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Ertl N, Freeman TP, Mokrysz C, Ofori S, Borissova A, Petrilli K, Curran HV, Lawn W, Wall MB. Acute effects of different types of cannabis on young adult and adolescent resting-state brain networks. Neuropsychopharmacology 2024:10.1038/s41386-024-01891-6. [PMID: 38806583 DOI: 10.1038/s41386-024-01891-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/28/2023] [Revised: 05/02/2024] [Accepted: 05/10/2024] [Indexed: 05/30/2024]
Abstract
Adolescence is a time of rapid neurodevelopment and the endocannabinoid system is particularly prone to change during this time. Cannabis is a commonly used drug with a particularly high prevalence of use among adolescents. The two predominant phytocannabinoids are Delta-9-tetrahydrocannabinol (THC) and cannabidiol (CBD), which affect the endocannabinoid system. It is unknown whether this period of rapid development makes adolescents more or less vulnerable to the effects of cannabis on brain-network connectivity, and whether CBD may attenuate the effects of THC. Using fMRI, we explored the impact of vaporized cannabis (placebo, THC: 8 mg/75 kg, THC + CBD: 8 mg/75 kg THC & 24 mg/75 kg CBD) on resting-state networks in groups of semi-regular cannabis users (usage frequency between 0.5 and 3 days/week), consisting of 22 adolescents (16-17 years) and 24 young adults (26-29 years) matched for cannabis use frequency. Cannabis caused reductions in within-network connectivity in the default mode (F[2,88] = 3.97, P = 0.022, η² = 0.018), executive control (F[2,88] = 18.62, P < 0.001, η² = 0.123), salience (F[2,88] = 12.12, P < 0.001, η² = 0.076), hippocampal (F[2,88] = 14.65, P < 0.001, η² = 0.087), and limbic striatal (F[2,88] = 16.19, P < 0.001, η² = 0.102) networks compared to placebo. Whole-brain analysis showed cannabis significantly disrupted functional connectivity with cortical regions and the executive control, salience, hippocampal, and limbic striatal networks compared to placebo. CBD did not counteract THC's effects and further reduced connectivity both within networks and the whole brain. While age-related differences were observed, there were no interactions between age group and cannabis treatment in any brain network. Overall, these results challenge the assumption that CBD can make cannabis safer, as CBD did not attenuate THC effects (and in some cases potentiated them); furthermore, they show that cannabis causes similar disruption to resting-state connectivity in the adolescent and adult brain.
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Affiliation(s)
- Natalie Ertl
- Invicro London, Burlington Danes Building, Hammersmith Hospital, Du Cane Road, W12 0NN, London, UK
- Faculty of Medicine, Imperial College London, Hammersmith Hospital, Du Cane Road, W12 0NN, London, UK
| | - Tom P Freeman
- Clinical Psychopharmacology Unit, University College London, 1-19 Torrington Place, WC1E 7HB, London, UK
- Addiction and Mental Health Group (AIM), Department of Psychology, University of Bath, Bath, UK
| | - Claire Mokrysz
- Clinical Psychopharmacology Unit, University College London, 1-19 Torrington Place, WC1E 7HB, London, UK
| | - Shelan Ofori
- Clinical Psychopharmacology Unit, University College London, 1-19 Torrington Place, WC1E 7HB, London, UK
| | - Anna Borissova
- Clinical Psychopharmacology Unit, University College London, 1-19 Torrington Place, WC1E 7HB, London, UK
- National Addiction Centre, Institute of Psychiatry Psychology and Neuroscience, King's College London, London, UK
| | - Kat Petrilli
- Addiction and Mental Health Group (AIM), Department of Psychology, University of Bath, Bath, UK
| | - H Valerie Curran
- Clinical Psychopharmacology Unit, University College London, 1-19 Torrington Place, WC1E 7HB, London, UK
| | - Will Lawn
- Clinical Psychopharmacology Unit, University College London, 1-19 Torrington Place, WC1E 7HB, London, UK
- National Addiction Centre, Institute of Psychiatry Psychology and Neuroscience, King's College London, London, UK
| | - Matthew B Wall
- Invicro London, Burlington Danes Building, Hammersmith Hospital, Du Cane Road, W12 0NN, London, UK.
- Faculty of Medicine, Imperial College London, Hammersmith Hospital, Du Cane Road, W12 0NN, London, UK.
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2
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Wei H, Xu Z, Ni Y, Yang L, Sun L, Gong J, Zhang S, Qu S, Xu W. Mixed-Dimensional Nanoparticle-Nanowire Channels for Flexible Optoelectronic Artificial Synapse with Enhanced Photoelectric Response and Asymmetric Bidirectional Plasticity. NANO LETTERS 2023; 23:8743-8752. [PMID: 37698378 DOI: 10.1021/acs.nanolett.3c02836] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 09/13/2023]
Abstract
A mixed-dimensional dual-channel synaptic transistor composed of inorganic nanoparticles and organic nanowires was fabricated to expand the photoelectric gain range. The device can actualize the sensitization features of the nociceptor and shows improved responsiveness to visible light. Under electrical pulses with different polarities, the apparatus exhibits reconfigurable asymmetric bidirectional plasticity. Moreover, the devices demonstrate good operational tolerance and mechanical stability, retaining more than 60% of their maximum responsiveness after 100 consecutive/bidirectional and 1000 flex/flat operations. The improved photoelectric response of the device endows a high image recognition accuracy of greater than 80%. Asymmetric bidirectional plasticity is used as punishment/reward in a psychological experiment to emulate the improvement of learning motivation and enables real-time forward and backward deflection (+7 and -25°) of artificial muscle. The mixed-dimensional optoelectronic artificial synapses with switchable behavior and electron/hole transport type have important prospects for neuromorphic processing and artificial somatosensory nerves.
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Affiliation(s)
- Huanhuan Wei
- Institute of Photoelectronic Thin Film Devices and Technology of Nankai University, Key Laboratory of Optoelectronic Thin Film Devices and Technology of Tianjin, Engineering Research Center of Thin Film Optoelectronics Technology, College of Electronic Information and Optical Engineering of Nankai University, National Institute for Advanced Materials, Nankai University, Ministry of Education, Tianjin 300350, People's Republic of China
- Institutes of Physical Science and Information Technology, School of Materials Science and Engineering, Key Laboratory of Structure and Functional Regulation of Hybrid Materials, Anhui University, Ministry of Education, Hefei 230601, People's Republic of China
| | - Zhipeng Xu
- Institute of Photoelectronic Thin Film Devices and Technology of Nankai University, Key Laboratory of Optoelectronic Thin Film Devices and Technology of Tianjin, Engineering Research Center of Thin Film Optoelectronics Technology, College of Electronic Information and Optical Engineering of Nankai University, National Institute for Advanced Materials, Nankai University, Ministry of Education, Tianjin 300350, People's Republic of China
| | - Yao Ni
- Institute of Photoelectronic Thin Film Devices and Technology of Nankai University, Key Laboratory of Optoelectronic Thin Film Devices and Technology of Tianjin, Engineering Research Center of Thin Film Optoelectronics Technology, College of Electronic Information and Optical Engineering of Nankai University, National Institute for Advanced Materials, Nankai University, Ministry of Education, Tianjin 300350, People's Republic of China
| | - Lu Yang
- Institute of Photoelectronic Thin Film Devices and Technology of Nankai University, Key Laboratory of Optoelectronic Thin Film Devices and Technology of Tianjin, Engineering Research Center of Thin Film Optoelectronics Technology, College of Electronic Information and Optical Engineering of Nankai University, National Institute for Advanced Materials, Nankai University, Ministry of Education, Tianjin 300350, People's Republic of China
| | - Lin Sun
- Institute of Photoelectronic Thin Film Devices and Technology of Nankai University, Key Laboratory of Optoelectronic Thin Film Devices and Technology of Tianjin, Engineering Research Center of Thin Film Optoelectronics Technology, College of Electronic Information and Optical Engineering of Nankai University, National Institute for Advanced Materials, Nankai University, Ministry of Education, Tianjin 300350, People's Republic of China
| | - Jiangdong Gong
- Institute of Photoelectronic Thin Film Devices and Technology of Nankai University, Key Laboratory of Optoelectronic Thin Film Devices and Technology of Tianjin, Engineering Research Center of Thin Film Optoelectronics Technology, College of Electronic Information and Optical Engineering of Nankai University, National Institute for Advanced Materials, Nankai University, Ministry of Education, Tianjin 300350, People's Republic of China
| | - Song Zhang
- Institute of Photoelectronic Thin Film Devices and Technology of Nankai University, Key Laboratory of Optoelectronic Thin Film Devices and Technology of Tianjin, Engineering Research Center of Thin Film Optoelectronics Technology, College of Electronic Information and Optical Engineering of Nankai University, National Institute for Advanced Materials, Nankai University, Ministry of Education, Tianjin 300350, People's Republic of China
| | - Shangda Qu
- Institute of Photoelectronic Thin Film Devices and Technology of Nankai University, Key Laboratory of Optoelectronic Thin Film Devices and Technology of Tianjin, Engineering Research Center of Thin Film Optoelectronics Technology, College of Electronic Information and Optical Engineering of Nankai University, National Institute for Advanced Materials, Nankai University, Ministry of Education, Tianjin 300350, People's Republic of China
| | - Wentao Xu
- Institute of Photoelectronic Thin Film Devices and Technology of Nankai University, Key Laboratory of Optoelectronic Thin Film Devices and Technology of Tianjin, Engineering Research Center of Thin Film Optoelectronics Technology, College of Electronic Information and Optical Engineering of Nankai University, National Institute for Advanced Materials, Nankai University, Ministry of Education, Tianjin 300350, People's Republic of China
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3
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Cárdenas-García SP, Ijaz S, Pereda AE. The components of an electrical synapse as revealed by expansion microscopy of a single synaptic contact. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.07.25.550347. [PMID: 37546897 PMCID: PMC10402082 DOI: 10.1101/2023.07.25.550347] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 08/08/2023]
Abstract
Most nervous systems combine both transmitter-mediated and direct cell-cell communication, known as 'chemical' and 'electrical' synapses, respectively. Chemical synapses can be identified by their multiple structural components. Electrical synapses are, on the other hand, generally defined by the presence of a 'gap junction' (a cluster of intercellular channels) between two neuronal processes. However, while gap junctions provide the communicating mechanism, it is unknown whether electrical transmission requires the contribution of additional cellular structures. We investigated this question at identifiable single synaptic contacts on the zebrafish Mauthner cells, at which gap junctions coexist with specializations for neurotransmitter release and where the contact defines the anatomical limits of a synapse. Expansion microscopy of these contacts revealed a detailed map of the incidence and spatial distribution of proteins pertaining to various synaptic structures. Multiple gap junctions of variable size were identified by the presence of their molecular components. Remarkably, most of the synaptic contact's surface was occupied by interleaving gap junctions and components of adherens junctions, suggesting a close functional association between these two structures. In contrast, glutamate receptors were confined to small peripheral portions of the contact, indicating that most of the synaptic area works as an electrical synapse. Thus, our results revealed the overarching organization of an electrical synapse that operates with not one, but multiple gap junctions, in close association with structural and signaling molecules known to be components of AJs. The relationship between these intercellular structures will aid in establishing the boundaries of electrical synapses found throughout animal connectomes and provide insight into the structural organization and functional diversity of electrical synapses.
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Affiliation(s)
- Sandra P. Cárdenas-García
- Dominick P. Purpura Department of Neuroscience, Albert Einstein College of Medicine, Bronx, NY 10461, USA
| | - Sundas Ijaz
- Dominick P. Purpura Department of Neuroscience, Albert Einstein College of Medicine, Bronx, NY 10461, USA
| | - Alberto E. Pereda
- Dominick P. Purpura Department of Neuroscience, Albert Einstein College of Medicine, Bronx, NY 10461, USA
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Ursino M, Cesaretti N, Pirazzini G. A model of working memory for encoding multiple items and ordered sequences exploiting the theta-gamma code. Cogn Neurodyn 2022; 17:489-521. [PMID: 37007198 PMCID: PMC10050512 DOI: 10.1007/s11571-022-09836-9] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2021] [Revised: 02/25/2022] [Accepted: 05/27/2022] [Indexed: 11/24/2022] Open
Abstract
AbstractRecent experimental evidence suggests that oscillatory activity plays a pivotal role in the maintenance of information in working memory, both in rodents and humans. In particular, cross-frequency coupling between theta and gamma oscillations has been suggested as a core mechanism for multi-item memory. The aim of this work is to present an original neural network model, based on oscillating neural masses, to investigate mechanisms at the basis of working memory in different conditions. We show that this model, with different synapse values, can be used to address different problems, such as the reconstruction of an item from partial information, the maintenance of multiple items simultaneously in memory, without any sequential order, and the reconstruction of an ordered sequence starting from an initial cue. The model consists of four interconnected layers; synapses are trained using Hebbian and anti-Hebbian mechanisms, in order to synchronize features in the same items, and desynchronize features in different items. Simulations show that the trained network is able to desynchronize up to nine items without a fixed order using the gamma rhythm. Moreover, the network can replicate a sequence of items using a gamma rhythm nested inside a theta rhythm. The reduction in some parameters, mainly concerning the strength of GABAergic synapses, induce memory alterations which mimic neurological deficits. Finally, the network, isolated from the external environment (“imagination phase”) and stimulated with high uniform noise, can randomly recover sequences previously learned, and link them together by exploiting the similarity among items.
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Affiliation(s)
- Mauro Ursino
- Department of Electrical, Electronic and Information Engineering “Guglielmo Marconi”, University of Bologna, Campus of Cesena Area di Campus Cesena Via Dell’Università 50, 47521 Cesena, FC Italy
| | - Nicole Cesaretti
- Department of Electrical, Electronic and Information Engineering “Guglielmo Marconi”, University of Bologna, Campus of Cesena Area di Campus Cesena Via Dell’Università 50, 47521 Cesena, FC Italy
| | - Gabriele Pirazzini
- Department of Electrical, Electronic and Information Engineering “Guglielmo Marconi”, University of Bologna, Campus of Cesena Area di Campus Cesena Via Dell’Università 50, 47521 Cesena, FC Italy
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5
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Xu L, Guan NN, Huang CX, Hua Y, Song J. A neuronal circuit that generates the temporal motor sequence for the defensive response in zebrafish larvae. Curr Biol 2021; 31:3343-3357.e4. [PMID: 34289386 DOI: 10.1016/j.cub.2021.06.054] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2021] [Revised: 06/06/2021] [Accepted: 06/21/2021] [Indexed: 01/11/2023]
Abstract
Animals use a precisely timed motor sequence to escape predators. This requires the nervous system to coordinate several motor behaviors and execute them in a temporal and smooth manner. We here describe a neuronal circuit that faithfully generates a defensive motor sequence in zebrafish larvae. The temporally specific defensive motor sequence consists of an initial escape and a subsequent swim behavior and can be initiated by unilateral stimulation of a single Mauthner cell (M-cell). The smooth transition from escape behavior to swim behavior is achieved by activating a neuronal chain circuit, which permits an M-cell to drive descending neurons in bilateral nucleus of medial longitudinal fascicle (nMLF) via activation of an intermediate excitatory circuit formed by interconnected hindbrain cranial relay neurons. The sequential activation of M-cells and neurons in bilateral nMLF via activation of hindbrain cranial relay neurons ensures the smooth execution of escape and swim behaviors in a timely manner. We propose an existence of a serial model that executes a temporal motor sequence involving three different brain regions that initiates the escape behavior and triggers a subsequent swim. This model has general implications regarding the neural control of complex motor sequences.
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Affiliation(s)
- Lulu Xu
- Motor Control Laboratory, Translational Research Institute of Brain and Brain-Like Intelligence, Department of Anatomy, Histology and Embryology, Shanghai Fourth People's Hospital, School of Medicine, Tongji University, Shanghai 200092, China
| | - Na N Guan
- Motor Control Laboratory, Translational Research Institute of Brain and Brain-Like Intelligence, Department of Anatomy, Histology and Embryology, Shanghai Fourth People's Hospital, School of Medicine, Tongji University, Shanghai 200092, China; Clinical Center for Brain and Spinal Cord Research, Tongji University, 200092 Shanghai, China
| | - Chun-Xiao Huang
- Motor Control Laboratory, Translational Research Institute of Brain and Brain-Like Intelligence, Department of Anatomy, Histology and Embryology, Shanghai Fourth People's Hospital, School of Medicine, Tongji University, Shanghai 200092, China
| | - Yunfeng Hua
- Shanghai Institute of Precision Medicine, Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai 200125, China
| | - Jianren Song
- Motor Control Laboratory, Translational Research Institute of Brain and Brain-Like Intelligence, Department of Anatomy, Histology and Embryology, Shanghai Fourth People's Hospital, School of Medicine, Tongji University, Shanghai 200092, China; Clinical Center for Brain and Spinal Cord Research, Tongji University, 200092 Shanghai, China.
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6
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Orr SA, Ahn S, Park C, Miller TH, Kassai M, Issa FA. Social Experience Regulates Endocannabinoids Modulation of Zebrafish Motor Behaviors. Front Behav Neurosci 2021; 15:668589. [PMID: 34045945 PMCID: PMC8144649 DOI: 10.3389/fnbeh.2021.668589] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2021] [Accepted: 04/08/2021] [Indexed: 11/13/2022] Open
Abstract
Social status-dependent modulation of neural circuits has been investigated extensively in vertebrate and invertebrate systems. However, the effects of social status on neuromodulatory systems that drive motor activity are poorly understood. Zebrafish form a stable social relationship that consists of socially dominant and subordinate animals. The locomotor behavior patterns differ according to their social ranks. The sensitivity of the Mauthner startle escape response in subordinates increases compared to dominants while dominants increase their swimming frequency compared to subordinates. Here, we investigated the role of the endocannabinoid system (ECS) in mediating these differences in motor activities. We show that brain gene expression of key ECS protein pathways are socially regulated. Diacylglycerol lipase (DAGL) expression significantly increased in dominants and significantly decreased in subordinates relative to controls. Moreover, brain gene expression of the cannabinoid 1 receptor (CB1R) was significantly increased in subordinates relative to controls. Secondly, increasing ECS activity with JZL184 reversed swimming activity patterns in dominant and subordinate animals. JZL184 did not affect the sensitivity of the startle escape response in dominants while it was significantly reduced in subordinates. Thirdly, blockage of CB1R function with AM-251 had no effect on dominants startle escape response sensitivity, but startle sensitivity was significantly reduced in subordinates. Additionally, AM-251 did not affect swimming activities in either social phenotypes. Fourthly, we demonstrate that the effects of ECS modulation of the startle escape circuit is mediated via the dopaminergic system specifically via the dopamine D1 receptor. Finally, our empirical results complemented with neurocomputational modeling suggest that social status influences the ECS to regulate the balance in synaptic strength between excitatory and inhibitory inputs to control the excitability of motor behaviors. Collectively, this study provides new insights of how social factors impact nervous system function to reconfigure the synergistic interactions of neuromodulatory pathways to optimize motor output.
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Affiliation(s)
- Stephen A Orr
- Department of Biology, East Carolina University, Greenville, NC, United States
| | - Sungwoo Ahn
- Department of Mathematics, East Carolina University, Greenville, NC, United States
| | - Choongseok Park
- Department of Mathematics, North Carolina A&T State University, Greensboro, NC, United States
| | - Thomas H Miller
- Department of Biology, East Carolina University, Greenville, NC, United States
| | - Miki Kassai
- Department of Biochemistry and Molecular Biology, Brody School of Medicine, East Carolina University, Greenville, NC, United States
| | - Fadi A Issa
- Department of Biology, East Carolina University, Greenville, NC, United States
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Wosniack ME, Kirchner JH, Chao LY, Zabouri N, Lohmann C, Gjorgjieva J. Adaptation of spontaneous activity in the developing visual cortex. eLife 2021; 10:61619. [PMID: 33722342 PMCID: PMC7963484 DOI: 10.7554/elife.61619] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2020] [Accepted: 02/03/2021] [Indexed: 12/11/2022] Open
Abstract
Spontaneous activity drives the establishment of appropriate connectivity in different circuits during brain development. In the mouse primary visual cortex, two distinct patterns of spontaneous activity occur before vision onset: local low-synchronicity events originating in the retina and global high-synchronicity events originating in the cortex. We sought to determine the contribution of these activity patterns to jointly organize network connectivity through different activity-dependent plasticity rules. We postulated that local events shape cortical input selectivity and topography, while global events homeostatically regulate connection strength. However, to generate robust selectivity, we found that global events should adapt their amplitude to the history of preceding cortical activation. We confirmed this prediction by analyzing in vivo spontaneous cortical activity. The predicted adaptation leads to the sparsification of spontaneous activity on a slower timescale during development, demonstrating the remarkable capacity of the developing sensory cortex to acquire sensitivity to visual inputs after eye-opening.
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Affiliation(s)
- Marina E Wosniack
- Computation in Neural Circuits Group, Max Planck Institute for Brain Research, Frankfurt, Germany.,School of Life Sciences Weihenstephan, Technical University of Munich, Freising, Germany
| | - Jan H Kirchner
- Computation in Neural Circuits Group, Max Planck Institute for Brain Research, Frankfurt, Germany.,School of Life Sciences Weihenstephan, Technical University of Munich, Freising, Germany
| | - Ling-Ya Chao
- Computation in Neural Circuits Group, Max Planck Institute for Brain Research, Frankfurt, Germany
| | - Nawal Zabouri
- Netherlands Institute for Neuroscience, Amsterdam, Netherlands
| | - Christian Lohmann
- Netherlands Institute for Neuroscience, Amsterdam, Netherlands.,Center for Neurogenomics and Cognitive Research, Vrije Universiteit, Amsterdam, Netherlands
| | - Julijana Gjorgjieva
- Computation in Neural Circuits Group, Max Planck Institute for Brain Research, Frankfurt, Germany.,School of Life Sciences Weihenstephan, Technical University of Munich, Freising, Germany
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8
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Piette C, Cui Y, Gervasi N, Venance L. Lights on Endocannabinoid-Mediated Synaptic Potentiation. Front Mol Neurosci 2020; 13:132. [PMID: 32848597 PMCID: PMC7399367 DOI: 10.3389/fnmol.2020.00132] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2020] [Accepted: 06/26/2020] [Indexed: 12/15/2022] Open
Abstract
The endocannabinoid (eCB) system is a lipid-based neurotransmitter complex that plays crucial roles in the neural control of learning and memory. The current model of eCB-mediated retrograde signaling is that eCBs released from postsynaptic elements travel retrogradely to presynaptic axon terminals, where they activate cannabinoid type-1 receptors (CB1Rs) and ultimately decrease neurotransmitter release on a short- or long-term scale. An increasing body of evidence has enlarged this view and shows that eCBs, besides depressing synaptic transmission, are also able to increase neurotransmitter release at multiple synapses of the brain. This indicates that eCBs act as bidirectional regulators of synaptic transmission and plasticity. Recently, studies unveiled links between the expression of eCB-mediated long-term potentiation (eCB-LTP) and learning, and between its dysregulation and several pathologies. In this review article, we first distinguish the various forms of eCB-LTP based on their mechanisms, resulting from homosynaptically or heterosynaptically-mediated processes. Next, we consider the neuromodulation of eCB-LTP, its behavioral impact on learning and memory, and finally, eCB-LTP disruptions in various pathologies and its potential as a therapeutic target in disorders such as stress coping, addiction, Alzheimer’s and Parkinson’s disease, and pain. Cannabis is gaining popularity as a recreational substance as well as a medicine, and multiple eCB-based drugs are under development. In this context, it is critical to understand eCB-mediated signaling in its multi-faceted complexity. Indeed, the bidirectional nature of eCB-based neuromodulation may offer an important key to interpret the functions of the eCB system and how it is impacted by cannabis and other drugs.
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Affiliation(s)
- Charlotte Piette
- Center for Interdisciplinary Research in Biology, College de France, INSERM U1050, CNRS UMR7241, Labex Memolife, Paris, France
| | - Yihui Cui
- Department of Neurobiology, Sir Run Run Shaw Hospital, Zhejiang University School of Medicine, Hangzhou, China
| | - Nicolas Gervasi
- Center for Interdisciplinary Research in Biology, College de France, INSERM U1050, CNRS UMR7241, Labex Memolife, Paris, France
| | - Laurent Venance
- Center for Interdisciplinary Research in Biology, College de France, INSERM U1050, CNRS UMR7241, Labex Memolife, Paris, France
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9
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Cachope R, Pereda AE. Regulatory Roles of Metabotropic Glutamate Receptors on Synaptic Communication Mediated by Gap Junctions. Neuroscience 2020; 456:85-94. [PMID: 32619474 DOI: 10.1016/j.neuroscience.2020.06.034] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2020] [Revised: 06/19/2020] [Accepted: 06/22/2020] [Indexed: 12/18/2022]
Abstract
Variations of synaptic strength are thought to underlie forms of learning and can functionally reshape neural circuits. Metabotropic glutamate receptors play key roles in regulating the strength of chemical synapses. However, information within neural circuits is also conveyed via a second modality of transmission: gap junction-mediated synapses. We review here evidence indicating that metabotropic glutamate receptors also play important roles in the regulation of synaptic communication mediated by neuronal gap junctions, also known as 'electrical synapses'. Activity-driven interactions between metabotropic glutamate receptors and neuronal gap junctions can lead to long-term changes in the strength of electrical synapses. Further, the regulatory action of metabotropic glutamate receptors on neuronal gap junctions is not restricted to adulthood but is also of critical relevance during brain development and contributes to the pathological mechanisms that follow brain injury.
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Affiliation(s)
- Roger Cachope
- CHDI Foundation, USA; Dominick P. Purpura Department of Neuroscience, Albert Einstein College of Medicine, Bronx, NY, USA
| | - Alberto E Pereda
- Dominick P. Purpura Department of Neuroscience, Albert Einstein College of Medicine, Bronx, NY, USA.
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10
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Lane BJ, Kick DR, Wilson DK, Nair SS, Schulz DJ. Dopamine maintains network synchrony via direct modulation of gap junctions in the crustacean cardiac ganglion. eLife 2018; 7:e39368. [PMID: 30325308 PMCID: PMC6199132 DOI: 10.7554/elife.39368] [Citation(s) in RCA: 15] [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: 06/25/2018] [Accepted: 10/11/2018] [Indexed: 01/14/2023] Open
Abstract
The Large Cell (LC) motor neurons of the crab cardiac ganglion have variable membrane conductance magnitudes even within the same individual, yet produce identical synchronized activity in the intact network. In a previous study we blocked a subset of K+ conductances across LCs, resulting in loss of synchronous activity (Lane et al., 2016). In this study, we hypothesized that this same variability of conductances makes LCs vulnerable to desynchronization during neuromodulation. We exposed the LCs to serotonin (5HT) and dopamine (DA) while recording simultaneously from multiple LCs. Both amines had distinct excitatory effects on LC output, but only 5HT caused desynchronized output. We further determined that DA rapidly increased gap junctional conductance. Co-application of both amines induced 5HT-like output, but waveforms remained synchronized. Furthermore, DA prevented desynchronization induced by the K+ channel blocker tetraethylammonium (TEA), suggesting that dopaminergic modulation of electrical coupling plays a protective role in maintaining network synchrony.
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Affiliation(s)
- Brian J Lane
- Division of Biological SciencesUniversity of MissouriColumbiaUnited States
| | - Daniel R Kick
- Division of Biological SciencesUniversity of MissouriColumbiaUnited States
| | - David K Wilson
- Division of Biological SciencesUniversity of MissouriColumbiaUnited States
| | - Satish S Nair
- Department of Electrical Engineering and Computer ScienceUniversity of MissouriColumbiaUnited States
| | - David J Schulz
- Division of Biological SciencesUniversity of MissouriColumbiaUnited States
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11
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Dopamine-endocannabinoid interactions mediate spike-timing-dependent potentiation in the striatum. Nat Commun 2018; 9:4118. [PMID: 30297767 PMCID: PMC6175920 DOI: 10.1038/s41467-018-06409-5] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2016] [Accepted: 08/30/2018] [Indexed: 01/01/2023] Open
Abstract
Dopamine modulates striatal synaptic plasticity, a key substrate for action selection and procedural learning. Thus, characterizing the repertoire of activity-dependent plasticity in striatum and its dependence on dopamine is of crucial importance. We recently unraveled a striatal spike-timing-dependent long-term potentiation (tLTP) mediated by endocannabinoids (eCBs) and induced with few spikes (~5–15). Whether this eCB-tLTP interacts with the dopaminergic system remains to be investigated. Here, we report that eCB-tLTP is impaired in a rodent model of Parkinson’s disease and rescued by L-DOPA. Dopamine controls eCB-tLTP via dopamine type-2 receptors (D2R) located presynaptically in cortical terminals. Dopamine–endocannabinoid interactions via D2R are required for the emergence of tLTP in response to few coincident pre- and post-synaptic spikes and control eCB-plasticity by modulating the long-term potentiation (LTP)/depression (LTD) thresholds. While usually considered as a depressing synaptic function, our results show that eCBs in the presence of dopamine constitute a versatile system underlying bidirectional plasticity implicated in basal ganglia pathophysiology. Dopamine tightly regulates plasticity at corticostriatal synapses. Here, the authors report that endocannabinoid dependent LTP induced with few spikes in the striatum is impaired in a rodent model of Parkinson’s disease, requires dopamine through presynaptic D2 receptors located on corticostriatal inputs.
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12
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Berg EM, Björnfors ER, Pallucchi I, Picton LD, El Manira A. Principles Governing Locomotion in Vertebrates: Lessons From Zebrafish. Front Neural Circuits 2018; 12:73. [PMID: 30271327 PMCID: PMC6146226 DOI: 10.3389/fncir.2018.00073] [Citation(s) in RCA: 53] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2018] [Accepted: 08/27/2018] [Indexed: 11/24/2022] Open
Abstract
Locomotor behaviors are critical for survival and enable animals to navigate their environment, find food and evade predators. The circuits in the brain and spinal cord that initiate and maintain such different modes of locomotion in vertebrates have been studied in numerous species for over a century. In recent decades, the zebrafish has emerged as one of the main model systems for the study of locomotion, owing to its experimental amenability, and work in zebrafish has revealed numerous new insights into locomotor circuit function. Here, we review the literature that has led to our current understanding of the neural circuits controlling swimming and escape in zebrafish. We highlight recent studies that have enriched our comprehension of key topics, such as the interactions between premotor excitatory interneurons (INs) and motoneurons (MNs), supraspinal and spinal circuits that coordinate escape maneuvers, and developmental changes in overall circuit composition. We also discuss roles for neuromodulators and sensory inputs in modifying the relative strengths of constituent circuit components to provide flexibility in zebrafish behavior, allowing the animal to accommodate changes in the environment. We aim to provide a coherent framework for understanding the circuitry in the brain and spinal cord of zebrafish that allows the animal to flexibly transition between different speeds, and modes, of locomotion.
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Affiliation(s)
- Eva M Berg
- Department of Neuroscience, Karolinska Institute (KI), Stockholm, Sweden
| | | | - Irene Pallucchi
- Department of Neuroscience, Karolinska Institute (KI), Stockholm, Sweden
| | - Laurence D Picton
- Department of Neuroscience, Karolinska Institute (KI), Stockholm, Sweden
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13
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Welzel G, Schuster S. Long-term potentiation in an innexin-based electrical synapse. Sci Rep 2018; 8:12579. [PMID: 30135467 PMCID: PMC6105662 DOI: 10.1038/s41598-018-30966-w] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2018] [Accepted: 08/09/2018] [Indexed: 11/08/2022] Open
Abstract
Electrical synapses are formed by two unrelated gap junction protein families, the primordial innexins (invertebrates) or the connexins (vertebrates). Although molecularly different, innexin- and connexin-based electrical synapses are strikingly similar in their membrane topology. However, it remains unclear if this similarity extends also to more sophisticated functions such as long-term potentiation which is only known in connexin-based synapses. Here we show that this capacity is not unique to connexin-based synapses. Using a method that allowed us to quantitatively measure gap-junction conductance we provide the first and unequivocal evidence of long-term potentiation in an innexin-based electrical synapse. Our findings suggest that long-term potentiation is a property that has likely existed already in ancestral gap junctions. They therefore could provide a highly potent system to dissect shared molecular mechanisms of electrical synapse plasticity.
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Affiliation(s)
- Georg Welzel
- Department of Animal Physiology, University of Bayreuth, 95440, Bayreuth, Germany.
| | - Stefan Schuster
- Department of Animal Physiology, University of Bayreuth, 95440, Bayreuth, Germany.
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14
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Cui Y, Perez S, Venance L. Endocannabinoid-LTP Mediated by CB1 and TRPV1 Receptors Encodes for Limited Occurrences of Coincident Activity in Neocortex. Front Cell Neurosci 2018; 12:182. [PMID: 30026689 PMCID: PMC6041431 DOI: 10.3389/fncel.2018.00182] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2018] [Accepted: 06/11/2018] [Indexed: 11/25/2022] Open
Abstract
Synaptic efficacy changes, long-term potentiation (LTP) and depression (LTD), underlie various forms of learning and memory. Synaptic plasticity is generally assessed under prolonged activation, whereas learning can emerge from few or even a single trial. Here, we investigated the existence of rapid responsiveness of synaptic plasticity in response to a few number of spikes, in neocortex in a synaptic Hebbian learning rule, the spike-timing-dependent plasticity (STDP). We investigated the effect of lowering the number of pairings from 100 to 50, and 10 on STDP expression, using whole-cell recordings from pyramidal cells in rodent somatosensory cortical brain slices. We found that a low number of paired stimulations induces LTP at neocortical layer 4–2/3 synapses. Besides the asymmetric Hebbian STDP reported in the neocortex induced by 100 pairings, we observed a symmetric anti-Hebbian LTD for 50 pairings and unveiled a unidirectional Hebbian spike-timing-dependent LTP (tLTP) induced by 10–15 pairings. This tLTP was not mediated by NMDA receptor activation but requires CB1 receptors and transient receptor potential vanilloid type-1 (TRPV1) activated by endocannabinoids (eCBs). eCBs have been widely described as mediating short- and long-term synaptic depression. Here, the eCB-tLTP reported at neocortical synapses could constitute a substrate operating in the online learning of new associative memories or during the initial stages of learning. In addition, these findings should provide useful insight into the mechanisms underlying eCB-plasticity occurring during marijuana intoxication.
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Affiliation(s)
- Yihui Cui
- Center for Interdisciplinary Research in Biology (CIRB), College de France, INSERM U1050, CNRS UMR7241, Paris Sciences et Lettres Research University, Paris, France
| | - Sylvie Perez
- Center for Interdisciplinary Research in Biology (CIRB), College de France, INSERM U1050, CNRS UMR7241, Paris Sciences et Lettres Research University, Paris, France
| | - Laurent Venance
- Center for Interdisciplinary Research in Biology (CIRB), College de France, INSERM U1050, CNRS UMR7241, Paris Sciences et Lettres Research University, Paris, France
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15
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Abstract
Cortical oscillations are thought to be involved in many cognitive functions and processes. Several mechanisms have been proposed to regulate oscillations. One prominent but understudied mechanism is gap junction coupling. Gap junctions are ubiquitous in cortex between GABAergic interneurons. Moreover, recent experiments indicate their strength can be modified in an activity-dependent manner, similar to chemical synapses. We hypothesized that activity-dependent gap junction plasticity acts as a mechanism to regulate oscillations in the cortex. We developed a computational model of gap junction plasticity in a recurrent cortical network based on recent experimental findings. We showed that gap junction plasticity can serve as a homeostatic mechanism for oscillations by maintaining a tight balance between two network states: asynchronous irregular activity and synchronized oscillations. This homeostatic mechanism allows for robust communication between neuronal assemblies through two different mechanisms: transient oscillations and frequency modulation. This implies a direct functional role for gap junction plasticity in information transmission in cortex.
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Affiliation(s)
- Guillaume Pernelle
- Bioengineering Department, Imperial College London, London, United Kingdom
| | - Wilten Nicola
- Bioengineering Department, Imperial College London, London, United Kingdom
| | - Claudia Clopath
- Bioengineering Department, Imperial College London, London, United Kingdom
- * E-mail:
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16
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Park C, Clements KN, Issa FA, Ahn S. Effects of Social Experience on the Habituation Rate of Zebrafish Startle Escape Response: Empirical and Computational Analyses. Front Neural Circuits 2018; 12:7. [PMID: 29459823 PMCID: PMC5807392 DOI: 10.3389/fncir.2018.00007] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2017] [Accepted: 01/16/2018] [Indexed: 12/15/2022] Open
Abstract
While the effects of social experience on nervous system function have been extensively investigated in both vertebrate and invertebrate systems, our understanding of how social status differentially affects learning remains limited. In the context of habituation, a well-characterized form of non-associative learning, we investigated how the learning processes differ between socially dominant and subordinate in zebrafish (Danio rerio). We found that social status and frequency of stimulus inputs influence the habituation rate of short latency C-start escape response that is initiated by the Mauthner neuron (M-cell). Socially dominant animals exhibited higher habituation rates compared to socially subordinate animals at a moderate stimulus frequency, but low stimulus frequency eliminated this difference of habituation rates between the two social phenotypes. Moreover, habituation rates of both dominants and subordinates were higher at a moderate stimulus frequency compared to those at a low stimulus frequency. We investigated a potential mechanism underlying these status-dependent differences by constructing a simplified neurocomputational model of the M-cell escape circuit. The computational study showed that the change in total net excitability of the model M-cell was able to replicate the experimental results. At moderate stimulus frequency, the model M-cell with lower total net excitability, that mimicked a dominant-like phenotype, exhibited higher habituation rates. On the other hand, the model with higher total net excitability, that mimicked the subordinate-like phenotype, exhibited lower habituation rates. The relationship between habituation rates and characteristics (frequency and amplitude) of the repeated stimulus were also investigated. We found that habituation rates are decreasing functions of amplitude and increasing functions of frequency while these rates depend on social status (higher for dominants and lower for subordinates). Our results show that social status affects habituative learning in zebrafish, which could be mediated by a summative neuromodulatory input to the M-cell escape circuit, which enables animals to readily learn to adapt to changes in their social environment.
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Affiliation(s)
- Choongseok Park
- Department of Mathematics, North Carolina A&T State University, Greensboro, NC, United States
| | - Katie N Clements
- Department of Biology, East Carolina University, Greenville, NC, United States
| | - Fadi A Issa
- Department of Biology, East Carolina University, Greenville, NC, United States
| | - Sungwoo Ahn
- Department of Mathematics, East Carolina University, Greenville, NC, United States
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17
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Nagy JI, Pereda AE, Rash JE. Electrical synapses in mammalian CNS: Past eras, present focus and future directions. BIOCHIMICA ET BIOPHYSICA ACTA. BIOMEMBRANES 2018; 1860:102-123. [PMID: 28577972 PMCID: PMC5705454 DOI: 10.1016/j.bbamem.2017.05.019] [Citation(s) in RCA: 40] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/13/2017] [Revised: 05/26/2017] [Accepted: 05/27/2017] [Indexed: 12/19/2022]
Abstract
Gap junctions provide the basis for electrical synapses between neurons. Early studies in well-defined circuits in lower vertebrates laid the foundation for understanding various properties conferred by electrical synaptic transmission. Knowledge surrounding electrical synapses in mammalian systems unfolded first with evidence indicating the presence of gap junctions between neurons in various brain regions, but with little appreciation of their functional roles. Beginning at about the turn of this century, new approaches were applied to scrutinize electrical synapses, revealing the prevalence of neuronal gap junctions, the connexin protein composition of many of those junctions, and the myriad diverse neural systems in which they occur in the mammalian CNS. Subsequent progress indicated that electrical synapses constitute key elements in synaptic circuitry, govern the collective activity of ensembles of electrically coupled neurons, and in part orchestrate the synchronized neuronal network activity and rhythmic oscillations that underlie fundamental integrative processes. This article is part of a Special Issue entitled: Gap Junction Proteins edited by Jean Claude Herve.
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Affiliation(s)
- James I Nagy
- Department of Physiology and Pathophysiology, University of Manitoba, Winnipeg, Manitoba, Canada.
| | - Alberto E Pereda
- Dominick P. Purpura Department of Neuroscience, Albert Einstein College of Medicine, Bronx, NY, 10461, United States
| | - John E Rash
- Department of Biomedical Sciences, and Program in Molecular, Cellular and Integrative Neurosciences, Colorado State University, Fort Collins, CO 80523, United States
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18
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Araque A, Castillo PE, Manzoni OJ, Tonini R. Synaptic functions of endocannabinoid signaling in health and disease. Neuropharmacology 2017. [PMID: 28625718 DOI: 10.1016/j.neuropharm.2017.06.017] [Citation(s) in RCA: 145] [Impact Index Per Article: 20.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Endocannabinoids (eCBs) are a family of lipid molecules that act as key regulators of synaptic transmission and plasticity. They are synthetized "on demand" following physiological and/or pathological stimuli. Once released from postsynaptic neurons, eCBs typically act as retrograde messengers to activate presynaptic type 1 cannabinoid receptors (CB1) and induce short- or long-term depression of neurotransmitter release. Besides this canonical mechanism of action, recent findings have revealed a number of less conventional mechanisms by which eCBs regulate neural activity and synaptic function, suggesting that eCB-mediated plasticity is mechanistically more diverse than anticipated. These mechanisms include non-retrograde signaling, signaling via astrocytes, participation in long-term potentiation, and the involvement of mitochondrial CB1. Focusing on paradigmatic brain areas, such as hippocampus, striatum, and neocortex, we review typical and novel signaling mechanisms, and discuss the functional implications in normal brain function and brain diseases. In summary, eCB signaling may lead to different forms of synaptic plasticity through activation of a plethora of mechanisms, which provide further complexity to the functional consequences of eCB signaling. This article is part of the Special Issue entitled "A New Dawn in Cannabinoid Neurobiology".
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Affiliation(s)
- Alfonso Araque
- Department of Neuroscience, University of Minnesota, Minneapolis, MN 55455, USA.
| | - Pablo E Castillo
- Dominick P. Purpura Department of Neuroscience, Albert Einstein College of Medicine, New York, NY 10461, USA.
| | - Olivier J Manzoni
- Institut National de la Santé et et de la Recherche Médicale U901 Marseille, France, Université de la Méditerranée UMR S901 Aix-Marseille Marseille, France, INMED Marseille, France.
| | - Raffaella Tonini
- Neuroscience and Brain Technologies Department, Istituto Italiano di Tecnologia, Genova, Italy.
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19
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Sevetson J, Fittro S, Heckman E, Haas JS. A calcium-dependent pathway underlies activity-dependent plasticity of electrical synapses in the thalamic reticular nucleus. J Physiol 2017; 595:4417-4430. [PMID: 28369952 DOI: 10.1113/jp274049] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2017] [Accepted: 03/14/2017] [Indexed: 11/08/2022] Open
Abstract
KEY POINTS Electrical synapses are modified by various forms of activity, including paired activity in coupled neurons and tetanization of the input to coupled neurons. We show that plasticity of electrical synapses that results from paired spiking activity in coupled neurons depends on calcium influx and calcium-initiated signalling pathways. Plasticity that results from tetanization of input fibres does not depend on calcium influx or dynamics. These results imply that electrically coupled neurons have distinct sets of mechanisms for adjusting coupling according to the specific type of activity they experience. ABSTRACT Recent results have demonstrated modification of electrical synapse strength by varied forms of neuronal activity. However, the mechanisms underlying plasticity induction in central mammalian neurons are unclear. Here we show that the two established inductors of plasticity at electrical synapses in the thalamic reticular nucleus - paired burst spiking in coupled neurons, and mGluR-dependent tetanization of synaptic input - are separate pathways that converge at a common downstream endpoint. Using occlusion experiments and pharmacology in patched pairs of coupled neurons in vitro, we show that burst-induced depression depends on calcium entry via voltage-gated channels, is blocked by BAPTA chelation, and recruits intracellular calcium release on its way to activation of phosphatase activity. In contrast, mGluR-dependent plasticity is independent of calcium entry or calcium dynamics. Together, these results show that the spiking-initiated mechanisms underlying electrical synapse plasticity are similar to those that induce plasticity at chemical synapses, and offer the possibility that calcium-regulated mechanisms may also lead to alternate outcomes, such as potentiation. Because these mechanistic elements are widely found in mature neurons, we expect them to apply broadly to electrical synapses across the brain, acting as the crucial link between neuronal activity and electrical synapse strength.
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Affiliation(s)
- Jessica Sevetson
- Department of Biological Sciences, Lehigh University, 111 Research Drive, Bethlehem, PA, 18015, USA
| | - Sarah Fittro
- Department of Biological Sciences, Lehigh University, 111 Research Drive, Bethlehem, PA, 18015, USA
| | - Emily Heckman
- Department of Biological Sciences, Lehigh University, 111 Research Drive, Bethlehem, PA, 18015, USA
| | - Julie S Haas
- Department of Biological Sciences, Lehigh University, 111 Research Drive, Bethlehem, PA, 18015, USA
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20
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Miller AC, Pereda AE. The electrical synapse: Molecular complexities at the gap and beyond. Dev Neurobiol 2017; 77:562-574. [PMID: 28170151 DOI: 10.1002/dneu.22484] [Citation(s) in RCA: 31] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2016] [Revised: 01/04/2017] [Accepted: 01/04/2017] [Indexed: 12/21/2022]
Abstract
Gap junctions underlie electrical synaptic transmission between neurons. Generally perceived as simple intercellular channels, "electrical synapses" have demonstrated to be more functionally sophisticated and structurally complex than initially anticipated. Electrical synapses represent an assembly of multiple molecules, consisting of channels, adhesion complexes, scaffolds, regulatory machinery, and trafficking proteins, all required for their proper function and plasticity. Additionally, while electrical synapses are often viewed as strictly symmetric structures, emerging evidence has shown that some components forming electrical synapses can be differentially distributed at each side of the junction. We propose that the molecular complexity and asymmetric distribution of proteins at the electrical synapse provides rich potential for functional diversity. © 2016 Wiley Periodicals, Inc. Develop Neurobiol 77: 562-574, 2017.
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Affiliation(s)
- Adam C Miller
- Institute of Neuroscience, Department of Biology, University of Oregon, Eugene, Oregon
| | - Alberto E Pereda
- Dominick P. Purpura Department of Neuroscience, Albert Einstein College of Medicine, Bronx, New York
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21
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Social Status-Dependent Shift in Neural Circuit Activation Affects Decision Making. J Neurosci 2017; 37:2137-2148. [PMID: 28093472 DOI: 10.1523/jneurosci.1548-16.2017] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2016] [Revised: 01/10/2017] [Accepted: 01/13/2017] [Indexed: 11/21/2022] Open
Abstract
In a social group, animals make behavioral decisions that fit their social ranks. These behavioral choices are dependent on the various social cues experienced during social interactions. In vertebrates, little is known of how social status affects the underlying neural mechanisms regulating decision-making circuits that drive competing behaviors. Here, we demonstrate that social status in zebrafish (Danio rerio) influences behavioral decisions by shifting the balance in neural circuit activation between two competing networks (escape and swim). We show that socially dominant animals enhance activation of the swim circuit. Conversely, social subordinates display a decreased activation of the swim circuit, but an enhanced activation of the escape circuit. In an effort to understand how social status mediates these effects, we constructed a neurocomputational model of the escape and swim circuits. The model replicates our findings and suggests that social status-related shift in circuit dynamics could be mediated by changes in the relative excitability of the escape and swim networks. Together, our results reveal that changes in the excitabilities of the Mauthner command neuron for escape and the inhibitory interneurons that regulate swimming provide a cellular mechanism for the nervous system to adapt to changes in social conditions by permitting the animal to select a socially appropriate behavioral response.SIGNIFICANCE STATEMENT Understanding how social factors influence nervous system function is of great importance. Using zebrafish as a model system, we demonstrate how social experience affects decision making to enable animals to produce socially appropriate behavior. Based on experimental evidence and computational modeling, we show that behavioral decisions reflect the interplay between competing neural circuits whose activation thresholds shift in accordance with social status. We demonstrate this through analysis of the behavior and neural circuit responses that drive escape and swim behaviors in fish. We show that socially subordinate animals favor escape over swimming, while socially dominants favor swimming over escape. We propose that these differences are mediated by shifts in relative circuit excitability.
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22
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Haas JS, Greenwald CM, Pereda AE. Activity-dependent plasticity of electrical synapses: increasing evidence for its presence and functional roles in the mammalian brain. BMC Cell Biol 2016; 17 Suppl 1:14. [PMID: 27230776 PMCID: PMC4896267 DOI: 10.1186/s12860-016-0090-z] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
Abstract
Gap junctions mediate electrical synaptic transmission between neurons. While the actions of neurotransmitter modulators on the conductance of gap junctions have been extensively documented, increasing evidence indicates they can also be influenced by the ongoing activity of neural networks, in most cases via local interactions with nearby glutamatergic synapses. We review here early evidence for the existence of activity-dependent regulatory mechanisms as well recent examples reported in mammalian brain. The ubiquitous distribution of both neuronal connexins and the molecules involved suggest this phenomenon is widespread and represents a property of electrical transmission in general.
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Affiliation(s)
- Julie S Haas
- Department of Biological Sciences, Lehigh University, Bethlehem, PA, 18015, USA.
| | - Corey M Greenwald
- Department of Biological Sciences, Lehigh University, Bethlehem, PA, 18015, USA
| | - Alberto E Pereda
- Dominick P. Purpura Department of Neuroscience, Albert Einstein College of Medicine, Bronx, New York, NY, 10461, USA
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23
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Castellano P, Nwagbo C, Martinez LR, Eugenin EA. Methamphetamine compromises gap junctional communication in astrocytes and neurons. J Neurochem 2016; 137:561-75. [PMID: 26953131 DOI: 10.1111/jnc.13603] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2016] [Revised: 02/22/2016] [Accepted: 02/26/2016] [Indexed: 12/18/2022]
Abstract
Methamphetamine (meth) is a central nervous system (CNS) stimulant that results in psychological and physical dependency. The long-term effects of meth within the CNS include neuronal plasticity changes, blood-brain barrier compromise, inflammation, electrical dysfunction, neuronal/glial toxicity, and an increased risk to infectious diseases including HIV. Most of the reported meth effects in the CNS are related to dysregulation of chemical synapses by altering the release and uptake of neurotransmitters, especially dopamine, norepinephrine, and epinephrine. However, little is known about the effects of meth on connexin (Cx) containing channels, such as gap junctions (GJ) and hemichannels (HC). We examined the effects of meth on Cx expression, function, and its role in NeuroAIDS. We found that meth altered Cx expression and localization, decreased GJ communication between neurons and astrocytes, and induced the opening of Cx43/Cx36 HC. Furthermore, we found that these changes in GJ and HC induced by meth treatment were mediated by activation of dopamine receptors, suggesting that dysregulation of dopamine signaling induced by meth is essential for GJ and HC compromise. Meth-induced changes in GJ and HC contributed to amplified CNS toxicity by dysregulating glutamate metabolism and increasing the susceptibility of neurons and astrocytes to bystander apoptosis induced by HIV. Together, our results indicate that connexin containing channels, GJ and HC, are essential in the pathogenesis of meth and increase the sensitivity of the CNS to HIV CNS disease. Methamphetamine (meth) is an extremely addictive central nervous system stimulant. Meth reduced gap junctional (GJ) communication by inducing internalization of connexin-43 (Cx43) in astrocytes and reducing expression of Cx36 in neurons by a mechanism involving activation of dopamine receptors (see cartoon). Meth-induced changes in Cx containing channels increased extracellular levels of glutamate and resulted in higher sensitivity of neurons and astrocytes to apoptosis in response to HIV infection.
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Affiliation(s)
- Paul Castellano
- Public Health Research Institute (PHRI), New Jersey Medical School, Rutgers University, Newark, New Jersey, USA.,Department of Microbiology and Molecular Genetics, New Jersey Medical School, Rutgers University, Newark, New Jersey, USA
| | - Chisom Nwagbo
- Public Health Research Institute (PHRI), New Jersey Medical School, Rutgers University, Newark, New Jersey, USA.,Department of Microbiology and Molecular Genetics, New Jersey Medical School, Rutgers University, Newark, New Jersey, USA
| | - Luis R Martinez
- New York Institute of Technology College of Osteopathic Medicine, Old Westbury, New York, USA
| | - Eliseo A Eugenin
- Public Health Research Institute (PHRI), New Jersey Medical School, Rutgers University, Newark, New Jersey, USA.,Department of Microbiology and Molecular Genetics, New Jersey Medical School, Rutgers University, Newark, New Jersey, USA
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24
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Cui Y, Prokin I, Xu H, Delord B, Genet S, Venance L, Berry H. Endocannabinoid dynamics gate spike-timing dependent depression and potentiation. eLife 2016; 5:e13185. [PMID: 26920222 PMCID: PMC4811336 DOI: 10.7554/elife.13185] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2015] [Accepted: 02/26/2016] [Indexed: 11/13/2022] Open
Abstract
Synaptic plasticity is a cardinal cellular mechanism for learning and memory. The endocannabinoid (eCB) system has emerged as a pivotal pathway for synaptic plasticity because of its widely characterized ability to depress synaptic transmission on short- and long-term scales. Recent reports indicate that eCBs also mediate potentiation of the synapse. However, it is not known how eCB signaling may support bidirectionality. Here, we combined electrophysiology experiments with mathematical modeling to question the mechanisms of eCB bidirectionality in spike-timing dependent plasticity (STDP) at corticostriatal synapses. We demonstrate that STDP outcome is controlled by eCB levels and dynamics: prolonged and moderate levels of eCB lead to eCB-mediated long-term depression (eCB-tLTD) while short and large eCB transients produce eCB-mediated long-term potentiation (eCB-tLTP). Moreover, we show that eCB-tLTD requires active calcineurin whereas eCB-tLTP necessitates the activity of presynaptic PKA. Therefore, just like glutamate or GABA, eCB form a bidirectional system to encode learning and memory.
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Affiliation(s)
- Yihui Cui
- Center for Interdisciplinary Research in Biology, College de France, INSERM U1050, CNRS UMR7241, Labex Memolife, Paris, France.,University Pierre et Marie Curie, ED 158, Paris, France
| | - Ilya Prokin
- INRIA, Villeurbanne, France.,LIRIS UMR5205, University of Lyon, Villeurbanne, France
| | - Hao Xu
- Center for Interdisciplinary Research in Biology, College de France, INSERM U1050, CNRS UMR7241, Labex Memolife, Paris, France.,University Pierre et Marie Curie, ED 158, Paris, France
| | - Bruno Delord
- University Pierre et Marie Curie, ED 158, Paris, France.,Institute of Intelligent Systems and Robotics, Paris, France
| | - Stephane Genet
- University Pierre et Marie Curie, ED 158, Paris, France.,Institute of Intelligent Systems and Robotics, Paris, France
| | - Laurent Venance
- Center for Interdisciplinary Research in Biology, College de France, INSERM U1050, CNRS UMR7241, Labex Memolife, Paris, France.,University Pierre et Marie Curie, ED 158, Paris, France
| | - Hugues Berry
- INRIA, Villeurbanne, France.,LIRIS UMR5205, University of Lyon, Villeurbanne, France
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25
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Maciunas K, Snipas M, Paulauskas N, Bukauskas FF. Reverberation of excitation in neuronal networks interconnected through voltage-gated gap junction channels. ACTA ACUST UNITED AC 2016; 147:273-88. [PMID: 26880752 PMCID: PMC4772373 DOI: 10.1085/jgp.201511488] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2015] [Accepted: 01/05/2016] [Indexed: 11/20/2022]
Abstract
Voltage-dependent gap junction gating contributes to reverberation in neuronal circuits. We combined Hodgkin–Huxley equations and gating models of gap junction (GJ) channels to simulate the spread of excitation in two-dimensional networks composed of neurons interconnected by voltage-gated GJs. Each GJ channel contains two fast and slow gates, each exhibiting current–voltage (I-V) rectification and gating properties that depend on transjunctional voltage (Vj). The data obtained show how junctional conductance (gj), which is necessary for synchronization of the neuronal network, depends on its size and the intrinsic firing rate of neurons. A phase shift between action potentials (APs) of neighboring neurons creates bipolar, short-lasting Vj spikes of approximately ±100 mV that induce Vj gating, leading to a small decay of gj, which can accumulate into larger decays during bursting activity of neurons. We show that I-V rectification of GJs in local regions of the two-dimensional network of neurons can lead to unidirectional AP transfer and consequently to reverberation of excitation. This reverberation can be initiated by a single electrical pulse and terminated by a low-amplitude pulse applied in a specific window of reverberation cycle. Thus, the model accounts for the influence of dynamically modulatable electrical synapses in shaping the function of a neuronal network and the formation of reverberation, which, as proposed earlier, may be important for the development of short-term memory and its consolidation into long-term memory.
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Affiliation(s)
- Kestutis Maciunas
- Institute of Cardiology, Lithuanian University of Health Sciences, 50009 Kaunas, Lithuania
| | - Mindaugas Snipas
- Institute of Cardiology, Lithuanian University of Health Sciences, 50009 Kaunas, Lithuania Department of Mathematical Modelling, Kaunas University of Technology, 51368 Kaunas, Lithuania
| | - Nerijus Paulauskas
- Institute of Cardiology, Lithuanian University of Health Sciences, 50009 Kaunas, Lithuania
| | - Feliksas F Bukauskas
- Institute of Cardiology, Lithuanian University of Health Sciences, 50009 Kaunas, Lithuania Dominick P. Purpura Department of Neuroscience, Albert Einstein College of Medicine, New York, NY 10461
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26
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Pezzulo G, Levin M. Re-membering the body: applications of computational neuroscience to the top-down control of regeneration of limbs and other complex organs. Integr Biol (Camb) 2015; 7:1487-517. [PMID: 26571046 DOI: 10.1039/c5ib00221d] [Citation(s) in RCA: 93] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
A major goal of regenerative medicine and bioengineering is the regeneration of complex organs, such as limbs, and the capability to create artificial constructs (so-called biobots) with defined morphologies and robust self-repair capabilities. Developmental biology presents remarkable examples of systems that self-assemble and regenerate complex structures toward their correct shape despite significant perturbations. A fundamental challenge is to translate progress in molecular genetics into control of large-scale organismal anatomy, and the field is still searching for an appropriate theoretical paradigm for facilitating control of pattern homeostasis. However, computational neuroscience provides many examples in which cell networks - brains - store memories (e.g., of geometric configurations, rules, and patterns) and coordinate their activity towards proximal and distant goals. In this Perspective, we propose that programming large-scale morphogenesis requires exploiting the information processing by which cellular structures work toward specific shapes. In non-neural cells, as in the brain, bioelectric signaling implements information processing, decision-making, and memory in regulating pattern and its remodeling. Thus, approaches used in computational neuroscience to understand goal-seeking neural systems offer a toolbox of techniques to model and control regenerative pattern formation. Here, we review recent data on developmental bioelectricity as a regulator of patterning, and propose that target morphology could be encoded within tissues as a kind of memory, using the same molecular mechanisms and algorithms so successfully exploited by the brain. We highlight the next steps of an unconventional research program, which may allow top-down control of growth and form for numerous applications in regenerative medicine and synthetic bioengineering.
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Affiliation(s)
- G Pezzulo
- Institute of Cognitive Sciences and Technologies, National Research Council, Rome, Italy
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27
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Navarrete M, Díez A, Araque A. Astrocytes in endocannabinoid signalling. Philos Trans R Soc Lond B Biol Sci 2015; 369:20130599. [PMID: 25225093 DOI: 10.1098/rstb.2013.0599] [Citation(s) in RCA: 80] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023] Open
Abstract
Astrocytes are emerging as integral functional components of synapses, responding to synaptically released neurotransmitters and regulating synaptic transmission and plasticity. Thus, they functionally interact with neurons establishing tripartite synapses: a functional concept that refers to the existence of communication between astrocytes and neurons and its crucial role in synaptic function. Here, we discuss recent evidence showing that astrocytes are involved in the endocannabinoid (ECB) system, responding to exogenous cannabinoids as well as ECBs through activation of type 1 cannabinoid receptors, which increase intracellular calcium and stimulate the release of glutamate that modulates synaptic transmission and plasticity. We also discuss the consequences of ECB signalling in tripartite synapses on the astrocyte-mediated regulation of synaptic function, which reveal novel properties of synaptic regulation by ECBs, such as the spatially controlled dual effect on synaptic strength and the lateral potentiation of synaptic efficacy. Finally, we discuss the potential implications of ECB signalling for astrocytes in brain pathology and animal behaviour.
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Affiliation(s)
| | | | - Alfonso Araque
- Instituto Cajal, CSIC, Madrid 28002, Spain Department of Neuroscience, University of Minnesota, Minneapolis, MN 55455, USA
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28
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Song J, Ampatzis K, Ausborn J, El Manira A. A Hardwired Circuit Supplemented with Endocannabinoids Encodes Behavioral Choice in Zebrafish. Curr Biol 2015; 25:2610-20. [PMID: 26412127 DOI: 10.1016/j.cub.2015.08.042] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2015] [Revised: 07/19/2015] [Accepted: 08/20/2015] [Indexed: 12/25/2022]
Abstract
Animals constantly make behavioral choices to facilitate moving efficiently through their environment. When faced with a threat, animals make decisions in the midst of other ongoing behaviors through a context-dependent integration of sensory stimuli. In vertebrates, the mechanisms underlying behavioral selection are poorly understood. Here, we show that ongoing swimming in zebrafish is suppressed by escape. The selection of escape over swimming is mediated by switching between two distinct motoneuron pools. A hardwired circuit mediates this switch by acting as a clutch-like mechanism to disengage the swimming motoneuron pool and engage the escape motoneuron pool. Threshold for escape initiation is lowered and swimming suppression is prolonged by endocannabinoid neuromodulation. Thus, our results reveal a novel cellular mechanism involving a hardwired circuit supplemented with endocannabinoids acting as a clutch-like mechanism to engage/disengage distinct motor pools to ensure behavioral selection and a smooth execution of motor action sequences in a vertebrate system.
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Affiliation(s)
- Jianren Song
- Department of Neuroscience, Karolinska Institute, 171 77 Stockholm, Sweden
| | | | - Jessica Ausborn
- Department of Neuroscience, Karolinska Institute, 171 77 Stockholm, Sweden
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29
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DOP-2 D2-Like Receptor Regulates UNC-7 Innexins to Attenuate Recurrent Sensory Motor Neurons during C. elegans Copulation. J Neurosci 2015; 35:9990-10004. [PMID: 26156999 DOI: 10.1523/jneurosci.0940-15.2015] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023] Open
Abstract
UNLABELLED Neuromodulation of self-amplifying circuits directs context-dependent behavioral executions. Although recurrent networks are found throughout the Caenorhabditis elegans connectome, few reports describe the mechanisms that regulate reciprocal neural activity during complex behavior. We used C. elegans male copulation to dissect how a goal-oriented motor behavior is regulated by recurrently wired sensory-motor neurons. As the male tail presses against the hermaphrodite's vulva, cholinergic and glutamatergic reciprocal innervations of post cloaca sensilla (PCS) neurons (PCA, PCB, and PCC), hook neurons (HOA, HOB), and their postsynaptic sex muscles execute rhythmic copulatory spicule thrusts. These repetitive spicule movements continue until the male shifts off the vulva or genital penetration is accomplished. However, the signaling mechanism that temporally and spatially restricts repetitive intromission attempts to vulva cues was unclear. Here, we report that confinement of spicule insertion attempts to the vulva is facilitated by D2-like receptor modulation of gap-junctions between PCB and the hook sensillum. We isolated a missense mutation in the UNC-7(L) gap-junction isoform, which perturbs DOP-2 signaling in the PCB neuron and its electrical partner, HOA. The glutamate-gated chloride channel AVR-14 is expressed in HOA. Our analysis of the unc-7 mutant allele indicates that when DOP-2 promotes UNC-7 electrical communication, AVR-14-mediated inhibitory signals pass from HOA to PCB. As a consequence, PCB is less receptive to be stimulated by its recurrent synaptic partner, PCA. Behavioral observations suggest that dopamine neuromodulation of UNC-7 ensures attenuation of recursive intromission attempts when the male disengages or is dislodged from the hermaphrodite genitalia. SIGNIFICANCE STATEMENT Using C. elegans male copulation as a model, we found that the neurotransmitter dopamine stimulates D2-like receptors in two sensory circuits to terminate futile behavioral loops. The D2-like receptors promote inhibitory electrical junction activity between a chemosensory and a mechanosensory circuit. Therefore, both systems are attenuated and the animal ceases the recursive behavior.
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30
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Moore KB, O'Brien J. Connexins in neurons and glia: targets for intervention in disease and injury. Neural Regen Res 2015; 10:1013-7. [PMID: 26330808 PMCID: PMC4541216 DOI: 10.4103/1673-5374.160092] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 05/14/2015] [Indexed: 01/13/2023] Open
Abstract
Both neurons and glia throughout the central nervous system are organized into networks by gap junctions. Among glia, gap junctions facilitate metabolic homeostasis and intercellular communication. Among neurons, gap junctions form electrical synapses that function primarily for communication. However, in neurodegenerative states due to disease or injury gap junctions may be detrimental to survival. Electrical synapses may facilitate hyperactivity and bystander killing among neurons, while gap junction hemichannels in glia may facilitate inflammatory signaling and scar formation. Advances in understanding mechanisms of plasticity of electrical synapses and development of molecular therapeutics to target glial gap junctions and hemichannels offer new hope to pharmacologically limit neuronal degeneration and enhance recovery.
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Affiliation(s)
- Keith B Moore
- Richard S. Ruiz, M.D. Department of Ophthalmology & Visual Science, The University of Texas Health Science Center at Houston, TX, USA
| | - John O'Brien
- Richard S. Ruiz, M.D. Department of Ophthalmology & Visual Science, The University of Texas Health Science Center at Houston, TX, USA ; The University of Texas Graduate School of Biomedical Sciences, Houston, TX, USA
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31
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Cachope R, Pereda AE. Opioids potentiate electrical transmission at mixed synapses on the Mauthner cell. J Neurophysiol 2015; 114:689-97. [PMID: 26019311 DOI: 10.1152/jn.00165.2015] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2015] [Accepted: 05/20/2015] [Indexed: 11/22/2022] Open
Abstract
Opioid receptors were shown to modulate a variety of cellular processes in the vertebrate central nervous system, including synaptic transmission. While the effects of opioid receptors on chemically mediated transmission have been extensively investigated, little is known of their actions on gap junction-mediated electrical synapses. Here we report that pharmacological activation of mu-opioid receptors led to a long-term enhancement of electrical (and glutamatergic) transmission at identifiable mixed synapses on the goldfish Mauthner cells. The effect also required activation of both dopamine D1/5 receptors and postsynaptic cAMP-dependent protein kinase A, suggesting that opioid-evoked actions are mediated indirectly via the release of dopamine from varicosities known to be located in the vicinity of the synaptic contacts. Moreover, inhibitory inputs situated in the immediate vicinity of these excitatory synapses on the lateral dendrite of the Mauthner cell were not affected by activation of mu-opioid receptors, indicating that their actions are restricted to electrical and glutamatergic transmissions co-existing at mixed contacts. Thus, as their chemical counterparts, electrical synapses can be a target for the modulatory actions of the opioid system. Because gap junctions at these mixed synapses are formed by fish homologs of the neuronal connexin 36, which is widespread in mammalian brain, it is likely that this regulatory property applies to electrical synapses elsewhere as well.
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Affiliation(s)
- Roger Cachope
- Dominick P. Purpura Department of Neuroscience, Albert Einstein College of Medicine, Bronx, New York; and
| | - Alberto E Pereda
- Dominick P. Purpura Department of Neuroscience, Albert Einstein College of Medicine, Bronx, New York; and Marine Biological Laboratory, Woods Hole, Massachusetts
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32
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Cui Y, Paillé V, Xu H, Genet S, Delord B, Fino E, Berry H, Venance L. Endocannabinoids mediate bidirectional striatal spike-timing-dependent plasticity. J Physiol 2015; 593:2833-49. [PMID: 25873197 DOI: 10.1113/jp270324] [Citation(s) in RCA: 48] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2015] [Accepted: 04/10/2015] [Indexed: 01/27/2023] Open
Abstract
KEY POINTS Although learning can arise from few or even a single trial, synaptic plasticity is commonly assessed under prolonged activation. Here, we explored the existence of rapid responsiveness of synaptic plasticity at corticostriatal synapses in a major synaptic learning rule, spike-timing-dependent plasticity (STDP). We found that spike-timing-dependent depression (tLTD) progressively disappears when the number of paired stimulations (below 50 pairings) is decreased whereas spike-timing-dependent potentiation (tLTP) displays a biphasic profile: tLTP is observed for 75-100 pairings, is absent for 25-50 pairings and re-emerges for 5-10 pairings. This tLTP induced by low numbers of pairings (5-10) depends on activation of the endocannabinoid system, type-1 cannabinoid receptor and the transient receptor potential vanilloid type-1. Endocannabinoid-tLTP may represent a physiological mechanism operating during the rapid learning of new associative memories and behavioural rules characterizing the flexible behaviour of mammals or during the initial stages of habit learning. ABSTRACT Synaptic plasticity, a main substrate for learning and memory, is commonly assessed with prolonged stimulations. Since learning can arise from few or even a single trial, synaptic strength is expected to adapt rapidly. However, whether synaptic plasticity occurs in response to limited event occurrences remains elusive. To answer this question, we investigated whether a low number of paired stimulations can induce plasticity in a major synaptic learning rule, spike-timing-dependent plasticity (STDP). It is known that 100 pairings induce bidirectional STDP, i.e. spike-timing-dependent potentiation (tLTP) and depression (tLTD) at most central synapses. In rodent striatum, we found that tLTD progressively disappears when the number of paired stimulations is decreased (below 50 pairings) whereas tLTP displays a biphasic profile: tLTP is observed for 75-100 pairings, absent for 25-50 pairings and re-emerges for 5-10 pairings. This tLTP, induced by very few pairings (∼5-10) depends on the endocannabinoid (eCB) system. This eCB-dependent tLTP (eCB-tLTP) involves postsynaptic endocannabinoid synthesis, requires paired activity (post- and presynaptic) and the activation of type-1 cannabinoid receptor (CB1R) and transient receptor potential vanilloid type-1 (TRPV1). eCB-tLTP occurs in both striatopallidal and striatonigral medium-sized spiny neurons (MSNs) and is dopamine dependent. Lastly, we show that eCB-LTP and eCB-LTD can be induced sequentially in the same neuron, depending on the cellular conditioning protocol. Thus, while endocannabinoids are usually thought simply to depress synaptic function, they also constitute a versatile system underlying bidirectional plasticity. Our results reveal a novel form of synaptic plasticity, eCB-tLTP, which may underlie rapid learning capabilities characterizing behavioural flexibility.
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Affiliation(s)
- Yihui Cui
- Centre for Interdisciplinary Research in Biology, College de France, INSERM U1050, CNRS UMR7241, Labex Memolife, Paris, France.,University Pierre et Marie Curie, ED 158, Paris, France
| | - Vincent Paillé
- Centre for Interdisciplinary Research in Biology, College de France, INSERM U1050, CNRS UMR7241, Labex Memolife, Paris, France.,University Pierre et Marie Curie, ED 158, Paris, France
| | - Hao Xu
- Centre for Interdisciplinary Research in Biology, College de France, INSERM U1050, CNRS UMR7241, Labex Memolife, Paris, France.,University Pierre et Marie Curie, ED 158, Paris, France
| | - Stéphane Genet
- University Pierre et Marie Curie, ED 158, Paris, France.,Institute of Intelligent Systems and Robotics (ISIR), Paris, France
| | - Bruno Delord
- University Pierre et Marie Curie, ED 158, Paris, France.,Institute of Intelligent Systems and Robotics (ISIR), Paris, France
| | - Elodie Fino
- Centre for Interdisciplinary Research in Biology, College de France, INSERM U1050, CNRS UMR7241, Labex Memolife, Paris, France.,University Pierre et Marie Curie, ED 158, Paris, France
| | - Hugues Berry
- INRIA, Villeurbanne, France.,University of Lyon, LIRIS UMR5205, Villeurbanne, France
| | - Laurent Venance
- Centre for Interdisciplinary Research in Biology, College de France, INSERM U1050, CNRS UMR7241, Labex Memolife, Paris, France.,University Pierre et Marie Curie, ED 158, Paris, France
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33
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Yao C, Vanderpool KG, Delfiner M, Eddy V, Lucaci AG, Soto-Riveros C, Yasumura T, Rash JE, Pereda AE. Electrical synaptic transmission in developing zebrafish: properties and molecular composition of gap junctions at a central auditory synapse. J Neurophysiol 2014; 112:2102-13. [PMID: 25080573 PMCID: PMC4274921 DOI: 10.1152/jn.00397.2014] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2014] [Accepted: 07/29/2014] [Indexed: 11/22/2022] Open
Abstract
In contrast to the knowledge of chemical synapses, little is known regarding the properties of gap junction-mediated electrical synapses in developing zebrafish, which provide a valuable model to study neural function at the systems level. Identifiable "mixed" (electrical and chemical) auditory synaptic contacts known as "club endings" on Mauthner cells (2 large reticulospinal neurons involved in tail-flip escape responses) allow exploration of electrical transmission in fish. Here, we show that paralleling the development of auditory responses, electrical synapses at these contacts become anatomically identifiable at day 3 postfertilization, reaching a number of ∼6 between days 4 and 9. Furthermore, each terminal contains ∼18 gap junctions, representing between 2,000 and 3,000 connexon channels formed by the teleost homologs of mammalian connexin 36. Electrophysiological recordings revealed that gap junctions at each of these contacts are functional and that synaptic transmission has properties that are comparable with those of adult fish. Thus a surprisingly small number of mixed synapses are responsible for the acquisition of auditory responses by the Mauthner cells, and these are likely sufficient to support escape behaviors at early developmental stages.
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Affiliation(s)
- Cong Yao
- Dominick P. Purpura Department of Neuroscience, Albert Einstein College of Medicine, Bronx, New York
| | - Kimberly G Vanderpool
- Department of Biomedical Sciences, Colorado State University, Fort Collins, Colorado; and
| | - Matthew Delfiner
- Dominick P. Purpura Department of Neuroscience, Albert Einstein College of Medicine, Bronx, New York
| | - Vanessa Eddy
- Dominick P. Purpura Department of Neuroscience, Albert Einstein College of Medicine, Bronx, New York
| | - Alexander G Lucaci
- Dominick P. Purpura Department of Neuroscience, Albert Einstein College of Medicine, Bronx, New York
| | - Carolina Soto-Riveros
- Dominick P. Purpura Department of Neuroscience, Albert Einstein College of Medicine, Bronx, New York
| | - Thomas Yasumura
- Department of Biomedical Sciences, Colorado State University, Fort Collins, Colorado; and
| | - John E Rash
- Department of Biomedical Sciences, Colorado State University, Fort Collins, Colorado; and Program in Molecular, Cellular and Integrative Neurosciences, Colorado State University, Fort Collins, Colorado
| | - Alberto E Pereda
- Dominick P. Purpura Department of Neuroscience, Albert Einstein College of Medicine, Bronx, New York;
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Bosier B, Muccioli GG, Lambert DM. The FAAH inhibitor URB597 efficiently reduces tyrosine hydroxylase expression through CB₁- and FAAH-independent mechanisms. Br J Pharmacol 2014; 169:794-807. [PMID: 22970888 DOI: 10.1111/j.1476-5381.2012.02208.x] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2012] [Revised: 08/23/2012] [Accepted: 09/03/2012] [Indexed: 11/30/2022] Open
Abstract
BACKGROUND Anandamide and 2-arachidonoylglycerol are neuromodulatory lipids interacting with cannabinoid receptors, whose availability is regulated by the balance between 'on demand' generation and enzymatic degradation [by fatty acid amide hydrolase (FAAH)/monoacylglycerol lipase]. Given the reported effects of anandamide on dopamine transmission, we investigated the influence of endocannabinoids and URB597, a well-known FAAH inhibitor, on the expression of tyrosine hydroxylase (TH), the rate-limiting enzyme in dopamine synthesis. EXPERIMENTAL APPROACH We investigated TH expression in N1E115 neuroblastoma using a reporter gene assay, as well as mRNA and protein quantifications. FAAH inhibition was confirmed by measuring radiolabelled substrate hydrolysis and endogenous endocannabinoids. KEY RESULTS Anandamide decreased TH promoter activity in N1E115 cells through CB₁ receptor activation. Unexpectedly, URB597 reduced TH expression (pEC₅₀ = 8.7 ± 0.2) through FAAH-independent mechanisms. Indeed, four structurally unrelated inhibitors of FAAH had no influence on TH expression, although all the inhibitors increased endocannabinoid levels. At variance with the endocannabinoid responses, the use of selective antagonists indicated that the URB597-mediated decrease in TH expression was not directed by the CB₁ receptor, but rather by abnormal-cannabidiol-sensitive receptors and PPARs. Further supporting the physiological relevance of these in vitro data, URB597 administration resulted in reduced TH mRNA levels in mice brain. CONCLUSIONS While confirming the implication of endocannabinoids on the modulation of TH, we provide strong evidence for additional physiologically relevant off-target effects of URB597. In light of the numerous preclinical studies involving URB597, particularly in anxiety and depression, the existence of non-CB₁ and non-FAAH mediated influences of URB597 on key enzymes of the catecholaminergic transmission system should be taken into account when interpreting the data.
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Affiliation(s)
- Barbara Bosier
- Medicinal Chemistry Research Group, Louvain Drug Research Institute, Université Catholique de Louvain, Bruxelles, Belgium
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35
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Gómez-Gonzalo M, Navarrete M, Perea G, Covelo A, Martín-Fernández M, Shigemoto R, Luján R, Araque A. Endocannabinoids Induce Lateral Long-Term Potentiation of Transmitter Release by Stimulation of Gliotransmission. Cereb Cortex 2014; 25:3699-712. [PMID: 25260706 DOI: 10.1093/cercor/bhu231] [Citation(s) in RCA: 90] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
Endocannabinoids (eCBs) play key roles in brain function, acting as modulatory signals in synaptic transmission and plasticity. They are recognized as retrograde messengers that mediate long-term synaptic depression (LTD), but their ability to induce long-term potentiation (LTP) is poorly known. We show that eCBs induce the long-term enhancement of transmitter release at single hippocampal synapses through stimulation of astrocytes when coincident with postsynaptic activity. This LTP requires the coordinated activity of the 3 elements of the tripartite synapse: 1) eCB-evoked astrocyte calcium signal that stimulates glutamate release; 2) postsynaptic nitric oxide production; and 3) activation of protein kinase C and presynaptic group I metabotropic glutamate receptors, whose location at presynaptic sites was confirmed by immunoelectron microscopy. Hence, while eCBs act as retrograde signals to depress homoneuronal synapses, they serve as lateral messengers to induce LTP in distant heteroneuronal synapses through stimulation of astrocytes. Therefore, eCBs can trigger LTP through stimulation of astrocyte-neuron signaling, revealing novel cellular mechanisms of eCB effects on synaptic plasticity.
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Affiliation(s)
| | - Marta Navarrete
- Instituto Cajal, CSIC, Madrid 28002, Spain Current address: Department of Neurobiology, Centro de Biología Molecular "Severo Ochoa," (CSIC/UAM), Madrid, Spain
| | | | - Ana Covelo
- Department of Neuroscience, University of Minnesota, Minneapolis, MN 55455, USA
| | | | - Ryuichi Shigemoto
- Division of Cerebral Structure, National Institute for Physiological Sciences, Okazaki 444-8787, Japan
| | - Rafael Luján
- Instituto de Investigación en Discapacidades Neurológicas (IDINE), Departamento de Ciencias Médicas, Facultad de Medicina, Universidad Castilla-La Mancha, Albacete 02006, Spain
| | - Alfonso Araque
- Instituto Cajal, CSIC, Madrid 28002, Spain Department of Neuroscience, University of Minnesota, Minneapolis, MN 55455, USA
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36
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Zhang Y, Xie H, Lei G, Li F, Pan J, Liu C, Liu Z, Liu L, Cao X. Regulatory effects of anandamide on intracellular Ca(2+) concentration increase in trigeminal ganglion neurons. Neural Regen Res 2014; 9:878-87. [PMID: 25206906 PMCID: PMC4146256 DOI: 10.4103/1673-5374.131607] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 03/21/2014] [Indexed: 12/20/2022] Open
Abstract
Activation of cannabinoid receptor type 1 on presynaptic neurons is postulated to suppress neurotransmission by decreasing Ca2+ influx through high voltage-gated Ca2+ channels. However, recent studies suggest that cannabinoids which activate cannabinoid receptor type 1 can increase neurotransmitter release by enhancing Ca2+ influx in vitro. The aim of the present study was to investigate the modulation of intracellular Ca2+ concentration by the cannabinoid receptor type 1 agonist anandamide, and its underlying mechanisms. Using whole cell voltage-clamp and calcium imaging in cultured trigeminal ganglion neurons, we found that anandamide directly caused Ca2+ influx in a dose-dependent manner, which then triggered an increase of intracellular Ca2+ concentration. The cyclic adenosine and guanosine monophosphate-dependent protein kinase systems, but not the protein kinase C system, were involved in the increased intracellular Ca2+ concentration by anandamide. This result showed that anandamide increased intracellular Ca2+ concentration and inhibited high voltage-gated Ca2+ channels through different signal transduction pathways.
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Affiliation(s)
- Yi Zhang
- Department of Anesthesiology, Tongji Hospital Affiliated to Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei Province, China
| | - Hong Xie
- Jingzhou Central Hospital, Jingzhou, Hubei Province, China
| | - Gang Lei
- Department of Physiology, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei Province, China
| | - Fen Li
- Department of Physiology, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei Province, China
| | - Jianping Pan
- Department of Physiology, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei Province, China
| | - Changjin Liu
- Department of Physiology, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei Province, China
| | - Zhiguo Liu
- Department of Bioengineering, Wuhan Institute of Engineering, Wuhan, Hubei Province, China
| | - Lieju Liu
- Department of Bioengineering, Wuhan Institute of Engineering, Wuhan, Hubei Province, China
| | - Xuehong Cao
- Department of Physiology, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei Province, China ; Department of Bioengineering, Wuhan Institute of Engineering, Wuhan, Hubei Province, China
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37
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Palacios-Prado N, Chapuis S, Panjkovich A, Fregeac J, Nagy JI, Bukauskas FF. Molecular determinants of magnesium-dependent synaptic plasticity at electrical synapses formed by connexin36. Nat Commun 2014; 5:4667. [PMID: 25135336 PMCID: PMC4142521 DOI: 10.1038/ncomms5667] [Citation(s) in RCA: 40] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2014] [Accepted: 07/11/2014] [Indexed: 01/28/2023] Open
Abstract
Neuronal gap junction (GJ) channels composed of connexin36 (Cx36) play an important role in neuronal synchronization and network dynamics. Here we show that Cx36-containing electrical synapses between inhibitory neurons of the thalamic reticular nucleus are bidirectionally modulated by changes in intracellular free magnesium concentration ([Mg(2+)]i). Chimeragenesis demonstrates that the first extracellular loop of Cx36 contains a Mg(2+)-sensitive domain, and site-directed mutagenesis shows that the pore-lining residue D47 is critical in determining high Mg(2+)-sensitivity. Single-channel analysis of Mg(2+)-sensitive chimeras and mutants reveals that [Mg(2+)]i controls the strength of electrical coupling mostly via gating mechanisms. In addition, asymmetric transjunctional [Mg(2+)]i induces strong instantaneous rectification, providing a novel mechanism for electrical rectification in homotypic Cx36 GJs. We suggest that Mg(2+)-dependent synaptic plasticity of Cx36-containing electrical synapses could underlie neuronal circuit reconfiguration via changes in brain energy metabolism that affects neuronal levels of intracellular ATP and [Mg(2+)]i.
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Affiliation(s)
- Nicolás Palacios-Prado
- Dominick P. Purpura Department of Neuroscience, Albert Einstein College of Medicine, NY 10461, USA
- Grass Laboratory, Marine Biological Laboratory, Woods Hole, MA 02543, USA
| | - Sandrine Chapuis
- Dominick P. Purpura Department of Neuroscience, Albert Einstein College of Medicine, NY 10461, USA
| | - Alejandro Panjkovich
- European Molecular Biology Laboratory, Hamburg Outstation, 22603 Hamburg, Germany
| | - Julien Fregeac
- Dominick P. Purpura Department of Neuroscience, Albert Einstein College of Medicine, NY 10461, USA
| | - James I. Nagy
- Department of Physiology, University of Manitoba, Winnipeg, Manitoba R3E 0J9, Canada
| | - Feliksas F. Bukauskas
- Dominick P. Purpura Department of Neuroscience, Albert Einstein College of Medicine, NY 10461, USA
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38
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Medan V, Preuss T. The Mauthner-cell circuit of fish as a model system for startle plasticity. ACTA ACUST UNITED AC 2014; 108:129-40. [PMID: 25106811 DOI: 10.1016/j.jphysparis.2014.07.006] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2014] [Revised: 07/18/2014] [Accepted: 07/21/2014] [Indexed: 11/30/2022]
Abstract
The Mauthner-cell (M-cell) system of teleost fish has a long history as an experimental model for addressing a wide range of neurobiological questions. Principles derived from studies on this system have contributed significantly to our understanding at multiple levels, from mechanisms of synaptic transmission and synaptic plasticity to the concepts of a decision neuron that initiates key aspects of the startle behavior. Here we will review recent work that focuses on the neurophysiological and neuropharmacological basis for modifications in the M-cell circuit. After summarizing the main excitatory and inhibitory inputs to the M-cell, we review experiments showing startle response modulation by temperature, social status, and sensory filtering. Although very different in nature, actions of these three sources of modulation converge in the M-cell network. Mechanisms of modulation include altering the excitability of the M-cell itself as well as changes in excitatory and inhibitor drive, highlighting the role of balanced excitation and inhibition for escape decisions. One of the most extensively studied forms of startle plasticity in vertebrates is prepulse inhibition (PPI), a sensorimotor gating phenomenon, which is impaired in several information processing disorders. Finally, we review recent work in the M-cell system which focuses on the cellular mechanisms of PPI and its modulation by serotonin and dopamine.
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Affiliation(s)
- Violeta Medan
- Dept. de Fisiología y Biología Molecular y Celular, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Intendente Guiraldes 2160, Buenos Aires 1428, Argentina; Instituto de Fisiología, Biología Molecular y Neurociencias, CONICET, Argentina.
| | - Thomas Preuss
- Psychology Dept. Hunter College, City University of New York, 695 Park Ave., New York, NY 10065, USA.
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39
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Synaptically induced long-term modulation of electrical coupling in the inferior olive. Neuron 2014; 81:1290-1296. [PMID: 24656251 PMCID: PMC3988996 DOI: 10.1016/j.neuron.2014.01.005] [Citation(s) in RCA: 58] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 12/10/2013] [Indexed: 11/24/2022]
Abstract
Electrical coupling mediated by gap junctions is widespread in the mammalian CNS, and the interplay between chemical and electrical synapses on the millisecond timescale is crucial for determining patterns of synchrony in many neural circuits. Here we show that activation of glutamatergic synapses drives long-term depression of electrical coupling between neurons of the inferior olive. We demonstrate that this plasticity is not triggered by postsynaptic spiking alone and that it requires calcium entry following synaptic NMDA receptor activation. These results reveal that glutamatergic synapses can instruct plasticity at electrical synapses, providing a means for excitatory inputs to homeostatically regulate the long-term dynamics of microzones in olivocerebellar circuits. Chemical synapses trigger long-term depression of inferior olive electrical coupling Depression of electrical coupling requires NMDAR activation and calcium entry Plasticity is not triggered by postsynaptic spiking alone and EPSPs remain unchanged Excitatory inputs can thus homeostatically regulate synchrony patterns in the olive
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40
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Electrical synapses and their functional interactions with chemical synapses. Nat Rev Neurosci 2014; 15:250-63. [PMID: 24619342 DOI: 10.1038/nrn3708] [Citation(s) in RCA: 297] [Impact Index Per Article: 29.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Brain function relies on the ability of neurons to communicate with each other. Interneuronal communication primarily takes place at synapses, where information from one neuron is rapidly conveyed to a second neuron. There are two main modalities of synaptic transmission: chemical and electrical. Far from functioning independently and serving unrelated functions, mounting evidence indicates that these two modalities of synaptic transmission closely interact, both during development and in the adult brain. Rather than conceiving synaptic transmission as either chemical or electrical, this article emphasizes the notion that synaptic transmission is both chemical and electrical, and that interactions between these two forms of interneuronal communication might be required for normal brain development and function.
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41
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Garkun Y, Maffei A. Cannabinoid-dependent potentiation of inhibition at eye opening in mouse V1. Front Cell Neurosci 2014; 8:46. [PMID: 24600349 PMCID: PMC3928593 DOI: 10.3389/fncel.2014.00046] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2013] [Accepted: 02/01/2014] [Indexed: 11/26/2022] Open
Abstract
Cannabinoid (CB) signaling is a well established regulator of synaptic transmission. Recent work demonstrated that CB release is necessary for the induction of inhibitory synaptic plasticity. In primary visual cortex (V1) CB receptors are present throughout life, though their level of expression is developmentally regulated. In the input layer of V1 (layer 4, L4) these receptors show low levels of expression and colocalize with GABAergic terminals suggesting that they may play an important role in regulating GABAergic transmission. Here we show that in the developmental window extending from eye opening to the onset of the critical period for visual cortical plasticity L4 inhibitory inputs onto pyramidal neurons are highly sensitive to activation of CB release. More specifically, application of synthetic and endogenous CB receptors agonists led to a significant increase in the amplitude and frequency of both spontaneous inhibitory post-synaptic currents and miniature inhibitory post-synaptic currents. This form of inhibitory potentiation is activity-dependent, induced by repetitive bursting of pyramidal neurons and regulated by the time of eye opening. CB-dependent regulation of inhibitory drive may be a mechanism for the regulating L4 pyramidal neurons excitability and function at a time in which V1 transitions from being activated by spontaneous activity to being driven by visual inputs.
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Affiliation(s)
- Yury Garkun
- Department of Neurobiology and Behavior, The State University of New York-Stony Brook University Stony Brook, NY, USA
| | - Arianna Maffei
- Department of Neurobiology and Behavior, The State University of New York-Stony Brook University Stony Brook, NY, USA
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42
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Rash JR, Curti S, Vanderpool KGV, Kamasawa N, Nannapaneni S, Palacios-Prado N, Flores CE, Yasumura T, O’Brien J, Lynn BD, Bukauskas F, Nagy JI, Pereda AE. Molecular and functional asymmetry at a vertebrate electrical synapse. Neuron 2013; 79:957-69. [PMID: 24012008 PMCID: PMC4020187 DOI: 10.1016/j.neuron.2013.06.037] [Citation(s) in RCA: 58] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 06/13/2013] [Indexed: 12/20/2022]
Abstract
Electrical synapses are abundant in the vertebrate brain, but their functional and molecular complexities are still poorly understood. We report here that electrical synapses between auditory afferents and goldfish Mauthner cells are constructed by apposition of hemichannels formed by two homologs of mammalian connexin 36 (Cx36) and that, while Cx35 is restricted to presynaptic hemiplaques, Cx34.7 is restricted to postsynaptic hemiplaques, forming heterotypic junctions. This molecular asymmetry is associated with rectification of electrical transmission that may act to promote cooperativity between auditory afferents. Our data suggest that, in similarity to pre- and postsynaptic sites at chemical synapses, one side in electrical synapses should not necessarily be considered the mirror image of the other. While asymmetry based on the presence of two Cx36 homologs is restricted to teleost fish, it might also be based on differences in posttranslational modifications of individual connexins or in the complement of gap junction-associated proteins.
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Affiliation(s)
- John R. Rash
- Department of Biomedical Sciences and Program in Molecular, Cellular and Integrative Neurosciences, Colorado State University, Fort Collins, Colorado
| | - Sebastian Curti
- Dominick P. Purpura Department of Neuroscience, Albert Einstein College of Medicine, Bronx, New York
- Laboratorio de Neurofisiología Celular, Departamento de Fisiología, Facultad de Medicina, Universidad de la República, Montevideo, Uruguay
| | - Kimberly G. V. Vanderpool
- Department of Biomedical Sciences and Program in Molecular, Cellular and Integrative Neurosciences, Colorado State University, Fort Collins, Colorado
| | | | - Srikant Nannapaneni
- Dominick P. Purpura Department of Neuroscience, Albert Einstein College of Medicine, Bronx, New York
| | - Nicolas Palacios-Prado
- Dominick P. Purpura Department of Neuroscience, Albert Einstein College of Medicine, Bronx, New York
| | - Carmen E. Flores
- Dominick P. Purpura Department of Neuroscience, Albert Einstein College of Medicine, Bronx, New York
| | - Thomas Yasumura
- Department of Biomedical Sciences and Program in Molecular, Cellular and Integrative Neurosciences, Colorado State University, Fort Collins, Colorado
| | - John O’Brien
- University of Texas Health Science Center, Houston, Texas, USA
| | - Bruce D. Lynn
- Department of Physiology, University of Manitoba, Winnipeg, Manitoba, Canada
| | - Feliksas Bukauskas
- Dominick P. Purpura Department of Neuroscience, Albert Einstein College of Medicine, Bronx, New York
| | - James I. Nagy
- Department of Physiology, University of Manitoba, Winnipeg, Manitoba, Canada
| | - Alberto E. Pereda
- Dominick P. Purpura Department of Neuroscience, Albert Einstein College of Medicine, Bronx, New York
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43
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Harvey-Girard E, Giassi ACC, Ellis W, Maler L. Expression of the cannabinoid CB1 receptor in the gymnotiform fish brain and its implications for the organization of the teleost pallium. J Comp Neurol 2013; 521:949-75. [PMID: 22886386 DOI: 10.1002/cne.23212] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2012] [Revised: 07/05/2012] [Accepted: 08/03/2012] [Indexed: 12/14/2022]
Abstract
Cannabinoid CB1 receptors (CB1R) are widely distributed in the brains of many vertebrates, but whether their functions are conserved is unknown. The weakly electric fish, Apteronotus leptorhynchus (Apt), has been well studied for its brain structure, behavior, sensory processing, and learning and memory. It therefore offers an attractive model for comparative studies of CB1R functions. We sequenced partial AptCB1R mRNAs and performed in situ hybridization to localize its expression. Partial AptCB1R protein sequence was highly conserved to zebrafish (90.7%) and mouse (81.9%) orthologs. AptCB1R mRNA was highly expressed in the telencephalon. Subpallial neurons (dorsal, central, intermediate regions and part of the ventral region, Vd/Vc/Vi, and Vv) expressed high levels of AptCB1R transcript. The central region of dorsocentral telencephalon (DC(core) ) strongly expressed CB1R mRNA; cells in DC(core) project to midbrain regions involved in electrosensory/visual function. The lateral and rostral regions of DC surrounding DC(core) (DC(shell) ) lack AptCB1R mRNA. The rostral division of the dorsomedial telencephalon (DM1) highly expresses AptCB1R mRNA. In dorsolateral division (DL) AptCB1R mRNA was expressed in a gradient that declined in a rostrocaudal manner. In diencephalon, AptCB1R RNA probe weakly stained the central-posterior (CP) and prepacemaker (PPn) nuclei. In mesencephalon, AptCB1R mRNA is expressed in deep layers of the dorsal (electrosensory) torus semicircularis (TSd). In hindbrain, AptCB1R RNA probe weakly labeled inhibitory interneurons in the electrosensory lateral line lobe (ELL). Unlike mammals, only few cerebellar granule cells expressed AptCB1R transcripts and these were located in the center of eminentia granularis pars posterior (EGp), a cerebellar region involved in feedback to ELL.
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Affiliation(s)
- Erik Harvey-Girard
- Department of Cellular and Molecular Medicine, University of Ottawa, Ottawa, Canada K1H 8M5.
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44
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Cachope R. Functional diversity on synaptic plasticity mediated by endocannabinoids. Philos Trans R Soc Lond B Biol Sci 2013; 367:3242-53. [PMID: 23108543 DOI: 10.1098/rstb.2011.0386] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023] Open
Abstract
Endocannabinoids (eCBs) act as modulators of synaptic transmission through activation of a number of receptors, including, but not limited to, cannabinoid receptor 1 (CB1). eCBs share CB1 receptors as a common target with Δ(9)-tetrahydrocannabinol (THC), the main psychoactive ingredient in marijuana. Although THC has been used for recreational and medicinal purposes for thousands of years, little was known about its effects at the cellular level or on neuronal circuits. Identification of CB1 receptors and the subsequent development of its specific ligands has therefore enhanced our ability to study and bring together a substantial amount of knowledge regarding how marijuana and eCBs modify interneuronal communication. To date, the eCB system, composed of cannabinoid receptors, ligands and the relevant enzymes, is recognized as the best-described retrograde signalling system in the brain. Its impact on synaptic transmission is widespread and more diverse than initially thought. The aim of this review is to succinctly present the most common forms of eCB-mediated modulation of synaptic transmission, while also illustrating the multiplicity of effects resulting from specializations of this signalling system at the circuital level.
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Affiliation(s)
- Roger Cachope
- Department of Anatomy and Neurobiology, University of Maryland School of Medicine, Baltimore, MD 21201, USA.
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45
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Belousov AB, Fontes JD. Neuronal gap junctions: making and breaking connections during development and injury. Trends Neurosci 2013; 36:227-36. [PMID: 23237660 PMCID: PMC3609876 DOI: 10.1016/j.tins.2012.11.001] [Citation(s) in RCA: 95] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2012] [Revised: 11/02/2012] [Accepted: 11/02/2012] [Indexed: 01/08/2023]
Abstract
In the mammalian central nervous system (CNS), coupling of neurons by gap junctions (i.e., electrical synapses) and the expression of the neuronal gap junction protein, connexin 36 (Cx36), transiently increase during early postnatal development. The levels of both subsequently decline and remain low in the adult, confined to specific subsets of neurons. However, following neuronal injury [such as ischemia, traumatic brain injury (TBI), and epilepsy], the coupling and expression of Cx36 rise. Here we summarize new findings on the mechanisms of regulation of Cx36-containing gap junctions in the developing and mature CNS and following injury. We also review recent studies suggesting various roles for neuronal gap junctions and in particular their role in glutamate-mediated neuronal death.
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Affiliation(s)
- Andrei B Belousov
- Department of Molecular and Integrative Physiology, University of Kansas Medical Center, Kansas City, KS 66160, USA.
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46
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del Corsso C, Iglesias R, Zoidl G, Dermietzel R, Spray DC. Calmodulin dependent protein kinase increases conductance at gap junctions formed by the neuronal gap junction protein connexin36. Brain Res 2012; 1487:69-77. [PMID: 22796294 PMCID: PMC4355912 DOI: 10.1016/j.brainres.2012.06.058] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2012] [Revised: 06/26/2012] [Accepted: 06/30/2012] [Indexed: 11/27/2022]
Abstract
The major neuronal gap junction protein connexin36 (Cx36) exhibits the remarkable property of "run-up", in which junctional conductance typically increases by 10-fold or more within 5-10min following cell break-in with patch pipettes. Such conductance "run-up" is a unique property of Cx36, as it has not been seen in cell pairs expressing other connexins. Because of the recent observation describing CaMKII binding and phosphorylation sites in Cx36 and evidence that calmodulin dependent protein kinase II (CaMKII) may potentiate electrical coupling in neurons of teleosts, we have explored whether CaMKII activates mammalian Cx36. Consistent with this hypothesis, certain Cx36 mutants lacking the CaMKII binding and phosphorylation sites or wild type Cx36 treated with certain cognate peptides corresponding to binding or phosphorylation sites blocked or strongly attenuated run-up of junctional conductance. Likewise, KN-93, an inhibitor of CaMKII, blocked run-up, as did a membrane permeable peptide corresponding to the CaMKII autoinhibitory domain. Furthermore, run-up was blocked by phosphatase delivered within the pipette and not affected by treatment with the phosphatase inhibitor okadaic acid. These results imply that phosphorylation by CaMKII strengthens junctional currents of Cx36 channels, thereby conferring functional plasticity on electrical synapses formed of this protein.
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Affiliation(s)
- Cristiane del Corsso
- Dominick P. Purpura Department of Neuroscience, Albert Einstein College of Medicine, Bronx, NY,10461, USA
| | - Rodolfo Iglesias
- Dominick P. Purpura Department of Neuroscience, Albert Einstein College of Medicine, Bronx, NY,10461, USA
| | | | | | - David C. Spray
- Dominick P. Purpura Department of Neuroscience, Albert Einstein College of Medicine, Bronx, NY,10461, USA
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47
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Huntingford FA. The physiology of fish behaviour: a selective review of developments over the past 40 years(§). JOURNAL OF FISH BIOLOGY 2012; 81:2103-2126. [PMID: 23252730 DOI: 10.1111/j.1095-8649.2012.03480.x] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
During the past 40 years many new techniques have emerged that have been pivotal in furthering understanding of the physiology of fish behaviour. Behavioural studies have been enhanced by video recording systems and software for computerized event recording analysis, fine scale anatomical studies by fluorescence confocal microscopy, neurophysiological studies by visualisation and neuroendocrinology with techniques for identifying, localizing and quantifying many neurochemicals within the central nervous system. This array of approaches has been complemented by developments in molecular biology that include the ability to monitor expression profiles for known genes in specific neural structures and within the whole transcriptome. This article explores how the deployment of new techniques during the last four decades has advanced the understanding of two extensively studied systems. The first of these is the fast-start escape response, concentrating on work on goldfish Carassius auratus and zebrafish Danio rerio. The second is the link between social experience and neuroendocrinology and how this relates to life-history traits in the cichlid Burton's mouthbrooder Astatotilapia burtoni. These two case studies are then used to explore the extent to which the behaviour of animals can be explained in terms of underlying physiological mechanisms.
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Affiliation(s)
- F A Huntingford
- Institute of Biodiversity, Animal Health and Comparative Medicine, College of Medical, Veterinary & Life Sciences, University of Glasgow, Glasgow G12 8QQ, UK.
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48
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Mu Y, Li XQ, Zhang B, Du JL. Visual input modulates audiomotor function via hypothalamic dopaminergic neurons through a cooperative mechanism. Neuron 2012; 75:688-99. [PMID: 22920259 DOI: 10.1016/j.neuron.2012.05.035] [Citation(s) in RCA: 67] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 05/24/2012] [Indexed: 12/18/2022]
Abstract
Visual cues often modulate auditory signal processing, leading to improved sound detection. However, the synaptic and circuit mechanism underlying this cross-modal modulation remains poorly understood. Using larval zebrafish, we first established a cross-modal behavioral paradigm in which a preceding flash enhances sound-evoked escape behavior, which is known to be executed through auditory afferents (VIII(th) nerves) and command-like neurons (Mauthner cells). In vivo recording revealed that the visual enhancement of auditory escape is achieved by increasing sound-evoked Mauthner cell responses. This increase in Mauthner cell responses is accounted for by the increase in the signal-to-noise ratio of sound-evoked VIII(th) nerve spiking and efficacy of VIII(th) nerve-Mauthner cell synapses. Furthermore, the visual enhancement of Mauthner cell response and escape behavior requires light-responsive dopaminergic neurons in the caudal hypothalamus and D1 dopamine receptor activation. Our findings illustrate a cooperative neural mechanism for visual modulation of audiomotor processing that involves dopaminergic neuromodulation.
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Affiliation(s)
- Yu Mu
- Institute of Neuroscience and State Key Laboratory of Neuroscience, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai 200031, China
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49
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Hartveit E, Veruki ML. Electrical synapses between AII amacrine cells in the retina: Function and modulation. Brain Res 2012; 1487:160-72. [PMID: 22776293 DOI: 10.1016/j.brainres.2012.05.060] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2012] [Accepted: 05/09/2012] [Indexed: 12/24/2022]
Abstract
Adaptation enables the visual system to operate across a large range of background light intensities. There is evidence that one component of this adaptation is mediated by modulation of gap junctions functioning as electrical synapses, thereby tuning and functionally optimizing specific retinal microcircuits and pathways. The AII amacrine cell is an interneuron found in most mammalian retinas and plays a crucial role for processing visual signals in starlight, twilight and daylight. AII amacrine cells are connected to each other by gap junctions, potentially serving as a substrate for signal averaging and noise reduction, and there is evidence that the strength of electrical coupling is modulated by the level of background light. Whereas there is extensive knowledge concerning the retinal microcircuits that involve the AII amacrine cell, it is less clear which signaling pathways and intracellular transduction mechanisms are involved in modulating the junctional conductance between electrically coupled AII amacrine cells. Here we review the current state of knowledge, with a focus on the recent evidence that suggests that the modulatory control involves activity-dependent changes in the phosphorylation of the gap junction channels between AII amacrine cells, potentially linked to their intracellular Ca(2+) dynamics. This article is part of a Special Issue entitled Electrical Synapses.
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Affiliation(s)
- Espen Hartveit
- University of Bergen, Department of Biomedicine, Bergen, Norway.
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50
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Cachope R, Pereda AE. Two independent forms of activity-dependent potentiation regulate electrical transmission at mixed synapses on the Mauthner cell. Brain Res 2012; 1487:173-82. [PMID: 22771708 DOI: 10.1016/j.brainres.2012.05.059] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2012] [Revised: 04/24/2012] [Accepted: 05/09/2012] [Indexed: 10/28/2022]
Abstract
Mixed (electrical and chemical) synaptic contacts on the Mauthner cells, known as Club endings, constitute a valuable model for the study of vertebrate electrical transmission. While electrical synapses are still perceived by many as passive intercellular channels that lack modifiability, a wealth of experimental evidence shows that gap junctions at Club endings are subject to dynamic regulatory control by two independent activity-dependent mechanisms that lead to potentiation of electrical transmission. One of those mechanisms relies on activation of NMDA receptors and postsynaptic CaMKII. A second mechanism relies on mGluR activation and endocannabinoid production and is indirectly mediated via the release of dopamine from nearby varicosities, which in turn leads to potentiation of the synaptic response via a PKA-mediated postsynaptic mechanism. We review here these two forms of potentiation and their signaling mechanisms, which include the activation of two kinases with well-established roles as regulators of synaptic strength, as well as the functional implications of these two forms of potentiation. Special Issue entitled Electrical Synapses.
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Affiliation(s)
- Roger Cachope
- Dominick P. Purpura Department of Neuroscience, Albert Einstein College of Medicine of Yeshiva University, Bronx, NY 10461, USA
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