired glutamate-driven GABA release was observed in BDNF (+/-) mice. Furthermore, the overall balance in the strength of cortical excitation to inhibition shifted towards a decreased inhibition. Finally, the reversal potential for chloride-mediated evoked IPSCs was not affected. These findings suggested that chronically reduced levels of BDNF strongly impair the GABAergic inhibitory function in visual cortex by altering postsynaptic properties and by reducing presynaptic GABA release as well as the overall strength of inhibition onto pyramidal neurons within the cortical network. These impairments of inhibitory function are compatible with a rather immature status of the GABAergic system in BDNF (+/-) mice, which supports the hypothesis that the level of expression for BDNF critically affects maturation and function of the GABAergic inhibition.
Collapse
Affiliation(s)
- Ismail Abidin
- Department of Neurophysiology, MA 4/149, Ruhr-University Bochum, D-44780 Bochum, Germany
| | | | | | | |
Collapse
|
113
|
Oliveira CS, Rigon AP, Leal RB, Rossi FM. The activation of ERK1/2 and p38 mitogen‐activated protein kinases is dynamically regulated in the developing rat visual system. Int J Dev Neurosci 2008; 26:355-62. [DOI: 10.1016/j.ijdevneu.2007.12.007] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2007] [Revised: 12/11/2007] [Accepted: 12/12/2007] [Indexed: 10/22/2022] Open
Affiliation(s)
- Camila Salum Oliveira
- Laboratório de Neuroquímica‐3, Departamento de BioquímicaCentro de Ciências Biológicas, Universidade Federal de Santa CatarinaFlorianópolisSC88040‐900Brazil
| | - Ana Paula Rigon
- Laboratório de Neuroquímica‐3, Departamento de BioquímicaCentro de Ciências Biológicas, Universidade Federal de Santa CatarinaFlorianópolisSC88040‐900Brazil
| | - Rodrigo Bainy Leal
- Laboratório de Neuroquímica‐3, Departamento de BioquímicaCentro de Ciências Biológicas, Universidade Federal de Santa CatarinaFlorianópolisSC88040‐900Brazil
| | - Francesco Mattia Rossi
- Laboratório de Neuroquímica‐3, Departamento de BioquímicaCentro de Ciências Biológicas, Universidade Federal de Santa CatarinaFlorianópolisSC88040‐900Brazil
| |
Collapse
|
114
|
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?
Collapse
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.
| |
Collapse
|
115
|
Ben-Ari Y, Gaiarsa JL, Tyzio R, Khazipov R. GABA: a pioneer transmitter that excites immature neurons and generates primitive oscillations. Physiol Rev 2007; 87:1215-84. [PMID: 17928584 DOI: 10.1152/physrev.00017.2006] [Citation(s) in RCA: 892] [Impact Index Per Article: 52.5] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Developing networks follow common rules to shift from silent cells to coactive networks that operate via thousands of synapses. This review deals with some of these rules and in particular those concerning the crucial role of the neurotransmitter gamma-aminobuytric acid (GABA), which operates primarily via chloride-permeable GABA(A) receptor channels. In all developing animal species and brain structures investigated, neurons have a higher intracellular chloride concentration at an early stage leading to an efflux of chloride and excitatory actions of GABA in immature neurons. This triggers sodium spikes, activates voltage-gated calcium channels, and acts in synergy with NMDA channels by removing the voltage-dependent magnesium block. GABA signaling is also established before glutamatergic transmission, suggesting that GABA is the principal excitatory transmitter during early development. In fact, even before synapse formation, GABA signaling can modulate the cell cycle and migration. The consequence of these rules is that developing networks generate primitive patterns of network activity, notably the giant depolarizing potentials (GDPs), largely through the excitatory actions of GABA and its synergistic interactions with glutamate signaling. These early types of network activity are likely required for neurons to fire together and thus to "wire together" so that functional units within cortical networks are formed. In addition, depolarizing GABA has a strong impact on synaptic plasticity and pathological insults, notably seizures of the immature brain. In conclusion, it is suggested that an evolutionary preserved role for excitatory GABA in immature cells provides an important mechanism in the formation of synapses and activity in neuronal networks.
Collapse
Affiliation(s)
- Yehezkel Ben-Ari
- Insititut de Neurobiologie de la Méditerranée, Institut National de la Santé et de la Recherche Médicale U. 29, Marseille, France.
| | | | | | | |
Collapse
|
116
|
Hooks BM, Chen C. Critical Periods in the Visual System: Changing Views for a Model of Experience-Dependent Plasticity. Neuron 2007; 56:312-26. [DOI: 10.1016/j.neuron.2007.10.003] [Citation(s) in RCA: 187] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
|
117
|
Akaneya Y. Activity regulates the expression of AMPA receptor subunit GluR4 in developing visual cortex. Eur J Neurosci 2007; 25:1641-6. [PMID: 17432955 DOI: 10.1111/j.1460-9568.2007.05388.x] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
In the developing visual cortex, the expression of alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptor (AMPAR) subunit GluR4 precedes that of the other AMPAR subunits GluR1-3, and then declines to become almost absent in adults. The current study shows that the neuronal activity regulates the expression of GluR4 by a culture system in vitro and a dark-rearing (DR) system in vivo. Membrane depolarization by treatment of cultured neurons of the visual cortex with a high concentration of KCl (35 mm; HK) promoted a decline in the expression of GluR4. This effect of HK on the expression of GluR4 was significantly blocked by the addition of an N-methyl-d-aspartate receptor (NMDAR) antagonist, (D)-2-amino-5-phosphonovaleric acid (APV), but not by the voltage-sensitive calcium channel antagonist nifedipine. Moreover, the Ca(2+)-calmodulin-dependent kinase (CaMKII) inhibitor KN62 and the cAMP-dependent protein kinase A (PKA) inhibitor H-89 blocked this effect, which suggests the involvement of Ca(2+) influx via NMDAR and the subsequent activation of CaMKII and PKA. Conversely, the MAP kinase inhibitor PD98059 promoted the effect of HK on the expression of GluR4. Significantly, APV, KN62, H-89 and PD98059 either promoted or inhibited the expression of GluR4 even in normal KCl (5 mm) conditions. The developmental change in the expression of GluR4 was significantly attenuated in DR in vivo, and the results suggest that neuronal activity such as visual experience may be involved in the mechanism of the expression of GluR4, which is mediated by NMDAR and tuned by certain protein kinases at an early developmental stage in the visual cortex.
Collapse
Affiliation(s)
- Yukio Akaneya
- Division of Neurophysiology, Department of Neuroscience, Osaka University Graduate School of Medicine, 2-2 Yamadaoka, Suita, Japan.
| |
Collapse
|
118
|
Ciucci F, Putignano E, Baroncelli L, Landi S, Berardi N, Maffei L. Insulin-like growth factor 1 (IGF-1) mediates the effects of enriched environment (EE) on visual cortical development. PLoS One 2007; 2:e475. [PMID: 17534425 PMCID: PMC1871611 DOI: 10.1371/journal.pone.0000475] [Citation(s) in RCA: 83] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2007] [Accepted: 05/04/2007] [Indexed: 11/18/2022] Open
Abstract
Enriched environment (EE) has been recently shown to affect visual cortex development and plasticity, and to prevent dark rearing effects. The factors mediating EE effects on visual cortical development and plasticity are still unclear. We have investigated whether IGF-1 is involved in mediating EE effects on the developing visual cortex. We show that EE increases the number of IGF-1 positive neurons in the visual cortex at P18. Increasing IGF-1 in the visual cortex of non-EE rats by means of osmotic minipumps implanted at P18 mimics EE effects, accelerating visual acuity development, assessed with Visual Evoked Potentials (VEPs). Blocking IGF-1 action in the visual cortex of EE rats by means of the IGF-1 receptor antagonist JB1 from P18 completely blocks EE action on visual acuity development. These results show that IGF-1 is a key factor mediating EE effects on visual cortical development. We then show that IGF-1 affects GAD65 immunoreactivity in perisomatic innervation and the condensation of Chondroitin Sulphate Proteoglycans (CSPGs) in perineuronal nets (PNNs) in the visual cortex. This suggests that IGF-1 action in mediating EE effects could be exerted through the modulation of intracortical inhibitory circuitry and PNN development.
Collapse
|
119
|
Caleo M, Restani L, Gianfranceschi L, Costantin L, Rossi C, Rossetto O, Montecucco C, Maffei L. Transient synaptic silencing of developing striate cortex has persistent effects on visual function and plasticity. J Neurosci 2007; 27:4530-40. [PMID: 17460066 PMCID: PMC6672996 DOI: 10.1523/jneurosci.0772-07.2007] [Citation(s) in RCA: 49] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Neural circuits in the cerebral cortex are shaped by experience during "critical periods" early in life. For example, visual cortex is immature at the time of eye opening and gradually develops its functional properties during a sensitive period. Very few reports have addressed the role of intrinsic neural activity in cortical maturation. Here we have exploited the bacterial enzyme botulinum neurotoxin E (BoNT/E) to produce a unilateral, reversible blockade of neural activity in rat visual cortex during the sensitive period. BoNT/E is a highly selective protease that interferes with transmitter release via cleavage of the synaptic protein SNAP-25 (synaptosomal-associated protein of 25 kDa). Unilateral, intracortical injections of BoNT/E were made at the time of eye opening and resulted in the silencing of the treated, but not contralateral, hemisphere for a period of 2 weeks. We found that visual acuity was permanently reduced in the blocked hemisphere, and the critical period for ocular dominance plasticity persisted into adulthood. Unexpectedly, these effects extended equally to the contralateral, uninjected side, demonstrating a fundamental role for interhemispheric connections in cortical maturation.
Collapse
Affiliation(s)
- Matteo Caleo
- Istituto di Neuroscienze, Consiglio Nazionale delle Ricerche, 56100 Pisa, Italy.
| | | | | | | | | | | | | | | |
Collapse
|
120
|
Engelhardt M, Di Cristo G, Berardi N, Maffei L, Wahle P. Differential effects of NT-4, NGF and BDNF on development of neurochemical architecture and cell size regulation in rat visual cortex during the critical period. Eur J Neurosci 2007; 25:529-40. [PMID: 17284195 DOI: 10.1111/j.1460-9568.2006.05301.x] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Development of inhibition is a crucial determinant of the time course of visual cortical plasticity. BDNF strongly affects interneuron development and the onset and closure of the critical period for ocular dominance plasticity. Less is known on the effects of NT-4 despite a clear involvement in ocular dominance plasticity. We have investigated the effects of NT-4 on interneuron development by supplying NT-4 with osmotic minipumps during two time windows overlapping the onset (P12-20) and the peak (P20-28) of the critical period. We assessed the expression of interneuronal markers and soma size maturation either after the end of the infusion periods or at the end of the critical period (P45). We found that NT-4 was very effective in regulating interneuron development. NPY, SOM and PARV neuron somata grew faster during both infusion periods whereas CR neurons only responded during the early infusion period. The effects of soma size elicited during the earlier infusion period were still present at P45. In PARV neurons, NT-4 caused a long-lasting stabilization of CB and NPY expression. Furthermore, NT-4 accelerated the expression of GAD-65 mRNA in a subset of non-PARV neurons of layer V, which normally up-regulate GAD-65 towards the end of the critical period. Most of these effects were shared by NT-4 and BDNF. Some were unexpectedly also shared by NGF, which promoted growth of layer V PARV neurons, stabilized the CB expression and accelerated the GAD-65 expression. The results suggest that neurotrophins act on critical period plasticity by strengthening inhibition.
Collapse
Affiliation(s)
- Maren Engelhardt
- AG Entwicklungsneurobiologie ND 6/72, Fakultät für Biologie, Ruhr-Universität, 44780 Bochum, Germany
| | | | | | | | | |
Collapse
|
121
|
Subcortical regulation of cortical development: some effects of early, selective deprivations. PROGRESS IN BRAIN RESEARCH 2007; 164:23-37. [DOI: 10.1016/s0079-6123(07)64002-3] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
|
122
|
Razak KA, Pallas SL. Dark rearing reveals the mechanism underlying stimulus size tuning of superior colliculus neurons. Vis Neurosci 2006; 23:741-8. [PMID: 17020630 DOI: 10.1017/s0952523806230062] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2006] [Accepted: 03/30/2006] [Indexed: 11/07/2022]
Abstract
Neurons in the superficial layers of the midbrain superior colliculus (SC) exhibit distinct tuning properties for visual stimuli, but, unlike neurons in the geniculocortical visual pathway, most respond best to visual stimuli that are smaller than the classical receptive field (RF). The mechanism underlying this size selectivity may depend on the number and pattern of feedforward retinal inputs and/or the balance between inhibition and excitation within the RF. We have previously shown that chronic blockade of NMDA receptors (NMDA-R), which increases the convergence of retinal afferents onto SC neurons, does not alter size selectivity in the SC. This suggests that the number of retinal inputs does not determine size selectivity. Here we show, using single unit extracellular recordings from the SC of normal hamsters, that size selectivity in neurons selective for small stimulus size is correlated with the strength of inhibition within the RF. We also show that dark rearing causes concomitant reductions in both inhibition and size selectivity. In addition, dark rearing increases the percentage of neurons non-selective for stimulus size. Finally, we show that chronic blockade of NMDA-R, a procedure that does not alter size tuning, also does not change the strength of inhibition within the RF. Taken together, these results argue that inhibition within the RF underlies selectivity for small stimulus size and that inhibition must be intact for size tuning to be preserved after developmental manipulations of activity. In addition, these results suggest that regulation of the balance between excitation and inhibition within the RF does not require NMDA-R activity but does depend on visual experience. These results suggest that developmental experience influences neural response properties through an alteration of inhibitory circuitry.
Collapse
Affiliation(s)
- Khaleel A Razak
- Graduate Program in Neurobiology and Behavior, Department of Biology, Georgia State University, Atlanta, Georgia 30303, USA
| | | |
Collapse
|
123
|
Landi S, Sale A, Berardi N, Viegi A, Maffei L, Cenni MC. Retinal functional development is sensitive to environmental enrichment: a role for BDNF. FASEB J 2006; 21:130-9. [PMID: 17135370 DOI: 10.1096/fj.06-6083com] [Citation(s) in RCA: 70] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Retina has long been considered less plastic than cortex or hippocampus, the very sites of experience-dependent plasticity. Now, we show that retinal development is responsive to the experience provided by an enriched environment (EE): the maturation of retinal acuity, which is a sensitive index of retinal circuitry development, is strongly accelerated in EE rats. This effect is present also in rats exposed to EE up to P10, that is before eye opening, suggesting that factors sufficient to trigger retinal acuity development are affected by EE during the first days of life. Brain derived neurotrophic factor (BDNF) is precociously expressed in the ganglion cell layer of EE with respect to non-EE rats and reduction of BDNF expression in EE animals counteracts EE effects on retinal acuity. Thus, EE controls the development of retinal circuitry, and this action depends on retinal BDNF expression.
Collapse
Affiliation(s)
- S Landi
- Laboratorio di Neurobiologia, Scuola Normale Superiore c/o Istituto di Neuroscienze del CNR, Via G. Moruzzi, 1, 56100 Pisa, Italy.
| | | | | | | | | | | |
Collapse
|
124
|
Takahashi M, Kakita A, Futamura T, Watanabe Y, Mizuno M, Sakimura K, Castren E, Nabeshima T, Someya T, Nawa H. Sustained brain-derived neurotrophic factor up-regulation and sensorimotor gating abnormality induced by postnatal exposure to phencyclidine: comparison with adult treatment. J Neurochem 2006; 99:770-80. [PMID: 16903871 DOI: 10.1111/j.1471-4159.2006.04106.x] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Brain-derived neurotrophic factor (BDNF) is involved in synaptic development and plasticity, and alterations in BDNF expression or signaling are implicated in drug addiction and psychiatric diseases, such as depression and schizophrenia. In this study, we administered phencyclidine to postnatal and adult rats with different time schedules, and determined the correlations between BDNF expression and the behavioral effects. Both single and repeated phencyclidine injections into adult rats induced BDNF up-regulation in the corticolimbic system and a decrease in prepulse inhibition, both of which were transient. In contrast, subchronic postnatal administration increased BDNF protein and mRNA levels in the hippocampus and entorhinal cortex, which were sustained until 8 weeks of age. In parallel, the postnatal rats treated with phencyclidine developed a persistent decrease in prepulse inhibition at the adult stage. The chronic BDNF increase appeared to contribute to the prepulse inhibition abnormality, as subchronic BDNF infusion into the hippocampus of normal rats mimicked the prepulse inhibition deficits. This study suggests that phencyclidine exposure during brain development induces sustained BDNF up-regulation in the limbic system with a biological link to sensorimotor gating deficits.
Collapse
MESH Headings
- Aging/physiology
- Animals
- Animals, Newborn/physiology
- Blotting, Northern
- Blotting, Western
- Brain/pathology
- Brain Chemistry/drug effects
- Brain-Derived Neurotrophic Factor/biosynthesis
- Brain-Derived Neurotrophic Factor/pharmacology
- Brain-Derived Neurotrophic Factor/physiology
- Hallucinogens/pharmacology
- Hippocampus
- Immunoenzyme Techniques
- Mice
- Mice, Inbred C57BL
- Mice, Knockout
- Microinjections
- Phencyclidine/pharmacology
- Rats
- Rats, Wistar
- Receptors, N-Methyl-D-Aspartate/biosynthesis
- Receptors, N-Methyl-D-Aspartate/drug effects
- Receptors, N-Methyl-D-Aspartate/genetics
- Reflex, Startle/drug effects
- Signal Transduction/drug effects
- Up-Regulation/drug effects
- Up-Regulation/physiology
Collapse
Affiliation(s)
- Makoto Takahashi
- Department of Psychiatry, Niigata University Graduate School of Medical and Dental Sciences, Niigata, Japan
| | | | | | | | | | | | | | | | | | | |
Collapse
|
125
|
Ho BC, Milev P, O’Leary DS, Librant A, Andreasen NC, Wassink TH. Cognitive and magnetic resonance imaging brain morphometric correlates of brain-derived neurotrophic factor Val66Met gene polymorphism in patients with schizophrenia and healthy volunteers. ACTA ACUST UNITED AC 2006; 63:731-40. [PMID: 16818862 PMCID: PMC3065118 DOI: 10.1001/archpsyc.63.7.731] [Citation(s) in RCA: 213] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
CONTEXT Relatively little is known about genetic determinants of cognitive dysfunction in schizophrenia. Recent studies suggest that a brain-derived neurotrophic factor (BDNF) prodomain single nucleotide polymorphism resulting in a valine (Val)-to-methionine (Met) substitution is associated with impaired declarative memory in healthy volunteers and patients with schizophrenia. These studies indicate that the BDNF(Met) variant may mediate hippocampal cognitive functions by modulating intracellular trafficking and activity-dependent BDNF release. To our knowledge, the way in which this functional single nucleotide polymorphism affects other neurocognitive measures has not been examined. Its role in determining cognitive deficits in schizophrenia has also not been systematically studied. OBJECTIVES To characterize the neurocognitive and brain morphometric phenotypic correlates of the BDNF Val66Met polymorphism and to test the specificity of the BDNF(Met) variant on cognitive dysfunction in schizophrenia. DESIGN, SETTING, AND PARTICIPANTS A comprehensive battery of standardized neuropsychological tests was administered to 144 healthy volunteers and 293 patients with schizophrenia spectrum disorder at a tertiary care university hospital. Approximately two thirds of the sample also underwent high-resolution magnetic resonance imaging brain scans. MAIN OUTCOME MEASURES Genotype effects (in Met allele carriers vs Val homozygotes) on 5 cognitive domain z scores and magnetic resonance imaging gray matter brain volume measures (Talairach atlas-based cerebral lobes and optimized voxel-based morphometry) were examined using general linear models. RESULTS On verbal memory, there was a significant genotype effect but no genotype x diagnosis effects. In both patients with schizophrenia and healthy volunteers, Met allele carriers had poorer verbal memory performance than their Val-homozygous counterparts. On visuospatial abilities, there were significant genotype and genotype x diagnosis effects. Met allele-associated visuospatial impairment was specific to patients with schizophrenia but not healthy volunteers. There were significant genotype effects on gray matter volumes within brain regions known to subserve these 2 cognitive domains, with Met allele carriers having smaller temporal and occipital lobar gray matter volumes. Optimized voxel-based morphometry further suggests that parietal heteromodal cortical gray matter deficits may underlie visuospatial impairment in patients with schizophrenia carrying the Met allele. CONCLUSIONS We replicated the association between the BDNF(Met) variant and poor medial temporal lobe-related memory performance. The consonance of our cognitive and brain morphology findings further suggests that the BDNF(Met) variant may have a specific role in conferring visuospatial dysfunction in schizophrenia.
Collapse
Affiliation(s)
- Beng-Choon Ho
- Department of Psychiatry, Roy J. and Lucille A. Carver College of Medicine, University of Iowa, Iowa City, Iowa, USA
| | - Peter Milev
- Department of Psychiatry, University of Minnesota Medical School, Minneapolis, Minnesota, USA
| | - Daniel S. O’Leary
- Department of Psychiatry, Roy J. and Lucille A. Carver College of Medicine, University of Iowa, Iowa City, Iowa, USA
| | - Amy Librant
- Department of Psychiatry, Roy J. and Lucille A. Carver College of Medicine, University of Iowa, Iowa City, Iowa, USA
| | - Nancy C. Andreasen
- Department of Psychiatry, Roy J. and Lucille A. Carver College of Medicine, University of Iowa, Iowa City, Iowa, USA
- The MIND Institute and Department of Psychiatry, University of New Mexico, Albuquerque, New Mexico, USA
| | - Thomas H. Wassink
- Department of Psychiatry, Roy J. and Lucille A. Carver College of Medicine, University of Iowa, Iowa City, Iowa, USA
| |
Collapse
|
126
|
Kuczewski N, Aztiria E, Domenici L. Developmental modulation of synaptic transmission by acetylcholine in the primary visual cortex. Brain Res 2006; 1095:43-50. [PMID: 16730341 DOI: 10.1016/j.brainres.2006.04.022] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2005] [Revised: 04/03/2006] [Accepted: 04/03/2005] [Indexed: 10/24/2022]
Abstract
Despite the evidence that cortical synaptic organization and cognitive functions are influenced by the activity of the cholinergic system during postnatal development, so far no information is available on the effects produced by acetylcholine (ACh) on synaptic transmission. In the present article, we show that the ability of visual cortex slices to respond to ACh depends on postnatal age. In adulthood, ACh exerts mainly a facilitatory action on synaptic transmission, depressing field potential (FP) amplitude only if applied at high concentrations (millimolar range). During early postnatal development, at postnatal day 13 (P13), facilitation by ACh was lacking, with depression of FP observed with concentration of ACh in the micromolar range. The magnitude of ACh facilitatory effects increases with age. The time course of ACh-dependent facilitation overlaps the developmental maturation of acetylcholinesterase (AChE), suggesting a close relationship between ACh action and AChE activity. Thus, age-dependent modification of the cholinergic modulatory action may affect cortical maturation by regulating the magnitude of synaptic transmission.
Collapse
Affiliation(s)
- Nicola Kuczewski
- Scuola Internazionale Superiore di Studi Avanzati, S.I.S.S.A., Settore di Neuroscienze Cognitive, Via Beirut 2-4, Trieste 34014, Italy
| | | | | |
Collapse
|
127
|
Tongiorgi E, Domenici L, Simonato M. What is the biological significance of BDNF mRNA targeting in the dendrites? Clues from epilepsy and cortical development. Mol Neurobiol 2006; 33:17-32. [PMID: 16388108 DOI: 10.1385/mn:33:1:017] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2005] [Accepted: 06/02/2005] [Indexed: 01/19/2023]
Abstract
The neurotrophin brain-derived neurotrophic factor (BDNF) is a regulatory factor of several, partially contrasting, aspects of the biology of neural cells, including survival, growth, differentiation, and cell death. Regulation of the local availability of BDNF at distinct subcellular domains such as the cell soma, dendrites, axons, and spines appears to be the key to conferring spatial and temporal specificity of the different effects elicited by this neurotrophin. This article reviews recent findings in the context of epileptogenesis and visual cortex maturation that showed that different BDNF messenger RNA (mRNA) transcripts are localized at different subcellular locations in hippocampal and cortical neurons. It also reviews findings demonstrating that strong depolarizing stimuli, both in vitro and in vivo, elicit accumulation of BDNF mRNA and protein in the distal dendrites through a signaling pathway involving the activation of the N-methyl-D-aspartate and tyrosine kinase B receptors and an intracellular increase in Ca2+ concentration. Finally, this article proposes that the regulation of the delivery of BDNF mRNA and protein to the different subcellular domains--particularly the dendritic compartment--may represent a fundamental aspect of the processes of cellular and synaptic morphological rearrangements underlying epileptogenesis and postnatal development of the visual cortex.
Collapse
Affiliation(s)
- Enrico Tongiorgi
- BRAIN Centre for Neuroscience, Department of Biology, University of Trieste, Trieste, Italy.
| | | | | |
Collapse
|
128
|
Hartman KN, Pal SK, Burrone J, Murthy VN. Activity-dependent regulation of inhibitory synaptic transmission in hippocampal neurons. Nat Neurosci 2006; 9:642-9. [PMID: 16582905 DOI: 10.1038/nn1677] [Citation(s) in RCA: 164] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2005] [Accepted: 03/03/2006] [Indexed: 11/09/2022]
Abstract
Neural activity regulates the number and properties of GABAergic synapses in the brain, but the mechanisms underlying these changes are unclear. We found that blocking spike activity globally in developing hippocampal neurons from rats reduced the density of GABAergic terminals as well as the frequency and amplitude of miniature inhibitory postsynaptic currents (mIPSCs). Chronic inactivity later in development led to a reduction in the mIPSC amplitude, without any change in GABAergic synapse density. By contrast, hyperpolarizing or abolishing spike activity in single neurons did not alter GABAergic synaptic inputs. Suppressing activity in individual presynaptic GABAergic neurons also failed to decrease synaptic output. Our results indicate that GABAergic synapses are regulated by the level of activity in surrounding neurons. Notably, we found that the expression of GABAergic plasticity involves changes in the amount of neurotransmitter in individual vesicles.
Collapse
Affiliation(s)
- Kenichi N Hartman
- Department of Molecular and Cellular Biology, Harvard University, 16 Divinity Avenue, Cambridge, Massachusetts 02138, USA
| | | | | | | |
Collapse
|
129
|
Cang J, Kalatsky VA, Löwel S, Stryker MP. Optical imaging of the intrinsic signal as a measure of cortical plasticity in the mouse. Vis Neurosci 2006; 22:685-91. [PMID: 16332279 PMCID: PMC2553096 DOI: 10.1017/s0952523805225178] [Citation(s) in RCA: 120] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2005] [Accepted: 05/18/2005] [Indexed: 11/06/2022]
Abstract
The responses of cells in the visual cortex to stimulation of the two eyes changes dramatically following a period of monocular visual deprivation (MD) during a critical period in early life. This phenomenon, referred to as ocular dominance (OD) plasticity, is a widespread model for understanding cortical plasticity. In this study, we designed stimulus patterns and quantification methods to analyze OD in the mouse visual cortex using optical imaging of intrinsic signals. Using periodically drifting bars restricted to the binocular portion of the visual field, we obtained cortical maps for both contralateral (C) and ipsilateral (I) eyes and computed OD maps as (C - I)/(C + I). We defined the OD index (ODI) for individual animals as the mean of the OD map. The ODI obtained from an imaging session of less than 30 min gives reliable measures of OD for both normal and monocularly deprived mice under Nembutal anesthesia. Surprisingly, urethane anesthesia, which yields excellent topographic maps, did not produce consistent OD findings. Normal Nembutal-anesthetized mice have positive ODI (0.22 +/- 0.01), confirming a contralateral bias in the binocular zone. For mice monocularly deprived during the critical period, the ODI of the cortex contralateral to the deprived eye shifted negatively towards the nondeprived, ipsilateral eye (ODI after 2-day MD: 0.12 +/- 0.02, 4-day: 0.03 +/- 0.03, and 6- to 7-day MD: -0.01 +/- 0.04). The ODI shift induced by 4-day MD appeared to be near maximal, consistent with previous findings using single-unit recordings. We have thus established optical imaging of intrinsic signals as a fast and reliable screening method to study OD plasticity in the mouse.
Collapse
Affiliation(s)
- Jianhua Cang
- W.M. Keck Foundation Center for Integrative Neuroscience, Department of Physiology, University of California, San Francisco, CA 94143-0444, USA
| | | | | | | |
Collapse
|
130
|
Guan Z, Fang J. Peripheral immune activation by lipopolysaccharide decreases neurotrophins in the cortex and hippocampus in rats. Brain Behav Immun 2006; 20:64-71. [PMID: 15922558 DOI: 10.1016/j.bbi.2005.04.005] [Citation(s) in RCA: 177] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/11/2005] [Revised: 04/11/2005] [Accepted: 04/18/2005] [Indexed: 12/22/2022] Open
Abstract
Lipopolysaccharide (LPS), a cell wall component of Gram-negative bacteria, induces neuronal death, decreases neurogenesis, and impairs synaptic plasticity and memory, but the mechanisms for these effects are not well understood. We hypothesize that neurotrophin levels in the brain are influenced by LPS. To test this hypothesis, we determined effects of LPS on brain-derived neurotrophic factor (BDNF), nerve growth factor (NGF), and NT-3 levels in the brain after intraperitoneal injection of saline or LPS (0.1, 0.3 or 1.0mg/kg) in rats. LPS significantly decreased BDNF in the hippocampus (-20%), frontal cortex (-19%), parietal cortex (-63%), temporal cortex (-29%), and occipital cortex (-41%). LPS also significantly decreased NGF levels by 10-20% in the hippocampus and different cortical regions, except in the occipital cortex. Finally, LPS decreased NT-3 by 15-25% in the frontal cortex. These observations indicate that the neuroprotection mediated by neurotrophins in the brain are compromised by systemic immune activation induced by LPS.
Collapse
Affiliation(s)
- Zhiwei Guan
- Department of Psychiatry, Pennsylvania State University College of Medicine, Hershey, PA 17033, USA
| | | |
Collapse
|
131
|
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.
Collapse
Affiliation(s)
- Takao K Hensch
- RIKEN Brain Science Institute, 2-1 Hirosawa, Wako-shi, Saitama, 351-0198, Japan.
| |
Collapse
|
132
|
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.
Collapse
Affiliation(s)
- Bin Jiang
- Mind/Brain Institute 338 Krieger Hall, Johns Hopkins University, 3400 N. Charles Street, Baltimore, MD 21218, USA
| | | | | | | |
Collapse
|
133
|
Chattopadhyaya B, Di Cristo G, Higashiyama H, Knott GW, Kuhlman SJ, Welker E, Huang ZJ. Experience and activity-dependent maturation of perisomatic GABAergic innervation in primary visual cortex during a postnatal critical period. J Neurosci 2005; 24:9598-611. [PMID: 15509747 PMCID: PMC6730138 DOI: 10.1523/jneurosci.1851-04.2004] [Citation(s) in RCA: 471] [Impact Index Per Article: 24.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
The neocortical GABAergic network consists of diverse interneuron cell types that display distinct physiological properties and target their innervations to subcellular compartments of principal neurons. Inhibition directed toward the soma and proximal dendrites is crucial in regulating the output of pyramidal neurons, but the development of perisomatic innervation is poorly understood because of the lack of specific synaptic markers. In the primary visual cortex, for example, it is unknown whether, and to what extent, the formation and maturation of perisomatic synapses are intrinsic to cortical circuits or are regulated by sensory experience. Using bacterial artificial chromosome transgenic mice that label a defined class of perisomatic synapses with green fluorescent protein, here we show that perisomatic innervation developed during a protracted postnatal period after eye opening. Maturation of perisomatic innervation was significantly retarded by visual deprivation during the third, but not the fifth, postnatal week, implicating an important role for sensory input. To examine the role of cortical intrinsic mechanisms, we developed a method to visualize perisomatic synapses from single basket interneurons in cortical organotypic cultures. Characteristic perisomatic synapses formed through a stereotyped process, involving the extension of distinct terminal branches and proliferation of perisomatic boutons. Neuronal spiking in organotypic cultures was necessary for the proliferation of boutons and the extension, but not the maintenance, of terminal branches. Together, our results suggest that although the formation of perisomatic synapses is intrinsic to the cortex, visual experience can influence the maturation and pattern of perisomatic innervation during a postnatal critical period by modulating the level of neural activity within cortical circuits.
Collapse
|
134
|
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.
Collapse
Affiliation(s)
- Takao K Hensch
- Laboratory for Neuronal Circuit Development, RIKEN Brain Science Institute, Saitama, Japan
| |
Collapse
|
135
|
Canas N, Pereira IT, Ribeiro JA, Sebastião AM. Brain-derived neurotrophic factor facilitates glutamate and inhibits GABA release from hippocampal synaptosomes through different mechanisms. Brain Res 2004; 1016:72-8. [PMID: 15234254 DOI: 10.1016/j.brainres.2004.04.070] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 04/09/2004] [Indexed: 10/26/2022]
Abstract
Brain-derived neurotrophic factor (BDNF) has an acute excitatory effect on rat hippocampal synaptic transmission. To compare the action of BDNF upon the release of excitatory and inhibitory neurotransmitters in the hippocampus, we studied the effect of acutely applied BDNF on the K+-evoked glutamate and on the K+-evoked gamma-aminobutyric acid (GABA) release from rat hippocampal nerve terminals (synaptosomes). The acute application of BDNF (30-100 ng/ml) enhanced the K+-evoked [3H]glutamate release. This effect involved tyrosine-kinase B (TrkB) receptor phosphorylation and Ca2+ entry into synaptosomes through voltage-sensitive calcium channels, since it was abolished by K252a (200 nM), which prevents TrkB-mediated phosphorylation, and by CdCl2 (0.2 mM), a blocker of voltage-sensitive calcium channels. In contrast, BDNF (3-100 ng/ml) inhibited K+-evoked [3H]GABA release from hippocampal synaptosomes. This action was also mediated by phosphorylation of the TrkB receptor, but was independent of Ca2+ entry into synaptosomes through voltage-sensitive calcium channels. Blockade of transport of GABA with SKF 89976a (20 microM) prevented the inhibitory action of BDNF upon GABA release, indicating that BDNF influences the activity of GABA transporters. It is concluded that BDNF influences in an opposite way, through distinct mechanisms, the release of glutamate and the release of GABA from hippocampal synaptosomes.
Collapse
Affiliation(s)
- Nuno Canas
- Laboratory of Neurosciences, Faculty of Medicine, University of Lisbon, Av. Prof. Egas Moniz, Lisbon 1649-028, Portugal
| | | | | | | |
Collapse
|
136
|
Bartoletti A, Medini P, Berardi N, Maffei L. Environmental enrichment prevents effects of dark-rearing in the rat visual cortex. Nat Neurosci 2004; 7:215-6. [PMID: 14966527 DOI: 10.1038/nn1201] [Citation(s) in RCA: 74] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2003] [Accepted: 01/06/2004] [Indexed: 11/08/2022]
Abstract
Environmental enrichment potentiates neural plasticity, enhancing acquisition and consolidation of memory traces. In the sensory cortices, after cortical circuit maturation and sensory function acquisition are completed, neural plasticity declines and the critical period 'closes'. In the visual cortex, this process can be prevented by dark-rearing, and here we show that environmental enrichment can promote physiological maturation and consolidation of visual cortical connections in dark-reared rats, leading to critical period closure.
Collapse
|