1
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Nakagawa N, Iwasato T. Activity-dependent dendrite patterning in the postnatal barrel cortex. Front Neural Circuits 2024; 18:1409993. [PMID: 38827189 PMCID: PMC11140076 DOI: 10.3389/fncir.2024.1409993] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2024] [Accepted: 05/06/2024] [Indexed: 06/04/2024] Open
Abstract
For neural circuit construction in the brain, coarse neuronal connections are assembled prenatally following genetic programs, being reorganized postnatally by activity-dependent mechanisms to implement area-specific computational functions. Activity-dependent dendrite patterning is a critical component of neural circuit reorganization, whereby individual neurons rearrange and optimize their presynaptic partners. In the rodent primary somatosensory cortex (barrel cortex), driven by thalamocortical inputs, layer 4 (L4) excitatory neurons extensively remodel their basal dendrites at neonatal stages to ensure specific responses of barrels to the corresponding individual whiskers. This feature of barrel cortex L4 neurons makes them an excellent model, significantly contributing to unveiling the activity-dependent nature of dendrite patterning and circuit reorganization. In this review, we summarize recent advances in our understanding of the activity-dependent mechanisms underlying dendrite patterning. Our focus lays on the mechanisms revealed by in vivo time-lapse imaging, and the role of activity-dependent Golgi apparatus polarity regulation in dendrite patterning. We also discuss the type of neuronal activity that could contribute to dendrite patterning and hence connectivity.
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Affiliation(s)
- Naoki Nakagawa
- Laboratory of Mammalian Neural Circuits, National Institute of Genetics, Mishima, Japan
- Graduate Institute for Advanced Studies, SOKENDAI, Mishima, Japan
| | - Takuji Iwasato
- Laboratory of Mammalian Neural Circuits, National Institute of Genetics, Mishima, Japan
- Graduate Institute for Advanced Studies, SOKENDAI, Mishima, Japan
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2
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Nakagawa N, Iwasato T. Golgi polarity shift instructs dendritic refinement in the neonatal cortex by mediating NMDA receptor signaling. Cell Rep 2023; 42:112843. [PMID: 37516101 DOI: 10.1016/j.celrep.2023.112843] [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: 03/07/2023] [Revised: 05/15/2023] [Accepted: 07/05/2023] [Indexed: 07/31/2023] Open
Abstract
Dendritic refinement is a critical component of activity-dependent neuronal circuit maturation, through which individual neurons establish specific connectivity with their target axons. Here, we demonstrate that the developmental shift of Golgi polarity is a key process in dendritic refinement. During neonatal development, the Golgi apparatus in layer 4 spiny stellate (SS) neurons in the mouse barrel cortex lose their original apical positioning and acquire laterally polarized distributions. This lateral Golgi polarity, which is oriented toward the barrel center, peaks on postnatal days 5-7 (P5-P7) and disappears by P15, which aligns with the developmental time course of SS neuron dendritic refinement. Genetic ablation of N-methyl-D-aspartate (NMDA) receptors, key players in dendritic refinement, disturbs the lateral Golgi polarity. Golgi polarity manipulation disrupts the asymmetric dendritic projection pattern and the primary-whisker-specific response of SS neurons. Our results elucidate activity-dependent Golgi dynamics and their critical role in developmental neuronal circuit refinement.
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Affiliation(s)
- Naoki Nakagawa
- Laboratory of Mammalian Neural Circuits, National Institute of Genetics (NIG), Mishima, Shizuoka 411-8540, Japan; Graduate Institute for Advanced Studies, SOKENDAI, Mishima, Shizuoka 411-8540, Japan.
| | - Takuji Iwasato
- Laboratory of Mammalian Neural Circuits, National Institute of Genetics (NIG), Mishima, Shizuoka 411-8540, Japan; Graduate Institute for Advanced Studies, SOKENDAI, Mishima, Shizuoka 411-8540, Japan.
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3
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Massengill CI, Day-Cooney J, Mao T, Zhong H. Genetically encoded sensors towards imaging cAMP and PKA activity in vivo. J Neurosci Methods 2021; 362:109298. [PMID: 34339753 PMCID: PMC8659126 DOI: 10.1016/j.jneumeth.2021.109298] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2021] [Revised: 07/22/2021] [Accepted: 07/29/2021] [Indexed: 12/26/2022]
Abstract
Cyclic adenosine monophosphate (cAMP) is a universal second messenger that plays a crucial role in diverse biological functions, ranging from transcription to neuronal plasticity, and from development to learning and memory. In the nervous system, cAMP integrates inputs from many neuromodulators across a wide range of timescales - from seconds to hours - to modulate neuronal excitability and plasticity in brain circuits during different animal behavioral states. cAMP signaling events are both cell-specific and subcellularly compartmentalized. The same stimulus may result in different, sometimes opposite, cAMP dynamics in different cells or subcellular compartments. Additionally, the activity of protein kinase A (PKA), a major cAMP effector, is also spatiotemporally regulated. For these reasons, many laboratories have made great strides toward visualizing the intracellular dynamics of cAMP and PKA. To date, more than 80 genetically encoded sensors, including original and improved variants, have been published. It is starting to become possible to visualize cAMP and PKA signaling events in vivo, which is required to study behaviorally relevant cAMP/PKA signaling mechanisms. Despite significant progress, further developments are needed to enhance the signal-to-noise ratio and practical utility of these sensors. This review summarizes the recent advances and challenges in genetically encoded cAMP and PKA sensors with an emphasis on in vivo imaging in the brain during behavior.
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Affiliation(s)
| | - Julian Day-Cooney
- Vollum Institute, Oregon Health & Science University, Portland, OR 97239, USA
| | - Tianyi Mao
- Vollum Institute, Oregon Health & Science University, Portland, OR 97239, USA.
| | - Haining Zhong
- Vollum Institute, Oregon Health & Science University, Portland, OR 97239, USA.
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4
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Rao MS, Mizuno H. Elucidating mechanisms of neuronal circuit formation in layer 4 of the somatosensory cortex via intravital imaging. Neurosci Res 2020; 167:47-53. [PMID: 33309867 DOI: 10.1016/j.neures.2020.10.007] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2020] [Revised: 09/27/2020] [Accepted: 10/01/2020] [Indexed: 12/13/2022]
Abstract
The cerebral cortex has complex yet perfectly wired neuronal circuits that are important for high-level brain functions such as perception and cognition. The rodent's somatosensory system is widely used for understanding the mechanisms of circuit formation during early developmental periods. In this review, we summarize the developmental processes of circuit formation in layer 4 of the somatosensory cortex, and we describe the molecules involved in layer 4 circuit formation and neuronal activity-dependent mechanisms of circuit formation. We also introduce the dynamic mechanisms of circuit formation in layer 4 revealed by intravital two-photon imaging technologies, which include time-lapse imaging of neuronal morphology and calcium imaging of neuronal activity in newborn mice.
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Affiliation(s)
- Madhura S Rao
- Laboratory of Multi-dimensional Imaging, International Research Center for Medical Sciences (IRCMS), Kumamoto University, Kumamoto, 860-0811, Japan; Graduate School of Medical Sciences, Kumamoto University, Kumamoto, 860-0811, Japan
| | - Hidenobu Mizuno
- Laboratory of Multi-dimensional Imaging, International Research Center for Medical Sciences (IRCMS), Kumamoto University, Kumamoto, 860-0811, Japan; Graduate School of Medical Sciences, Kumamoto University, Kumamoto, 860-0811, Japan.
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5
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Iwasato T. In vivo imaging of neural circuit formation in the neonatal mouse barrel cortex. Dev Growth Differ 2020; 62:476-486. [DOI: 10.1111/dgd.12693] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2020] [Revised: 09/13/2020] [Accepted: 09/27/2020] [Indexed: 01/21/2023]
Affiliation(s)
- Takuji Iwasato
- Laboratory of Mammalian Neural Circuits National Institute of Genetics Mishima Japan
- Department of Genetics SOKENDAI Mishima Japan
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6
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Clark EA, Rutlin M, Capano LS, Aviles S, Saadon JR, Taneja P, Zhang Q, Bullis JB, Lauer T, Myers E, Schulmann A, Forrest D, Nelson SB. Cortical RORβ is required for layer 4 transcriptional identity and barrel integrity. eLife 2020; 9:e52370. [PMID: 32851975 PMCID: PMC7492084 DOI: 10.7554/elife.52370] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2019] [Accepted: 08/26/2020] [Indexed: 02/01/2023] Open
Abstract
Retinoic acid-related orphan receptor beta (RORβ) is a transcription factor (TF) and marker of layer 4 (L4) neurons, which are distinctive both in transcriptional identity and the ability to form aggregates such as barrels in rodent somatosensory cortex. However, the relationship between transcriptional identity and L4 cytoarchitecture is largely unknown. We find RORβ is required in the cortex for L4 aggregation into barrels and thalamocortical afferent (TCA) segregation. Interestingly, barrel organization also degrades with age in wildtype mice. Loss of RORβ delays excitatory input and disrupts gene expression and chromatin accessibility, with down-regulation of L4 and up-regulation of L5 genes, suggesting a disruption in cellular specification. Expression and binding site accessibility change for many other TFs, including closure of neurodevelopmental TF binding sites and increased expression and binding capacity of activity-regulated TFs. Lastly, a putative target of RORβ, Thsd7a, is down-regulated without RORβ, and Thsd7a knock-out alone disrupts TCA organization in adult barrels.
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MESH Headings
- Animals
- Antigens, Surface/chemistry
- Antigens, Surface/genetics
- Antigens, Surface/metabolism
- Female
- Male
- Membrane Proteins/chemistry
- Membrane Proteins/genetics
- Membrane Proteins/metabolism
- Mice
- Mice, Knockout
- Neurons/chemistry
- Neurons/cytology
- Neurons/metabolism
- Nuclear Receptor Subfamily 1, Group F, Member 2/chemistry
- Nuclear Receptor Subfamily 1, Group F, Member 2/genetics
- Nuclear Receptor Subfamily 1, Group F, Member 2/metabolism
- Somatosensory Cortex/chemistry
- Somatosensory Cortex/cytology
- Somatosensory Cortex/metabolism
- Somatosensory Cortex/physiology
- Thalamus/chemistry
- Thalamus/metabolism
- Transcription Factors/chemistry
- Transcription Factors/genetics
- Transcription Factors/metabolism
- Transcriptome/genetics
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Affiliation(s)
- Erin A Clark
- Department of Biology and Program in Neuroscience, Brandeis UniversityWalthamUnited States
| | - Michael Rutlin
- Department of Biology and Program in Neuroscience, Brandeis UniversityWalthamUnited States
| | - Lucia S Capano
- Department of Biology and Program in Neuroscience, Brandeis UniversityWalthamUnited States
| | - Samuel Aviles
- Department of Biology and Program in Neuroscience, Brandeis UniversityWalthamUnited States
| | - Jordan R Saadon
- Department of Biology and Program in Neuroscience, Brandeis UniversityWalthamUnited States
| | - Praveen Taneja
- Department of Biology and Program in Neuroscience, Brandeis UniversityWalthamUnited States
| | - Qiyu Zhang
- Department of Biology and Program in Neuroscience, Brandeis UniversityWalthamUnited States
| | - James B Bullis
- Department of Biology and Program in Neuroscience, Brandeis UniversityWalthamUnited States
| | - Timothy Lauer
- Department of Biology and Program in Neuroscience, Brandeis UniversityWalthamUnited States
| | - Emma Myers
- Department of Biology and Program in Neuroscience, Brandeis UniversityWalthamUnited States
| | | | - Douglas Forrest
- Laboratory of Endocrinology and Receptor Biology, National Institutes of Health, NIDDKBethesdaUnited States
| | - Sacha B Nelson
- Department of Biology and Program in Neuroscience, Brandeis UniversityWalthamUnited States
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7
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Zhang M, Lu M, Huang H, Liu X, Su H, Li H. Maturation of thalamocortical synapses in the somatosensory cortex depends on neocortical AKAP5 expression. Neurosci Lett 2019; 709:134374. [PMID: 31310785 DOI: 10.1016/j.neulet.2019.134374] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2019] [Revised: 07/01/2019] [Accepted: 07/09/2019] [Indexed: 11/18/2022]
Abstract
Sensory cortex topographic maps consist of organized arrays of thalamocortical afferents (TCAs) that project into distinct areas of the cortex. Formation of topographic maps in sensory cortices is a prerequisite for functional maturation of the neocortex. Studies have shown that the formation of topographic maps and the maturation of thalamocortical synapses in the somatosensory cortex depend on the cyclic adenosine 5'-monophosphate-(cAMP)-protein kinase A (PKA) signaling pathway. AKAP5 is a scaffold protein (also called AKAP79 in humans or AKAP150 in rodents; AKAP79/150) that serves as a signaling hub that links cAMP and PKA signaling. Whether AKAP5 plays a role in topographic map formation and the maturation of thalamocortical synapses during development of the somatosensory cortex is still unknown. Here, we generated cortex-specific AKAP5-knockout mice (CxAKAP5KO) to examine its roles in somatosensory cortex development. We found that CxAKAP5KO mice displayed impaired cortical barrel maps. Electrophysiological recordings showed that the AMPA/NMDA ratio was reduced, and silent synapses were increased in thalamocortical synapses of CxAKAP5KO mice during postnatal development. Morphological analysis of layer IV cortical neurons demonstrated that dendritic refinement of these neurons was abnormal. These results indicate that AKAP5 is necessary for both topographic map formation and maturation of thalamocortical synapses as well as morphological development of cortical neurons in the somatosensory cortex.
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Affiliation(s)
- Min Zhang
- Department of Physiology, Anhui Medical College, Anhui 230601, China
| | - Meifang Lu
- Department of Histology and Embryology, School of Basic Medical Sciences, Anhui Medical University, Anhui 230032, China
| | - Hao Huang
- Department of Histology and Embryology, School of Basic Medical Sciences, Anhui Medical University, Anhui 230032, China
| | - Xiaoyan Liu
- Department of Histology and Embryology, School of Basic Medical Sciences, Anhui Medical University, Anhui 230032, China
| | - Haoran Su
- Department of Electronic Engineering, City University of Hong Kong, Hong Kong, China
| | - Hong Li
- Department of Histology and Embryology, School of Basic Medical Sciences, Anhui Medical University, Anhui 230032, China.
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8
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Sun X, Lv Y, Wang J, Cheng H, Huang J, Du Y, Dong J. Differential protein expression profiling by iTRAQ‐2D‐LC‐MS/MS of rats treated with oxaliplatin. J Cell Biochem 2019; 120:18128-18141. [PMID: 31237037 DOI: 10.1002/jcb.29116] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2019] [Revised: 05/13/2019] [Accepted: 05/15/2019] [Indexed: 01/05/2023]
Affiliation(s)
- Xianjun Sun
- Department of Integrative Medicine, Huashan Hospital Fudan University Shanghai China
- Qingpu Chinese Medicine Hospital Institutes of Integrative Medicine, Fudan University Shanghai China
| | - Yubao Lv
- Department of Integrative Medicine, Huashan Hospital Fudan University Shanghai China
- Qingpu Chinese Medicine Hospital Institutes of Integrative Medicine, Fudan University Shanghai China
| | - Junjun Wang
- Qingpu Chinese Medicine Hospital Institutes of Integrative Medicine, Fudan University Shanghai China
| | - HuiQin Cheng
- Department of Prevention and Healthcare Yangpu Daqiao Community Health Service Center Shanghai China
| | - Jianhua Huang
- Department of Integrative Medicine, Huashan Hospital Fudan University Shanghai China
- Qingpu Chinese Medicine Hospital Institutes of Integrative Medicine, Fudan University Shanghai China
| | - Yijie Du
- Department of Integrative Medicine, Huashan Hospital Fudan University Shanghai China
- Qingpu Chinese Medicine Hospital Institutes of Integrative Medicine, Fudan University Shanghai China
| | - Jingcheng Dong
- Department of Integrative Medicine, Huashan Hospital Fudan University Shanghai China
- Qingpu Chinese Medicine Hospital Institutes of Integrative Medicine, Fudan University Shanghai China
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9
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Differential dynamics of cortical neuron dendritic trees revealed by long-term in vivo imaging in neonates. Nat Commun 2018; 9:3106. [PMID: 30082783 PMCID: PMC6078955 DOI: 10.1038/s41467-018-05563-0] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2017] [Accepted: 07/10/2018] [Indexed: 12/13/2022] Open
Abstract
Proper neuronal circuit function relies on precise dendritic projection, which is established through activity-dependent refinement during early postnatal development. Here we revealed dynamics of dendritic refinement in the mammalian brain by conducting long-term imaging of the neonatal mouse barrel cortex. By “retrospective” analyses, we identified “prospective” barrel-edge spiny stellate (SS) neurons in early neonates, which had an apical dendrite and primitive basal dendrites (BDs). These neurons retracted the apical dendrite gradually and established strong BD orientation bias through continuous “dendritic tree” turnover. A greater chance of survival was given to BD trees emerged in the barrel-center side, where thalamocortical axons (TCAs) cluster. When the spatial bias of TCA inputs to SS neurons was lost, BD tree turnover was suppressed, and most BD trees became stable and elaborated mildly. Thus, barrel-edge SS neurons could establish the characteristic BD projection pattern through differential dynamics of dendritic trees induced by spatially biased inputs. Layer 4 stellate neurons in barrel cortex have a characteristic dendritic pattern. Here, the authors conduct long-term imaging from postnatal day 3–6 to show that an orientation bias is established through dendritic tree turnover and selective elaboration, which may be induced by biased thalamocortical inputs.
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10
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Martini FJ, Moreno-Juan V, Filipchuk A, Valdeolmillos M, López-Bendito G. Impact of thalamocortical input on barrel cortex development. Neuroscience 2017; 368:246-255. [PMID: 28412498 DOI: 10.1016/j.neuroscience.2017.04.005] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2017] [Revised: 03/31/2017] [Accepted: 04/03/2017] [Indexed: 01/22/2023]
Abstract
The development of cortical maps requires the balanced interaction between genetically determined programs and input/activity-dependent signals generated spontaneously or triggered from the environment. The somatosensory pathway of mice provides an excellent scenario to study cortical map development because of its highly organized cytoarchitecture, known as the barrel field. This precise organization makes evident even small alterations in the cortical map layout. In this review, we will specially focus on the thalamic factors that control barrel field development. We will summarize the role of thalamic input integration and identity, neurotransmission and spontaneous activity in cortical map formation and early cross-modal plasticity.
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Affiliation(s)
- Francisco J Martini
- Instituto de Neurociencias de Alicante, Universidad Miguel Hernández-Consejo Superior de Investigaciones Científicas (UMH-CSIC), Sant Joan d'Alacant, Spain.
| | - Verónica Moreno-Juan
- Instituto de Neurociencias de Alicante, Universidad Miguel Hernández-Consejo Superior de Investigaciones Científicas (UMH-CSIC), Sant Joan d'Alacant, Spain
| | - Anton Filipchuk
- Instituto de Neurociencias de Alicante, Universidad Miguel Hernández-Consejo Superior de Investigaciones Científicas (UMH-CSIC), Sant Joan d'Alacant, Spain
| | - Miguel Valdeolmillos
- Instituto de Neurociencias de Alicante, Universidad Miguel Hernández-Consejo Superior de Investigaciones Científicas (UMH-CSIC), Sant Joan d'Alacant, Spain
| | - Guillermina López-Bendito
- Instituto de Neurociencias de Alicante, Universidad Miguel Hernández-Consejo Superior de Investigaciones Científicas (UMH-CSIC), Sant Joan d'Alacant, Spain.
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11
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Abstract
One approach to examining how higher sensory, motor, and cognitive faculties emerge in the neocortex is to elucidate the underlying wiring principles of the brain during development. The mammalian neocortex is a layered structure generated from a sheet of proliferating ventricular cells that progressively divide to form specific functional areas, such as the primary somatosensory (S1) and motor (M1) cortices. The basic wiring pattern in each of these functional areas is based on a similar framework, but is distinct in detail. Functional specialization in each area derives from a combination of molecular cues within the cortex and neuronal activity-dependent cues provided by innervating axons from the thalamus. One salient feature of neocortical development is the establishment of topographic maps in which neighboring neurons receive input relayed from neighboring sensory afferents. Barrels, which are prominent sensory units in the somatosensory cortex of rodents, have been examined in detail, and data suggest that the initial, gross formation of the barrel map relies on molecular cues, but the refinement of this topography depends on neuronal activity. Several excellent reviews have been published on the patterning and plasticity of the barrel cortex and the precise targeting of ventrobasal thalamic axons. In this review, the authors will focus on the formation and functional maturation of synapses between thalamocortical axons and cortical neurons, an event that coincides with the formation of the barrel map. They will briefly review cortical patterning and the initial targeting of thalamic axons, with an emphasis on recent findings. The rest of the review will be devoted to summarizing their understanding of the cellular and molecular mechanisms underlying thalamocortical synapse maturation and its role in barrel map formation.
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Affiliation(s)
- Melis Inan
- Program in Developmental Biology, Baylor College of Medicine, Houston TX, USA
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12
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Suzuki A, Lee LJ, Hayashi Y, Muglia L, Itohara S, Erzurumlu RS, Iwasato T. Thalamic adenylyl cyclase 1 is required for barrel formation in the somatosensory cortex. Neuroscience 2015; 290:518-29. [PMID: 25644422 DOI: 10.1016/j.neuroscience.2015.01.043] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2014] [Revised: 12/21/2014] [Accepted: 01/06/2015] [Indexed: 12/22/2022]
Abstract
Cyclic AMP signaling is critical for activity-dependent refinement of neuronal circuits. Global disruption of adenylyl cyclase 1 (AC1), the major calcium/calmodulin-stimulated adenylyl cyclase in the brain, impairs formation of whisker-related discrete neural modules (the barrels) in cortical layer 4 in mice. Since AC1 is expressed both in the thalamus and the neocortex, the question of whether pre- or postsynaptic (or both) AC1 plays a role in barrel formation has emerged. Previously, we generated cortex-specific AC1 knockout (Cx-AC1KO) mice and found that these animals develop histologically normal barrels, suggesting a potentially more prominent role for thalamic AC1 in barrel formation. To determine this, we generated three new lines of mice: one in which AC1 is disrupted in nearly half of the thalamic ventrobasal nucleus cells in addition to the cortical excitatory neurons (Cx/pTh-AC1KO mouse), and another in which AC1 is disrupted in the thalamus but not in the cortex or brainstem nuclei of the somatosensory system (Th-AC1KO mouse). Cx/pTh-AC1KO mice show severe deficits in barrel formation. Th-AC1KO mice show even more severe disruption in barrel patterning. In these two lines, single thalamocortical (TC) axon labeling revealed a larger lateral extent of TC axons in layer 4 compared to controls. In the third line, all calcium-stimulated adenylyl cyclases (both AC1 and AC8) are deleted in cortical excitatory neurons. These mice have normal barrels. Taken together, these results indicate that thalamic AC1 plays a major role in patterning and refinement of the mouse TC circuitry.
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Affiliation(s)
- A Suzuki
- Division of Neurogenetics, National Institute of Genetics (NIG), Mishima, Shizuoka 411-8540, Japan; Department of Genetics, The Graduate University for Advanced Studies (SOKENDAI), Mishima, Shizuoka 411-8540, Japan
| | - L-J Lee
- Department of Anatomy and Cell Biology, National Taiwan University, Taipei, Taiwan
| | - Y Hayashi
- Laboratory for Behavioral Genetics, RIKEN Brain Science (BSI) Institute, Wako, Saitama 351-0198, Japan
| | - L Muglia
- Perinatal Institute, Cincinnati Children's Hospital Medical Center, Department of Pediatrics, University of Cincinnati College of Medicine, Cincinnati, OH 45229, USA
| | - S Itohara
- Laboratory for Behavioral Genetics, RIKEN Brain Science (BSI) Institute, Wako, Saitama 351-0198, Japan
| | - R S Erzurumlu
- Department of Anatomy and Neurobiology, University of Maryland, Baltimore, MD 21201-1075, USA
| | - T Iwasato
- Division of Neurogenetics, National Institute of Genetics (NIG), Mishima, Shizuoka 411-8540, Japan; Department of Genetics, The Graduate University for Advanced Studies (SOKENDAI), Mishima, Shizuoka 411-8540, Japan.
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13
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Vitali I, Jabaudon D. Synaptic biology of barrel cortex circuit assembly. Semin Cell Dev Biol 2014; 35:156-64. [PMID: 25080022 DOI: 10.1016/j.semcdb.2014.07.009] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2014] [Revised: 07/10/2014] [Accepted: 07/17/2014] [Indexed: 02/04/2023]
Abstract
Mature neuronal circuits arise from the coordinated interplay of cell-intrinsic differentiation programs, target-derived signals and activity-dependent processes. Typically, cell-intrinsic mechanisms predominate at early stages of differentiation, while input-dependent processes modulate circuit formation at later stages of development. The whisker barrel cortex of rodents is particularly well suited to study this latter phase. During the first few days after birth, thalamocortical axons (TCA) from the somatosensory ventral posteromedial nucleus (VPM) form synapses onto layer 4 (L4) neurons, which aggregate to form barrels, whose spatial organization corresponds to the distribution of the whiskers on the snout. Besides specific genetic programs, which control TCA and L4 neuron specification, the establishment of the barrel pattern also depends on the information resulting from whisker activation. The plasticity of this system during the first few days after birth is critical for barrel formation: damage to the sensory periphery impairs TCA patterning, while lesions after this period have less pronounced effects. Here, we will review the role and position of L4 neurons within cortical columnar circuits and synaptogenesis during barrel formation.
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Affiliation(s)
- Ilaria Vitali
- Department of Basic Neurosciences, University of Geneva, Switzerland
| | - Denis Jabaudon
- Department of Basic Neurosciences, University of Geneva, Switzerland.
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14
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Lokmane L, Garel S. Map transfer from the thalamus to the neocortex: inputs from the barrel field. Semin Cell Dev Biol 2014; 35:147-55. [PMID: 25020201 DOI: 10.1016/j.semcdb.2014.07.005] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2014] [Revised: 07/03/2014] [Accepted: 07/04/2014] [Indexed: 01/05/2023]
Abstract
Sensory perception relies on the formation of stereotyped maps inside the brain. This feature is particularly well illustrated in the mammalian neocortex, which is subdivided into distinct cortical sensory areas that comprise topological maps, such as the somatosensory homunculus in humans or the barrel field of the large whiskers in rodents. How somatosensory maps are formed and relayed into the neocortex remain essential questions in developmental neuroscience. Here, we will present our current knowledge on whisker map transfer in the mouse model, with the goal of linking embryonic and postnatal studies into a comprehensive framework.
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Affiliation(s)
- Ludmilla Lokmane
- Ecole Normale Supérieure, Institut de Biologie de l'ENS, IBENS, 46 rue d'Ulm, Paris F-75005, France; Inserm, U1024, Paris F-75005, France; CNRS, UMR 8197, Paris F-75005, France.
| | - Sonia Garel
- Ecole Normale Supérieure, Institut de Biologie de l'ENS, IBENS, 46 rue d'Ulm, Paris F-75005, France; Inserm, U1024, Paris F-75005, France; CNRS, UMR 8197, Paris F-75005, France.
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15
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Crocker-Buque A, Brown SM, Kind PC, Isaac JTR, Daw MI. Experience-Dependent, Layer-Specific Development of Divergent Thalamocortical Connectivity. Cereb Cortex 2014; 25:2255-66. [PMID: 24610243 PMCID: PMC4494033 DOI: 10.1093/cercor/bhu031] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
Abstract
The main input to primary sensory cortex is via thalamocortical (TC) axons that form the greatest number of synapses in layer 4, but also synapse onto neurons in layer 6. The development of the TC input to layer 4 has been widely studied, but less is known about the development of the layer 6 input. Here, we show that, in neonates, the input to layer 6 is as strong as that to layer 4. Throughout the first postnatal week, there is an experience-dependent strengthening specific to layer 4, which correlates with the ability of synapses in layer 4, but not in layer 6, to undergo long-term potentiation (LTP). This strengthening consists of an increase in axon branching and the divergence of connectivity in layer 4 without a change in the strength of individual connections. We propose that experience-driven LTP stabilizes transient TC synapses in layer 4 to increase strength and divergence specifically in layer 4 over layer 6.
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Affiliation(s)
- Alex Crocker-Buque
- Centre for Integrative Physiology, University of Edinburgh, Edinburgh, UK
| | - Sarah M Brown
- Centre for Integrative Physiology, University of Edinburgh, Edinburgh, UK
| | - Peter C Kind
- Centre for Integrative Physiology, University of Edinburgh, Edinburgh, UK
| | - John T R Isaac
- Developmental Synaptic Plasticity Section, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD 20892, USA Current address: Lilly UK, Erl Wood Manor, Windlesham, UK
| | - Michael I Daw
- Centre for Integrative Physiology, University of Edinburgh, Edinburgh, UK
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Isensee J, Diskar M, Waldherr S, Buschow R, Hasenauer J, Prinz A, Allgöwer F, Herberg FW, Hucho T. Pain modulators regulate the dynamics of PKA-RII phosphorylation in subgroups of sensory neurons. J Cell Sci 2013; 127:216-29. [PMID: 24190886 DOI: 10.1242/jcs.136580] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
Knowledge about the molecular structure of protein kinase A (PKA) isoforms is substantial. In contrast, the dynamics of PKA isoform activity in living primary cells has not been investigated in detail. Using a high content screening microscopy approach, we identified the RIIβ subunit of PKA-II to be predominantly expressed in a subgroup of sensory neurons. The RIIβ-positive subgroup included most neurons expressing nociceptive markers (TRPV1, NaV1.8, CGRP, IB4) and responded to pain-eliciting capsaicin with calcium influx. Isoform-specific PKA reporters showed in sensory-neuron-derived F11 cells that the inflammatory mediator PGE₂ specifically activated PKA-II but not PKA-I. Accordingly, pain-sensitizing inflammatory mediators and activators of PKA increased the phosphorylation of RII subunits (pRII) in subgroups of primary sensory neurons. Detailed analyses revealed basal pRII to be regulated by the phosphatase PP2A. Increase of pRII was followed by phosphorylation of CREB in a PKA-dependent manner. Thus, we propose RII phosphorylation to represent an isoform-specific readout for endogenous PKA-II activity in vivo, suggest RIIβ as a novel nociceptive subgroup marker, and extend the current model of PKA-II activation by introducing a PP2A-dependent basal state.
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Affiliation(s)
- Joerg Isensee
- University Hospital Cologne, Department of Anesthesiology and Intensive Care Medicine, Experimental Anesthesiology and Pain Research, Robert Koch Str. 10, 50931 Cologne, Germany
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17
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Arnoux I, Hoshiko M, Mandavy L, Avignone E, Yamamoto N, Audinat E. Adaptive phenotype of microglial cells during the normal postnatal development of the somatosensory "Barrel" cortex. Glia 2013; 61:1582-94. [PMID: 23893820 DOI: 10.1002/glia.22503] [Citation(s) in RCA: 69] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2012] [Accepted: 03/08/2013] [Indexed: 11/06/2022]
Abstract
Accumulative evidence indicates that microglial cells influence the normal development of central nervous system (CNS) synapses. Yet, the functional properties of microglia in relation with synapse development remain unclear. We recently showed that in layer 4 of the whisker-related barrel field of the mouse somatosensory cortex, microglial cells are recruited only after postnatal day (P)5 in the center of the barrels where thalamo-cortical synapses are concentrated and begin their maturation. In the present study, we analyzed the phenotype of microglia during this developmental process. We show that between P5 and P7 microglial cells acquire a more ramified morphology with a smaller soma, they express classical markers of microglia (Iba1, CD11b, and CD68) but never markers of activation (Mac-2 and MHCII) and rarely the proliferation marker Ki67. Electrophysiological recordings in acute cortical slices showed that at P5 a proportion of layer 4 microglia transiently express voltage-dependant potassium currents of the delayed rectifier family, mostly mediated by Kv1.3 subunits, which are usually expressed by activated microglia under pathological conditions. This proportion of cells with rectifying properties doubles between P5 and P6, in concomitance with the beginning of microglia invasion of the barrel centers. Finally, analysis of the responses mediated by purinergic receptors indicated that a higher percentage of rectifying microglia expressed functional P2Y6 and P2Y12 receptors, as compared with nonrectifying cells, whereas all cells expressed functional P2X7 receptors. Our results indicate that during normal cortical development distinct microglia properties mature differentially, some of them being exquisitely influenced by the local environment of the maturating neuronal network.
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Affiliation(s)
- Isabelle Arnoux
- Inserm, U603, Paris, France; CNRS UMR, 8154, Paris, France; Paris Descartes University, Paris, France
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18
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Abstract
In primary sensory neocortical areas of mammals, the distribution of sensory receptors is mapped with topographic precision and amplification in proportion to the peripheral receptor density. The visual, somatosensory and auditory cortical maps are established during a critical period in development. Throughout this window in time, the developing cortical maps are vulnerable to deleterious effects of sense organ damage or sensory deprivation. The rodent barrel cortex offers an invaluable model system with which to investigate the mechanisms underlying the formation of topographic maps and their plasticity during development. Five rows of mystacial vibrissa (whisker) follicles on the snout and an array of sinus hairs are represented by layer IV neural modules ('barrels') and thalamocortical axon terminals in the primary somatosensory cortex. Perinatal damage to the whiskers or the sensory nerve innervating them irreversibly alters the structural organization of the barrels. Earlier studies emphasized the role of the sensory periphery in dictating whisker-specific brain maps and patterns. Recent advances in molecular genetics and analyses of genetically altered mice allow new insights into neural pattern formation in the neocortex and the mechanisms underlying critical period plasticity. Here, we review the development and patterning of the barrel cortex and the critical period plasticity.
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Affiliation(s)
- Reha S Erzurumlu
- Department of Anatomy and Neurobiology, University of Maryland School of Medicine, Baltimore, MD 21201-1075, USA.
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19
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Hirayama T, Tarusawa E, Yoshimura Y, Galjart N, Yagi T. CTCF is required for neural development and stochastic expression of clustered Pcdh genes in neurons. Cell Rep 2012; 2:345-57. [PMID: 22854024 DOI: 10.1016/j.celrep.2012.06.014] [Citation(s) in RCA: 134] [Impact Index Per Article: 11.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2012] [Revised: 06/13/2012] [Accepted: 06/15/2012] [Indexed: 12/17/2022] Open
Abstract
The CCCTC-binding factor (CTCF) is a key molecule for chromatin conformational changes that promote cellular diversity, but nothing is known about its role in neurons. Here, we produced mice with a conditional knockout (cKO) of CTCF in postmitotic projection neurons, mostly in the dorsal telencephalon. The CTCF-cKO mice exhibited postnatal growth retardation and abnormal behavior and had defects in functional somatosensory mapping in the brain. In terms of gene expression, 390 transcripts were expressed at significantly different levels between CTCF-deficient and control cortex and hippocampus. In particular, the levels of 53 isoforms of the clustered protocadherin (Pcdh) genes, which are stochastically expressed in each neuron, declined markedly. Each CTCF-deficient neuron showed defects in dendritic arborization and spine density during brain development. Their excitatory postsynaptic currents showed normal amplitude but occurred with low frequency. Our results indicate that CTCF regulates functional neural development and neuronal diversity by controlling clustered Pcdh expression.
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Affiliation(s)
- Teruyoshi Hirayama
- KOKORO-Biology Group, Laboratories for Integrated Biology, Graduate School of Frontier Biosciences, Osaka University, Suita, Japan
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20
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Zaccaria KJ, McCasland JS. Emergence of layer IV barrel cytoarchitecture is delayed in somatosensory cortex of GAP-43 deficient mice following delayed development of dendritic asymmetry. Somatosens Mot Res 2012; 29:77-88. [PMID: 22759196 DOI: 10.3109/08990220.2012.686936] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
The emergence of barrel cytoarchitecture in mouse somatosensory cortex is extremely well defined. However, mechanisms underlying the development of this cellular organization are not completely understood. While it is generally accepted that hollows emerge via passive displacement of cortical cells by dense thalamocortical afferent clusters in barrel centers, it is not known what causes cellular segregation of barrel sides and septa. Here, we hypothesized that the emergence of sides and septa is related to the progressive asymmetry of dendrites from the cells of the barrel side toward the barrel hollow during development. We tested this hypothesis in the barrel cortex of growth-associated protein-43 heterozygous mice (GAP43 (+/-) mice) that display a 2-day delay in retraction of septally oriented dendrites compared to (+/+) littermates. We predicted that this delayed retraction would result in a subsequent 2-day delay in the emergence of barrel sides and septa. Using cresyl violet staining of barrel cortex, we found that initial emergence of hollows was not different between GAP43 (+/-) mice and (+/+) littermate controls. However, the emergence of sides and septa was delayed by 2 days, supporting our hypothesis that the emergence of barrel sides and septa is related to, and perhaps reliant upon, the developmental step of dendritic orientation toward barrel hollows. This process, which is mechanistically distinct from the emergence of barrel hollows, is likely due to both active and passive events resulting from asymmetric cell orientation.
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Affiliation(s)
- Kimberly J Zaccaria
- Department of Cell & Developmental Biology, SUNY Upstate Medical University, Syracuse, NY, USA.
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Neurotransmitter release at the thalamocortical synapse instructs barrel formation but not axon patterning in the somatosensory cortex. J Neurosci 2012; 32:6183-96. [PMID: 22553025 DOI: 10.1523/jneurosci.0343-12.2012] [Citation(s) in RCA: 69] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023] Open
Abstract
To assess the impact of synaptic neurotransmitter release on neural circuit development, we analyzed barrel cortex formation after thalamic or cortical ablation of RIM1 and RIM2 proteins, which control synaptic vesicle fusion. Thalamus-specific deletion of RIMs reduced neurotransmission efficacy by 67%. A barrelless phenotype was found with a dissociation of effects on the presynaptic and postsynaptic cellular elements of the barrel. Presynaptically, thalamocortical axons formed a normal whisker map, whereas postsynaptically the cytoarchitecture of layer IV neurons was altered as spiny stellate neurons were evenly distributed and their dendritic trees were symmetric. Strikingly, cortex-specific deletion of the RIM genes did not modify barrel development. Adult mice with thalamic-specific RIM deletion showed a lack of activity-triggered immediate early gene expression and altered sensory-related behaviors. Thus, efficient synaptic release is required at thalamocortical but not at corticocortical synapses for building the whisker to barrel map and for efficient sensory function.
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22
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Wu CS, Ballester Rosado CJ, Lu HC. What can we get from 'barrels': the rodent barrel cortex as a model for studying the establishment of neural circuits. Eur J Neurosci 2012; 34:1663-76. [PMID: 22103423 DOI: 10.1111/j.1460-9568.2011.07892.x] [Citation(s) in RCA: 51] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Sensory inputs triggered by external stimuli are projected into discrete arrays of neuronal modules in the primary sensory cortex. This whisker-to-barrel pathway has gained in popularity as a model system for studying the development of cortical circuits and sensory processing because its clear patterns facilitate the identification of genetically modified mice with whisker map deficits and make possible coordinated in vitro and in vivo electrophysiological studies. Numerous whisker map determinants have been identified in the past two decades. In this review, we summarize what have we learned from the detailed studies conducted in various mutant mice with cortical whisker map deficits. We will specifically focus on the anatomical and functional establishment of the somatosensory thalamocortical circuits.
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Affiliation(s)
- Chia-Shan Wu
- The Cain Foundation Laboratories, Jan and Dan Duncan Neurological Research Institute at Texas Children's Hospital, Houston, TX, USA
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23
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Till SM, Wijetunge LS, Seidel VG, Harlow E, Wright AK, Bagni C, Contractor A, Gillingwater TH, Kind PC. Altered maturation of the primary somatosensory cortex in a mouse model of fragile X syndrome. Hum Mol Genet 2012; 21:2143-56. [DOI: 10.1093/hmg/dds030] [Citation(s) in RCA: 77] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
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Hardingham NR, Gould T, Fox K. Anatomical and sensory experiential determinants of synaptic plasticity in layer 2/3 pyramidal neurons of mouse barrel cortex. J Comp Neurol 2011; 519:2090-124. [PMID: 21452214 DOI: 10.1002/cne.22583] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
A minority of layer 2/3 (L2/3) pyramidal neurons exhibit spike-timing-dependent long-term potentiation (LTP) in normally reared adolescent mice. To determine whether particular subtypes of L2/3 neurons have a greater capacity for LTP than others, we correlated the morphological and electrophysiological properties of L2/3 neurons with their ability to undergo LTP by using a spike-timing-dependent protocol applied via layer 4 inputs from the neighboring barrel column. No correlation was found between the incidence of LTP and the cell's electrophysiological properties, nor with their laminar or columnar location. However, in cortex of normal, undeprived mice, neurons that exhibited LTP had dendrites that extended farther horizontally than those that showed no plasticity, and this horizontal spread was due to off-axis apical dendrites. From a sample of reconstructed neurons, two-thirds of neurons' dendritic arborizations reached into at least one adjacent barrel column. We also tested whether this relationship persisted following a short period of whisker deprivation. The probability of inducing LTP increased from 33% in cortex of undeprived mice to 53% following 7 days of whisker deprivation, and the incidence of LTD with the same protocol decreased from 49% to 9%. In deprived cortex, neurons exhibiting LTP did not extend any farther horizontally than those that showed no plasticity. Whisker deprivation did not affect horizontal spread of dendrites nor dendritic structure in general but did produced an increase in spine density, both on basal and on apical dendrites, suggesting a possible substrate for the increased levels of LTP observed in deprived cortex.
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Affiliation(s)
- Neil R Hardingham
- Cardiff School of Bioscience, Cardiff University, Cardiff CF10 3AX, UK.
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25
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Abstract
The somatosensory cortex of many rodents, lagomorphs, and marsupials contains distinct cytoarchitectonic features named "barrels" that reflect the pattern of large facial whiskers on the snout. Barrels are composed of clustered thalamocortical afferents relaying sensory information from one whisker surrounded by cell-dense walls or "barrels" in layer 4 of the cortex. In many ways, barrels are a simple and relatively accessible canonical cortical column, making them a common model system for the examination of cortical development and function. Despite their experimental accessibility and popularity, we still lack a basic understanding of how and why barrels form in the first place. In this review, we will examine what is known about mechanisms of barrel development, focusing specifically on the recent literature using the molecular-genetic power of mice as a model system for examining brain development.
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Affiliation(s)
- Hong Li
- Department of Neurobiology, Yale University School of Medicine, New Haven, Connecticut, USA
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26
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Wang GL, Jiang PJ, Wang XH, Chen W. Construction of a eukaryotic expression plasmid encoding the human PKAR IIβ gene and its expression in human gastric cancer BGC-823 cells. Shijie Huaren Xiaohua Zazhi 2011; 19:1446-1450. [DOI: 10.11569/wcjd.v19.i14.1446] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
AIM: To construct a eukaryotic expression plasmid encoding the human protein kinase A regulatory subunit II beta (PKAR IIβ) gene and to examine its expression and localization in BGC-823 gastric cells using green fluorescent protein as a reporter.
METHODS: The coding sequence of the PKAR IIβ gene was amplified from the plasmid pRSETB-PKARIIβ by PCR and subcloned into pEGFP-C1 vector after digestion with Xho I and EcoR I. After the identity of recombinant plasmid was verified by direct sequencing, the plasmid was transfected into BGC-823 cells. The expression of the recombinant plasmid in BGC-823 cells was detected by Western blot. The localization of GFP-PKARIIβ in BGC-823 cells was observed by laser scanning confocal microscopy.
RESULTS: The coding sequence of the PKARIIβ gene was inserted into the pEGFP-C1 vector successfully. Restriction enzymes digestion showed that the length of the insert was 1.2 kb, matching the expected size. The expression of GFP-PKARIIβ fusion protein, which had a molecular weight of 72 000 Da, was detected in BGC-823 cells by Western blot. The GFP-PKARIIβ protein was localized predominantly to the cytoplasm but sparsely to the nucleus of HEK293 and BGC-823 cells.
CONCLUSION: A recombinant plasmid expressing the PKARIIβ gene has been successfully constructed and provides a tool for future investigation of PKARIIβ functions. The GFP-PKARIIβ fusion protein was expressed mainly in the cytoplasm of HEK293 and BGC7901 cells.
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Han L, Itoh K, Yaoi T, Moriwaki S, Kato S, Nakamura K, Fushiki S. Prenatal and Lactational Exposure to Bisphenol A in Mice Alters Expression of Genes Involved in Cortical Barrel Development without Morphological Changes. Acta Histochem Cytochem 2011; 44:25-33. [PMID: 21448315 PMCID: PMC3061449 DOI: 10.1267/ahc.10042] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2010] [Accepted: 01/05/2011] [Indexed: 01/01/2023] Open
Abstract
It has been reported that premature infants in neonatal intensive care units are exposed to a high rate of bisphenol A (BPA), an endocrine disrupting chemical. Our previous studies demonstrated that corticothalamic projection was disrupted by prenatal exposure to BPA, which persisted even in adult mice. We therefore analyzed whether prenatal and lactational exposure to low doses of BPA affected the formation of the cortical barrel, the barreloid of the thalamus, and the barrelette of the brainstem in terms of the histology and the expression of genes involved in the barrel development. Pregnant mice were injected subcutaneously with 20 µg/kg of BPA daily from embryonic day 0 (E0) to postnatal 3 weeks (P3W), while the control mice received a vehicle alone. The barrel, barreloid and barrelette of the adult mice were examined by cytochrome C oxidase (COX) staining. There were no significant differences in the total and septal areas and the patterning of the posterior medial barrel subfield (PMBSF), barreloid and barrelette, between the BPA-exposure and control groups in the adult mice. The developmental study at postnatal day 1 (PD1), PD4 and PD8 revealed that the cortical barrel vaguely appeared at PD4 and completely formed at PD8 in both groups. The expression pattern of some genes was spatiotemporally altered depending on the sex and the treatment. These results suggest that the trigeminal projection and the thalamic relay to the cortical barrel were spared after prenatal and lactational exposure to low doses of BPA, although prenatal exposure to BPA was previously shown to disrupt the corticothalamic projection.
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Affiliation(s)
- Longzhe Han
- Department of Pathology and Applied Neurobiology, Graduate School of Medical Science, Kyoto Prefectural University of Medicine
| | - Kyoko Itoh
- Department of Pathology and Applied Neurobiology, Graduate School of Medical Science, Kyoto Prefectural University of Medicine
| | - Takeshi Yaoi
- Department of Pathology and Applied Neurobiology, Graduate School of Medical Science, Kyoto Prefectural University of Medicine
| | - Sanzo Moriwaki
- Department of Pathology and Applied Neurobiology, Graduate School of Medical Science, Kyoto Prefectural University of Medicine
| | - Shingo Kato
- Department of Pathology and Applied Neurobiology, Graduate School of Medical Science, Kyoto Prefectural University of Medicine
| | - Keiko Nakamura
- Department of Pathology and Applied Neurobiology, Graduate School of Medical Science, Kyoto Prefectural University of Medicine
| | - Shinji Fushiki
- Department of Pathology and Applied Neurobiology, Graduate School of Medical Science, Kyoto Prefectural University of Medicine
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mGluR5 in cortical excitatory neurons exerts both cell-autonomous and -nonautonomous influences on cortical somatosensory circuit formation. J Neurosci 2011; 30:16896-909. [PMID: 21159961 DOI: 10.1523/jneurosci.2462-10.2010] [Citation(s) in RCA: 57] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
Glutamatergic neurotransmission plays important roles in sensory map formation. The absence of the group I metabotropic glutamate receptor 5 (mGluR5) leads to abnormal sensory map formation throughout the mouse somatosensory pathway. To examine the role of cortical mGluR5 expression on barrel map formation, we generated cortex-specific mGluR5 knock-out (KO) mice. Eliminating mGluR5 function solely in cortical excitatory neurons affects, not only the whisker-related organization of cortical neurons (barrels), but also the patterning of their presynaptic partners, the thalamocortical axons (TCAs). In contrast, subcortical whisker maps develop normally in cortical-mGluR5 KO mice. In the S1 cortex of cortical-mGluR5 KO, layer IV neurons are homogenously distributed and have no clear relationship to the location of TCA clusters. The altered dendritic morphology of cortical layer IV spiny stellate neurons in cortical-mGluR5 KO mice argues for a cell-autonomous role of mGluR5 in dendritic patterning. Furthermore, morphometric analysis of single TCAs in both cortical- and global-mGluR5 KO mice demonstrated that in these mice, the complexity of axonal arbors is reduced, while the area covered by TCA arbors is enlarged. Using voltage-clamp whole-cell recordings in acute thalamocortical brain slices, we found that KO of mGluR5 from cortical excitatory neurons reduced inhibitory but not excitatory inputs onto layer IV neurons. This suggests that mGluR5 signaling in cortical excitatory neurons nonautonomously modulates the functional development of GABAergic circuits. Together, our data provide strong evidence that mGluR5 signaling in cortical principal neurons exerts both cell-autonomous and -nonautonomous influences to modulate the formation of cortical sensory circuits.
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Maklad A, Conway M, Hodges C, Hansen LA. Development of innervation to maxillary whiskers in mice. Anat Rec (Hoboken) 2010; 293:1553-67. [PMID: 20648571 DOI: 10.1002/ar.21194] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
The maxillary vibrissal pad is a unique, richly innervated sensory apparatus. It is highly evolved in the rodent that it constitutes a major source of sensory information to the somatosensory cortex. In this report, indocarbocyanine tracing and immunofluorescence were used to study the embryonic and early neonatal development of innervation to maxillary vibrissal follicles in mice. The first sign of vibrissal follicle innervation occurred at embryonic day 12 (E12), when the lateral nasal and maxillary processes were penetrated by nerve branches with small terminal plexuses assuming the positions of vibrissal follicle primordia. Between E13 and E15, the nerve plexuses at the presumptive follicles grew in size and became more numerous with no signs of specific receptor subtype formation. By E17, the nerve plexuses had grown further in size and the region-specific receptor subtype specification developed. At birth (P0), the superficial vibrissal nerves began to innervate the apical part of the inner conical body, whereas the deep vibrissal nerve gave off the recurrent cavernous branches. At P3, all of the different sets of receptor subtypes had regional distributions, densities and morphologies comparable to those described in adult mice. A 3-day old mouse had all complements of sensory receptors necessary for somatosensory transduction as revealed not only by neuroanatomic tracing but also with immunofluorescence for several markers of neurosensory differentiation. Our data reveal a hitherto unknown time table for the development of peripheral sensory receptors in the vibrissal follicles. This time table parallels that of their central targets in the somatosensory barrel cortex, which develops at P4.
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Affiliation(s)
- Adel Maklad
- Department of Anatomy, University of Mississippi Medical Center, Jackson, Mississippi 39216, USA.
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30
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Abstract
NMDARs (N-methyl-D-aspartate receptors) are critical for synaptic function throughout the CNS (central nervous system). NMDAR-mediated Ca(2+) influx is implicated in neuronal differentiation, neuronal migration, synaptogenesis, structural remodelling, long-lasting forms of synaptic plasticity and higher cognitive functions. NMDAR-mediated Ca(2+) signalling in dendritic spines is not static, but can be remodelled in a cell- and synapse-specific manner by NMDAR subunit composition, protein kinases and neuronal activity during development and in response to sensory experience. Recent evidence indicates that Ca(2+) permeability of neuronal NMDARs, NMDAR-mediated Ca(2+) signalling in spines and induction of NMDAR-dependent LTP (long-term potentiation) at hippocampal Schaffer collateral-CA1 synapses are under control of the cAMP/PKA (protein kinase A) signalling cascade. Thus, by enhancing Ca(2+) influx through NMDARs in spines, PKA can regulate the induction of LTP. An emerging concept is that activity-dependent regulation of NMDAR-mediated Ca(2+) signalling by PKA and by extracellular signals that modulate cAMP or protein phosphatases at synaptic sites provides a dynamic and potentially powerful mechanism for bi-directional regulation of synaptic efficacy and remodelling.
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31
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Kelly EA, Tremblay ME, McCasland JS, Majewska AK. Postsynaptic deregulation in GAP-43 heterozygous mouse barrel cortex. Cereb Cortex 2009; 20:1696-707. [PMID: 19915093 DOI: 10.1093/cercor/bhp231] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
Formation of whisker-related barrels in primary somatosensory cortex (S1) requires communication between presynaptic thalamocortical afferents (TCAs) and postsynaptic cortical neurons. GAP-43 is crucially involved in targeting TCAs to postsynaptic S1 neurons but its influence on the interactions between these 2 elements has not been explored. Here, we tested the hypothesis that reduced early expression of presynaptic GAP-43 (GAP-43 heterozygous [HZ] mice) alters postsynaptic differentiation of barrel cells. We found a transient increase in cytochrome oxidase staining between P6 and P14 in HZ animals, indicative of increased metabolic activity in barrel cortex during this time. Golgi impregnation and microtubule-associated protein 2 immunohistochemistry showed anomalous dendritic patterning in GAP-43 HZ cortex at P5, with altered dendritic length and branching and abnormal retention of dendrites that extend into developing septa. This deficiency was no longer apparent at P7, suggesting partial recovery of dendritic pruning processes. Finally, we showed early defects in synaptogenesis from P4 to P5 with increased colocalization of NR1 and GluR1 staining in HZ mice. By P7, this colocalization had normalized to wild type levels. Taken together, our findings suggest abnormal postsynaptic differentiation in GAP-43 HZ cortex during early barrel development, followed by adaptive compensation and partial phenotypic rescue.
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Affiliation(s)
- Emily A Kelly
- Department of Neurobiology and Anatomy, University of Rochester School of Medicine and Dentistry, Rochester, NY 14642, USA
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32
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Early development of the thalamic inhibitory feedback loop in the primary somatosensory system of the newborn mice. J Neurosci 2009; 29:9930-40. [PMID: 19657043 DOI: 10.1523/jneurosci.1671-09.2009] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Spontaneous neuronal activity plays an important role during the final development of the brain circuits and the formation of the primary sensory maps. In young rats, spindle bursts have been recorded in the primary somatosensory cortex. They are correlated with spontaneous muscle twitches and occur before active whisking. They bear similarities with the spindles recorded in adult brain that occur during early stages of sleep and rely on a thalamic feedback loop between the glutamatergic nucleus ventroposterior medialis (nVPM) and the GABAergic nucleus reticularis thalami (nRT). However, whether a functional nVPM-nRT loop exists in newborn rodents is unknown. We studied the reciprocal synaptic connections between nVPM and nRT in thalamic acute slices from mice from birth [postnatal day 0 (P0)] until P9. We first demonstrated that nVPM-to-nRT EPSCs could be distinguished from corticothalamic EPSCs by their inhibition by 5-HT attributable to the transient expression of functional presynaptic serotonin 1B receptors. The nVPM-to-nRT EPSCs and nRT-to-nVPM IPSCs were both detected the first day after birth; their amplitude near 2 nS was relatively stable until P5. At P6-P7, there was a rapid and simultaneous increase of both nVPM-to-nRT EPSCs and nRT-to-nVPM IPSCs that reached 8 and 9 nS, respectively. Our results show that the thalamic synapses implicated in spindle activity are functional shortly after birth, suggesting that they could already generate spindles during the first postnatal week. Our results also suggest an inhibitory action of 5-HT on the spindle bursts of the newborn mice.
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Zhong H, Sia GM, Sato TR, Gray NW, Mao T, Khuchua Z, Huganir RL, Svoboda K. Subcellular dynamics of type II PKA in neurons. Neuron 2009; 62:363-74. [PMID: 19447092 PMCID: PMC2702487 DOI: 10.1016/j.neuron.2009.03.013] [Citation(s) in RCA: 96] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2008] [Revised: 11/12/2008] [Accepted: 03/18/2009] [Indexed: 02/05/2023]
Abstract
Protein kinase A (PKA) plays multiple roles in neurons. The localization and specificity of PKA are largely controlled by A-kinase anchoring proteins (AKAPs). However, the dynamics of PKA in neurons and the roles of specific AKAPs are poorly understood. We imaged the distribution of type II PKA in hippocampal and cortical layer 2/3 pyramidal neurons in vitro and in vivo. PKA was concentrated in dendritic shafts compared to the soma, axons, and dendritic spines. This spatial distribution was imposed by the microtubule-binding protein MAP2, indicating that MAP2 is the dominant AKAP in neurons. Following cAMP elevation, catalytic subunits dissociated from the MAP2-tethered regulatory subunits and rapidly became enriched in nearby spines. The spatial gradient of type II PKA between dendritic shafts and spines was critical for the regulation of synaptic strength and long-term potentiation. Therefore, the localization and activity-dependent translocation of type II PKA are important determinants of PKA function.
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Affiliation(s)
- Haining Zhong
- Howard Hughes Medical Institute Janelia Farm Research Campus, Ashburn, VA 20147, USA.
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Kajana S, Goshgarian HG. Systemic administration of rolipram increases medullary and spinal cAMP and activates a latent respiratory motor pathway after high cervical spinal cord injury. J Spinal Cord Med 2009; 32:175-82. [PMID: 19569465 PMCID: PMC2678289 DOI: 10.1080/10790268.2009.11760769] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/21/2022] Open
Abstract
BACKGROUND/OBJECTIVE High cervical spinal cord hemisection interrupts descending respiratory drive from the rostral ventral respiratory group in the medulla to the ipsilateral phrenic motoneurons. Hemisection results in the paralysis of the ipsilateral hemidiaphragm. Chronic administration of rolipram, a specific phosphodiesterase-IV inhibitor, promotes synaptic plasticity and restores phrenic nerve function after a high cervical spinal cord lesion. Here, we test the hypothesis that an acute administration of rolipram will increase spinal and medullary levels of 3',5'-cyclic adenosine monophosphate (cAMP) and induce phrenic nerve recovery after cervical (C2) spinal cord hemisection. METHODS Male Sprague-Dawley rats were subjected to left C2 hemisection surgery 1 week before experimentation. Bilateral phrenic nerve activity was recorded in anesthetized, vagotomized, and pancuronium paralyzed rats, and rolipram was intravenously applied (2 mg/kg). RESULTS Intravenous administration of rolipram increased phrenic nerve output in uninjured control and left C2 spinal cord-hemisected rats. In addition, rolipram restored respiratory-related activity to the left phrenic nerve made quiescent by the hemisection. In both uninjured and hemisected rats, rolipram significantly enhanced phrenic inspiratory burst amplitude and burst area compared with predrug values. Also, rolipram concomitantly increased spinal and medullary cAMP. CONCLUSIONS These results suggest that a phosphodiesterase inhibitor capable of elevating cAMP levels can enhance phrenic nerve output and restore respiratory-related phrenic nerve function after high cervical spinal cord injury. Thus, targeting the cAMP signaling cascade can be a useful therapeutic approach in promoting synaptic efficacy and respiratory recovery after cervical spinal cord injury.
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She WC, Quairiaux C, Albright MJ, Wang YC, Sanchez DE, Chang PS, Welker E, Lu HC. Roles of mGluR5 in synaptic function and plasticity of the mouse thalamocortical pathway. Eur J Neurosci 2009; 29:1379-96. [PMID: 19519626 DOI: 10.1111/j.1460-9568.2009.06696.x] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The group I metabotropic glutamate receptor 5 (mGluR5) has been implicated in the development of cortical sensory maps. However, its precise roles in the synaptic function and plasticity of thalamocortical (TC) connections remain unknown. Here we first show that in mGluR5 knockout (KO) mice bred onto a C57BL6 background cytoarchitectonic differentiation into barrels is missing, but the representations for large whiskers are identifiable as clusters of TC afferents. The altered dendritic morphology of cortical layer IV spiny stellate neurons in mGluR5 KO mice implicates a role for mGluR5 in the dendritic morphogenesis of excitatory neurons. Next, in vivo single-unit recordings of whisker-evoked activity in mGluR5 KO adults demonstrated a preserved topographical organization of the whisker representation, but a significantly diminished temporal discrimination of center to surround whiskers in the responses of individual neurons. To evaluate synaptic function at TC synapses in mGluR5 KO mice, whole-cell voltage-clamp recording was conducted in acute TC brain slices prepared from postnatal day 4-11 mice. At mGluR5 KO TC synapses, N-methyl-D-aspartate (NMDA) currents decayed faster and synaptic strength was more easily reduced, but more difficult to strengthen by Hebbian-type pairing protocols, despite a normal developmental increase in alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptor (AMPAR)-mediated currents and presynaptic function. We have therefore demonstrated that mGluR5 is required for synaptic function/plasticity at TC synapses as barrels are forming, and we propose that these functional alterations at the TC synapse are the basis of the abnormal anatomical and functional development of the somatosensory cortex in the mGluR5 KO mouse.
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Affiliation(s)
- Wei-Chi She
- Department of Pediatrics, The Cain Foundation Laboratories, Baylor College of Medicine, Houston, TX 77030, USA
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Abstract
We have previously reported that mGluR5 signaling via PLC-beta1 regulates the development of whisker patterns within S1 (barrel) cortex of mice (Hannan et al., 2001). However, whether these defects arise from the loss of postsynaptic mGluR5 signaling, and whether the level of mGluR5 is important for barrel formation, was not examined. Furthermore, whether mGluR5 regulates other developmental processes that occur before or after barrel development is not known. We now show that mGluR5 is present postsynaptically at thalamocortical synapses during barrel formation. In addition, Mglur5(+/-) mice exhibit normal TCA patch formation but reduced cellular segregation in layer 4, indicating a dose-dependent role for mGluR5 in the regulation of pattern formation. Furthermore Mglur5(-/-) and Mglur5(+/-) mice display normal cortical arealization, layer formation, and size of PMBSF indicating the defects within S1 do not result from general abnormalities of cortical mapping during earlier stages of development. At P21 layer 4 neurons from Mglur5(-/-) and Mglur5(+/-) mice show a significant reduction in spine density but normal dendritic complexity compared with Mglur5(+/+) mice indicating a role in synaptogenesis during cortical development. Finally, mGluR5 regulates pattern formation throughout the trigeminal system of mice as the representation of the AS whiskers in the PrV, VpM, and S1 cortex was disrupted in Mglur5(-/-) mice. Together these data indicate a key role for mGluR5 at both early and late stages of neuronal development in the trigeminal system of mice.
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Sequential changes in AMPA receptor targeting in the developing neocortical excitatory circuit. J Neurosci 2009; 28:13918-28. [PMID: 19091980 DOI: 10.1523/jneurosci.3229-08.2008] [Citation(s) in RCA: 66] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
Many principal neurons undergo an early developmental switch from GluR2-lacking to GluR2-containing synaptic glutamate receptors. We tested the generality and timing of the GluR2 switch in excitatory neurons of rat somatosensory cortex. Previous studies show that the switch occurs between postnatal day 14 (P14) and P16 in layer 5 pyramidal neurons. We show, using sensitivity to intracellular spermine, that a similar switch occurs between P12 and P14 in layer 2/3 pyramidal cells and between P7 and P8 in layer 4 stellate cells. The presence of GluR2-lacking receptors in layer 2/3 pyramidal cells before P12 was confirmed by demonstrating sensitivity to blockade by 1-naphthyl-acetyl-spermine and large single-channel conductances. GluR2 and the postsynaptic protein PSD95 show progressive colocalization in tissue from P10, P14, and P24 rats, mirroring electrophysiological developments. To distinguish whether changes in GluR2 expression or targeting underlie the switch, we characterized dendritic AMPA receptor responses using focal photolysis of caged glutamate. Contrary to synaptic responses, dendritic responses at all ages studied (P6-P40) were characteristic of GluR2-containing receptors. In addition, dendritically and synaptically evoked responses showed a corresponding decrease in NMDA/AMPA ratios in pyramidal cells, suggesting parallel mechanisms that regulate neuronal calcium levels. These data suggest that the GluR2 switch results from changes in AMPA receptor targeting during early postnatal development, and that rather than following the laminar sequence of cortical development, it proceeds sequentially from layer 4 to layer 2/3 and finally to layer 5b.
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Bahia CP, Houzel JC, Picanço-Diniz CW, Pereira A. Spatiotemporal distribution of proteoglycans in the developing rat's barrel field and the effects of early deafferentation. J Comp Neurol 2008; 510:145-57. [DOI: 10.1002/cne.21781] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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Yang Y, Takeuchi K, Rodenas-Ruano A, Takayasu Y, Bennett MVL, Zukin RS. Developmental switch in requirement for PKA RIIbeta in NMDA-receptor-dependent synaptic plasticity at Schaffer collateral to CA1 pyramidal cell synapses. Neuropharmacology 2008; 56:56-65. [PMID: 18789341 DOI: 10.1016/j.neuropharm.2008.08.013] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2008] [Revised: 08/01/2008] [Accepted: 08/01/2008] [Indexed: 11/24/2022]
Abstract
The cAMP/protein kinase A (PKA) signaling cascade is crucial for synaptic plasticity in a wide variety of species. PKA regulates Ca2+ permeation through NMDA receptors (NMDARs) and induction of NMDAR-dependent synaptic plasticity at the Schaffer collateral to CA1 pyramidal cell synapse. Whereas the role of PKA in induction of NMDAR-dependent LTP at CA1 synapses is established, the identity of PKA isoforms involved in this phenomenon is less clear. Here we report that protein synthesis-independent NMDAR-dependent LTP at the Schaffer collateral-CA1 synapse in the hippocampus is deficient, but NMDAR-dependent LTD is normal, in young (postnatal day 10 (P10)-P14) mice lacking PKA RIIbeta, the PKA regulatory protein that links PKA to NMDARs at synaptic sites. In contrast, in young adult (P21-P28) mice lacking PKA RIIbeta, LTP is normal and LTD is abolished. These findings indicate that distinct PKA isoforms may subserve distinct forms of synaptic plasticity and are consistent with a developmental switch in the signaling cascades required for LTP induction.
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Affiliation(s)
- Yupeng Yang
- Dominick P. Purpura Department of Neuroscience, Kennedy Center Room 602B, Albert Einstein College of Medicine, 1300 Morris Park Avenue, Bronx, NY 10461, USA
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Kichula EA, Huntley GW. Developmental and comparative aspects of posterior medial thalamocortical innervation of the barrel cortex in mice and rats. J Comp Neurol 2008; 509:239-58. [PMID: 18496871 DOI: 10.1002/cne.21690] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
The thalamocortical projection to the rodent barrel cortex consists of inputs from the ventral posterior medial (VPM) and posterior medial (POm) nuclei that terminate in largely nonoverlapping territories in and outside of layer IV. This projection in both rats and mice has been used extensively to study development and plasticity of highly organized synaptic circuits. Whereas the VPM pathway has been well characterized in both rats and mice, organization of the POm pathway has only been described in rats, and no studies have focused exclusively on the development of the POm projection. Here, using transport of Phaseolus vulgaris leucoagglutinin(PHA-L) or carbocyanine dyes, we characterize the POm thalamocortical innervation of adult mouse barrel cortex and describe its early postnatal development in both mice and rats. In adult mice, POm inputs form a dense plexus in layer Va that extends uniformly underneath layer IV barrels and septa. Innervation of layer IV is very sparse; a clear septal innervation pattern is evident only at the layer IV/Va border. This pattern differs subtly from that described previously in rats. Developmentally, in both species, POm axons are present in barrel cortex at birth. In mice, they occupy layer IV as it differentiates, whereas in rats, POm axons do not enter layer IV until 1-2 days after its emergence from the cortical plate. In both species, arbors undergo progressive and directed growth. However, no layer IV septal innervation pattern emerges until several days after the cytoarchitectonic appearance of barrels and well after the emergence of whisker-related clusters of VPM thalamocortical axons. The mature pattern resolves earlier in rats than in mice. Taken together, these data reveal anatomical differences between mice and rats in the development and organization of POm inputs to barrel cortex, with implications for species differences in the nature and plasticity of lemniscal and paralemniscal information processing.
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Affiliation(s)
- Elizabeth A Kichula
- Fishberg Department of Neuroscience, The Mount Sinai School of Medicine, New York, New York 10029-6574, USA
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Kajana S, Goshgarian HG. Spinal activation of the cAMP-PKA pathway induces respiratory motor recovery following high cervical spinal cord injury. Brain Res 2008; 1232:206-13. [PMID: 18656458 DOI: 10.1016/j.brainres.2008.07.012] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2008] [Revised: 07/02/2008] [Accepted: 07/02/2008] [Indexed: 11/18/2022]
Abstract
The present study investigated the involvement of the adenosine 3'5'-cyclic monophosphate-dependent protein kinase A (cAMP-PKA) pathway in the activation of the crossed-phrenic pathways after left C2 spinal cord hemisection. Experiments were conducted on left C2 spinal cord hemisected, anesthetized, vagotomized, pancuronium paralyzed, and artificially ventilated male Sprague-Dawley rats. One week post-injury, the ipsilateral phrenic nerve exhibited no respiratory-related activity indicating a functionally complete hemisection. Intrathecal spinal cord administration of the cAMP analog, 8-Br-cAMP at the level of the phrenic nucleus resulted in an enhancement of contralateral phrenic nerve output and a restoration of respiratory-related activity in the phrenic nerve ipsilateral to the hemisection. Furthermore, pre-treatment with Rp-8-Br-cAMP, a PKA inhibitor, abolished the effects of 8-Br-cAMP. These results suggest that PKA activation is necessary for the cAMP-mediated respiratory recovery following high cervical spinal cord injury and that activation of intracellular signaling cascades may represent an important strategy for improving respiratory function after spinal cord injury.
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Affiliation(s)
- S Kajana
- Department of Anatomy and Cell Biology, Wayne State University School of Medicine, 540 East Canfield, Detroit, MI 48201, USA
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Cortical adenylyl cyclase 1 is required for thalamocortical synapse maturation and aspects of layer IV barrel development. J Neurosci 2008; 28:5931-43. [PMID: 18524897 DOI: 10.1523/jneurosci.0815-08.2008] [Citation(s) in RCA: 60] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Experimental evidence from mutant or genetically altered mice indicates that the formation of barrels and the proper maturation of thalamocortical (TC) synapses in the primary somatosensory (barrel) cortex depend on mechanisms mediated by neural activity. Type 1 adenylyl cyclase (AC1), which catalyzes the formation of cAMP, is stimulated by increases in intracellular Ca(2+) levels in an activity-dependent manner. The AC1 mutant mouse, barrelless (brl), lacks typical barrel cytoarchitecture, and displays presynaptic and postsynaptic functional defects at TC synapses. However, because AC1 is expressed throughout the trigeminal pathway, the barrel cortex phenotype of brl mice may be a consequence of AC1 disruption in cortical or subcortical regions. To examine the role of cortical AC1 in the development of morphological barrels and TC synapses, we generated cortex-specific AC1 knock-out (CxAC1KO) mice. We found that neurons in layer IV form grossly normal barrels and TC axons fill barrel hollows in CxAC1KO mice. In addition, whisker lesion-induced critical period plasticity was not impaired in these mice. However, we found quantitative reductions in the quality of cortical barrel cytoarchitecture and dendritic asymmetry of layer IV barrel neurons in CxAC1KO mice. Electrophysiologically, CxAC1KO mice have deficits in the postsynaptic but not in the presynaptic maturation of TC synapses. These results suggest that activity-dependent postsynaptic AC1-cAMP signaling is required for functional maturation of TC synapses and the development of normal barrel cortex cytoarchitecture. They also suggest that the formation of the gross morphological features of barrels is independent of postsynaptic AC1 in the barrel cortex.
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In DRG11 knock-out mice, trigeminal cell death is extensive and does not account for failed brainstem patterning. J Neurosci 2008; 28:3577-85. [PMID: 18385316 DOI: 10.1523/jneurosci.4203-07.2008] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
A previous study (Ding et al., 2003) showed that the homeodomain transcription factor DRG11 is necessary for pattern formation in the trigeminal nucleus principalis (PrV), the requisite brainstem nucleus for development of the whisker-to-barrel cortex pathway. However, it is not known how DRG11 contributes to pattern formation. Anatomical studies were performed in DRG11 knock-out (-/-) and DRG11/Bax double -/- mice to test the hypotheses that DRG11 is required for neuronal survival in the V pathway and that PrV cell death is sufficient to explain pattern alterations. At birth, DRG11(-/-) mice had equivalent cell loss in the V ganglion, PrV, and spinal V subnucleus interpolaris (SpVi). Because whisker-related patterns were normal in the SpVi, cell death would not appear to explain failed pattern formation in the mutant PrV. Electron microscopy revealed exuberant apoptosis and necrosis as the mechanisms of PrV cell death occurring in the late prenatal and newborn DRG11(-/-), when such cell death was up to six times more prevalent than normal. DRG11 heterozygote and Bax(-/-) mice were crossed in an attempt to dissociate PrV patterning anomalies from exuberant apoptosis in DRG11(-/-) mice. Both DRG11(-/-) and DRG11/Bax double -/- mutants lacked whisker-related patterning in their PrV, despite Bax(-/-)-induced rescue of V ganglion and PrV cells. Thus, apoptotic cell death is not a sufficient cause of failed pattern formation in the PrV of the DRG11(-/-). A signaling pathway involving DRG11 may, therefore, be the elusive PrV pattern maker.
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Abstract
The rodent barrel cortex is a useful system to study the role of genes and neuronal activity in the patterning of the nervous system. Several genes encoding either intracellular signaling molecules or neurotransmitter receptors are required for barrel formation. Neurofibromin is a tumor suppressor protein that has Ras GTPase activity, thus attenuating the MAPK (mitogen-activated protein kinase) and and PI-3 kinase (phosphatidylinositol 3-kinase) pathways, and is mutated in humans with the condition neurofibromatosis type 1 (NF1). Neurofibromin is widely expressed in the developing and adult nervous system, and a common feature of NF1 is deficits in intellectual development. In addition, NF1 is an uncommonly high disorder among individuals with autism. Thus, NF1 may have important roles in normal CNS development and function. To explore roles for neurofibromin in the development of the CNS, we took advantage of a mouse conditional allele. We show that mice that lack neurofibromin in the majority of cortical neurons and astrocytes fail to form cortical barrels in the somatosensory cortex, whereas segregation of thalamic axons within the somatosensory cortex appears unaffected.
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Kajana S, Goshgarian HG. Administration of phosphodiesterase inhibitors and an adenosine A1 receptor antagonist induces phrenic nerve recovery in high cervical spinal cord injured rats. Exp Neurol 2008; 210:671-80. [PMID: 18289533 DOI: 10.1016/j.expneurol.2007.12.021] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2007] [Revised: 12/20/2007] [Accepted: 12/21/2007] [Indexed: 02/01/2023]
Abstract
High cervical spinal cord hemisection interrupts the descending respiratory drive from the medulla to the ipsilateral phrenic motoneurons, consequently leading to the paralysis of the ipsilateral hemidiaphragm. Previous studies have shown that chronic oral administration of theophylline, a phosphodiesterase inhibitor and an adenosine receptor antagonist, can restore function to the quiescent phrenic nerve and hemidiaphragm ipsilateral to hemisection. Both of these actions of theophylline result in an increase in 3'-5'-cyclic adenosine monophosphate (cAMP). Furthermore, the chronic theophylline-mediated respiratory recovery persists long after the animals have been weaned from the drug. To date, the precise cellular mechanisms underlying the recovery induced by theophylline are still not known. Since theophylline has two modes of action, in the present study we tested whether chronic administration of pentoxifylline, a non-selective phosphodiesterase inhibitor, rolipram, a phosphodiesterase-4 specific inhibitor, and 8-cyclopentyl-1,3-dipropylxanthine (DPCPX), an adenosine A1 receptor antagonist, would induce recovery similar to that induced by theophylline in male Sprague-Dawley rats following a left C2 spinal cord lesion. Recovery of left phrenic nerve activity was assessed at 5 or 10 days after the last drug administrations to assess the persistent nature of the recovery. Pentoxifylline, rolipram and DPCPX, all capable of modulating 3',5'-cyclic monophosphate (cAMP) levels, brought about long-term respiratory recovery in the phrenic nerve ipsilateral to the left C2 lesion at 5 and 10 days after the last drug administration. Therefore, these results suggest that compounds capable of regulating cAMP levels may be therapeutically useful in promoting functional recovery following spinal cord injury.
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Affiliation(s)
- S Kajana
- Department of Anatomy and Cell Biology, Wayne State University, School of Medicine, Detroit, MI 48201, USA
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Gong B, Wang H, Gu S, Heximer SP, Zhuo M. Genetic evidence for the requirement of adenylyl cyclase 1 in synaptic scaling of forebrain cortical neurons. Eur J Neurosci 2007; 26:275-88. [PMID: 17650106 DOI: 10.1111/j.1460-9568.2007.05669.x] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Homeostatic plasticity is important to stabilize the activity level of neuronal circuits. Molecular mechanisms underlying neuronal homeostatic plasticity in response to activity deprivation are not completely understood. We found that prolonged alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) receptor blockade by 6-cyano-7-nitroquinoxaline-2,3-dione (CNQX) resulted in larger, faster miniature excitatory postsynaptic current (mEPSC) events with enhanced frequency in cultured forebrain cortical neurons. Furthermore, GluR1 protein level and CREB-dependent transcription were up-regulated. Blockade of L-type Ca(2+) channels but not kainate receptors produced similar effects to the AMPA receptor blockade. Genetic deletion of AC1 (adenylyl cyclase 1), but not AC8, a key neuronal adenylyl cyclase, significantly reduced inactivity-induced GluR1 changes. Our results indicate the synthesis of homomeric GluR1 AMPA receptors and their possible insertion into synapses due to synaptic inactivity in the cortex. AC1 plays a subtype selective role in this process by coupling signals from L-type Ca(2+) channels to downstream signalling pathways.
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MESH Headings
- 6-Cyano-7-nitroquinoxaline-2,3-dione/pharmacology
- Adenylyl Cyclases/genetics
- Adenylyl Cyclases/physiology
- Animals
- Blotting, Western
- Calcium Channels, L-Type/drug effects
- Cells, Cultured
- Cerebral Cortex/cytology
- Cerebral Cortex/enzymology
- Cerebral Cortex/physiology
- Cyclic AMP/physiology
- Data Interpretation, Statistical
- Electrophysiology
- Excitatory Amino Acid Antagonists/pharmacology
- Genes, Reporter/genetics
- Luciferases/genetics
- Luciferases/metabolism
- Mice
- Mice, Knockout
- Neurons/enzymology
- Neurons/physiology
- Patch-Clamp Techniques
- Prosencephalon/enzymology
- Prosencephalon/physiology
- Receptors, AMPA/drug effects
- Receptors, Kainic Acid/drug effects
- Receptors, N-Methyl-D-Aspartate/drug effects
- Signal Transduction/physiology
- Synapses/enzymology
- Synapses/physiology
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Affiliation(s)
- Bo Gong
- Department of Physiology, Faculty of Medicine, University of Toronto, 1 King's College Circle, Toronto, Ontario, Canada
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Albright MJ, Weston MC, Inan M, Rosenmund C, Crair MC. Increased thalamocortical synaptic response and decreased layer IV innervation in GAP-43 knockout mice. J Neurophysiol 2007; 98:1610-25. [PMID: 17581849 DOI: 10.1152/jn.00219.2007] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
The growth-associated protein, GAP-43, is an axonally localized neuronal protein with high expression in the developing brain and in regenerating neurites. Mice that lack GAP-43 (GAP-43 -/-) fail to form a whisker-related barrel map. In this study, we use GAP-43 -/- mice to examine GAP-43 synaptic function in the context of thalamocortical synapse development and cortical barrel map formation. Examination of thalamocortical synaptic currents in an acute brain slice preparation and in autaptic thalamic neurons reveals that GAP-43 -/- synapses have larger alpha-amino-3-hydroxyl-5-methyl-4-isoxazolepropionate receptor (AMPAR)-mediated currents than controls despite similar AMPAR function and normal probability of vesicular release. Interestingly, GAP-43 -/- synapses are less sensitive to blockade by a competitive glutamate receptor antagonist, suggesting higher levels of neurotransmitter in the cleft during synaptic transmission. Field excitatory postsynaptic potentials (EPSPs) from GAP-43 -/- thalamocortical synapses reveal a reduced fiber response, and anatomical analysis shows reduced thalamic innervation of barrel cortex in GAP-43 -/- mice. Despite this fact synaptic responses in the field EPSPs are similar in GAP-43 -/- mice and wild-type littermate controls, and the ratio of AMPAR-mediated to N-methyl-d-aspartate receptor (NMDAR)-mediated currents (AMPAR:NMDAR ratio) is larger than normal. This suggests that GAP-43 -/- mice form fewer thalamocortical synapses in layer IV because of decreased anatomical innervation of the cortex, but the remaining contacts are individually stronger possibly due to increased neurotransmitter concentration in the synaptic cleft. Together, these results indicate that in addition to its well known role in axonal pathfinding GAP-43 plays a functional role in regulating neurotransmitter release.
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Affiliation(s)
- Michael J Albright
- Department of Neuroscience, Baylor College of Medicine, Houston, Texas, USA
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Leamey CA, Flett DL, Ho SM, Marotte LR. Development of structural and functional connectivity in the thalamocortical somatosensory pathway in the wallaby. Eur J Neurosci 2007; 25:3058-70. [PMID: 17561819 DOI: 10.1111/j.1460-9568.2007.05556.x] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Neuronal activity is implicated as a driving force in the development of sensory systems. In order for it to play a developmental role, however, the pathways involved must be capable of transmitting this activity. The relationship between afferent arrival, synapse formation and the onset of chemical neurotransmission has been examined using the advantageous model of a marsupial mammal, the wallaby (Macropus eugenii), to determine at what stage activity has the capacity to influence cortical development. It is known that thalamocortical afferents arrive in the somatosensory cortex on postnatal day (P)15 and that their growth cones reach to the base of the compact cell zone of the cortical plate. However, electronmicroscopy showed that thalamocortical synapses were absent at this stage. Glutamatergic responses were recorded in the cortex following stimulation of the thalamus in slices at this time but only in magnesium-free conditions. The responses were mediated entirely by N-methyl-d-aspartate (NMDA) receptors. From P28, responses could be recorded in normal magnesium and comprised a dominant NMDA-mediated component and a non-NMDA mediated component. At this time thalamocortical synapses were first identified and they were in the cortical plate. By P63 the non-NMDA-mediated component had increased relative to the NMDA-mediated component, and by P70 layer IV began to emerge and contained thalamocortical synapses. By P76 a fast non-NMDA-mediated peak dominated the response. This coincides with the appearance of cortical whisker-related patches and the onset in vivo of responses to peripheral stimulation of the whiskers.
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Affiliation(s)
- C A Leamey
- Departments of Physiology and Anatomy & Histology, School of Medical Sciences and Bosch Institute for Medical Research, University of Sydney, Sydney, New South Wales, 2006, Australia.
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Golshani P, Hutnick L, Schweizer F, Fan G. Conditional Dnmt1 deletion in dorsal forebrain disrupts development of somatosensory barrel cortex and thalamocortical long-term potentiation. ACTA ACUST UNITED AC 2007; 3:227-233. [PMID: 17710197 PMCID: PMC1948851 DOI: 10.1017/s1472928807000222] [Citation(s) in RCA: 59] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
The transcriptional mechanisms governing the development and plasticity of somatopic sensory maps in the cerebral cortex have not been extensively studied. In particular, no studies have addressed the role of epigenetic mechanisms in the development of sensory maps. DNA methylation is one the main epigenetic mechanisms available to mammalian cells to regulate gene transcription. As demethylation results in embryonic lethality, it has been very difficult to study the role of DNA methylation in brain development. We have used cre-lox technology to generate forebrain-specific deletion of DNA methyltransferase 1 (Dnmt1), the enzyme required for the maintenance of DNA methylation. We find that demethylation of neurons in the cerebral cortex results in the failure of development of somatosensory barrel cortex. We also find that in spite of functional thalamocortical neurotransmission, thalamocortical long-term potentiation cannot be induced in slices from Dnmt1 conditional mutants. These studies emphasize the importance of DNA methylation for the development of sensory maps and suggest epigenetic mechanisms may play a role in the development of synaptic plasticity.
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Affiliation(s)
- Peyman Golshani
- Department of Neurology, David Geffen School of Medicine, UCLA, Los Angeles, CA 90095
| | - Leah Hutnick
- Neuroscience Interdepartmental Program, David Geffen School of Medicine, UCLA, Los Angeles, CA 90095
| | - Felix Schweizer
- Department of Neurobiology, David Geffen School of Medicine, UCLA, Los Angeles, CA 90095
| | - Guoping Fan
- Department of Human Genetics, David Geffen School of Medicine, UCLA, Los Angeles, CA 90095
- * Correspondence: Guoping Fan, Ph.D., Department of Human Genetics, David Geffen School of Medicine, University of California, Los Angeles, 695 Charles Young Drive South, Los Angeles, CA 90095, Phone: (310) 267-0439, Fax: (310) 794-5446,
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Daw MI, Scott HL, Isaac JTR. Developmental synaptic plasticity at the thalamocortical input to barrel cortex: mechanisms and roles. Mol Cell Neurosci 2007; 34:493-502. [PMID: 17329121 PMCID: PMC1952688 DOI: 10.1016/j.mcn.2007.01.001] [Citation(s) in RCA: 60] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2006] [Revised: 12/21/2006] [Accepted: 01/03/2007] [Indexed: 11/28/2022] Open
Abstract
The thalamocortical (TC) input to layer IV provides the major pathway for ascending sensory information to the mammalian sensory cortex. During development there is a dramatic refinement of this input that underlies the maturation of the topographical map in layer IV. Over the last 10 years our understanding of the mechanisms of the developmental and experience-driven changes in synaptic function at TC synapses has been greatly advanced. Here we describe these studies that point to a key role for NMDA receptor-dependent synaptic plasticity, a role for kainate receptors and for a rapid maturation in GABAergic inhibition. The expression mechanisms of some of the forms of neonatal synaptic plasticity are novel and, in combination with other mechanisms, produce a layer IV circuit that exhibits functional properties necessary for mature sensory processing.
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Affiliation(s)
- Michael I Daw
- MRC Centre for Synaptic Plasticity, Department of Anatomy, University of Bristol, University Walk, Bristol BS8 1TD, UK.
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