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Huang YB, Hu CR, Zhang L, Yin W, Hu B. In Vivo Study of Dynamics and Stability of Dendritic Spines on Olfactory Bulb Interneurons in Xenopus laevis Tadpoles. PLoS One 2015; 10:e0140752. [PMID: 26485435 PMCID: PMC4617280 DOI: 10.1371/journal.pone.0140752] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2015] [Accepted: 09/30/2015] [Indexed: 01/27/2023] Open
Abstract
Dendritic spines undergo continuous remodeling during development of the nervous system. Their stability is essential for maintaining a functional neuronal circuit. Spine dynamics and stability of cortical excitatory pyramidal neurons have been explored extensively in mammalian animal models. However, little is known about spiny interneurons in non-mammalian vertebrate models. In the present study, neuronal morphology was visualized by single-cell electroporation. Spiny neurons were surveyed in the Xenopus tadpole brain and observed to be widely distributed in the olfactory bulb and telencephalon. DsRed- or PSD95-GFP-expressing spiny interneurons in the olfactory bulb were selected for in vivo time-lapse imaging. Dendritic protrusions were classified as filopodia, thin, stubby, or mushroom spines based on morphology. Dendritic spines on the interneurons were highly dynamic, especially the filopodia and thin spines. The stubby and mushroom spines were relatively more stable, although their stability significantly decreased with longer observation intervals. The 4 spine types exhibited diverse preferences during morphological transitions from one spine type to others. Sensory deprivation induced by severing the olfactory nerve to block the input of mitral/tufted cells had no significant effects on interneuron spine stability. Hence, a new model was established in Xenopus laevis tadpoles to explore dendritic spine dynamics in vivo.
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Affiliation(s)
- Yu-Bin Huang
- Chinese Academy of Sciences Key Laboratory of Brain Function and Disease, and School of Life Sciences, University of Science and Technology of China, Hefei, Anhui Province, P. R. China
| | - Chun-Rui Hu
- Chinese Academy of Sciences Key Laboratory of Brain Function and Disease, and School of Life Sciences, University of Science and Technology of China, Hefei, Anhui Province, P. R. China
| | - Li Zhang
- Chinese Academy of Sciences Key Laboratory of Brain Function and Disease, and School of Life Sciences, University of Science and Technology of China, Hefei, Anhui Province, P. R. China
| | - Wu Yin
- Chinese Academy of Sciences Key Laboratory of Brain Function and Disease, and School of Life Sciences, University of Science and Technology of China, Hefei, Anhui Province, P. R. China
| | - Bing Hu
- Chinese Academy of Sciences Key Laboratory of Brain Function and Disease, and School of Life Sciences, University of Science and Technology of China, Hefei, Anhui Province, P. R. China
- * E-mail:
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52
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Gabor C, Lymer J, Phan A, Choleris E. Rapid effects of the G-protein coupled oestrogen receptor (GPER) on learning and dorsal hippocampus dendritic spines in female mice. Physiol Behav 2015; 149:53-60. [DOI: 10.1016/j.physbeh.2015.05.017] [Citation(s) in RCA: 66] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2015] [Revised: 05/13/2015] [Accepted: 05/19/2015] [Indexed: 12/24/2022]
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Hayashi-Takagi A, Yagishita S, Nakamura M, Shirai F, Wu YI, Loshbaugh AL, Kuhlman B, Hahn KM, Kasai H. Labelling and optical erasure of synaptic memory traces in the motor cortex. Nature 2015; 525:333-8. [PMID: 26352471 PMCID: PMC4634641 DOI: 10.1038/nature15257] [Citation(s) in RCA: 437] [Impact Index Per Article: 48.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2014] [Accepted: 08/03/2015] [Indexed: 01/07/2023]
Abstract
Dendritic spines are the major loci of synaptic plasticity and are considered as possible structural correlates of memory. Nonetheless, systematic manipulation of specific subsets of spines in the cortex has been unattainable, and thus, the link between spines and memory has been correlational. We developed a novel synaptic optoprobe, AS-PaRac1 (activated synapse targeting photoactivatable Rac1), that can label recently potentiated spines specifically, and induce the selective shrinkage of AS-PaRac1-containing spines. In vivo imaging of AS-PaRac1 revealed that a motor learning task induced substantial synaptic remodelling in a small subset of neurons. The acquired motor learning was disrupted by the optical shrinkage of the potentiated spines, whereas it was not affected by the identical manipulation of spines evoked by a distinct motor task in the same cortical region. Taken together, our results demonstrate that a newly acquired motor skill depends on the formation of a task-specific dense synaptic ensemble.
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Affiliation(s)
- Akiko Hayashi-Takagi
- Laboratory of Structural Physiology, Center for Disease Biology and Integrative Medicine, Faculty of Medicine, University of Tokyo, Bunkyo-ku, Tokyo 113-0033.,PRESTO, Japan Science and Technology Agency, 4-1-8 Honcho, Kawaguchi, Saitama 332-0012, Japan
| | - Sho Yagishita
- Laboratory of Structural Physiology, Center for Disease Biology and Integrative Medicine, Faculty of Medicine, University of Tokyo, Bunkyo-ku, Tokyo 113-0033.,CREST, Japan Science and Technology Agency, 4-1-8 Honcho, Kawaguchi, Saitama 332-0012, Japan
| | - Mayumi Nakamura
- Laboratory of Structural Physiology, Center for Disease Biology and Integrative Medicine, Faculty of Medicine, University of Tokyo, Bunkyo-ku, Tokyo 113-0033
| | - Fukutoshi Shirai
- Laboratory of Structural Physiology, Center for Disease Biology and Integrative Medicine, Faculty of Medicine, University of Tokyo, Bunkyo-ku, Tokyo 113-0033
| | - Yi I Wu
- Center for Cell Analysis and Modeling, University of Connecticut Health Center, Farmington, Connecticut 06032, USA
| | - Amanda L Loshbaugh
- Lineberger Comprehensive Cancer Center, University of North Carolina, Chapel Hill, North Carolina 27599, USA.,Department of Biochemistry and Biophysics, University of North Carolina, Chapel Hill, North Carolina 27599, USA
| | - Brian Kuhlman
- Lineberger Comprehensive Cancer Center, University of North Carolina, Chapel Hill, North Carolina 27599, USA.,Department of Biochemistry and Biophysics, University of North Carolina, Chapel Hill, North Carolina 27599, USA
| | - Klaus M Hahn
- Lineberger Comprehensive Cancer Center, University of North Carolina, Chapel Hill, North Carolina 27599, USA.,Department of Pharmacology, University of North Carolina, Chapel Hill, North Carolina 27599, USA
| | - Haruo Kasai
- Laboratory of Structural Physiology, Center for Disease Biology and Integrative Medicine, Faculty of Medicine, University of Tokyo, Bunkyo-ku, Tokyo 113-0033.,CREST, Japan Science and Technology Agency, 4-1-8 Honcho, Kawaguchi, Saitama 332-0012, Japan
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55
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Lin JB, Zheng CJ, Zhang X, Chen J, Liao WJ, Wan Q. Effects of Tetramethylpyrazine on Functional Recovery and Neuronal Dendritic Plasticity after Experimental Stroke. EVIDENCE-BASED COMPLEMENTARY AND ALTERNATIVE MEDICINE : ECAM 2015; 2015:394926. [PMID: 26379744 PMCID: PMC4563062 DOI: 10.1155/2015/394926] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/28/2014] [Revised: 12/22/2014] [Accepted: 12/26/2014] [Indexed: 12/17/2022]
Abstract
The 2,3,5,6-tetramethylpyrazine (TMP) has been widely used in the treatment of ischemic stroke by Chinese doctors. Here, we report the effects of TMP on functional recovery and dendritic plasticity after ischemic stroke. A classical model of middle cerebral artery occlusion (MCAO) was established in this study. The rats were assigned into 3 groups: sham group (sham operated rats treated with saline), model group (MCAO rats treated with saline) and TMP group (MCAO rats treated with 20 mg/kg/d TMP). The neurological function test of animals was evaluated using the modified neurological severity score (mNSS) at 3 d, 7 d, and 14 d after MCAO. Animals were euthanized for immunohistochemical labeling to measure MAP-2 levels in the peri-infarct area. Golgi-Cox staining was performed to test effect of TMP on dendritic plasticity at 14 d after MCAO. TMP significantly improved neurological function at 7 d and 14 d after ischemia, increased MAP-2 level at 14 d after ischemia, and enhanced spine density of basilar dendrites. TMP failed to affect the spine density of apical dendrites and the total dendritic length. Data analyses indicate that there was significant negative correlation between mNSS and plasticity measured at 14 d after MCAO. Thus, enhanced dendritic plasticity contributes to TMP-elicited functional recovery after ischemic stroke.
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Affiliation(s)
- Jun-Bin Lin
- Department of Rehabilitation Medicine, Zhongnan Hospital of Wuhan University, Wuhan 430071, China
| | - Chan-Juan Zheng
- Department of Rehabilitation Medicine, Zhongnan Hospital of Wuhan University, Wuhan 430071, China
- Department of Rehabilitation Medicine, Center of Brain Department, Hubei Xinhua Hospital, Wuhan 430015, China
| | - Xuan Zhang
- Department of Rehabilitation Medicine, Zhongnan Hospital of Wuhan University, Wuhan 430071, China
| | - Juan Chen
- Department of Physiology, School of Medicine, Wuhan University, Wuhan 430071, China
| | - Wei-Jing Liao
- Department of Rehabilitation Medicine, Zhongnan Hospital of Wuhan University, Wuhan 430071, China
| | - Qi Wan
- Department of Physiology, School of Medicine, Wuhan University, Wuhan 430071, China
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56
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Zhang K, Zhang J, Zhou Y, Chen C, Li W, Ma L, Zhang L, Zhao J, Gan W, Zhang L, Tang P. Remodeling the Dendritic Spines in the Hindlimb Representation of the Sensory Cortex after Spinal Cord Hemisection in Mice. PLoS One 2015; 10:e0132077. [PMID: 26132157 PMCID: PMC4489092 DOI: 10.1371/journal.pone.0132077] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2015] [Accepted: 06/09/2015] [Indexed: 01/01/2023] Open
Abstract
Spinal cord injury (SCI) can induce remodeling of multiple levels of the cerebral cortex system especially in the sensory cortex. The aim of this study was to assess, in vivo and bilaterally, the remodeling of dendritic spines in the hindlimb representation of the sensory cortex after spinal cord hemisection. Thy1-YFP transgenic mice were randomly divided into the control group and the SCI group, and the spinal vertebral plates (T11–T12) of all mice were excised. Next, the left hemisphere of the spinal cord (T12) was hemisected in the SCI group. The hindlimb representations of the sensory cortex in both groups were imaged bilaterally on the day before (0d), and three days (3d), two weeks (2w), and one month (1m) after the SCI. The rates of stable, newly formed, and eliminated spines were calculated by comparing images of individual dendritic spine in the same areas at different time points. In comparison to the control group, the rate of newly formed spines in the contralateral sensory cortex of the SCI group increased at three days and two weeks after injury. The rates of eliminated spines in the bilateral sensory cortices increased and the rate of stable spines in the bilateral cortices declined at two weeks and one month. From three days to two weeks, the stable rates of bilaterally stable spines in the SCI group decreased. In comparison to the control group and contralateral cortex in the SCI group, the re-emerging rate of eliminated spines in ipsilateral cortex of the SCI group decreased significantly. The stable rates of newly formed spines in bilateral cortices of the SCI group decreased from two weeks to one month. We found that the remodeling in the hindlimb representation of the sensory cortex after spinal cord hemisection occurred bilaterally. This remodeling included eliminating spines and forming new spines, as well as changing the reorganized regions of the brain cortex after the SCI over time. Soon after the SCI, the cortex was remodeled by increasing spine formation in the contralateral cortex. Then it was remodeled prominently by eliminating spines of bilateral cortices. Spinal cord hemisection also caused traditional stable spines to become unstable and led the eliminated spines even more hard to recur especially in the ipsilateral cortex of the SCI group. In addition, it also made the new formed spines unstable.
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Affiliation(s)
- Kexue Zhang
- Department of Orthopaedics, General Hospital of Chinese PLA, Beijing, 100853, People's Republic of China
| | - Jinhui Zhang
- Department of Orthopaedics, General Hospital of Chinese PLA, Beijing, 100853, People's Republic of China
| | - Yanmei Zhou
- Drug Discovery Center, Key Laboratory of Chemical Genomics, Peking University Shenzhen Graduate School, Shenzhen, 518055, People's Republic of China
| | - Chao Chen
- Department of Orthopaedics, General Hospital of Chinese PLA, Beijing, 100853, People's Republic of China
| | - Wei Li
- Drug Discovery Center, Key Laboratory of Chemical Genomics, Peking University Shenzhen Graduate School, Shenzhen, 518055, People's Republic of China
| | - Lei Ma
- Drug Discovery Center, Key Laboratory of Chemical Genomics, Peking University Shenzhen Graduate School, Shenzhen, 518055, People's Republic of China
| | - Licheng Zhang
- Department of Orthopaedics, General Hospital of Chinese PLA, Beijing, 100853, People's Republic of China
| | - Jingxin Zhao
- Department of Orthopaedics, General Hospital of Chinese PLA, Beijing, 100853, People's Republic of China
| | - Wenbiao Gan
- Department of Physiology and Neuroscience, New York University School of Medicine, New York, New York, 10016, United States of America
| | - Lihai Zhang
- Department of Orthopaedics, General Hospital of Chinese PLA, Beijing, 100853, People's Republic of China
| | - Peifu Tang
- Department of Orthopaedics, General Hospital of Chinese PLA, Beijing, 100853, People's Republic of China
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57
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Zemmar A, Kast B, Lussi K, Luft AR, Schwab ME. Acquisition of a High-precision Skilled Forelimb Reaching Task in Rats. J Vis Exp 2015:e53010. [PMID: 26131653 DOI: 10.3791/53010] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/31/2022] Open
Abstract
Movements are the main measurable output of central nervous system function. Developing behavioral paradigms that allow detailed analysis of motor learning and execution is of critical importance in order to understand the principles and processes that underlie motor function. Here we present a paradigm to study movement acquisition within a daily session of training (within-session) representing the fast learning component and primary acquisition as well as skilled motor learning over several training sessions (between-session) representing the slow learning component and consolidation of the learned task. This behavioral paradigm increases the degree of difficulty and complexity of the motor skill task due to two features: First, the animal realigns its body prior to each pellet retrieval forcing renewed orientation and preventing movement execution from the same angle. Second, pellets are grasped from a vertical post that matches the diameter of the pellet and is placed in front of the cage. This requires a precise grasp for successful pellet retrieval and thus prevents simple pulling of the pellet towards the animal. In combination with novel genetics, imaging and electrophysiological technologies, this behavioral method will aid to understand the morphological, anatomical and molecular underpinnings of motor learning and memory.
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Affiliation(s)
- Ajmal Zemmar
- Brain Research Institute, University of Zurich; Department of Biology and Department of Health Sciences and Technology, ETH Zurich;
| | - Brigitte Kast
- Brain Research Institute, University of Zurich; Department of Biology and Department of Health Sciences and Technology, ETH Zurich
| | - Karin Lussi
- Brain Research Institute, University of Zurich; Department of Biology and Department of Health Sciences and Technology, ETH Zurich
| | - Andreas R Luft
- Clinical Neurorehabilitation, Department of Neurology, University of Zurich & University Hospital Zurich
| | - Martin E Schwab
- Brain Research Institute, University of Zurich; Department of Biology and Department of Health Sciences and Technology, ETH Zurich;
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58
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Motor cortex layer V pyramidal neurons exhibit dendritic regression, spine loss, and increased synaptic excitation in the presymptomatic hSOD1(G93A) mouse model of amyotrophic lateral sclerosis. J Neurosci 2015; 35:643-7. [PMID: 25589758 DOI: 10.1523/jneurosci.3483-14.2015] [Citation(s) in RCA: 92] [Impact Index Per Article: 10.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Motor cortex layer V pyramidal neurons (LVPNs) regulate voluntary control of motor output and selectively degenerate (along with lower motor neurons) in amyotrophic lateral sclerosis. Using dye-filling and whole-cell patch clamping in brain slices, together with high-resolution spinning disk confocal z-stack mosaics, we characterized the earliest presymptomatic cortical LVPN morphologic and electrophysiological perturbations in hSOD1(G93A) (SOD1) mice to date. Apical dendritic regression occurred from postnatal day (P) 28, dendritic spine loss from P21, and increased EPSC frequency from P21 in SOD1 LVPNs. These findings demonstrate extensive early changes in motor cortex of the SOD1 mouse model, which thus recapitulates clinically relevant cortical pathophysiology more faithfully than previously thought.
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59
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Arendt KL, Zhang Y, Jurado S, Malenka RC, Südhof TC, Chen L. Retinoic Acid and LTP Recruit Postsynaptic AMPA Receptors Using Distinct SNARE-Dependent Mechanisms. Neuron 2015; 86:442-56. [PMID: 25843403 DOI: 10.1016/j.neuron.2015.03.009] [Citation(s) in RCA: 57] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2014] [Revised: 02/06/2015] [Accepted: 02/26/2015] [Indexed: 11/28/2022]
Abstract
Retinoic acid (RA)-dependent homeostatic plasticity and NMDA receptor-dependent long-term potentiation (LTP), a form of Hebbian plasticity, both enhance synaptic strength by increasing the abundance of postsynaptic AMPA receptors (AMPARs). However, it is unclear whether the molecular mechanisms mediating AMPAR trafficking during homeostatic and Hebbian plasticity differ, and it is unknown how RA signaling impacts Hebbian plasticity. Here, we show that RA increases postsynaptic AMPAR abundance using an activity-dependent mechanism that requires a unique SNARE (soluble NSF-attachment protein receptor)-dependent fusion machinery different from that mediating LTP. Specifically, RA-induced AMPAR trafficking did not involve complexin, which activates SNARE complexes containing syntaxin-1 or -3, but not complexes containing syntaxin-4, whereas LTP required complexin. Moreover, RA-induced AMPAR trafficking utilized the Q-SNARE syntaxin-4, whereas LTP utilized syntaxin-3; both additionally required the Q-SNARE SNAP-47 and the R-SNARE synatobrevin-2. Finally, acute RA treatment blocked subsequent LTP expression, probably by increasing AMPAR trafficking. Thus, RA-induced homeostatic plasticity involves a novel, activity-dependent postsynaptic AMPAR-trafficking pathway mediated by a unique SNARE-dependent fusion machinery.
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Affiliation(s)
- Kristin L Arendt
- Department of Neurosurgery, Stanford University School of Medicine, 265 Campus Drive, Stanford, CA 94305-5453, USA
| | - Yingsha Zhang
- Department of Molecular and Cellular Physiology, Stanford University School of Medicine, 265 Campus Drive, Stanford, CA 94305-5453, USA
| | - Sandra Jurado
- Nancy Pritzker Laboratory, Department of Psychiatry and Behavioral Sciences, Stanford University School of Medicine, 265 Campus Drive, Stanford, CA 94305-5453, USA
| | - Robert C Malenka
- Nancy Pritzker Laboratory, Department of Psychiatry and Behavioral Sciences, Stanford University School of Medicine, 265 Campus Drive, Stanford, CA 94305-5453, USA
| | - Thomas C Südhof
- Department of Molecular and Cellular Physiology, Stanford University School of Medicine, 265 Campus Drive, Stanford, CA 94305-5453, USA; Howard Hughes Medical Institute, Stanford University School of Medicine, 265 Campus Drive, Stanford, CA 94305-5453, USA
| | - Lu Chen
- Department of Neurosurgery, Stanford University School of Medicine, 265 Campus Drive, Stanford, CA 94305-5453, USA.
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60
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Mostany R, Miquelajauregui A, Shtrahman M, Portera-Cailliau C. Two-photon excitation microscopy and its applications in neuroscience. Methods Mol Biol 2015; 1251:25-42. [PMID: 25391792 PMCID: PMC9809210 DOI: 10.1007/978-1-4939-2080-8_2] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
Two-photon excitation (2PE) overcomes many challenges in fluorescence microscopy. Compared to confocal microscopy, 2PE microscopy improves depth penetration, owing to the longer excitation wavelength required and to the ability to collect scattered emission photons as a useful signal. It also minimizes photodamage because lower energy photons are used and because fluorescence is confined to the geometrical focus of the laser spot. 2PE is therefore ideal for high-resolution, deep-tissue, time-lapse imaging of dynamic processes in cell biology. Here, we provide examples of important applications of 2PE for in vivo imaging of neuronal structure and signals; we also describe how it can be combined with optogenetics or photolysis of caged molecules to simultaneously probe and control neuronal activity.
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Affiliation(s)
- Ricardo Mostany
- Department of Neurology, David Geffen School of Medicine at UCLA, 710 Westwood Plaza, Los Angeles, CA, 90095, USA
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61
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Kanamori T, Togashi K, Koizumi H, Emoto K. Dendritic Remodeling. INTERNATIONAL REVIEW OF CELL AND MOLECULAR BIOLOGY 2015; 318:1-25. [DOI: 10.1016/bs.ircmb.2015.05.001] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
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de Xivry JJO, Shadmehr R. Electrifying the motor engram: effects of tDCS on motor learning and control. Exp Brain Res 2014; 232:3379-95. [PMID: 25200178 PMCID: PMC4199902 DOI: 10.1007/s00221-014-4087-6] [Citation(s) in RCA: 43] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2014] [Accepted: 08/26/2014] [Indexed: 01/08/2023]
Abstract
Learning to control our movements is accompanied by neuroplasticity of motor areas of the brain. The mechanisms of neuroplasticity are diverse and produce what is referred to as the motor engram, i.e., the neural trace of the motor memory. Transcranial direct current stimulation (tDCS) alters the neural and behavioral correlates of motor learning, but its precise influence on the motor engram is unknown. In this review, we summarize the effects of tDCS on neural activity and suggest a few key principles: (1) Firing rates are increased by anodal polarization and decreased by cathodal polarization, (2) anodal polarization strengthens newly formed associations, and (3) polarization modulates the memory of new/preferred firing patterns. With these principles in mind, we review the effects of tDCS on motor control, motor learning, and clinical applications. The increased spontaneous and evoked firing rates may account for the modulation of dexterity in non-learning tasks by tDCS. The facilitation of new association may account for the effect of tDCS on learning in sequence tasks while the ability of tDCS to strengthen memories of new firing patterns may underlie the effect of tDCS on consolidation of skills. We then describe the mechanisms of neuroplasticity of motor cortical areas and how they might be influenced by tDCS. We end with current challenges for the fields of brain stimulation and motor learning.
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Affiliation(s)
- Jean-Jacques Orban de Xivry
- Institute of Information and Communication Technologies, Electronics and Applied Mathematics (ICTEAM) and Institute of Neuroscience (IoNS), Université catholique de Louvain, Louvain-La-Neuve, Belgium
| | - Reza Shadmehr
- Laboratory for Computational Motor Control, Department of Biomedical Engineering Johns Hopkins School of Medicine, Baltimore, MD, USA
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63
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Neutralization of Nogo-A enhances synaptic plasticity in the rodent motor cortex and improves motor learning in vivo. J Neurosci 2014; 34:8685-98. [PMID: 24966370 DOI: 10.1523/jneurosci.3817-13.2014] [Citation(s) in RCA: 68] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
The membrane protein Nogo-A is known as an inhibitor of axonal outgrowth and regeneration in the CNS. However, its physiological functions in the normal adult CNS remain incompletely understood. Here, we investigated the role of Nogo-A in cortical synaptic plasticity and motor learning in the uninjured adult rodent motor cortex. Nogo-A and its receptor NgR1 are present at cortical synapses. Acute treatment of slices with function-blocking antibodies (Abs) against Nogo-A or against NgR1 increased long-term potentiation (LTP) induced by stimulation of layer 2/3 horizontal fibers. Furthermore, anti-Nogo-A Ab treatment increased LTP saturation levels, whereas long-term depression remained unchanged, thus leading to an enlarged synaptic modification range. In vivo, intrathecal application of Nogo-A-blocking Abs resulted in a higher dendritic spine density at cortical pyramidal neurons due to an increase in spine formation as revealed by in vivo two-photon microscopy. To investigate whether these changes in synaptic plasticity correlate with motor learning, we trained rats to learn a skilled forelimb-reaching task while receiving anti-Nogo-A Abs. Learning of this cortically controlled precision movement was improved upon anti-Nogo-A Ab treatment. Our results identify Nogo-A as an influential molecular modulator of synaptic plasticity and as a regulator for learning of skilled movements in the motor cortex.
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64
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Hu F, Xu L, Liu ZH, Ge MM, Ruan DY, Wang HL. Developmental lead exposure alters synaptogenesis through inhibiting canonical Wnt pathway in vivo and in vitro. PLoS One 2014; 9:e101894. [PMID: 24999626 PMCID: PMC4084981 DOI: 10.1371/journal.pone.0101894] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2014] [Accepted: 06/12/2014] [Indexed: 11/19/2022] Open
Abstract
Lead (Pb) exposure has been implicated in the impairment of synaptic plasticity in the developing hippocampus, but the mechanism remains unclear. Here, we investigated whether developmental lead exposure affects the dendritic spine formation through Wnt signaling pathway in vivo and in vitro. Sprague–Dawley rats were exposed to lead throughout the lactation period and Golgi-Cox staining method was used to examine the spine density of pyramidal neurons in the hippocampal CA1 area of rats. We found that lead exposure significantly decreased the spine density in both 14 and 21 days-old pups, accompanied by a significant age-dependent decline of the Wnt7a expression and stability of its downstream protein (β-catenin). Furthermore, in cultured hippocampal neurons, lead (0.1 and 1 µM lead acetate) significantly decreased the spine density in a dose-dependent manner. Exogenous Wnt7a application attenuated the decrease of spine density and increased the stability of the downstream molecules in Wnt signaling pathway. Together, our results suggest that lead has a negative impact on spine outgrowth in the developing hippocampus through altering the canonical Wnt pathway.
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Affiliation(s)
- Fan Hu
- School of Biotechnology and Food Engineering, Hefei University of Technology, Hefei, Anhui, China
| | - Li Xu
- School of Biotechnology and Food Engineering, Hefei University of Technology, Hefei, Anhui, China
| | - Zhi-Hua Liu
- School of Biotechnology and Food Engineering, Hefei University of Technology, Hefei, Anhui, China
| | - Meng-Meng Ge
- School of Biotechnology and Food Engineering, Hefei University of Technology, Hefei, Anhui, China
| | - Di-Yun Ruan
- School of Biotechnology and Food Engineering, Hefei University of Technology, Hefei, Anhui, China
- School of Life Sciences, University of Science and Technology of China, Hefei, Anhui, China
| | - Hui-Li Wang
- School of Biotechnology and Food Engineering, Hefei University of Technology, Hefei, Anhui, China
- * E-mail:
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65
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Knoblauch A, Körner E, Körner U, Sommer FT. Structural synaptic plasticity has high memory capacity and can explain graded amnesia, catastrophic forgetting, and the spacing effect. PLoS One 2014; 9:e96485. [PMID: 24858841 PMCID: PMC4032253 DOI: 10.1371/journal.pone.0096485] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2013] [Accepted: 04/08/2014] [Indexed: 11/19/2022] Open
Abstract
Although already William James and, more explicitly, Donald Hebb's theory of cell assemblies have suggested that activity-dependent rewiring of neuronal networks is the substrate of learning and memory, over the last six decades most theoretical work on memory has focused on plasticity of existing synapses in prewired networks. Research in the last decade has emphasized that structural modification of synaptic connectivity is common in the adult brain and tightly correlated with learning and memory. Here we present a parsimonious computational model for learning by structural plasticity. The basic modeling units are "potential synapses" defined as locations in the network where synapses can potentially grow to connect two neurons. This model generalizes well-known previous models for associative learning based on weight plasticity. Therefore, existing theory can be applied to analyze how many memories and how much information structural plasticity can store in a synapse. Surprisingly, we find that structural plasticity largely outperforms weight plasticity and can achieve a much higher storage capacity per synapse. The effect of structural plasticity on the structure of sparsely connected networks is quite intuitive: Structural plasticity increases the "effectual network connectivity", that is, the network wiring that specifically supports storage and recall of the memories. Further, this model of structural plasticity produces gradients of effectual connectivity in the course of learning, thereby explaining various cognitive phenomena including graded amnesia, catastrophic forgetting, and the spacing effect.
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Affiliation(s)
- Andreas Knoblauch
- Engineering Faculty, Albstadt-Sigmaringen University, Albstadt, Germany
- Honda Research Institute Europe, Offenbach am Main, Germany
| | - Edgar Körner
- Honda Research Institute Europe, Offenbach am Main, Germany
| | - Ursula Körner
- Honda Research Institute Europe, Offenbach am Main, Germany
| | - Friedrich T. Sommer
- Redwood Center for Theoretical Neuroscience, University of California, Berkeley, California, United States of America
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66
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Yu X, Zuo Y. Two-photon in vivo imaging of dendritic spines in the mouse cortex using a thinned-skull preparation. J Vis Exp 2014. [PMID: 24894563 DOI: 10.3791/51520] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023] Open
Abstract
In the mammalian cortex, neurons form extremely complicated networks and exchange information at synapses. Changes in synaptic strength, as well as addition/removal of synapses, occur in an experience-dependent manner, providing the structural foundation of neuronal plasticity. As postsynaptic components of the most excitatory synapses in the cortex, dendritic spines are considered to be a good proxy of synapses. Taking advantages of mouse genetics and fluorescent labeling techniques, individual neurons and their synaptic structures can be labeled in the intact brain. Here we introduce a transcranial imaging protocol using two-photon laser scanning microscopy to follow fluorescently labeled postsynaptic dendritic spines over time in vivo. This protocol utilizes a thinned-skull preparation, which keeps the skull intact and avoids inflammatory effects caused by exposure of the meninges and the cortex. Therefore, images can be acquired immediately after surgery is performed. The experimental procedure can be performed repetitively over various time intervals ranging from hours to years. The application of this preparation can also be expanded to investigate different cortical regions and layers, as well as other cell types, under physiological and pathological conditions.
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Affiliation(s)
- Xinzhu Yu
- Department of Molecular Cell and Developmental Biology, University of California, Santa Cruz
| | - Yi Zuo
- Department of Molecular Cell and Developmental Biology, University of California, Santa Cruz;
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67
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Chen CC, Lu J, Zuo Y. Spatiotemporal dynamics of dendritic spines in the living brain. Front Neuroanat 2014; 8:28. [PMID: 24847214 PMCID: PMC4023020 DOI: 10.3389/fnana.2014.00028] [Citation(s) in RCA: 70] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2014] [Accepted: 04/18/2014] [Indexed: 02/01/2023] Open
Abstract
Dendritic spines are ubiquitous postsynaptic sites of most excitatory synapses in the mammalian brain, and thus may serve as structural indicators of functional synapses. Recent works have suggested that neuronal coding of memories may be associated with rapid alterations in spine formation and elimination. Technological advances have enabled researchers to study spine dynamics in vivo during development as well as under various physiological and pathological conditions. We believe that better understanding of the spatiotemporal patterns of spine dynamics will help elucidate the principles of experience-dependent circuit modification and information processing in the living brain.
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Affiliation(s)
- Chia-Chien Chen
- Department of Molecular, Cell and Developmental Biology, University of California at Santa Cruz Santa Cruz, CA, USA
| | - Ju Lu
- Department of Biological Sciences and James H. Clark Center, Stanford University Stanford, CA, USA
| | - Yi Zuo
- Department of Molecular, Cell and Developmental Biology, University of California at Santa Cruz Santa Cruz, CA, USA
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68
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Chen CC, Gilmore A, Zuo Y. Study motor skill learning by single-pellet reaching tasks in mice. J Vis Exp 2014. [PMID: 24637358 DOI: 10.3791/51238] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023] Open
Abstract
Reaching for and retrieving objects require precise and coordinated motor movements in the forelimb. When mice are repeatedly trained to grasp and retrieve food rewards positioned at a specific location, their motor performance (defined as accuracy and speed) improves progressively over time, and plateaus after persistent training. Once such reaching skill is mastered, its further maintenance does not require constant practice. Here we introduce a single-pellet reaching task to study the acquisition and maintenance of skilled forelimb movements in mice. In this video, we first describe the behaviors of mice that are commonly encountered in this learning and memory paradigm, and then discuss how to categorize these behaviors and quantify the observed results. Combined with mouse genetics, this paradigm can be utilized as a behavioral platform to explore the anatomical underpinnings, physiological properties, and molecular mechanisms of learning and memory.
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Affiliation(s)
- Chia-Chien Chen
- Department of Molecular, Cell and Developmental Biology, University of California, Santa Cruz
| | - Anthony Gilmore
- Department of Molecular, Cell and Developmental Biology, University of California, Santa Cruz
| | - Yi Zuo
- Department of Molecular, Cell and Developmental Biology, University of California, Santa Cruz;
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69
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Olini N, Huber R. Diurnal changes in electrocorticogram sleep slow-wave activity during development in rats. J Sleep Res 2014; 23:261-7. [PMID: 24456043 DOI: 10.1111/jsr.12124] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2013] [Accepted: 11/26/2013] [Indexed: 12/01/2022]
Abstract
According to the homeostatic regulation of sleep, sleep pressure accumulates during wakefulness, further increases during sleep deprivation and dissipates during subsequent sleep. Sleep pressure is electrophysiologically reflected by electroencephalogram slow-wave activity during non-rapid eye movement sleep, and is thought to be stable across time. During childhood and adolescence the brain undergoes massive reorganization processes. Slow-wave activity during these developmental periods has been shown in humans to follow an inverted U-shaped trajectory, which recently was replicated in rats. The goal of this study was to investigate in rats the diurnal changes of slow-wave activity during the inverted U-shaped developmental trajectory of slow-wave activity. To do so, we performed longitudinal electrocorticogram recordings, and compared the level of slow-wave activity at the beginning with the slow-wave activity level at the end of 24-h baselines in two sets of Sprague-Dawley rats. In younger animals (n = 17) we investigated specific postnatal days when overall slow-wave activity increases (postnatal day 26), peaks (postnatal day 28) and decreases (>postnatal day 28). The same analysis was performed in older animals (postnatal day 48, n = 6). Our results show a gain of slow-wave activity across 24 h on postnatal day 26, followed by no net changes on postnatal day 28, which was then followed by a loss of slow-wave activity during subsequent days (>postnatal day 28). Older animals did not show any net changes in slow-wave activity across 24 h. These results cannot be explained by differences in vigilance states. Thus, slow-wave activity during this developmental period may not only reflect the trajectory of sleep pressure but may additionally reflect maturational processes.
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Affiliation(s)
- Nadja Olini
- Child Development Center, University Children's Hospital Zurich, Zurich, Switzerland; Neuroscience Center Zurich (ZNZ), University of Zurich, Zurich, Switzerland
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70
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Dendritic spine remodeling induced by hindlimb unloading in adult rat sensorimotor cortex. Behav Brain Res 2013; 249:1-7. [DOI: 10.1016/j.bbr.2013.04.015] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2013] [Revised: 04/10/2013] [Accepted: 04/13/2013] [Indexed: 01/21/2023]
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71
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Abstract
The recent advent of in vivo two-photon microscopy has allowed the repeat imaging of cortical structures at microscopic resolution within intact brains. Recent data obtained using this imaging technique shows that dendritic spines, the postsynaptic sites of the majority of excitatory synapses in the central nervous system (CNS), rapidly remodel in response to changes in the visual environment. We combined two-photon microscopy of dendritic segments with intrinsic signal imaging of visual cortical responses in the developing ferret visual cortex, and showed that when one eye was deprived during the developmental critical period for ocular dominance plasticity, both dendritic spines and visual responses to the deprived eye were rapidly altered. A brief period of recovery where the eye was re-opened resulted in a return to pre-deprivation levels for both responses and dendritic spine density, showing that structural and functional changes are linked even at very rapid timescales. Additionally, two-photon microscopy can assay other functional and structural aspects of visual cortical function which I will review. Lastly, I will compare this technique to other imaging modalities available for assessment of the visual cortex in vivo.
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72
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Abstract
What is the neuroanatomical basis for the decline in brain function that occurs during normal aging? Previous postmortem studies have blamed it on a reduction in spine density, though results remain controversial and spine dynamics were not assessed. We used chronic in vivo two-photon imaging of dendritic spines and axonal boutons in somatosensory cortex for up to 1 year in thy1 GFP mice to test the hypothesis that aging is associated with alterations in synaptic dynamics. We find that the density of spines and en passant boutons (EPBs) in pyramidal cells increases throughout adult life but is stable between mature (8-15 months) and old (>20 months) mice. However, new spines and EPBs are two to three times more likely to be stabilized over 30 d in old mice, although the long-term retention (over months) of stable spines is lower in old animals. In old mice, spines are smaller on average but are still able to make synaptic connections regardless of their size, as assessed by serial section electron microscopy reconstructions of previously imaged dendrites. Thus, our data suggest that age-related deficits in sensory perception are not associated with synapse loss in somatosensory cortex (as might be expected) but with alterations in the size and stability of spines and boutons observed in this brain area. The changes we describe here likely result in weaker synapses that are less capable of short-term plasticity in aged individuals, and therefore to less efficient circuits.
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73
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Abstract
Aging is a major risk factor for many neurological diseases and is associated with mild cognitive decline. Previous studies suggest that aging is accompanied by reduced synapse number and synaptic plasticity in specific brain regions. However, most studies, to date, used either postmortem or ex vivo preparations and lacked key in vivo evidence. Thus, whether neuronal arbors and synaptic structures remain dynamic in the intact aged brain and whether specific synaptic deficits arise during aging remains unknown. Here we used in vivo two-photon imaging and a unique analysis method to rigorously measure and track the size and location of axonal boutons in aged mice. Unexpectedly, the aged cortex shows circuit-specific increased rates of axonal bouton formation, elimination, and destabilization. Compared with the young adult brain, large (i.e., strong) boutons show 10-fold higher rates of destabilization and 20-fold higher turnover in the aged cortex. Size fluctuations of persistent boutons, believed to encode long-term memories, also are larger in the aged brain, whereas bouton size and density are not affected. Our data uncover a striking and unexpected increase in axonal bouton dynamics in the aged cortex. The increased turnover and destabilization rates of large boutons indicate that learning and memory deficits in the aged brain arise not through an inability to form new synapses but rather through decreased synaptic tenacity. Overall our study suggests that increased synaptic structural dynamics in specific cortical circuits may be a mechanism for age-related cognitive decline.
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74
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Zuo Y, Yu X, Tennant K, Jones T. In vivo imaging of synapse plasticity in the mouse motor cortex. Methods Mol Biol 2013; 1010:45-57. [PMID: 23754218 DOI: 10.1007/978-1-62703-411-1_4] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
The mammalian motor cortex is capable of circuit reorganization driven by acquisition of novel motor skills. Time-lapse imaging of synaptic structures in the living brain provides valuable information on how motor learning rewires synaptic connections and how long-lasting memory is structurally encoded in the intact brain. Here we introduce a transcranial imaging protocol using two-photon laser scanning microscopy to follow fluorescently labeled postsynaptic dendritic spines in vivo. This protocol utilizes a thinned-skull preparation, which allows repetitive imaging of the same synapses over various intervals ranging from hours to years. Furthermore, intracortical microstimulation is performed at the end of repetitive imaging to confirm that images are taken from functionally responsive regions in the motor cortex.
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Affiliation(s)
- Yi Zuo
- Department of Molecular, Cell and Developmental Biology, University of California Santa Cruz, Santa Cruz, CA, USA
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75
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Low doses of 17β-estradiol rapidly improve learning and increase hippocampal dendritic spines. Neuropsychopharmacology 2012; 37:2299-309. [PMID: 22669167 PMCID: PMC3422494 DOI: 10.1038/npp.2012.82] [Citation(s) in RCA: 115] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
Abstract
While a great deal of research has been performed on the long-term genomic actions of estrogens, their rapid effects and implications for learning and memory are less well characterized. The often conflicting results of estrogenic effects on learning and memory may be due to complex and little understood interactions between genomic and rapid effects. Here, we investigated the effects of low, physiologically relevant, doses of 17β-estradiol on three different learning paradigms that assess social and non-social aspects of recognition memory and spatial memory, during a transcription independent period of memory maintenance. Ovariectomized female CD1 mice were subcutaneously administered vehicle, 1.5 μg/kg, 2 μg/kg, or 3 μg/kg of 17β-estradiol 15 minutes before social recognition, object recognition, or object placement learning. These paradigms were designed to allow the testing of learning effects within 40 min of hormone administration. In addition, using a different set of ovariectomized mice, we examined the rapid effects of 1.5 μg/kg, 2 μg/kg, or 3 μg/kg of 17β-estradiol on CA1 hippocampal dendritic spines. All 17β-estradiol doses tested impacted learning, memory, and CA1 hippocampal spines. 17β-Estradiol improved both social and object recognition, and may facilitate object placement learning and memory. In addition, 17β-estradiol increased dendritic spine density in the stratum radiatum subregion of the CA1 hippocampus, but did not affect dendritic spines in the lacunosum-moleculare, within 40 min of administration. These results demonstrate that the rapid actions of 17β-estradiol have important implications for general learning and memory processes that are not specific for a particular type of learning paradigm. These effects may be mediated by the rapid formation of new dendritic spines in the hippocampus.
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76
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Dendritic spines: from structure to in vivo function. EMBO Rep 2012; 13:699-708. [PMID: 22791026 DOI: 10.1038/embor.2012.102] [Citation(s) in RCA: 214] [Impact Index Per Article: 17.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2012] [Accepted: 06/22/2012] [Indexed: 12/19/2022] Open
Abstract
Dendritic spines arise as small protrusions from the dendritic shaft of various types of neuron and receive inputs from excitatory axons. Ever since dendritic spines were first described in the nineteenth century, questions about their function have spawned many hypotheses. In this review, we introduce understanding of the structural and biochemical properties of dendritic spines with emphasis on components studied with imaging methods. We then explore advances in in vivo imaging methods that are allowing spine activity to be studied in living tissue, from super-resolution techniques to calcium imaging. Finally, we review studies on spine structure and function in vivo. These new results shed light on the development, integration properties and plasticity of spines.
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77
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78
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Bibliography Current World Literature. CURRENT ORTHOPAEDIC PRACTICE 2012. [DOI: 10.1097/bco.0b013e318256e7f2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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79
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Fu M, Yu X, Lu J, Zuo Y. Repetitive motor learning induces coordinated formation of clustered dendritic spines in vivo. Nature 2012; 483:92-5. [PMID: 22343892 PMCID: PMC3292711 DOI: 10.1038/nature10844] [Citation(s) in RCA: 349] [Impact Index Per Article: 29.1] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2011] [Accepted: 01/09/2012] [Indexed: 11/27/2022]
Abstract
Many lines of evidence suggest that memory in the mammalian brain is stored with distinct spatiotemporal patterns1,2. Despite recent progresses in identifying neuronal populations involved in memory coding3–5, the synapse-level mechanism is still poorly understood. Computational models and electrophysiological data have shown that functional clustering of synapses along dendritic branches leads to nonlinear summation of synaptic inputs and greatly expands the computing power of a neural network6–10. However, whether neighboring synapses are involved in encoding similar memory and how task-specific cortical networks develop during learning remain elusive. Using transcranial two-photon microscopy11, we followed apical dendrites of layer 5 (L5) pyramidal neurons in the motor cortex while mice practiced novel forelimb skills. Here we show that a third of new dendritic spines (postsynaptic structures of most excitatory synapses) formed during the acquisition phase of learning emerge in clusters, and the majority of such clusters are neighboring spine pairs. These clustered new spines are more likely to persist throughout prolonged learning sessions and even long after training stops, compared to non-clustered counterparts. Moreover, formation of new spine clusters requires repetition of the same motor task, and the emergence of succedent new spine(s) accompanies the strengthening of the first new spine in the cluster. We also show that under control conditions new spines appear to avoid existing stable spines, rather than being uniformly added along dendrites. However, succedent new spines in clusters overcome such a spatial constraint and form in close vicinity to neighboring stable spines. Our findings suggest that clustering of new synapses along dendrites is induced by repetitive activation of the cortical circuitry during learning, providing a structural basis for spatial coding of motor memory in the mammalian brain.
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Affiliation(s)
- Min Fu
- Department of Molecular, Cell and Developmental Biology, University of California, Santa Cruz, California 95064, USA
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80
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Buch ER, Modir Shanechi A, Fourkas AD, Weber C, Birbaumer N, Cohen LG. Parietofrontal integrity determines neural modulation associated with grasping imagery after stroke. ACTA ACUST UNITED AC 2012; 135:596-614. [PMID: 22232595 DOI: 10.1093/brain/awr331] [Citation(s) in RCA: 96] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
Chronic stroke patients with heterogeneous lesions, but no direct damage to the primary sensorimotor cortex, are capable of longitudinally acquiring the ability to modulate sensorimotor rhythms using grasping imagery of the affected hand. Volitional modulation of neural activity can be used to drive grasping functions of the paralyzed hand through a brain-computer interface. The neural substrates underlying this skill are not known. Here, we investigated the impact of individual patient's lesion pathology on functional and structural network integrity related to this volitional skill. Magnetoencephalography data acquired throughout training was used to derive functional networks. Structural network models and local estimates of extralesional white matter microstructure were constructed using T(1)-weighted and diffusion-weighted magnetic resonance imaging data. We employed a graph theoretical approach to characterize emergent properties of distributed interactions between nodal brain regions of these networks. We report that interindividual variability in patients' lesions led to differential impairment of functional and structural network characteristics related to successful post-training sensorimotor rhythm modulation skill. Patients displaying greater magnetoencephalography global cost-efficiency, a measure of information integration within the distributed functional network, achieved greater levels of skill. Analysis of lesion damage to structural network connectivity revealed that the impact on nodal betweenness centrality of the ipsilesional primary motor cortex, a measure that characterizes the importance of a brain region for integrating visuomotor information between frontal and parietal cortical regions and related thalamic nuclei, correlated with skill. Edge betweenness centrality, an analogous measure, which assesses the role of specific white matter fibre pathways in network integration, showed a similar relationship between skill and a portion of the ipsilesional superior longitudinal fascicle connecting premotor and posterior parietal visuomotor regions known to be crucially involved in normal grasping behaviour. Finally, estimated white matter microstructure integrity in regions of the contralesional superior longitudinal fascicle adjacent to primary sensorimotor and posterior parietal cortex, as well as grey matter volume co-localized to these specific regions, positively correlated with sensorimotor rhythm modulation leading to successful brain-computer interface control. Thus, volitional modulation of ipsilesional neural activity leading to control of paralyzed hand grasping function through a brain-computer interface after longitudinal training relies on structural and functional connectivity in both ipsilesional and contralesional parietofrontal pathways involved in visuomotor information processing. Extant integrity of this structural network may serve as a future predictor of response to longitudinal therapeutic interventions geared towards training sensorimotor rhythms in the lesioned brain, secondarily improving grasping function through brain-computer interface applications.
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Affiliation(s)
- Ethan R Buch
- Human Cortical Physiology and Stroke Neurorehabilitation Section, NINDS, NIH, Bethesda, MD 20892, USA.
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81
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Jia H, Zhang XM, Zhang BA, Liu Y, Li JM. Dendritic morphology of neurons in medial prefrontal cortex and hippocampus in 2VO rats. Neurol Sci 2012; 33:1063-70. [PMID: 22218811 DOI: 10.1007/s10072-011-0898-4] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2011] [Accepted: 12/12/2011] [Indexed: 10/14/2022]
Abstract
Cerebral ischemia is the main cause of cognitive impairment. Changes in dendritic morphology and spines have been shown to occur with synaptic plasticity and cognitive function. Bilateral occlusion of the common carotid arteries (2VO) in rats was an effective model of chronic cerebral ischemia. In this experiment, SD rats were divided into model group (2VO) and sham-operated group. At 2, 4, 8 and 16 weeks, rats were tested in Morris water maze to observe learning and memory abilities, and then the brain tissue was stained by Golgi method to investigate the morphology of dendrites of pyramidal neurons under light microscope. Dendritic length and arborization and spine density of pyramidal neurons in medial prefrontal cortex (mPFC) and hippocampal CA1 were analyzed by ImageJ. Progressive learning and memory deficits appeared since 2 weeks. Compared to the sham-operated group, the dendritic length and arborization significantly decreased in the model group at 4, 8 and 16 weeks after 2VO in CA1, while there was no significant difference in mPFC. Dendritic spine density in hippocampal CA1 of the model group significantly decreased after 2 weeks, and it was decreased after 8 weeks in mPFC. The results suggest that under the condition of chronic cerebral ischemia, the alteration of dendritic morphology and spine density underlay cognitive impairment.
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Affiliation(s)
- He Jia
- The First Department of Neurology, The First Affiliated Hospital, Zhengzhou University, Zhengzhou, 450052 Henan, People's Republic of China
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82
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Chung WS, Barres BA. The role of glial cells in synapse elimination. Curr Opin Neurobiol 2011; 22:438-45. [PMID: 22036016 DOI: 10.1016/j.conb.2011.10.003] [Citation(s) in RCA: 67] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2011] [Revised: 09/27/2011] [Accepted: 10/06/2011] [Indexed: 12/13/2022]
Abstract
Excessive synapses generated during early development are eliminated extensively to form functionally mature neural circuits. Synapses in juvenile and mature brains are highly dynamic, and undergo remodeling processes through constant formation and elimination of dendritic spines. Although neural activity has been implicated in initiating the synapse elimination process cell-autonomously, the cellular and molecular mechanisms that transduce changes in correlated neural activity into structural changes in synapses are largely unknown. Recently, however, new findings provide evidence that in different species, glial cells, non-neuronal cell types in the nervous system are crucial in eliminating neural debris and unwanted synapses through phagocytosis. Glial cells not only clear fragmented axons and synaptic debris produced during synapse elimination, but also engulf unwanted synapses thereby actively promoting synapse elimination non-cell autonomously. These new findings support the important role of glial cells in the formation and maintenance of functional neural circuits in development as well as in adult stages and neurodegenerative diseases.
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Affiliation(s)
- Won-Suk Chung
- Department of Neurobiology, Stanford University, School of Medicine, Stanford, CA 94305, USA.
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83
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Sleep and waking modulate spine turnover in the adolescent mouse cortex. Nat Neurosci 2011; 14:1418-20. [PMID: 21983682 PMCID: PMC3203346 DOI: 10.1038/nn.2934] [Citation(s) in RCA: 216] [Impact Index Per Article: 16.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2011] [Accepted: 08/08/2011] [Indexed: 02/07/2023]
Abstract
Cortical development involves synaptic formation and elimination. While synaptogenesis predominates earlier and pruning later, the two processes are thought to happen concurrently. Since in adults synaptic strength is modulated by behavioral state, we asked if synaptic remodeling may be affected by sleep and wake. Using two-photon microscopy in adolescent mice, we found that wake results in a net increase in cortical spines, whereas sleep is associated with net spine loss.
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84
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Neuroplasticity of the sensorimotor cortex during learning. Neural Plast 2011; 2011:310737. [PMID: 21949908 PMCID: PMC3178113 DOI: 10.1155/2011/310737] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2011] [Accepted: 07/12/2011] [Indexed: 11/17/2022] Open
Abstract
We will discuss some of the current issues in understanding plasticity in the sensorimotor (SM) cortices on the behavioral, neurophysiological, and synaptic levels. We will focus our paper on reaching and grasping movements in the rat. In addition, we will discuss our preliminary work utilizing inhibition of protein kinase Mζ (PKMζ), which has recently been shown necessary and sufficient for the maintenance of long-term potentiation (LTP) (Ling et al., 2002). With this new knowledge and inhibitors to this system, as well as the ability to overexpress this system, we can start to directly modulate LTP and determine its influence on behavior as well as network level processing dependent at least in part due to this form of LTP. We will also briefly introduce the use of brain machine interface (BMI) paradigms to ask questions about sensorimotor plasticity and discuss current analysis techniques that may help in our understanding of neuroplasticity.
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85
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Fu M, Zuo Y. Experience-dependent structural plasticity in the cortex. Trends Neurosci 2011; 34:177-87. [PMID: 21397343 DOI: 10.1016/j.tins.2011.02.001] [Citation(s) in RCA: 206] [Impact Index Per Article: 15.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2010] [Revised: 02/07/2011] [Accepted: 02/07/2011] [Indexed: 10/18/2022]
Abstract
Synapses are the fundamental units of neuronal circuits. Synaptic plasticity can occur through changes in synaptic strength, as well as through the addition/removal of synapses. Two-photon microscopy in combination with fluorescence labeling offers a powerful tool to peek into the living brain and follow structural reorganization at individual synapses. Time-lapse imaging depicts a dynamic picture in which experience-dependent plasticity of synaptic structures varies between different cortical regions and layers, as well as between neuronal subtypes. Recent studies have demonstrated that the formation and elimination of synaptic structures happens rapidly in a subpopulation of cortical neurons during various sensorimotor learning experiences, and that stabilized synaptic structures are associated with long lasting memories for the task. Therefore, circuit plasticity, mediated by structural remodeling, provides an underlying mechanism for learning and memory.
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Affiliation(s)
- Min Fu
- Department of Molecular, Cell and Developmental Biology, University of California Santa Cruz, Santa Cruz, CA 95064, USA
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