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Kim YS, Lee CJ, Kim JH, Kim YB, Colwell CS, Kim YI. Activation of mGluR1 negatively modulates glutamate-induced phase shifts of the circadian pacemaker in the mouse suprachiasmatic nucleus. Neurobiol Sleep Circadian Rhythms 2023; 14:100089. [PMID: 36874931 PMCID: PMC9982032 DOI: 10.1016/j.nbscr.2023.100089] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2022] [Revised: 01/25/2023] [Accepted: 02/16/2023] [Indexed: 02/22/2023] Open
Abstract
In mammals, photic information delivered to the suprachiasmatic nucleus (SCN) via the retinohypothalamic tract (RHT) plays a crucial role in synchronizing the master circadian clock located in the SCN to the solar cycle. It is well known that glutamate released from the RHT terminals initiates the synchronizing process by activating ionotropic glutamate receptors (iGluRs) on retinorecipient SCN neurons. The potential role of metabotropic glutamate receptors (mGluRs) in modulating this signaling pathway has received less attention. In this study, using extracellular single-unit recordings in mouse SCN slices, we investigated the possible roles of the Gq/11 protein-coupled mGluRs, mGluR1 and mGluR5, in photic resetting. We found that mGluR1 activation in the early night produced phase advances in neural activity rhythms in the SCN, while activation in the late night produced phase delays. In contrast, mGluR5 activation had no significant effect on the phase of these rhythms. Interestingly, mGluR1 activation antagonized phase shifts induced by glutamate through a mechanism that was dependent upon CaV1.3 L-type voltage-gated Ca2+ channels (VGCCs). While both mGluR1-evoked phase delays and advances were inhibited by knockout (KO) of CaV1.3 L-type VGCCs, different signaling pathways appeared to be involved in mediating these effects, with mGluR1 working via protein kinase G in the early night and via protein kinase A signaling in the late night. We conclude that, in the mouse SCN, mGluR1s function to negatively modulate glutamate-evoked phase shifts.
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Affiliation(s)
- Yoon Sik Kim
- Department of Physiology and Neuroscience Research Institute, Korea University College of Medicine, Seoul, 136-705, Republic of Korea
| | - C Justin Lee
- Center for Cognition and Sociality, Institute for Basic Science (IBS), Daejeon, Republic of Korea
| | - Ji-Hyeon Kim
- Department of Physiology and Neuroscience Research Institute, Korea University College of Medicine, Seoul, 136-705, Republic of Korea
| | - Young-Beom Kim
- Department of Physiology and Neuroscience Research Institute, Korea University College of Medicine, Seoul, 136-705, Republic of Korea
| | - Christopher S Colwell
- Department of Psychiatry & Biobehavioral Sciences, University of California-Los Angeles, 760 Westwood Plaza, Los Angeles, CA, 90024, USA
| | - Yang In Kim
- Department of Physiology and Neuroscience Research Institute, Korea University College of Medicine, Seoul, 136-705, Republic of Korea
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2
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Zhu T, Wei S, Wang Y. Post-Inhibitory Rebound Firing of Dorsal Root Ganglia Neurons. J Pain Res 2022; 15:2029-2040. [PMID: 35923842 PMCID: PMC9342929 DOI: 10.2147/jpr.s370335] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2022] [Accepted: 07/02/2022] [Indexed: 01/06/2023] Open
Abstract
Background In the central nervous system, post-inhibitory rebound firing (RF) may mediate overactivity of neurons under pathophysiological condition. RF is also observed in dorsal root ganglion (IRA) neurons. However, the functional significance of RF in primary sensory neurons has remained unknown. After peripheral sensory nerve/neuron injury, DRG neurons exhibit hyperexcitability. Therefore, RF may play a role in neuropathic pain. Methods Chronic compression of DRG (CCD) is used as a neuropathic pain model. Rats were divided into 2 groups: Sham and CCD groups. Patch clamp was performed on the whole DRG and cultured DRG neurons to record RF and T-type Ca2+ currents. The blocker of T-type Ca2+ channels, NiCl2, was applied to DRG neurons. Results Rebound neurons were more excitable than non-rebound neurons. And they discharged RF with prominent after depolarizing potentials, which were blocked by NiCl2. After DRG injury, the proportion of rebound neurons augmented, and rebound neurons’ excitability increased. Meanwhile, the steady-state activation curve of T-type Ca2+ channels was shifted toward the left. Conclusion RF may be related to highly excitable neurons and sensitive to both depolarization and hyperpolarization. T-type Ca2+ channels were critical to RF, potentially enhancing the spontaneous firing of rebound neurons in response to resting membrane potential fluctuations.
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Affiliation(s)
- Tong Zhu
- Department of Physiology and Pathophysiology, School of Basic Medical Sciences, Xi’an Jiaotong University Health Science Center, Xi’an, Shaanxi, 710061, People’s Republic of China
- Clinical Experimental Center, Xi’an International Medical Center Hospital, Xi’an, Shaanxi, 710100, People’s Republic of China
| | - Siqi Wei
- Department of Physiology and Pathophysiology, School of Basic Medical Sciences, Xi’an Jiaotong University Health Science Center, Xi’an, Shaanxi, 710061, People’s Republic of China
| | - Yuying Wang
- Department of Physiology and Pathophysiology, School of Basic Medical Sciences, Xi’an Jiaotong University Health Science Center, Xi’an, Shaanxi, 710061, People’s Republic of China
- Institute of Neuroscience, Translational Medicine Institute, Xi’an Jiaotong University Health Science Center, Xi’an, Shaanxi, 710061, People’s Republic of China
- Key Laboratory of Environment and Genes Related to Diseases (Xi’an Jiaotong University), Ministry of Education, Xi’an, People’s Republic of China
- Correspondence: Yuying Wang, Email
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3
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Uematsu A, Tanaka M. Effects of GABAergic and Glutamatergic Inputs on Temporal Prediction Signals in the Primate Cerebellar Nucleus. Neuroscience 2022; 482:161-171. [PMID: 35031083 DOI: 10.1016/j.neuroscience.2021.11.047] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2021] [Revised: 11/28/2021] [Accepted: 11/29/2021] [Indexed: 12/19/2022]
Abstract
The cerebellum has been shown to be involved in temporal information processing. We recently demonstrated that neurons in the cerebellar dentate nucleus exhibited periodic activity predicting stimulus timing when monkeys attempted to detect a single omission of isochronous repetitive visual stimulus. In this study, we assessed the relative contribution of signals from Purkinje cells and mossy and climbing fibers to the periodic activity by comparing single neuronal firing before and during local infusion of GABA or glutamate receptor antagonists (gabazine or a mixture of 1,2,3,4-tetrahydro-6-nitro-2,3-dioxo-benzo[f]quinoxaline-7-sulfonamide hydrate (NBQX) and (±)-3-(2-carboxypiperazin-4-yl)-propyl-1-phosphonic acid (CPP)). Gabazine application reduced the magnitude of periodic activity and increased the baseline firing rate in most neurons. In contrast, during the blockade of glutamate receptors, both the magnitude of periodic firing modulation and the baseline activity remained unchanged in the population, while a minority of neurons significantly altered their activity. Furthermore, the amounts of changes in the baseline activity and the magnitude of periodic activity were inversely correlated in the gabazine experiments but not in the NBQX + CPP experiments. We also found that the variation of baseline activity decreased during gabazine application but sometimes increased during the blockade of glutamate receptors. These changes were not observed during prolonged recording without drug administration. These results suggest that the predictive neuronal activity in the dentate nucleus may mainly attribute to the inputs from the cerebellar cortex, while the signals from both mossy fibers and Purkinje cells may play a role in setting the level and variance of baseline activity during the task.
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Affiliation(s)
- Akiko Uematsu
- Department of Physiology, Hokkaido University School of Medicine, Sapporo 060-8638, Japan; Department of System Neuroscience, National Institute for Physiological Sciences, Okazaki 444-8585, Japan
| | - Masaki Tanaka
- Department of Physiology, Hokkaido University School of Medicine, Sapporo 060-8638, Japan.
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4
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Yang X, Yin H, Wang X, Sun Y, Bian X, Zhang G, Li A, Cao A, Li B, Ebrahimi-Fakhari D, Yang Z, Meisler MH, Liu Q. Social Deficits and Cerebellar Degeneration in Purkinje Cell Scn8a Knockout Mice. Front Mol Neurosci 2022; 15:822129. [PMID: 35557557 PMCID: PMC9087741 DOI: 10.3389/fnmol.2022.822129] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2021] [Accepted: 02/18/2022] [Indexed: 11/23/2022] Open
Abstract
Mutations in the SCN8A gene encoding the voltage-gated sodium channel α-subunit Nav1. 6 have been reported in individuals with epilepsy, intellectual disability and features of autism spectrum disorder. SCN8A is widely expressed in the central nervous system, including the cerebellum. Cerebellar dysfunction has been implicated in autism spectrum disorder. We investigated conditional Scn8a knockout mice under C57BL/6J strain background that specifically lack Scn8a expression in cerebellar Purkinje cells (Scn8a flox/flox , L7Cre + mice). Cerebellar morphology was analyzed by immunohistochemistry and MR imaging. Mice were subjected to a battery of behavioral tests including the accelerating rotarod, open field, elevated plus maze, light-dark transition box, three chambers, male-female interaction, social olfaction, and water T-maze tests. Patch clamp recordings were used to evaluate evoked action potentials in Purkinje cells. Behavioral phenotyping demonstrated that Scn8a flox/flox , L7Cre + mice have impaired social interaction, motor learning and reversal learning as well as increased repetitive behavior and anxiety-like behaviors. By 5 months of age, Scn8a flox/flox , L7Cre + mice began to exhibit cerebellar Purkinje cell loss and reduced molecular thickness. At 9 months of age, Scn8a flox/flox , L7Cre + mice exhibited decreased cerebellar size and a reduced number of cerebellar Purkinje cells more profoundly, with evidence of additional neurodegeneration in the molecular layer and deep cerebellar nuclei. Purkinje cells in Scn8a flox/flox , L7Cre + mice exhibited reduced repetitive firing. Taken together, our experiments indicated that loss of Scn8a expression in cerebellar Purkinje cells leads to cerebellar degeneration and several ASD-related behaviors. Our study demonstrated the specific contribution of loss of Scn8a in cerebellar Purkinje cells to behavioral deficits characteristic of ASD. However, it should be noted that our observed effects reported here are specific to the C57BL/6 genome type.
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Affiliation(s)
- Xiaofan Yang
- Department of Pediatrics, Qilu Hospital of Shandong University, Jinan, China.,Key Laboratory of Experimental Teratology, Ministry of Education, Department of Genetics, School of Basic Medical Sciences, Shandong University, Jinan, China
| | - Hongqiang Yin
- Medical School, State Key Laboratory of Medicinal Chemical Biology, Key Laboratory of Bioactive Materials for Ministry of Education, Nankai University, Tianjin, China.,Department of Operational Medicine, Tianjin Institute of Environmental & Operational Medicine, Tianjin, China
| | - Xiaojing Wang
- Key Laboratory of Experimental Teratology, Ministry of Education, Department of Genetics, School of Basic Medical Sciences, Shandong University, Jinan, China
| | - Yueqing Sun
- Key Laboratory of Experimental Teratology, Ministry of Education, Department of Genetics, School of Basic Medical Sciences, Shandong University, Jinan, China
| | - Xianli Bian
- Department of Neurology, Second Hospital of Shandong University, Jinan, China
| | - Gaorui Zhang
- Department of Radiology, Qilu Hospital of Shandong University, Jinan, China
| | - Anning Li
- Department of Radiology, Qilu Hospital of Shandong University, Jinan, China
| | - Aihua Cao
- Department of Pediatrics, Qilu Hospital of Shandong University, Jinan, China
| | - Baomin Li
- Department of Pediatrics, Qilu Hospital of Shandong University, Jinan, China
| | - Darius Ebrahimi-Fakhari
- Department of Neurology, The F.M. Kirby Neurobiology Center, Boston Children's Hospital, Harvard Medical School, Boston, MA, United States
| | - Zhuo Yang
- Medical School, State Key Laboratory of Medicinal Chemical Biology, Key Laboratory of Bioactive Materials for Ministry of Education, Nankai University, Tianjin, China
| | - Miriam H Meisler
- Department of Human Genetics, University of Michigan, Ann Arbor, MI, United States.,Department of Neurology, University of Michigan, Ann Arbor, MI, United States
| | - Qiji Liu
- Key Laboratory of Experimental Teratology, Ministry of Education, Department of Genetics, School of Basic Medical Sciences, Shandong University, Jinan, China.,Key Laboratory of Birth Regulation and Control Technology of National Health Commission of China, Maternal and Child Health Care Hospital of Shandong Province, Jinan, China
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5
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Wu YJ, Chien ME, Chiang CC, Huang YZ, Durand DM, Hsu KS. Delta oscillation underlies the interictal spike changes after repeated transcranial direct current stimulation in a rat model of chronic seizures. Brain Stimul 2021; 14:771-779. [PMID: 33989818 DOI: 10.1016/j.brs.2021.04.025] [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: 11/10/2020] [Revised: 04/27/2021] [Accepted: 04/29/2021] [Indexed: 02/06/2023] Open
Abstract
BACKGROUND Transcranial direct current stimulation (tDCS) provides a noninvasive polarity-specific constant current to treat epilepsy, through a mechanism possibly involving excitability modulation and neural oscillation. OBJECTIVE To determine whether EEG oscillations underlie the interictal spike changes after tDCS in rats with chronic spontaneous seizures. METHODS Rats with kainic acid-induced spontaneous seizures were subjected to cathodal tDCS or sham stimulation for 5 consecutive days. Video-EEG recordings were collected immediately pre- and post-stimulation and for the subsequent 2 weeks following stimulation. The acute pre-post stimulation and subacute follow-up changes of interictal spikes and EEG oscillations in tDCS-treated rats were compared with sham. Ictal EEG with seizure behaviors, hippocampal brain-derived neurotrophic factor (BDNF) protein expression, and mossy fiber sprouting were compared between tDCS and sham rats. RESULTS Interictal spike counts were reduced immediately following tDCS with augmented delta and diminished beta and gamma oscillations compared with sham. Cathodal tDCS also enhanced delta oscillations in normal rats. However, increased numbers of interictal spikes with a decrease of delta and theta oscillations were observed in tDCS-treated rats compared with sham during the following 2 weeks after stimulation. Resuming tDCS suppressed the increase of interictal spike activity. In tDCS rats, hippocampal BDNF protein expression was decreased while mossy fiber sprouting did not change compared with sham. CONCLUSIONS The inverse relationship between the changes of delta oscillation and interictal spikes during tDCS on and off stimulation periods indicates that an enhanced endogenous delta oscillation underlies the tDCS inhibitory effect on epileptic excitability.
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Affiliation(s)
- Yi-Jen Wu
- Institute of Clinical Medicine, College of Medicine, National Cheng Kung University, Tainan 70457, Taiwan; Department of Neurology, National Cheng Kung University Hospital, College of Medicine, National Cheng Kung University, Tainan 70403, Taiwan.
| | - Miao-Er Chien
- Institute of Clinical Medicine, College of Medicine, National Cheng Kung University, Tainan 70457, Taiwan
| | - Chia-Chu Chiang
- Department of Biomedical Engineering, Case Western Reserve University, Cleveland, OH 44106, USA
| | - Ying-Zu Huang
- Department of Neurology and Neuroscience Research Center, Chang Gung Memorial Hospital at Linkou, Taoyuan City, Taiwan; Medical School and Healthy Aging Research Center, College of Medicine, Chang Gung University, Taoyuan, Taiwan; Institute of Cognitive Neuroscience, National Central University, Taoyuan, Taiwan
| | - Dominique M Durand
- Department of Biomedical Engineering, Case Western Reserve University, Cleveland, OH 44106, USA
| | - Kuei-Sen Hsu
- Department of Pharmacology, College of Medicine, National Cheng Kung University, Tainan 70101, Taiwan; Institute of Basic Medical Sciences, College of Medicine, National Cheng Kung University, Tainan 70101, Taiwan.
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6
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O'Dell DE, Schreurs BG, Smith-Bell C, Wang D. Disruption of rat deep cerebellar perineuronal net alters eyeblink conditioning and neuronal electrophysiology. Neurobiol Learn Mem 2021; 177:107358. [PMID: 33285318 PMCID: PMC8279724 DOI: 10.1016/j.nlm.2020.107358] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2020] [Revised: 11/04/2020] [Accepted: 11/16/2020] [Indexed: 01/26/2023]
Abstract
The perineuronal net (PNN) is a specialized type of extracellular matrix found in the central nervous system. The PNN forms on fast spiking neurons during postnatal development but the ontogeny of PNN development has yet to be elucidated. By studying the development and prevalence of the PNN in the juvenile and adult rat brain, we may be able to understand the PNN's role in development and learning and memory. We show that the PNN is fully developed in the deep cerebellar nuclei (DCN) of rats by P18. By using enzymatic digestion of the PNN with chondroitinase ABC (ChABC), we are able to study how digestion of the PNN affects cerebellar-dependent eyeblink conditioning in vivo and perform electrophysiological recordings from DCN neurons in vitro. In vivo degradation of the PNN resulted in significant differences in eyeblink conditioning amplitude and area. Female animals in the vehicle group demonstrated higher levels of conditioning as well as significantly higher post-probe conditioned responses compared to males in that group, differences not present in the ChABC group. In vitro, we found that DCN neurons with a disrupted PNN following exposure to ChABC had altered membrane properties, fewer rebound spikes, and decreased intrinsic excitability. Together, this study further elucidates the role of the PNN in cerebellar learning in the DCN and is the first to demonstrate PNN degradation may erase sex differences in delay conditioning.
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Affiliation(s)
- Deidre E O'Dell
- Department of Neuroscience, Rockefeller Neuroscience Institute, WVU, 33 Medical Center Dr, Morgantown, WV 26505, United States.
| | - Bernard G Schreurs
- Department of Neuroscience, Rockefeller Neuroscience Institute, WVU, 33 Medical Center Dr, Morgantown, WV 26505, United States
| | - Carrie Smith-Bell
- Department of Neuroscience, Rockefeller Neuroscience Institute, WVU, 33 Medical Center Dr, Morgantown, WV 26505, United States
| | - Desheng Wang
- Department of Neuroscience, Rockefeller Neuroscience Institute, WVU, 33 Medical Center Dr, Morgantown, WV 26505, United States
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7
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Bao J, Graupner M, Astorga G, Collin T, Jalil A, Indriati DW, Bradley J, Shigemoto R, Llano I. Synergism of type 1 metabotropic and ionotropic glutamate receptors in cerebellar molecular layer interneurons in vivo. eLife 2020; 9:56839. [PMID: 32401196 PMCID: PMC7220378 DOI: 10.7554/elife.56839] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2020] [Accepted: 04/27/2020] [Indexed: 11/16/2022] Open
Abstract
Type 1 metabotropic glutamate receptors (mGluR1s) are key elements in neuronal signaling. While their function is well documented in slices, requirements for their activation in vivo are poorly understood. We examine this question in adult mice in vivo using 2-photon imaging of cerebellar molecular layer interneurons (MLIs) expressing GCaMP. In anesthetized mice, parallel fiber activation evokes beam-like Cai rises in postsynaptic MLIs which depend on co-activation of mGluR1s and ionotropic glutamate receptors (iGluRs). In awake mice, blocking mGluR1 decreases Cai rises associated with locomotion. In vitro studies and freeze-fracture electron microscopy show that the iGluR-mGluR1 interaction is synergistic and favored by close association of the two classes of receptors. Altogether our results suggest that mGluR1s, acting in synergy with iGluRs, potently contribute to processing cerebellar neuronal signaling under physiological conditions.
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Affiliation(s)
- Jin Bao
- Université de Paris, CNRS, SPPIN - Saints-Pères Paris Institute for the Neurosciences, Paris, France.,The Brain Cognition and Brain Disease Institute (BCBDI), Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences; Shenzhen-Hong Kong Institute of Brain Science-Shenzhen Fundamental Research Institutions, Shenzhen, China
| | - Michael Graupner
- Université de Paris, CNRS, SPPIN - Saints-Pères Paris Institute for the Neurosciences, Paris, France
| | - Guadalupe Astorga
- Université de Paris, CNRS, SPPIN - Saints-Pères Paris Institute for the Neurosciences, Paris, France
| | - Thibault Collin
- Université de Paris, CNRS, SPPIN - Saints-Pères Paris Institute for the Neurosciences, Paris, France
| | - Abdelali Jalil
- Université de Paris, CNRS, SPPIN - Saints-Pères Paris Institute for the Neurosciences, Paris, France
| | - Dwi Wahyu Indriati
- Division of Cerebral Structure, National Institute for Physiological Sciences, The Graduate University for Advanced Studies (Sokendai), Okazaki, Japan
| | - Jonathan Bradley
- Université de Paris, CNRS, SPPIN - Saints-Pères Paris Institute for the Neurosciences, Paris, France.,Institut de Biologie de l'Ecole Normale Superieure (IBENS), Ecole Normale Superieure, CNRS, INSERM, PSL Research University, Paris, France
| | - Ryuichi Shigemoto
- Division of Cerebral Structure, National Institute for Physiological Sciences, The Graduate University for Advanced Studies (Sokendai), Okazaki, Japan.,IST Austria, Klosterneuburg, Austria
| | - Isabel Llano
- Université de Paris, CNRS, SPPIN - Saints-Pères Paris Institute for the Neurosciences, Paris, France
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8
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Neonatal Sepsis Alters the Excitability of Regular Spiking Cells in the Nucleus of the Solitary Tract in Rats. Shock 2019; 54:265-271. [DOI: 10.1097/shk.0000000000001453] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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9
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Abstract
Rhythmicity is a universal timing mechanism in the brain, and the rhythmogenic mechanisms are generally dynamic. This is illustrated for the neuronal control of breathing, a behavior that occurs as a one-, two-, or three-phase rhythm. Each breath is assembled stochastically, and increasing evidence suggests that each phase can be generated independently by a dedicated excitatory microcircuit. Within each microcircuit, rhythmicity emerges through three entangled mechanisms: ( a) glutamatergic transmission, which is amplified by ( b) intrinsic bursting and opposed by ( c) concurrent inhibition. This rhythmogenic triangle is dynamically tuned by neuromodulators and other network interactions. The ability of coupled oscillators to reconfigure and recombine may allow breathing to remain robust yet plastic enough to conform to nonventilatory behaviors such as vocalization, swallowing, and coughing. Lessons learned from the respiratory network may translate to other highly dynamic and integrated rhythmic systems, if approached one breath at a time.
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Affiliation(s)
- Jan-Marino Ramirez
- Center for Integrative Brain Research, Seattle Children's Research Institute, Department of Neurological Surgery, University of Washington School of Medicine, Seattle, Washington 98101, USA;
| | - Nathan A Baertsch
- Center for Integrative Brain Research, Seattle Children's Research Institute, Department of Neurological Surgery, University of Washington School of Medicine, Seattle, Washington 98101, USA;
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10
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Perineuronal Nets in the Deep Cerebellar Nuclei Regulate GABAergic Transmission and Delay Eyeblink Conditioning. J Neurosci 2018; 38:6130-6144. [PMID: 29858484 DOI: 10.1523/jneurosci.3238-17.2018] [Citation(s) in RCA: 37] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2017] [Revised: 04/28/2018] [Accepted: 05/28/2018] [Indexed: 11/21/2022] Open
Abstract
Perineuronal nets (PNNs), composed mainly of chondroitin sulfate proteoglycans, are the extracellular matrix that surrounds cell bodies, proximal dendrites, and axon initial segments of adult CNS neurons. PNNs are known to regulate neuronal plasticity, although their physiological roles in cerebellar functions have yet to be elucidated. Here, we investigated the contribution of PNNs to GABAergic transmission from cerebellar Purkinje cells (PCs) to large glutamatergic neurons in the deep cerebellar nuclei (DCN) in male mice by recording IPSCs from cerebellar slices, in which PNNs were depleted with chondroitinase ABC (ChABC). We found that PNN depletion increased the amplitude of evoked IPSCs and enhanced the paired-pulse depression. ChABC treatment also facilitated spontaneous IPSCs and increased the miniature IPSC frequency without changing not only the amplitude but also the density of PC terminals, suggesting that PNN depletion enhances presynaptic GABA release. We also demonstrated that the enhanced GABAergic transmission facilitated rebound firing in large glutamatergic DCN neurons, which is expected to result in the efficient induction of synaptic plasticity at synapses onto DCN neurons. Furthermore, we tested whether PNN depletion affects cerebellar motor learning. Mice having received the enzyme into the interpositus nuclei, which are responsible for delay eyeblink conditioning, exhibited the conditioned response at a significantly higher rate than control mice. Therefore, our results suggest that PNNs of the DCN suppress GABAergic transmission between PCs and large glutamatergic DCN neurons and restrict synaptic plasticity associated with motor learning in the adult cerebellum.SIGNIFICANCE STATEMENT Perineuronal nets (PNNs) are one of the extracellular matrices of adult CNS neurons and implicated in regulating various brain functions. Here we found that enzymatic PNN depletion in the mouse deep cerebellar nuclei (DCN) reduced the paired-pulse ratio of IPSCs and increased the miniature IPSC frequency without changing the amplitude, suggesting that PNN depletion enhances GABA release from the presynaptic Purkinje cell (PC) terminals. Mice having received the enzyme in the interpositus nuclei exhibited a higher conditioned response rate in delay eyeblink conditioning than control mice. These results suggest that PNNs regulate presynaptic functions of PC terminals in the DCN and functional plasticity of synapses on DCN neurons, which influences the flexibility of adult cerebellar functions.
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11
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Ten Brinke MM, Boele HJ, De Zeeuw CI. Conditioned climbing fiber responses in cerebellar cortex and nuclei. Neurosci Lett 2018; 688:26-36. [PMID: 29689340 DOI: 10.1016/j.neulet.2018.04.035] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2018] [Revised: 04/17/2018] [Accepted: 04/18/2018] [Indexed: 11/30/2022]
Abstract
The eyeblink conditioning paradigm captures an elementary form of associative learning in a neural circuitry that is understood to an extraordinary degree. Cerebellar cortical Purkinje cell simple spike suppression is widely regarded as the main process underlying conditioned responses (CRs), leading to disinhibition of neurons in the cerebellar nuclei that innervate eyelid muscles downstream. However, recent work highlights the addition of a conditioned Purkinje cell complex spike response, which at the level of the interposed nucleus seems to translate to a transient spike suppression that can be followed by a rapid spike facilitation. Here, we review the characteristics of these responses at the cerebellar cortical and nuclear level, and discuss possible origins and functions.
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Affiliation(s)
- M M Ten Brinke
- Department of Neuroscience, Erasmus Medical Center, 3000 DR Rotterdam, The Netherlands.
| | - H J Boele
- Department of Neuroscience, Erasmus Medical Center, 3000 DR Rotterdam, The Netherlands
| | - C I De Zeeuw
- Department of Neuroscience, Erasmus Medical Center, 3000 DR Rotterdam, The Netherlands; Netherlands Institute for Neuroscience, Royal Academy of Arts and Sciences (KNAW), 1105 BA Amsterdam, The Netherlands.
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12
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Grimsley CA, Green DB, Sivaramakrishnan S. L-type calcium channels refine the neural population code of sound level. J Neurophysiol 2016; 116:2550-2563. [PMID: 27605536 DOI: 10.1152/jn.00657.2016] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2016] [Accepted: 09/07/2016] [Indexed: 11/22/2022] Open
Abstract
The coding of sound level by ensembles of neurons improves the accuracy with which listeners identify how loud a sound is. In the auditory system, the rate at which neurons fire in response to changes in sound level is shaped by local networks. Voltage-gated conductances alter local output by regulating neuronal firing, but their role in modulating responses to sound level is unclear. We tested the effects of L-type calcium channels (CaL: CaV1.1-1.4) on sound-level coding in the central nucleus of the inferior colliculus (ICC) in the auditory midbrain. We characterized the contribution of CaL to the total calcium current in brain slices and then examined its effects on rate-level functions (RLFs) in vivo using single-unit recordings in awake mice. CaL is a high-threshold current and comprises ∼50% of the total calcium current in ICC neurons. In vivo, CaL activates at sound levels that evoke high firing rates. In RLFs that increase monotonically with sound level, CaL boosts spike rates at high sound levels and increases the maximum firing rate achieved. In different populations of RLFs that change nonmonotonically with sound level, CaL either suppresses or enhances firing at sound levels that evoke maximum firing. CaL multiplies the gain of monotonic RLFs with dynamic range and divides the gain of nonmonotonic RLFs with the width of the RLF. These results suggest that a single broad class of calcium channels activates enhancing and suppressing local circuits to regulate the sensitivity of neuronal populations to sound level.
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Affiliation(s)
- Calum Alex Grimsley
- Department of Anatomy and Neurobiology, Northeast Ohio Medical University, Rootstown, Ohio
| | - David Brian Green
- Department of Anatomy and Neurobiology, Northeast Ohio Medical University, Rootstown, Ohio
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Kolaj M, Zhang L, Renaud LP. L-type calcium channels and MAP kinase contribute to thyrotropin-releasing hormone-induced depolarization in thalamic paraventricular nucleus neurons. Am J Physiol Regul Integr Comp Physiol 2016; 310:R1120-7. [PMID: 27009047 PMCID: PMC4935505 DOI: 10.1152/ajpregu.00082.2016] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2016] [Accepted: 03/18/2016] [Indexed: 12/11/2022]
Abstract
In rat paraventricular thalamic nucleus (PVT) neurons, activation of thyrotropin-releasing hormone (TRH) receptors enhances neuronal excitability via concurrent decrease in a G protein-coupled inwardly rectifying K (GIRK)-like conductance and opening of a cannabinoid receptor-sensitive transient receptor potential canonical (TRPC)-like conductance. Here, we investigated the calcium (Ca(2+)) contribution to the components of this TRH-induced response. TRH-induced membrane depolarization was reduced in the presence of intracellular BAPTA, also in media containing nominally zero [Ca(2+)]o, suggesting a critical role for both intracellular Ca(2+) release and Ca(2+) influx. TRH-induced inward current was unchanged by T-type Ca(2+) channel blockade, but was decreased by blockade of high-voltage-activated Ca(2+) channels (HVACCs). Both the pharmacologically isolated GIRK-like and the TRPC-like components of the TRH-induced response were decreased by nifedipine and increased by BayK8644, implying Ca(2+) influx via L-type Ca(2+) channels. Only the TRPC-like conductance was reduced by either thapsigargin or dantrolene, suggesting a role for ryanodine receptors and Ca(2+)-induced Ca(2+) release in this component of the TRH-induced response. In pituitary and other cell lines, TRH stimulates MAPK. In PVT neurons, only the GIRK-like component of the TRH-induced current was selectively decreased in the presence of PD98059, a MAPK inhibitor. Collectively, the data imply that TRH-induced depolarization and inward current in PVT neurons involve both a dependency on extracellular Ca(2+) influx via opening of L-type Ca(2+) channels, a sensitivity of a TRPC-like component to intracellular Ca(2+) release via ryanodine channels, and a modulation by MAPK of a GIRK-like conductance component.
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Affiliation(s)
- Miloslav Kolaj
- Ottawa Hospital Research Institute, Neuroscience Program and University of Ottawa, Department of Medicine, Ottawa, Ontario, Canada
| | - Li Zhang
- Ottawa Hospital Research Institute, Neuroscience Program and University of Ottawa, Department of Medicine, Ottawa, Ontario, Canada
| | - Leo P Renaud
- Ottawa Hospital Research Institute, Neuroscience Program and University of Ottawa, Department of Medicine, Ottawa, Ontario, Canada
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14
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Mercer AA, Palarz KJ, Tabatadze N, Woolley CS, Raman IM. Sex differences in cerebellar synaptic transmission and sex-specific responses to autism-linked Gabrb3 mutations in mice. eLife 2016; 5. [PMID: 27077953 PMCID: PMC4878876 DOI: 10.7554/elife.07596] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2015] [Accepted: 04/13/2016] [Indexed: 12/18/2022] Open
Abstract
Neurons of the cerebellar nuclei (CbN) transmit cerebellar signals to premotor areas. The cerebellum expresses several autism-linked genes, including GABRB3, which encodes GABAA receptor β3 subunits and is among the maternal alleles deleted in Angelman syndrome. We tested how this Gabrb3 m-/p+ mutation affects CbN physiology in mice, separating responses of males and females. Wild-type mice showed sex differences in synaptic excitation, inhibition, and intrinsic properties. Relative to females, CbN cells of males had smaller synaptically evoked mGluR1/5-dependent currents, slower Purkinje-mediated IPSCs, and lower spontaneous firing rates, but rotarod performances were indistinguishable. In mutant CbN cells, IPSC kinetics were unchanged, but mutant males, unlike females, showed enlarged mGluR1/5 responses and accelerated spontaneous firing. These changes appear compensatory, since mutant males but not females performed indistinguishably from wild-type siblings on the rotarod task. Thus, sex differences in cerebellar physiology produce similar behavioral output, but provide distinct baselines for responses to mutations.
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Affiliation(s)
- Audrey A Mercer
- Northwestern University Interdepartmental Neuroscience Program, Northwestern University, Evanston, United States.,Department of Neurobiology, Northwestern University, Evanston, United States
| | - Kristin J Palarz
- Department of Neurobiology, Northwestern University, Evanston, United States.,Integrated Science Program, Northwestern University, Evanston, United States
| | - Nino Tabatadze
- Department of Neurobiology, Northwestern University, Evanston, United States
| | - Catherine S Woolley
- Northwestern University Interdepartmental Neuroscience Program, Northwestern University, Evanston, United States.,Department of Neurobiology, Northwestern University, Evanston, United States
| | - Indira M Raman
- Northwestern University Interdepartmental Neuroscience Program, Northwestern University, Evanston, United States.,Department of Neurobiology, Northwestern University, Evanston, United States.,Integrated Science Program, Northwestern University, Evanston, United States
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15
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Dykstra S, Engbers JDT, Bartoletti TM, Turner RW. Determinants of rebound burst responses in rat cerebellar nuclear neurons to physiological stimuli. J Physiol 2016; 594:985-1003. [PMID: 26662168 DOI: 10.1113/jp271894] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2015] [Accepted: 12/05/2015] [Indexed: 01/28/2023] Open
Abstract
KEY POINTS Cerebellar Purkinje cells project GABAergic inhibitory input to neurons of the deep cerebellar nuclei (DCN) that generate a rebound increase in firing, but the specific patterns of input that might elicit a rebound response have not been established. We used recordings of Purkinje cell firing obtained during perioral whisker stimulation in vivo to create a physiological stimulus template to activate Purkinje cell afferents in vitro. DCN cell bursts were evoked by the stimulus pattern but not in relation to the perioral whisker stimulus, complex spikes or regular patterns within the Purkinje cell record. Reverse correlation revealed that bursts were triggered by an elevation-pause pattern of Purkinje cell firing, with pause duration a key factor in burst generation. Our data identify for the first time a physiological pattern of Purkinje cell input that can be encoded by the generation of rebound bursts in DCN cells. ABSTRACT The end result of signal processing in cerebellar cortex is encoded in the output of Purkinje cells that project inhibitory input to deep cerebellar nuclear (DCN) neurons. DCN cells can respond to a period of inhibition in vitro with a rebound burst of firing, yet the optimal physiological pattern of Purkinje cell input that might evoke a rebound burst is unknown. The current study used spike trains recorded from rat Purkinje cells in response to perioral stimuli in vivo to create a physiological pattern to stimulate Purkinje cell axons in vitro. The perioral stimulus-evoked Purkinje cell firing pattern proved to be virtually ineffective in evoking a rebound burst despite the ability to reliably evoke rebounds using a traditional brief 100 Hz stimulus. Similarly, neither complex spike firing nor Purkinje cell patterns identified by CV2 analysis were reliably associated with rebound bursts. Reverse correlation revealed that the optimal Purkinje cell input to evoke a rebound burst was a sequential increase in mean firing rate of at least 30 Hz above baseline over 250 ms followed by a reduction of 40-60 Hz below baseline for up to 500 ms. The most important factor was the duration of a pause in Purkinje cell firing that allowed DCN cells to recover from a state of net inhibitory influence. These data indicate that physiological patterns of Purkinje cell firing can elicit rebound bursts in DCN cells in vitro, with pauses in Purkinje cell firing rate acting as a key stimulus for DCN cell rebound responses.
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Affiliation(s)
- Steven Dykstra
- Department of Cell Biology and Anatomy, Hotchkiss Brain Institute, University of Calgary, Calgary, Alberta, Canada, T2N 4N1
| | - Jordan D T Engbers
- Department of Cell Biology and Anatomy, Hotchkiss Brain Institute, University of Calgary, Calgary, Alberta, Canada, T2N 4N1
| | - Theodore M Bartoletti
- Department of Cell Biology and Anatomy, Hotchkiss Brain Institute, University of Calgary, Calgary, Alberta, Canada, T2N 4N1
| | - Ray W Turner
- Department of Cell Biology and Anatomy, Hotchkiss Brain Institute, University of Calgary, Calgary, Alberta, Canada, T2N 4N1
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16
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White JJ, Arancillo M, King A, Lin T, Miterko LN, Gebre SA, Sillitoe RV. Pathogenesis of severe ataxia and tremor without the typical signs of neurodegeneration. Neurobiol Dis 2015; 86:86-98. [PMID: 26586559 DOI: 10.1016/j.nbd.2015.11.008] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2015] [Revised: 10/30/2015] [Accepted: 11/11/2015] [Indexed: 11/27/2022] Open
Abstract
Neurological diseases are especially devastating when they involve neurodegeneration. Neuronal destruction is widespread in cognitive disorders such as Alzheimer's and regionally localized in motor disorders such as Parkinson's, Huntington's, and ataxia. But, surprisingly, the onset and progression of these diseases can occur without neurodegeneration. To understand the origins of diseases that do not have an obvious neuropathology, we tested how loss of CAR8, a regulator of IP3R1-mediated Ca(2+)-signaling, influences cerebellar circuit formation and neural function as movement deteriorates. We found that faulty molecular patterning, which shapes functional circuits called zones, leads to alterations in cerebellar wiring and Purkinje cell activity, but not to degeneration. Rescuing Purkinje cell function improved movement and reducing their Ca(2+) influx eliminated ectopic zones. Our findings in Car8(wdl) mutant mice unveil a pathophysiological mechanism that may operate broadly to impact motor and non-motor conditions that do not involve degeneration.
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Affiliation(s)
- Joshua J White
- Department of Pathology & Immunology, 1250 Moursund Street, Suite 1325, Houston, TX 77030, USA; Department of Neuroscience, 1250 Moursund Street, Suite 1325, Houston, TX 77030, USA; Jan and Dan Duncan Neurological Research Institute of Texas Children's Hospital, 1250 Moursund Street, Suite 1325, Houston, TX 77030, USA
| | - Marife Arancillo
- Department of Pathology & Immunology, 1250 Moursund Street, Suite 1325, Houston, TX 77030, USA; Jan and Dan Duncan Neurological Research Institute of Texas Children's Hospital, 1250 Moursund Street, Suite 1325, Houston, TX 77030, USA
| | - Annesha King
- Department of Pathology & Immunology, 1250 Moursund Street, Suite 1325, Houston, TX 77030, USA; Jan and Dan Duncan Neurological Research Institute of Texas Children's Hospital, 1250 Moursund Street, Suite 1325, Houston, TX 77030, USA
| | - Tao Lin
- Department of Pathology & Immunology, 1250 Moursund Street, Suite 1325, Houston, TX 77030, USA; Jan and Dan Duncan Neurological Research Institute of Texas Children's Hospital, 1250 Moursund Street, Suite 1325, Houston, TX 77030, USA
| | - Lauren N Miterko
- Program in Developmental Biology, Baylor College of Medicine, 1250 Moursund Street, Suite 1325, Houston, TX 77030, USA; Jan and Dan Duncan Neurological Research Institute of Texas Children's Hospital, 1250 Moursund Street, Suite 1325, Houston, TX 77030, USA
| | - Samrawit A Gebre
- Department of Pathology & Immunology, 1250 Moursund Street, Suite 1325, Houston, TX 77030, USA; Jan and Dan Duncan Neurological Research Institute of Texas Children's Hospital, 1250 Moursund Street, Suite 1325, Houston, TX 77030, USA
| | - Roy V Sillitoe
- Department of Pathology & Immunology, 1250 Moursund Street, Suite 1325, Houston, TX 77030, USA; Department of Neuroscience, 1250 Moursund Street, Suite 1325, Houston, TX 77030, USA; Program in Developmental Biology, Baylor College of Medicine, 1250 Moursund Street, Suite 1325, Houston, TX 77030, USA; Jan and Dan Duncan Neurological Research Institute of Texas Children's Hospital, 1250 Moursund Street, Suite 1325, Houston, TX 77030, USA
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17
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Dillon J, Franks CJ, Murray C, Edwards RJ, Calahorro F, Ishihara T, Katsura I, Holden-Dye L, O'Connor V. Metabotropic Glutamate Receptors: MODULATORS OF CONTEXT-DEPENDENT FEEDING BEHAVIOUR IN C. ELEGANS. J Biol Chem 2015; 290:15052-65. [PMID: 25869139 DOI: 10.1074/jbc.m114.606608] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2014] [Indexed: 11/06/2022] Open
Abstract
Glutamatergic neurotransmission is evolutionarily conserved across animal phyla. A major class of glutamate receptors consists of the metabotropic glutamate receptors (mGluRs). In C. elegans, three mGluR genes, mgl-1, mgl-2, and mgl-3, are organized into three subgroups, similar to their mammalian counterparts. Cellular reporters identified expression of the mgls in the nervous system of C. elegans and overlapping expression in the pharyngeal microcircuit that controls pharyngeal muscle activity and feeding behavior. The overlapping expression of mgls within this circuit allowed the investigation of receptor signaling per se and in the context of receptor interactions within a neural network that regulates feeding. We utilized the pharmacological manipulation of neuronally regulated pumping of the pharyngeal muscle in the wild-type and mutants to investigate MGL function. This defined a net mgl-1-dependent inhibition of pharyngeal pumping that is modulated by mgl-3 excitation. Optogenetic activation of the pharyngeal glutamatergic inputs combined with electrophysiological recordings from the isolated pharyngeal preparations provided further evidence for a presynaptic mgl-1-dependent regulation of pharyngeal activity. Analysis of mgl-1, mgl-2, and mgl-3 mutant feeding behavior in the intact organism after acute food removal identified a significant role for mgl-1 in the regulation of an adaptive feeding response. Our data describe the molecular and cellular organization of mgl-1, mgl-2, and mgl-3. Pharmacological analysis identified that, in these paradigms, mgl-1 and mgl-3, but not mgl-2, can modulate the pharyngeal microcircuit. Behavioral analysis identified mgl-1 as a significant determinant of the glutamate-dependent modulation of feeding, further highlighting the significance of mGluRs in complex C. elegans behavior.
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Affiliation(s)
- James Dillon
- From the Centre for Biological Sciences, University of Southampton, University Road, Southampton, SO17 1BJ, United Kingdom,
| | - Christopher J Franks
- From the Centre for Biological Sciences, University of Southampton, University Road, Southampton, SO17 1BJ, United Kingdom
| | | | - Richard J Edwards
- School of Biotechnology and Biomolecular Sciences, University of New South Wales, Kensington, New South Wales 2052, Australia
| | - Fernando Calahorro
- From the Centre for Biological Sciences, University of Southampton, University Road, Southampton, SO17 1BJ, United Kingdom
| | - Takeshi Ishihara
- the Department of Biology, Graduate School of Science, Kyushu University, 6-10-1, Hakozaki, Higashi-ku, Fukuoka 812-8581, Japan, and
| | - Isao Katsura
- the National Institute of Genetics, Yata 1111, Mishima, Shizuoka-ken, 411-8540, Japan
| | - Lindy Holden-Dye
- From the Centre for Biological Sciences, University of Southampton, University Road, Southampton, SO17 1BJ, United Kingdom
| | - Vincent O'Connor
- From the Centre for Biological Sciences, University of Southampton, University Road, Southampton, SO17 1BJ, United Kingdom,
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18
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Abstract
Neurons in the cerebellar cortex, cerebellar nuclei, and inferior olive (IO) form a trisynaptic loop critical for motor learning. IO neurons excite Purkinje cells via climbing fibers and depress their parallel fiber inputs. Purkinje cells inhibit diverse cells in the cerebellar nuclei, including small GABAergic nucleo-olivary neurons that project to the IO. To investigate how these neurons integrate synaptic signals from Purkinje cells, we retrogradely labeled nucleo-olivary cells in the contralateral interpositus and lateral nuclei with cholera toxin subunit B-Alexa Fluor 488 and recorded their electrophysiological properties in cerebellar slices from weanling mice. Nucleo-olivary cells fired action potentials over a relatively narrow dynamic range (maximal rate, ∼ 70 spikes/s), unlike large cells that project to premotor areas (maximal rate, ∼ 400 spikes/s). GABA(A) receptor-mediated IPSCs evoked by electrical or optogenetic stimulation of Purkinje cells were more than 10-fold slower in nucleo-olivary cells (decay time, ∼ 25 ms) than in large cells (∼ 2 ms), and repetitive stimulation at 20-150 Hz evoked greatly summating IPSCs. Nucleo-olivary firing rates varied inversely with IPSP frequency, and the timing of Purkinje IPSPs and nucleo-olivary spikes was uncorrelated. These attributes contrast with large cells, whose brief IPSCs and rapid firing rates can permit well timed postinhibitory spiking. Thus, the intrinsic and synaptic properties of these two projection neurons from the cerebellar nuclei tailor them for differential integration and transmission of their Purkinje cell input.
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19
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Wang D, Schreurs BG. Maturation of membrane properties of neurons in the rat deep cerebellar nuclei. Dev Neurobiol 2014; 74:1268-76. [PMID: 24931427 DOI: 10.1002/dneu.22203] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2014] [Revised: 05/25/2014] [Accepted: 06/10/2014] [Indexed: 12/20/2022]
Abstract
Patch clamp recordings of neurons in the adult rat deep cerebellar nuclei have been limited by the availability of viable brain slices. Using a new slicing technique, this study was designed to explore the maturation of membrane properties of neurons in the deep cerebellar nuclei (DCN)-an area involved in rat eyeblink conditioning. Compared to whole-cell current-clamp recordings in DCN in rat pups at postnatal day 16 (P16) to P21, recordings from weanling rats at P22-P40 revealed a number of significant changes including an increase in the amplitude of the afterhyperpolarization (AHP)-an index of membrane excitability which has been shown to be important for eyeblink conditioning-a prolonged interval between the first and second evoked action potential, and an increase in AHP amplitude for hyperpolarization-induced rebound spikes. This is the first report of developmental changes in membrane properties of DCN which may contribute to the ontogeny of eyeblink conditioning in the rat.
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Affiliation(s)
- Desheng Wang
- Department of Physiology and Pharmacology, West Virginia University School of Medicine, Morgantown, West Virginia, 26506; Blanchette Rockefeller Neurosciences Institute, Morgantown, West Virginia, 26505
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20
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Abstract
Different modulatory inputs commonly elicit distinct rhythmic motor patterns from a central pattern generator (CPG), but they can instead elicit the same pattern. We are determining the rhythm-generating mechanisms in this latter situation, using the gastric mill (chewing) CPG in the crab (Cancer borealis) stomatogastric ganglion, where stimulating the projection neuron MCN1 (modulatory commissural neuron 1) or bath applying CabPK (C. borealis pyrokinin) peptide elicits the same gastric mill motor pattern, despite configuring different gastric mill circuits. In both cases, the core rhythm generator includes the same reciprocally inhibitory neurons LG (lateral gastric) and Int1 (interneuron 1), but the pyloric (food-filtering) circuit pacemaker neuron AB (anterior burster) is additionally necessary only for CabPK rhythm generation. MCN1 drives this rhythm generator by activating in the LG neuron the modulator-activated inward current (IMI), which waxes and wanes periodically due to phasic feedback inhibition of MCN1 transmitter release. Each buildup of IMI enables the LG neuron to generate a self-terminating burst and thereby alternate with Int1 activity. Here we establish that CabPK drives gastric mill rhythm generation by activating in the LG neuron IMI plus a slowly activating transient, low-threshold inward current (ITrans-LTS) that is voltage, time, and Ca(2+) dependent. Unlike MCN1, CabPK maintains a steady IMI activation, causing a subthreshold depolarization in LG that facilitates a periodic postinhibitory rebound burst caused by the regular buildup and decay of the availability of ITrans-LTS. Thus, different modulatory inputs can use different rhythm-generating mechanisms to drive the same neuronal rhythm. Additionally, the same ionic current (IMI) can play different roles under these different conditions, while different currents (IMI, ITrans-LTS) can play the same role.
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21
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Person AL, Raman IM. Synchrony and neural coding in cerebellar circuits. Front Neural Circuits 2012; 6:97. [PMID: 23248585 PMCID: PMC3518933 DOI: 10.3389/fncir.2012.00097] [Citation(s) in RCA: 92] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2012] [Accepted: 11/16/2012] [Indexed: 11/18/2022] Open
Abstract
The cerebellum regulates complex movements and is also implicated in cognitive tasks, and cerebellar dysfunction is consequently associated not only with movement disorders, but also with conditions like autism and dyslexia. How information is encoded by specific cerebellar firing patterns remains debated, however. A central question is how the cerebellar cortex transmits its integrated output to the cerebellar nuclei via GABAergic synapses from Purkinje neurons. Possible answers come from accumulating evidence that subsets of Purkinje cells synchronize their firing during behaviors that require the cerebellum. Consistent with models predicting that coherent activity of inhibitory networks has the capacity to dictate firing patterns of target neurons, recent experimental work supports the idea that inhibitory synchrony may regulate the response of cerebellar nuclear cells to Purkinje inputs, owing to the interplay between unusually fast inhibitory synaptic responses and high rates of intrinsic activity. Data from multiple laboratories lead to a working hypothesis that synchronous inhibitory input from Purkinje cells can set the timing and rate of action potentials produced by cerebellar nuclear cells, thereby relaying information out of the cerebellum. If so, then changing spatiotemporal patterns of Purkinje activity would allow different subsets of inhibitory neurons to control cerebellar output at different times. Here we explore the evidence for and against the idea that a synchrony code defines, at least in part, the input–output function between the cerebellar cortex and nuclei. We consider the literature on the existence of simple spike synchrony, convergence of Purkinje neurons onto nuclear neurons, and intrinsic properties of nuclear neurons that contribute to responses to inhibition. Finally, we discuss factors that may disrupt or modulate a synchrony code and describe the potential contributions of inhibitory synchrony to other motor circuits.
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Affiliation(s)
- Abigail L Person
- Department of Physiology and Biophysics, University of Colorado School of Medicine Aurora, CO, USA
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22
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Abstract
Functional aspects of network integration in the cerebellar cortex have been studied experimentally and modeled in much detail ever since the early work by theoreticians such as Marr, Albus and Braitenberg more than 40 years ago. In contrast, much less is known about cerebellar processing at the output stage, namely in the cerebellar nuclei (CN). Here, input from Purkinje cells converges to control CN neuron spiking via GABAergic inhibition, before the output from the CN reaches cerebellar targets such as the brainstem and the motor thalamus. In this article we review modeling studies that address how the CN may integrate cerebellar cortical inputs, and what kind of signals may be transmitted. Specific hypotheses in the literature contrast rate coding and temporal coding of information in the spiking output from the CN. One popular hypothesis states that post-inhibitory rebound spiking may be an important mechanism by which Purkinje cell inhibition is turned into CN output spiking, but this hypothesis remains controversial. Rate coding clearly does take place, but in what way it may be augmented by temporal codes remains to be more clearly established. Several candidate mechanisms distinct from rebound spiking are discussed, such as the significance of spike time correlations between Purkinje cell pools to determine CN spike timing, irregularity of Purkinje cell spiking as a determinant of CN firing rate, and shared brief pauses between Purkinje cell pools that may trigger individual CN spikes precisely.
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23
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Baumgärtel K, Mansuy IM. Neural functions of calcineurin in synaptic plasticity and memory. Learn Mem 2012; 19:375-84. [PMID: 22904368 DOI: 10.1101/lm.027201.112] [Citation(s) in RCA: 127] [Impact Index Per Article: 10.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
Major brain functions depend on neuronal processes that favor the plasticity of neuronal circuits while at the same time maintaining their stability. The mechanisms that regulate brain plasticity are complex and engage multiple cascades of molecular components that modulate synaptic efficacy. Protein kinases (PKs) and phosphatases (PPs) are among the most important of these components that act as positive and negative regulators of neuronal signaling and plasticity, respectively. In these cascades, the PP protein phosphatase 2B or calcineurin (CaN) is of particular interest because it is the only Ca(2+)-activated PP in the brain and a major regulator of key proteins essential for synaptic transmission and neuronal excitability. This review describes the primary properties of CaN and illustrates its functions and modes of action by focusing on several representative targets, in particular glutamate receptors, striatal enriched protein phosphatase (STEP), and neuromodulin (GAP43), and their functional significance for synaptic plasticity and memory.
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Affiliation(s)
- Karsten Baumgärtel
- Dorris Neuroscience Center, Department of Cell Biology, The Scripps Research Institute, La Jolla, California 92037-1000, USA
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24
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NMDA receptor-dependent synaptic activation of TRPC channels in olfactory bulb granule cells. J Neurosci 2012; 32:5737-46. [PMID: 22539836 DOI: 10.1523/jneurosci.3753-11.2012] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Canonical transient receptor potential (TRPC) channels are widely expressed throughout the nervous system including the olfactory bulb where their function is largely unknown. Here, we describe their contribution to central synaptic processing at the reciprocal mitral and tufted cell-granule cell microcircuit, the most abundant synapse of the mammalian olfactory bulb. Suprathreshold activation of the synapse causes sodium action potentials in mouse granule cells and a subsequent long-lasting depolarization (LLD) linked to a global dendritic postsynaptic calcium signal recorded with two-photon laser-scanning microscopy. These signals are not observed after action potentials evoked by current injection in the same cells. The LLD persists in the presence of group I metabotropic glutamate receptor antagonists but is entirely absent from granule cells deficient for the NMDA receptor subunit NR1. Moreover, both depolarization and Ca²⁺ rise are sensitive to the blockade of NMDA receptors. The LLD and the accompanying Ca²⁺ rise are also absent in granule cells from mice deficient for both TRPC channel subtypes 1 and 4, whereas the deletion of either TRPC1 or TRPC4 results in only a partial reduction of the LLD. Recordings from mitral cells in the absence of both subunits reveal a reduction of asynchronous neurotransmitter release from the granule cells during recurrent inhibition. We conclude that TRPC1 and TRPC4 can be activated downstream of NMDA receptor activation and contribute to slow synaptic transmission in the olfactory bulb, including the calcium dynamics required for asynchronous release from the granule cell spine.
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25
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Engbers JDT, Anderson D, Tadayonnejad R, Mehaffey WH, Molineux ML, Turner RW. Distinct roles for I(T) and I(H) in controlling the frequency and timing of rebound spike responses. J Physiol 2011; 589:5391-413. [PMID: 21969455 PMCID: PMC3240880 DOI: 10.1113/jphysiol.2011.215632] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2011] [Accepted: 09/26/2011] [Indexed: 12/22/2022] Open
Abstract
The ability for neurons to generate rebound bursts following inhibitory synaptic input relies on ion channels that respond in a unique fashion to hyperpolarization. Inward currents provided by T-type calcium channels (I(T)) and hyperpolarization-activated HCN channels (I(H)) increase in availability upon hyperpolarization, allowing for a rebound depolarization after a period of inhibition. Although rebound responses have long been recognized in deep cerebellar nuclear (DCN) neurons, the actual extent to which I(T) and I(H) contribute to rebound spike output following physiological levels of membrane hyperpolarization has not been clearly established. The current study used recordings and simulations of large diameter cells of the in vitro rat DCN slice preparation to define the roles for I(T) and I(H) in a rebound response. We find that physiological levels of hyperpolarization make only small proportions of the total I(T) and I(H) available, but that these are sufficient to make substantial contributions to a rebound response. At least 50% of the early phase of the rebound spike frequency increase is generated by an I(T)-mediated depolarization. An additional frequency increase is provided by I(H) in reducing the time constant and thus the extent of I(T) inactivation as the membrane returns from a hyperpolarized state to the resting level. An I(H)-mediated depolarization creates an inverse voltage-first spike latency relationship and produces a 35% increase in the precision of the first spike latency of a rebound. I(T) and I(H) can thus be activated by physiologically relevant stimuli and have distinct roles in the frequency, timing and precision of rebound responses.
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Affiliation(s)
- Jordan D T Engbers
- Hotchkiss Brain Institute, University of Calgary, 3330 Hospital Drive N.W., Calgary, AB, Canada T2N 4N1.
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