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Ransdell JL, Carrasquillo Y, Bosch MK, Mellor RL, Ornitz DM, Nerbonne JM. Loss of Intracellular Fibroblast Growth Factor 14 (iFGF14) Increases the Excitability of Mature Hippocampal and Cortical Pyramidal Neurons. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.05.04.592532. [PMID: 38746081 PMCID: PMC11092765 DOI: 10.1101/2024.05.04.592532] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/16/2024]
Abstract
Mutations in FGF14 , which encodes intracellular fibroblast growth factor 14 (iFGF14), have been linked to spinocerebellar ataxia type 27 (SCA27), a multisystem disorder associated with progressive deficits in motor coordination and cognitive function. Mice ( Fgf14 -/- ) lacking iFGF14 display similar phenotypes, and we have previously shown that the deficits in motor coordination reflect reduced excitability of cerebellar Purkinje neurons, owing to the loss of iFGF14-mediated regulation of the voltage-dependence of inactivation of the fast transient component of the voltage-gated Na + (Nav) current, I NaT . Here, we present the results of experiments designed to test the hypothesis that loss of iFGF14 also attenuates the intrinsic excitability of mature hippocampal and cortical pyramidal neurons. Current-clamp recordings from adult mouse hippocampal CA1 pyramidal neurons in acute in vitro slices, however, revealed that repetitive firing rates were higher in Fgf14 -/- , than in wild type (WT), cells. In addition, the waveforms of individual action potentials were altered in Fgf14 -/- hippocampal CA1 pyramidal neurons, and the loss of iFGF14 reduced the time delay between the initiation of axonal and somal action potentials. Voltage-clamp recordings revealed that the loss of iFGF14 altered the voltage-dependence of activation, but not inactivation, of I NaT in CA1 pyramidal neurons. Similar effects of the loss of iFGF14 on firing properties were evident in current-clamp recordings from layer 5 visual cortical pyramidal neurons. Additional experiments demonstrated that the loss of iFGF14 does not alter the distribution of anti-Nav1.6 or anti-ankyrin G immunofluorescence labeling intensity along the axon initial segments (AIS) of mature hippocampal CA1 or layer 5 visual cortical pyramidal neurons in situ . Taken together, the results demonstrate that, in contrast with results reported for neonatal (rat) hippocampal pyramidal neurons in dissociated cell culture, the loss of iFGF14 does not disrupt AIS architecture or Nav1.6 localization/distribution along the AIS of mature hippocampal (or cortical) pyramidal neurons in situ .
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Silva NT, Ramírez-Buriticá J, Pritchett DL, Carey MR. Climbing fibers provide essential instructive signals for associative learning. Nat Neurosci 2024; 27:940-951. [PMID: 38565684 PMCID: PMC11088996 DOI: 10.1038/s41593-024-01594-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2022] [Accepted: 02/05/2024] [Indexed: 04/04/2024]
Abstract
Supervised learning depends on instructive signals that shape the output of neural circuits to support learned changes in behavior. Climbing fiber (CF) inputs to the cerebellar cortex represent one of the strongest candidates in the vertebrate brain for conveying neural instructive signals. However, recent studies have shown that Purkinje cell stimulation can also drive cerebellar learning and the relative importance of these two neuron types in providing instructive signals for cerebellum-dependent behaviors remains unresolved. In the present study we used cell-type-specific perturbations of various cerebellar circuit elements to systematically evaluate their contributions to delay eyeblink conditioning in mice. Our findings reveal that, although optogenetic stimulation of either CFs or Purkinje cells can drive learning under some conditions, even subtle reductions in CF signaling completely block learning to natural stimuli. We conclude that CFs and corresponding Purkinje cell complex spike events provide essential instructive signals for associative cerebellar learning.
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Affiliation(s)
- N Tatiana Silva
- Neuroscience Program, Champalimaud Center for the Unknown, Lisbon, Portugal
| | | | - Dominique L Pritchett
- Neuroscience Program, Champalimaud Center for the Unknown, Lisbon, Portugal.
- Biology Department, Howard University, Washington, DC, USA.
| | - Megan R Carey
- Neuroscience Program, Champalimaud Center for the Unknown, Lisbon, Portugal.
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Kebschull JM, Casoni F, Consalez GG, Goldowitz D, Hawkes R, Ruigrok TJH, Schilling K, Wingate R, Wu J, Yeung J, Uusisaari MY. Cerebellum Lecture: the Cerebellar Nuclei-Core of the Cerebellum. CEREBELLUM (LONDON, ENGLAND) 2024; 23:620-677. [PMID: 36781689 PMCID: PMC10951048 DOI: 10.1007/s12311-022-01506-0] [Citation(s) in RCA: 9] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Accepted: 12/10/2022] [Indexed: 02/15/2023]
Abstract
The cerebellum is a key player in many brain functions and a major topic of neuroscience research. However, the cerebellar nuclei (CN), the main output structures of the cerebellum, are often overlooked. This neglect is because research on the cerebellum typically focuses on the cortex and tends to treat the CN as relatively simple output nuclei conveying an inverted signal from the cerebellar cortex to the rest of the brain. In this review, by adopting a nucleocentric perspective we aim to rectify this impression. First, we describe CN anatomy and modularity and comprehensively integrate CN architecture with its highly organized but complex afferent and efferent connectivity. This is followed by a novel classification of the specific neuronal classes the CN comprise and speculate on the implications of CN structure and physiology for our understanding of adult cerebellar function. Based on this thorough review of the adult literature we provide a comprehensive overview of CN embryonic development and, by comparing cerebellar structures in various chordate clades, propose an interpretation of CN evolution. Despite their critical importance in cerebellar function, from a clinical perspective intriguingly few, if any, neurological disorders appear to primarily affect the CN. To highlight this curious anomaly, and encourage future nucleocentric interpretations, we build on our review to provide a brief overview of the various syndromes in which the CN are currently implicated. Finally, we summarize the specific perspectives that a nucleocentric view of the cerebellum brings, move major outstanding issues in CN biology to the limelight, and provide a roadmap to the key questions that need to be answered in order to create a comprehensive integrated model of CN structure, function, development, and evolution.
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Affiliation(s)
- Justus M Kebschull
- Department of Biomedical Engineering, Johns Hopkins University, Baltimore, MD, 21205, USA.
| | - Filippo Casoni
- Division of Neuroscience, San Raffaele Scientific Institute, and San Raffaele University, Milan, Italy
| | - G Giacomo Consalez
- Division of Neuroscience, San Raffaele Scientific Institute, and San Raffaele University, Milan, Italy
| | - Daniel Goldowitz
- Department of Medical Genetics, Centre for Molecular Medicine and Therapeutics, University of British Columbia, Vancouver, Canada
| | - Richard Hawkes
- Department of Cell Biology & Anatomy and Hotchkiss Brain Institute, Cumming School of Medicine, University of Calgary, Calgary, Alberta, T2N 4N1, Canada
| | - Tom J H Ruigrok
- Department of Neuroscience, Erasmus MC, Rotterdam, the Netherlands
| | - Karl Schilling
- Department of Anatomy, Anatomy & Cell Biology, Rheinische Friedrich-Wilhelms-Universität, 53115, Bonn, Federal Republic of Germany
| | - Richard Wingate
- MRC Centre for Neurodevelopmental Disorders, Institute of Psychiatry, Psychology and Neuroscience, King's College London, London, UK
| | - Joshua Wu
- Department of Medical Genetics, Centre for Molecular Medicine and Therapeutics, University of British Columbia, Vancouver, Canada
| | - Joanna Yeung
- Department of Medical Genetics, Centre for Molecular Medicine and Therapeutics, University of British Columbia, Vancouver, Canada
| | - Marylka Yoe Uusisaari
- Neuronal Rhythms in Movement Unit, Okinawa Institute of Science and Technology, 1919-1 Tancha, Onna-Son, Kunigami-Gun, Okinawa, 904-0495, Japan.
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Wu S, Wardak A, Khan MM, Chen CH, Regehr WG. Implications of variable synaptic weights for rate and temporal coding of cerebellar outputs. eLife 2024; 13:e89095. [PMID: 38241596 PMCID: PMC10798666 DOI: 10.7554/elife.89095] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2023] [Accepted: 12/27/2023] [Indexed: 01/21/2024] Open
Abstract
Purkinje cell (PC) synapses onto cerebellar nuclei (CbN) neurons allow signals from the cerebellar cortex to influence the rest of the brain. PCs are inhibitory neurons that spontaneously fire at high rates, and many PC inputs are thought to converge onto each CbN neuron to suppress its firing. It has been proposed that PCs convey information using a rate code, a synchrony and timing code, or both. The influence of PCs on CbN neuron firing was primarily examined for the combined effects of many PC inputs with comparable strengths, and the influence of individual PC inputs has not been extensively studied. Here, we find that single PC to CbN synapses are highly variable in size, and using dynamic clamp and modeling we reveal that this has important implications for PC-CbN transmission. Individual PC inputs regulate both the rate and timing of CbN firing. Large PC inputs strongly influence CbN firing rates and transiently eliminate CbN firing for several milliseconds. Remarkably, the refractory period of PCs leads to a brief elevation of CbN firing prior to suppression. Thus, individual PC-CbN synapses are suited to concurrently convey rate codes and generate precisely timed responses in CbN neurons. Either synchronous firing or synchronous pauses of PCs promote CbN neuron firing on rapid time scales for nonuniform inputs, but less effectively than for uniform inputs. This is a secondary consequence of variable input sizes elevating the baseline firing rates of CbN neurons by increasing the variability of the inhibitory conductance. These findings may generalize to other brain regions with highly variable inhibitory synapse sizes.
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Affiliation(s)
- Shuting Wu
- Department of Neurobiology, Harvard Medical SchoolBostonUnited States
| | - Asem Wardak
- Department of Neurobiology, Harvard Medical SchoolBostonUnited States
| | - Mehak M Khan
- Department of Neurobiology, Harvard Medical SchoolBostonUnited States
| | - Christopher H Chen
- Department of Neurobiology, Harvard Medical SchoolBostonUnited States
- Department of Neural and Behavioral Sciences, Pennsylvania State University College of MedicineHersheyUnited States
| | - Wade G Regehr
- Department of Neurobiology, Harvard Medical SchoolBostonUnited States
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Broersen R, Canto CB, De Zeeuw CI. Cerebellar nuclei: Associative motor learning in zebrafish. Curr Biol 2023; 33:R867-R870. [PMID: 37607484 DOI: 10.1016/j.cub.2023.07.018] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 08/24/2023]
Abstract
Cerebellar output neurons integrate strong inhibitory input and weaker excitatory input during the control of spontaneous and learned movements. A new study sheds light on how those inputs are integrated during associative swimming in zebrafish larvae.
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Affiliation(s)
- Robin Broersen
- Department of Neuroscience, Erasmus MC, Wytemaweg 80, 3015 CN, Rotterdam, The Netherlands
| | - Cathrin B Canto
- Department of Neuroscience, Erasmus MC, Wytemaweg 80, 3015 CN, Rotterdam, The Netherlands; Department of Cerebellar Coordination & Cognition, Netherlands Institute for Neuroscience, Royal Netherlands Academy of Arts and Sciences, 1105 BA, Amsterdam, The Netherlands
| | - Chris I De Zeeuw
- Department of Neuroscience, Erasmus MC, Wytemaweg 80, 3015 CN, Rotterdam, The Netherlands; Department of Cerebellar Coordination & Cognition, Netherlands Institute for Neuroscience, Royal Netherlands Academy of Arts and Sciences, 1105 BA, Amsterdam, The Netherlands.
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Herzfeld DJ, Joshua M, Lisberger SG. Rate versus synchrony codes for cerebellar control of motor behavior. Neuron 2023; 111:2448-2460.e6. [PMID: 37536289 PMCID: PMC10424531 DOI: 10.1016/j.neuron.2023.07.002] [Citation(s) in RCA: 7] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2023] [Revised: 05/24/2023] [Accepted: 07/05/2023] [Indexed: 08/05/2023]
Abstract
Information transmission between neural populations could occur through either coordinated changes in firing rates or the precise transmission of spike timing. We investigate the code for information transmission from a part of the cerebellar cortex that is crucial for the accurate execution of a quantifiable motor behavior. Simultaneous recordings from Purkinje cell pairs in the cerebellum of rhesus macaques reveal how these cells coordinate their activity to drive smooth pursuit eye movements. Purkinje cells show millisecond-scale coordination of spikes (synchrony), but the level of synchrony is small and insufficient to impact the firing of downstream vestibular nucleus neurons. Analysis of previous metrics that purported to reveal Purkinje cell synchrony demonstrates that these metrics conflate changes in firing rate and neuron-neuron covariance. We conclude that the output of the cerebellar cortex uses primarily a rate rather than a synchrony code to drive the activity of downstream neurons and thus control motor behavior.
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Affiliation(s)
- David J Herzfeld
- Department of Neurobiology, Duke University School of Medicine, Durham, NC 27710, USA.
| | - Mati Joshua
- Edmond & Lily Safra Center for Brain Sciences, The Hebrew University of Jerusalem, Jerusalem, Israel
| | - Stephen G Lisberger
- Department of Neurobiology, Duke University School of Medicine, Durham, NC 27710, USA
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Nashef A, Spindle MS, Calame DJ, Person AL. A dual Purkinje cell rate and synchrony code sculpts reach kinematics. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.07.12.548720. [PMID: 37503038 PMCID: PMC10370034 DOI: 10.1101/2023.07.12.548720] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/29/2023]
Abstract
Cerebellar Purkinje cells (PCs) encode movement kinematics in their population firing rates. Firing rate suppression is hypothesized to disinhibit neurons in the cerebellar nuclei, promoting adaptive movement adjustments. Debates persist, however, about whether a second disinhibitory mechanism, PC simple spike synchrony, is a relevant population code. We addressed this question by relating PC rate and synchrony patterns recorded with high density probes, to mouse reach kinematics. We discovered behavioral correlates of PC synchrony that align with a known causal relationship between activity in cerebellar output. Reach deceleration was positively correlated with both Purkinje firing rate decreases and synchrony, consistent with both mechanisms disinhibiting target neurons, which are known to adjust reach velocity. Direct tests of the contribution of each coding scheme to nuclear firing using dynamic clamp, combining physiological rate and synchrony patterns ex vivo, confirmed that physiological levels of PC simple spike synchrony are highly facilitatory for nuclear firing. These findings suggest that PC firing rate and synchrony collaborate to exert fine control of movement.
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Affiliation(s)
- Abdulraheem Nashef
- Department of Physiology and Biophysics, Anschutz Medical Campus, University of Colorado, Aurora, 80045, CO, USA
| | - Michael S Spindle
- Department of Physiology and Biophysics, Anschutz Medical Campus, University of Colorado, Aurora, 80045, CO, USA
| | - Dylan J Calame
- Department of Physiology and Biophysics, Anschutz Medical Campus, University of Colorado, Aurora, 80045, CO, USA
| | - Abigail L Person
- Department of Physiology and Biophysics, Anschutz Medical Campus, University of Colorado, Aurora, 80045, CO, USA
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Wu S, Wardak A, Khan MM, Chen CH, Regehr WG. Implications of variable synaptic weights for rate and temporal coding of cerebellar outputs. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.05.25.542308. [PMID: 37292884 PMCID: PMC10245953 DOI: 10.1101/2023.05.25.542308] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Purkinje cell (PC) synapses onto cerebellar nuclei (CbN) neurons convey signals from the cerebellar cortex to the rest of the brain. PCs are inhibitory neurons that spontaneously fire at high rates, and many uniform sized PC inputs are thought to converge onto each CbN neuron to suppress or eliminate firing. Leading theories maintain that PCs encode information using either a rate code, or by synchrony and precise timing. Individual PCs are thought to have limited influence on CbN neuron firing. Here, we find that single PC to CbN synapses are highly variable in size, and using dynamic clamp and modelling we reveal that this has important implications for PC-CbN transmission. Individual PC inputs regulate both the rate and timing of CbN firing. Large PC inputs strongly influence CbN firing rates and transiently eliminate CbN firing for several milliseconds. Remarkably, the refractory period of PCs leads to a brief elevation of CbN firing prior to suppression. Thus, PC-CbN synapses are suited to concurrently convey rate codes, and generate precisely-timed responses in CbN neurons. Variable input sizes also elevate the baseline firing rates of CbN neurons by increasing the variability of the inhibitory conductance. Although this reduces the relative influence of PC synchrony on the firing rate of CbN neurons, synchrony can still have important consequences, because synchronizing even two large inputs can significantly increase CbN neuron firing. These findings may be generalized to other brain regions with highly variable sized synapses.
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Affiliation(s)
- Shuting Wu
- Department of Neurobiology, Harvard Medical School, Boston, MA 02115, USA
| | - Asem Wardak
- Department of Neurobiology, Harvard Medical School, Boston, MA 02115, USA
| | - Mehak M. Khan
- Department of Neurobiology, Harvard Medical School, Boston, MA 02115, USA
| | | | - Wade G. Regehr
- Department of Neurobiology, Harvard Medical School, Boston, MA 02115, USA
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Herzfeld DJ, Joshua M, Lisberger SG. Rate versus synchrony codes for cerebellar control of motor behavior. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.02.17.529019. [PMID: 36824885 PMCID: PMC9949136 DOI: 10.1101/2023.02.17.529019] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/20/2023]
Abstract
UNLABELLED Control of movement requires the coordination of multiple brain areas, each containing populations of neurons that receive inputs, process these inputs via recurrent dynamics, and then relay the processed information to downstream populations. Information transmission between neural populations could occur through either coordinated changes in firing rates or the precise transmission of spike timing. We investigate the nature of the code for transmission of signals to downstream areas from a part of the cerebellar cortex that is crucial for the accurate execution of a quantifiable motor behavior. Simultaneous recordings from Purkinje cell pairs in the cerebellar flocculus of rhesus macaques revealed how these cells coordinate their activity to drive smooth pursuit eye movements. Purkinje cells show millisecond-scale coordination of spikes (synchrony), but the level of synchrony is small and likely insufficient to impact the firing of downstream neurons in the vestibular nucleus. Further, analysis of previous metrics for assaying Purkinje cell synchrony demonstrates that these metrics conflate changes in firing rate and neuron-neuron covariance. We conclude that the output of the cerebellar cortex uses primarily a rate code rather than synchrony code to drive activity of downstream neurons and thus control motor behavior. IMPACT STATEMENT Information transmission in the brain can occur via changes in firing rate or via the precise timing of spikes. Simultaneous recordings from pairs of Purkinje cells in the floccular complex reveals that information transmission out of the cerebellar cortex relies almost exclusively on changes in firing rates rather than millisecond-scale coordination of spike timing across the Purkinje cell population.
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Affiliation(s)
- David J. Herzfeld
- Department of Neurobiology, Duke University School of Medicine, Durham, NC, USA
| | - Mati Joshua
- Edmond & Lily Safra Center for Brain Sciences, The Hebrew University of Jerusalem, Jerusalem, Israel
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10
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Kreko-Pierce T, Pugh JR. Altered Synaptic Transmission and Excitability of Cerebellar Nuclear Neurons in a Mouse Model of Duchenne Muscular Dystrophy. Front Cell Neurosci 2022; 16:926518. [PMID: 35865113 PMCID: PMC9294606 DOI: 10.3389/fncel.2022.926518] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2022] [Accepted: 05/24/2022] [Indexed: 11/13/2022] Open
Abstract
Duchenne muscular dystrophy (DMD) is generally regarded as a muscle-wasting disease. However, human patients and animal models of DMD also frequently display non-progressive cognitive deficits and high comorbidity with neurodevelopmental disorders, suggesting impaired central processing. Previous studies have identified the cerebellar circuit, and aberrant inhibitory transmission in Purkinje cells, in particular, as a potential site of dysfunction in the central nervous system (CNS). In this work, we investigate potential dysfunction in the output of the cerebellum, downstream of Purkinje cell (PC) activity. We examined synaptic transmission and firing behavior of excitatory projection neurons of the cerebellar nuclei, the primary output of the cerebellar circuit, in juvenile wild-type and mdx mice, a common mouse model of DMD. Using immunolabeling and electrophysiology, we found a reduced number of PC synaptic contacts, but no change in postsynaptic GABAA receptor expression or clustering in these cells. Furthermore, we found that the replenishment rate of synaptic vesicles in Purkinje terminals is reduced in mdx neurons, suggesting that dysfunction at these synapses may be primarily presynaptic. We also found changes in the excitability of cerebellar nuclear neurons. Specifically, we found greater spontaneous firing but reduced evoked firing from a hyperpolarized baseline in mdx neurons. Analysis of action potential waveforms revealed faster repolarization and greater after-hyperpolarization of evoked action potentials in mdx neurons, suggesting an increased voltage- or calcium- gated potassium current. We did not find evidence of dystrophin protein or messenger RNA (mRNA) expression in wild-type nuclear neurons, suggesting that the changes observed in these cells are likely due to the loss of dystrophin in presynaptic PCs. Together, these data suggest that the loss of dystrophin reduces the dynamic range of synaptic transmission and firing in cerebellar nuclear neurons, potentially disrupting the output of the cerebellar circuit to other brain regions and contributing to cognitive and neurodevelopmental deficits associated with DMD.
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Affiliation(s)
- Tabita Kreko-Pierce
- Department of Cellular and Integrative Physiology, University of Texas Health Science Center at San Antonio, San Antonio, TX, United States
| | - Jason R. Pugh
- Department of Cellular and Integrative Physiology, University of Texas Health Science Center at San Antonio, San Antonio, TX, United States
- Center for Biomedical Neuroscience, University of Texas Health Science Center at San Antonio, San Antonio, TX, United States
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Sedaghat-Nejad E, Pi JS, Hage P, Fakharian MA, Shadmehr R. Synchronous spiking of cerebellar Purkinje cells during control of movements. Proc Natl Acad Sci U S A 2022; 119:e2118954119. [PMID: 35349338 PMCID: PMC9168948 DOI: 10.1073/pnas.2118954119] [Citation(s) in RCA: 25] [Impact Index Per Article: 12.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2021] [Accepted: 02/13/2022] [Indexed: 11/18/2022] Open
Abstract
SignificanceThe information that one region of the brain transmits to another is usually viewed through the lens of firing rates. However, if the output neurons could vary the timing of their spikes, then, through synchronization, they would spotlight information that may be critical for control of behavior. Here we report that, in the cerebellum, Purkinje cell populations that share a preference for error convey, to the nucleus, when to decelerate the movement, by reducing their firing rates and temporally synchronizing the remaining spikes.
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Affiliation(s)
- Ehsan Sedaghat-Nejad
- Laboratory for Computational Motor Control, Department of Biomedical Engineering, Johns Hopkins School of Medicine, Baltimore, MD 21205
| | - Jay S. Pi
- Laboratory for Computational Motor Control, Department of Biomedical Engineering, Johns Hopkins School of Medicine, Baltimore, MD 21205
| | - Paul Hage
- Laboratory for Computational Motor Control, Department of Biomedical Engineering, Johns Hopkins School of Medicine, Baltimore, MD 21205
| | - Mohammad Amin Fakharian
- Laboratory for Computational Motor Control, Department of Biomedical Engineering, Johns Hopkins School of Medicine, Baltimore, MD 21205
- School of Cognitive Sciences, Institute for Research in Fundamental Sciences, Tehran, 1956836484, Iran
| | - Reza Shadmehr
- Laboratory for Computational Motor Control, Department of Biomedical Engineering, Johns Hopkins School of Medicine, Baltimore, MD 21205
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McAfee SS, Liu Y, Sillitoe RV, Heck DH. Cerebellar Coordination of Neuronal Communication in Cerebral Cortex. Front Syst Neurosci 2022; 15:781527. [PMID: 35087384 PMCID: PMC8787113 DOI: 10.3389/fnsys.2021.781527] [Citation(s) in RCA: 18] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2021] [Accepted: 12/10/2021] [Indexed: 11/13/2022] Open
Abstract
Cognitive processes involve precisely coordinated neuronal communications between multiple cerebral cortical structures in a task specific manner. Rich new evidence now implicates the cerebellum in cognitive functions. There is general agreement that cerebellar cognitive function involves interactions between the cerebellum and cerebral cortical association areas. Traditional views assume reciprocal interactions between one cerebellar and one cerebral cortical site, via closed-loop connections. We offer evidence supporting a new perspective that assigns the cerebellum the role of a coordinator of communication. We propose that the cerebellum participates in cognitive function by modulating the coherence of neuronal oscillations to optimize communications between multiple cortical structures in a task specific manner.
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Affiliation(s)
- Samuel S. McAfee
- Department of Diagnostic Imaging, St. Jude Children’s Research Hospital, Memphis, TN, United States
| | - Yu Liu
- Department of Anatomy and Neurobiology, University of Tennessee Health Science Center, Memphis, TN, United States
| | - Roy V. Sillitoe
- Department of Pathology and Immunology, Baylor College of Medicine, Houston, TX, United States
- Department of Neuroscience, Baylor College of Medicine, Houston, TX, United States
- Development, Disease Models & Therapeutics Graduate Program, Baylor College of Medicine, Houston, TX, United States
- Jan and Dan Duncan Neurological Research Institute of Texas Children’s Hospital, Houston, TX, United States
| | - Detlef H. Heck
- Department of Anatomy and Neurobiology, University of Tennessee Health Science Center, Memphis, TN, United States
- *Correspondence: Detlef H. Heck,
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Gilbert M. The Shape of Data: a Theory of the Representation of Information in the Cerebellar Cortex. THE CEREBELLUM 2021; 21:976-986. [PMID: 34902112 PMCID: PMC9596575 DOI: 10.1007/s12311-021-01352-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Accepted: 11/28/2021] [Indexed: 11/30/2022]
Abstract
This paper presents a model of rate coding in the cerebellar cortex. The pathway of input to output of the cerebellum forms an anatomically repeating, functionally modular network, whose basic wiring is preserved across vertebrate taxa. Each network is bisected centrally by a functionally defined cell group, a microzone, which forms part of the cerebellar circuit. Input to a network may be from tens of thousands of concurrently active mossy fibres. The model claims to quantify the conversion of input rates into the code received by a microzone. Recoding on entry converts input rates into an internal code which is homogenised in the functional equivalent of an imaginary plane, occupied by the centrally positioned microzone. Homogenised means the code exists in any random sample of parallel fibre signals over a minimum number. The nature of the code and the regimented architecture of the cerebellar cortex mean that the threshold can be represented by space so that the threshold can be met by the physical dimensions of the Purkinje cell dendritic arbour and planar interneuron networks. As a result, the whole population of a microzone receives the same code. This is part of a mechanism which orchestrates functionally indivisible behaviour of the cerebellar circuit and is necessary for coordinated control of the output cells of the circuit. In this model, fine control of Purkinje cells is by input rates to the system and not by learning so that it is in conflict with the for-years-dominant supervised learning model.
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Affiliation(s)
- Mike Gilbert
- School of Psychology, University of Birmingham, Birmingham, UK.
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14
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Impact of Purkinje Cell Simple Spike Synchrony on Signal Transmission from Flocculus. THE CEREBELLUM 2021; 21:879-904. [PMID: 34665396 DOI: 10.1007/s12311-021-01332-w] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Accepted: 10/04/2021] [Indexed: 10/20/2022]
Abstract
Purkinje cells (PCs) in the cerebellar flocculus carry rate-coded information that ultimately drives eye movement. Floccular PCs lying nearby each other exhibit partial synchrony of their simple spikes (SS). Elsewhere in the cerebellum, PC SS synchrony has been demonstrated to influence activity of the PCs' synaptic targets, and some suggest it constitutes another vector for information transfer. We investigated in the cerebellar flocculus the extent to which the rate code and PC synchrony interact. One motivation for the study was to explain the cerebellar deficits in ataxic mice like tottering; we speculated that PC synchrony has a positive effect on rate code transmission that is lost in the mutants. Working in transgenic mice whose PCs express channelrhodopsin, we exploited a property of optogenetics to control PC synchrony: pulsed photostimulation engenders stimulus-locked spiking, whereas continuous photostimulation engenders spiking whose timing is unconstrained. We photoactivated flocculus PCs using pulsed stimuli with sinusoidally varying timing vs. continuous stimuli with sinusoidally varying intensity. Recordings of PC pairs confirmed that pulsed stimuli engendered greater PC synchrony. We quantified the efficiency of transmission of the evoked PC firing rate modulation from the amplitudes of firing rate modulation and eye movement. Rate code transmission was slightly poorer in the conditions that generated greater PC synchrony, arguing against our motivating speculation regarding the origin of ataxia in tottering. Floccular optogenetic stimulation prominently augmented a 250-300 Hz local field potential oscillation, and we demonstrate relationships between the oscillation power and the evoked PC synchrony.
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Beekhof GC, Gornati SV, Canto CB, Libster AM, Schonewille M, De Zeeuw CI, Hoebeek FE. Activity of Cerebellar Nuclei Neurons Correlates with ZebrinII Identity of Their Purkinje Cell Afferents. Cells 2021; 10:2686. [PMID: 34685666 PMCID: PMC8534335 DOI: 10.3390/cells10102686] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2021] [Revised: 09/24/2021] [Accepted: 09/28/2021] [Indexed: 11/17/2022] Open
Abstract
Purkinje cells (PCs) in the cerebellar cortex can be divided into at least two main subpopulations: one subpopulation that prominently expresses ZebrinII (Z+), and shows a relatively low simple spike firing rate, and another that hardly expresses ZebrinII (Z-) and shows higher baseline firing rates. Likewise, the complex spike responses of PCs, which are evoked by climbing fiber inputs and thus reflect the activity of the inferior olive (IO), show the same dichotomy. However, it is not known whether the target neurons of PCs in the cerebellar nuclei (CN) maintain this bimodal distribution. Electrophysiological recordings in awake adult mice show that the rate of action potential firing of CN neurons that receive input from Z+ PCs was consistently lower than that of CN neurons innervated by Z- PCs. Similar in vivo recordings in juvenile and adolescent mice indicated that the firing frequency of CN neurons correlates to the ZebrinII identity of the PC afferents in adult, but not postnatal stages. Finally, the spontaneous action potential firing pattern of adult CN neurons recorded in vitro revealed no significant differences in intrinsic pacemaking activity between ZebrinII identities. Our findings indicate that all three main components of the olivocerebellar loop, i.e., PCs, IO neurons and CN neurons, operate at a higher rate in the Z- modules.
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Affiliation(s)
- Gerrit C. Beekhof
- Department of Neuroscience, Erasmus Medical Center, 3015 AA Rotterdam, The Netherlands; (G.C.B.); (S.V.G.)
- Netherlands Institute for Neuroscience, Royal Academy of Arts and Sciences (KNAW), 1105 BA Amsterdam, The Netherlands;
| | - Simona V. Gornati
- Department of Neuroscience, Erasmus Medical Center, 3015 AA Rotterdam, The Netherlands; (G.C.B.); (S.V.G.)
| | - Cathrin B. Canto
- Netherlands Institute for Neuroscience, Royal Academy of Arts and Sciences (KNAW), 1105 BA Amsterdam, The Netherlands;
| | - Avraham M. Libster
- Edmond & Lily Safra Center for Brain Sciences (ELSC), Department of Neurobiology, Institute of Life Sciences, The Hebrew University, Jerusalem 91904, Israel;
| | - Martijn Schonewille
- Department of Neuroscience, Erasmus Medical Center, 3015 AA Rotterdam, The Netherlands; (G.C.B.); (S.V.G.)
| | - Chris I. De Zeeuw
- Department of Neuroscience, Erasmus Medical Center, 3015 AA Rotterdam, The Netherlands; (G.C.B.); (S.V.G.)
- Netherlands Institute for Neuroscience, Royal Academy of Arts and Sciences (KNAW), 1105 BA Amsterdam, The Netherlands;
| | - Freek E. Hoebeek
- Department of Neuroscience, Erasmus Medical Center, 3015 AA Rotterdam, The Netherlands; (G.C.B.); (S.V.G.)
- Department for Developmental Origins of Disease, Wilhelmina Children’s Hospital, Brain Center, University Medical Center Utrecht, 3584 EA Utrecht, The Netherlands
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Abstract
Abstract
Purpose of review
As fields such as neurotoxicity evaluation and neuro-related drug research are increasing in popularity, there is a demand for the expansion of neurotoxicity research. Currently, neurotoxicity is assessed by measuring changes in weight and behavior. However, measurement of such changes does not allow the detection of subtle and inconspicuous neurotoxicity. In this review, methods for advancing neurotoxicity research are divided into molecule-, cell-, circuit-, and animal model-based methods, and the results of previous studies assessing neurotoxicity are provided and discussed.
Recent findings
In coming decades, cooperation between universities, national research institutes, industrial research institutes, governments, and the private sector will become necessary when identifying alternative methods for neurotoxicity evaluation, which is a current goal related to improving neurotoxicity assessment and an appropriate approach to neurotoxicity prediction. Many methods for measuring neurotoxicity in the field of neuroscience have recently been reported. This paper classifies the supplementary and complementary experimental measures for evaluating neurotoxicity.
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Abstract
Epilepsy is the fourth most common neurological disorder, but current treatment options provide limited efficacy and carry the potential for problematic adverse effects. There is an immense need to develop new therapeutic interventions in epilepsy, and targeting areas outside the seizure focus for neuromodulation has shown therapeutic value. While not traditionally associated with epilepsy, anatomical, clinical, and electrophysiological studies suggest the cerebellum can play a role in seizure networks, and importantly, may be a potential therapeutic target for seizure control. However, previous interventions targeting the cerebellum in both preclinical and clinical studies have produced mixed effects on seizures. These inconsistent results may be due in part to the lack of specificity inherent with open-loop electrical stimulation interventions. More recent studies, using more targeted closed-loop optogenetic approaches, suggest the possibility of robust seizure inhibition via cerebellar modulation for a range of seizure types. Therefore, while the mechanisms of cerebellar inhibition of seizures have yet to be fully elucidated, the cerebellum should be thoroughly revisited as a potential target for therapeutic intervention in epilepsy. This article is part of the Special Issue "NEWroscience 2018.
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Hirono M, Karube F, Yanagawa Y. Modulatory Effects of Monoamines and Perineuronal Nets on Output of Cerebellar Purkinje Cells. Front Neural Circuits 2021; 15:661899. [PMID: 34194302 PMCID: PMC8236809 DOI: 10.3389/fncir.2021.661899] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2021] [Accepted: 05/12/2021] [Indexed: 12/27/2022] Open
Abstract
Classically, the cerebellum has been thought to play a significant role in motor coordination. However, a growing body of evidence for novel neural connections between the cerebellum and various brain regions indicates that the cerebellum also contributes to other brain functions implicated in reward, language, and social behavior. Cerebellar Purkinje cells (PCs) make inhibitory GABAergic synapses with their target neurons: other PCs and Lugaro/globular cells via PC axon collaterals, and neurons in the deep cerebellar nuclei (DCN) via PC primary axons. PC-Lugaro/globular cell connections form a cerebellar cortical microcircuit, which is driven by serotonin and noradrenaline. PCs' primary outputs control not only firing but also synaptic plasticity of DCN neurons following the integration of excitatory and inhibitory inputs in the cerebellar cortex. Thus, strong PC-mediated inhibition is involved in cerebellar functions as a key regulator of cerebellar neural networks. In this review, we focus on physiological characteristics of GABAergic transmission from PCs. First, we introduce monoaminergic modulation of GABAergic transmission at synapses of PC-Lugaro/globular cell as well as PC-large glutamatergic DCN neuron, and a Lugaro/globular cell-incorporated microcircuit. Second, we review the physiological roles of perineuronal nets (PNNs), which are organized components of the extracellular matrix and enwrap the cell bodies and proximal processes, in GABA release from PCs to large glutamatergic DCN neurons and in cerebellar motor learning. Recent evidence suggests that alterations in PNN density in the DCN can regulate cerebellar functions.
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Affiliation(s)
- Moritoshi Hirono
- Department of Physiology, Wakayama Medical University, Wakayama, Japan
| | - Fuyuki Karube
- Lab of Histology and Cytology, Graduate School of Medicine, Hokkaido University, Sapporo, Japan
| | - Yuchio Yanagawa
- Department of Genetic and Behavioral Neuroscience, Gunma University Graduate School of Medicine, Maebashi, Japan
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Zang Y, Hong S, De Schutter E. Firing rate-dependent phase responses of Purkinje cells support transient oscillations. eLife 2020; 9:e60692. [PMID: 32895121 PMCID: PMC7478895 DOI: 10.7554/elife.60692] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2020] [Accepted: 08/20/2020] [Indexed: 01/09/2023] Open
Abstract
Both spike rate and timing can transmit information in the brain. Phase response curves (PRCs) quantify how a neuron transforms input to output by spike timing. PRCs exhibit strong firing-rate adaptation, but its mechanism and relevance for network output are poorly understood. Using our Purkinje cell (PC) model, we demonstrate that the rate adaptation is caused by rate-dependent subthreshold membrane potentials efficiently regulating the activation of Na+ channels. Then, we use a realistic PC network model to examine how rate-dependent responses synchronize spikes in the scenario of reciprocal inhibition-caused high-frequency oscillations. The changes in PRC cause oscillations and spike correlations only at high firing rates. The causal role of the PRC is confirmed using a simpler coupled oscillator network model. This mechanism enables transient oscillations between fast-spiking neurons that thereby form PC assemblies. Our work demonstrates that rate adaptation of PRCs can spatio-temporally organize the PC input to cerebellar nuclei.
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Affiliation(s)
- Yunliang Zang
- Computational Neuroscience Unit, Okinawa Institute of Science and Technology Graduate UniversityOkinawaJapan
| | - Sungho Hong
- Computational Neuroscience Unit, Okinawa Institute of Science and Technology Graduate UniversityOkinawaJapan
| | - Erik De Schutter
- Computational Neuroscience Unit, Okinawa Institute of Science and Technology Graduate UniversityOkinawaJapan
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20
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Climbing fiber synapses rapidly and transiently inhibit neighboring Purkinje cells via ephaptic coupling. Nat Neurosci 2020; 23:1399-1409. [PMID: 32895566 PMCID: PMC7606706 DOI: 10.1038/s41593-020-0701-z] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2020] [Accepted: 07/31/2020] [Indexed: 12/30/2022]
Abstract
Climbing fibers (CFs) from the inferior olive (IO) make strong excitatory synapses onto cerebellar Purkinje cell (PC) dendrites, and trigger distinctive responses known as complex spikes (CSs). We find that in awake mice, a CS in one PC suppresses conventional simple spikes (SSs) in neighboring PCs for several milliseconds. This involves a novel ephaptic coupling, in which an excitatory synapse generates large negative extracellular signals that nonsynaptically inhibit neighboring PCs. The distance dependence of CS-SS ephaptic signaling, combined with the known CF divergence, allows a single IO neuron to influence the output of the cerebellum by synchronously suppressing the firing of potentially over one hundred PCs. Optogenetic studies in vivo, and dynamic clamp studies in slice, indicate that such brief PC suppression, either as a result of ephaptic signaling or other mechanisms, can effectively promote firing in neurons in the deep cerebellar nuclei with remarkable speed and precision.
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Liang KJ, Carlson ES. Resistance, vulnerability and resilience: A review of the cognitive cerebellum in aging and neurodegenerative diseases. Neurobiol Learn Mem 2020; 170:106981. [PMID: 30630042 PMCID: PMC6612482 DOI: 10.1016/j.nlm.2019.01.004] [Citation(s) in RCA: 55] [Impact Index Per Article: 13.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2018] [Revised: 12/14/2018] [Accepted: 01/03/2019] [Indexed: 12/12/2022]
Abstract
In the context of neurodegeneration and aging, the cerebellum is an enigma. Genetic markers of cellular aging in cerebellum accumulate more slowly than in the rest of the brain, and it generates unknown factors that may slow or even reverse neurodegenerative pathology in animal models of Alzheimer's Disease (AD). Cerebellum shows increased activity in early AD and Parkinson's disease (PD), suggesting a compensatory function that may mitigate early symptoms of neurodegenerative pathophysiology. Perhaps most notably, different parts of the brain accumulate neuropathological markers of AD in a recognized progression and generally, cerebellum is the last brain region to do so. Taken together, these data suggest that cerebellum may be resistant to certain neurodegenerative mechanisms. On the other hand, in some contexts of accelerated neurodegeneration, such as that seen in chronic traumatic encephalopathy (CTE) following repeated traumatic brain injury (TBI), the cerebellum appears to be one of the most susceptible brain regions to injury and one of the first to exhibit signs of pathology. Cerebellar pathology in neurodegenerative disorders is strongly associated with cognitive dysfunction. In neurodegenerative or neurological disorders associated with cerebellar pathology, such as spinocerebellar ataxia, cerebellar cortical atrophy, and essential tremor, rates of cognitive dysfunction, dementia and neuropsychiatric symptoms increase. When the cerebellum shows AD pathology, such as in familial AD, it is associated with earlier onset and greater severity of disease. These data suggest that when neurodegenerative processes are active in the cerebellum, it may contribute to pathological behavioral outcomes. The cerebellum is well known for comparing internal representations of information with observed outcomes and providing real-time feedback to cortical regions, a critical function that is disturbed in neuropsychiatric disorders such as intellectual disability, schizophrenia, dementia, and autism, and required for cognitive domains such as working memory. While cerebellum has reciprocal connections with non-motor brain regions and likely plays a role in complex, goal-directed behaviors, it has proven difficult to establish what it does mechanistically to modulate these behaviors. Due to this lack of understanding, it's not surprising to see the cerebellum reflexively dismissed or even ignored in basic and translational neuropsychiatric literature. The overarching goals of this review are to answer the following questions from primary literature: When the cerebellum is affected by pathology, is it associated with decreased cognitive function? When it is intact, does it play a compensatory or protective role in maintaining cognitive function? Are there theoretical frameworks for understanding the role of cerebellum in cognition, and perhaps, illnesses characterized by cognitive dysfunction? Understanding the role of the cognitive cerebellum in neurodegenerative diseases has the potential to offer insight into origins of cognitive deficits in other neuropsychiatric disorders, which are often underappreciated, poorly understood, and not often treated.
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Affiliation(s)
- Katharine J Liang
- University of Washington School of Medicine, Department of Psychiatry and Behavioral Sciences, Seattle, WA, United States
| | - Erik S Carlson
- University of Washington School of Medicine, Seattle, WA, United States.
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22
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Streng ML, Krook-Magnuson E. Excitation, but not inhibition, of the fastigial nucleus provides powerful control over temporal lobe seizures. J Physiol 2019; 598:171-187. [PMID: 31682010 DOI: 10.1113/jp278747] [Citation(s) in RCA: 25] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2019] [Accepted: 10/21/2019] [Indexed: 12/13/2022] Open
Abstract
KEY POINTS On-demand optogenetic inhibition of glutamatergic neurons in the fastigial nucleus of the cerebellum does not alter hippocampal seizures in a mouse model of temporal lobe epilepsy. In contrast, on-demand optogenetic excitation of glutamatergic neurons in the fastigial nucleus successfully inhibits hippocampal seizures. With this approach, even a single 50 ms pulse of light is able to significantly inhibit seizures. On-demand optogenetic excitation of glutamatergic fastigial neurons either ipsilateral or contralateral to the seizure focus is able to inhibit seizures. Selective excitation of glutamatergic nuclear neurons provides greater seizure inhibition than broadly exciting nuclear neurons without cell-type specificity. ABSTRACT Temporal lobe epilepsy is the most common form of epilepsy in adults, but current treatment options provide limited efficacy, leaving as many as one-third of patients with uncontrolled seizures. Recently, attention has shifted towards more closed-loop therapies for seizure control, and on-demand optogenetic modulation of the cerebellar cortex was shown to be highly effective at attenuating hippocampal seizures. Intriguingly, both optogenetic excitation and inhibition of cerebellar cortical output neurons, Purkinje cells, attenuated seizures. The mechanisms by which the cerebellum impacts seizures, however, are unknown. In the present study, we targeted the immediate downstream projection of vermal Purkinje cells - the fastigial nucleus - in order to determine whether increases and/or decreases in fastigial output can underlie seizure cessation. Though Purkinje cell input to fastigial neurons is inhibitory, direct optogenetic inhibition of the fastigial nucleus had no effect on seizure duration. Conversely, however, fastigial excitation robustly attenuated hippocampal seizures. Seizure cessation was achieved at multiple stimulation frequencies, regardless of laterality relative to seizure focus, and even with single light pulses. Seizure inhibition was greater when selectively targeting glutamatergic fastigial neurons than when an approach that lacked cell-type specificity was used. Together, these results suggest that stimulating excitatory neurons in the fastigial nucleus may be a promising approach for therapeutic intervention in temporal lobe epilepsy.
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Affiliation(s)
- Martha L Streng
- Department of Neuroscience, University of Minnesota, Minneapolis, MN, USA
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23
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Casali S, Marenzi E, Medini C, Casellato C, D'Angelo E. Reconstruction and Simulation of a Scaffold Model of the Cerebellar Network. Front Neuroinform 2019; 13:37. [PMID: 31156416 PMCID: PMC6530631 DOI: 10.3389/fninf.2019.00037] [Citation(s) in RCA: 35] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2018] [Accepted: 04/29/2019] [Indexed: 02/05/2023] Open
Abstract
Reconstructing neuronal microcircuits through computational models is fundamental to simulate local neuronal dynamics. Here a scaffold model of the cerebellum has been developed in order to flexibly place neurons in space, connect them synaptically, and endow neurons and synapses with biologically-grounded mechanisms. The scaffold model can keep neuronal morphology separated from network connectivity, which can in turn be obtained from convergence/divergence ratios and axonal/dendritic field 3D geometries. We first tested the scaffold on the cerebellar microcircuit, which presents a challenging 3D organization, at the same time providing appropriate datasets to validate emerging network behaviors. The scaffold was designed to integrate the cerebellar cortex with deep cerebellar nuclei (DCN), including different neuronal types: Golgi cells, granule cells, Purkinje cells, stellate cells, basket cells, and DCN principal cells. Mossy fiber inputs were conveyed through the glomeruli. An anisotropic volume (0.077 mm3) of mouse cerebellum was reconstructed, in which point-neuron models were tuned toward the specific discharge properties of neurons and were connected by exponentially decaying excitatory and inhibitory synapses. Simulations using both pyNEST and pyNEURON showed the emergence of organized spatio-temporal patterns of neuronal activity similar to those revealed experimentally in response to background noise and burst stimulation of mossy fiber bundles. Different configurations of granular and molecular layer connectivity consistently modified neuronal activation patterns, revealing the importance of structural constraints for cerebellar network functioning. The scaffold provided thus an effective workflow accounting for the complex architecture of the cerebellar network. In principle, the scaffold can incorporate cellular mechanisms at multiple levels of detail and be tuned to test different structural and functional hypotheses. A future implementation using detailed 3D multi-compartment neuron models and dynamic synapses will be needed to investigate the impact of single neuron properties on network computation.
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Affiliation(s)
- Stefano Casali
- Neurophysiology Unit, Neurocomputational Laboratory, Department of Brain and Behavioral Sciences, University of Pavia, Pavia, Italy
| | - Elisa Marenzi
- Neurophysiology Unit, Neurocomputational Laboratory, Department of Brain and Behavioral Sciences, University of Pavia, Pavia, Italy
| | - Chaitanya Medini
- Neurophysiology Unit, Neurocomputational Laboratory, Department of Brain and Behavioral Sciences, University of Pavia, Pavia, Italy
| | - Claudia Casellato
- Neurophysiology Unit, Neurocomputational Laboratory, Department of Brain and Behavioral Sciences, University of Pavia, Pavia, Italy
| | - Egidio D'Angelo
- Neurophysiology Unit, Neurocomputational Laboratory, Department of Brain and Behavioral Sciences, University of Pavia, Pavia, Italy
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Miquel M, Nicola SM, Gil-Miravet I, Guarque-Chabrera J, Sanchez-Hernandez A. A Working Hypothesis for the Role of the Cerebellum in Impulsivity and Compulsivity. Front Behav Neurosci 2019; 13:99. [PMID: 31133834 PMCID: PMC6513968 DOI: 10.3389/fnbeh.2019.00099] [Citation(s) in RCA: 56] [Impact Index Per Article: 11.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2019] [Accepted: 04/23/2019] [Indexed: 12/27/2022] Open
Abstract
Growing evidence associates cerebellar abnormalities with several neuropsychiatric disorders in which compulsive symptomatology and impulsivity are part of the disease pattern. Symptomatology of autism, addiction, obsessive-compulsive (OCD), and attention deficit/hyperactivity (ADHD) disorders transcends the sphere of motor dysfunction and essentially entails integrative processes under control of prefrontal-thalamic-cerebellar loops. Patients with brain lesions affecting the cortico-striatum thalamic circuitry and the cerebellum indeed exhibit compulsive symptoms. Specifically, lesions of the posterior cerebellar vermis cause affective dysregulation and deficits in executive function. These deficits may be due to impairment of one of the main functions of the cerebellum, implementation of forward internal models of the environment. Actions that are independent of internal models may not be guided by predictive relationships or a mental representation of the goal. In this review article, we explain how this deficit might affect executive functions. Additionally, regionalized cerebellar lesions have been demonstrated to impair other brain functions such as the emergence of habits and behavioral inhibition, which are also altered in compulsive disorders. Similar to the infralimbic cortex, clinical studies and research in animal models suggest that the cerebellum is not required for learning goal-directed behaviors, but it is critical for habit formation. Despite this accumulating data, the role of the cerebellum in compulsive symptomatology and impulsivity is still a matter of discussion. Overall, findings point to a modulatory function of the cerebellum in terminating or initiating actions through regulation of the prefrontal cortices. Specifically, the cerebellum may be crucial for restraining ongoing actions when environmental conditions change by adjusting prefrontal activity in response to the new external and internal stimuli, thereby promoting flexible behavioral control. We elaborate on this explanatory framework and propose a working hypothesis for the involvement of the cerebellum in compulsive and impulsive endophenotypes.
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Affiliation(s)
- Marta Miquel
- Área de Psicobiología, School of Health Science, Universitat Jaume I, Castellón de la Plana, Spain
| | - Saleem M Nicola
- Dominick P. Purpura Department of Neuroscience, Albert Einstein College of Medicine, Bronx, NY, United States.,Department of Psychiatry and Behavioral Sciences, Albert Einstein College of Medicine, Bronx, NY, United States
| | - Isis Gil-Miravet
- Área de Psicobiología, School of Health Science, Universitat Jaume I, Castellón de la Plana, Spain
| | - Julian Guarque-Chabrera
- Área de Psicobiología, School of Health Science, Universitat Jaume I, Castellón de la Plana, Spain
| | - Aitor Sanchez-Hernandez
- Área de Psicobiología, School of Health Science, Universitat Jaume I, Castellón de la Plana, Spain
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25
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Han KS, Guo C, Chen CH, Witter L, Osorno T, Regehr WG. Ephaptic Coupling Promotes Synchronous Firing of Cerebellar Purkinje Cells. Neuron 2018; 100:564-578.e3. [PMID: 30293822 DOI: 10.1016/j.neuron.2018.09.018] [Citation(s) in RCA: 68] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2018] [Revised: 07/29/2018] [Accepted: 09/10/2018] [Indexed: 11/29/2022]
Abstract
Correlated neuronal activity at various timescales plays an important role in information transfer and processing. We find that in awake-behaving mice, an unexpectedly large fraction of neighboring Purkinje cells (PCs) exhibit sub-millisecond synchrony. Correlated firing usually arises from chemical or electrical synapses, but, surprisingly, neither is required to generate PC synchrony. We therefore assessed ephaptic coupling, a mechanism in which neurons communicate via extracellular electrical signals. In the neocortex, ephaptic signals from many neurons summate to entrain spiking on slow timescales, but extracellular signals from individual cells are thought to be too small to synchronize firing. Here we find that a single PC generates sufficiently large extracellular potentials to open sodium channels in nearby PC axons. Rapid synchronization is made possible because ephaptic signals generated by PCs peak during the rising phase of action potentials. These findings show that ephaptic coupling contributes to the prevalent synchronization of nearby PCs.
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Affiliation(s)
- Kyung-Seok Han
- Department of Neurobiology, Harvard Medical School, Boston, MA 02115, USA
| | - Chong Guo
- Department of Neurobiology, Harvard Medical School, Boston, MA 02115, USA
| | - Christopher H Chen
- Department of Neurobiology, Harvard Medical School, Boston, MA 02115, USA
| | - Laurens Witter
- Department of Neurobiology, Harvard Medical School, Boston, MA 02115, USA
| | - Tomas Osorno
- Department of Neurobiology, Harvard Medical School, Boston, MA 02115, USA
| | - Wade G Regehr
- Department of Neurobiology, Harvard Medical School, Boston, MA 02115, USA.
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26
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Locke TM, Soden ME, Miller SM, Hunker A, Knakal C, Licholai JA, Dhillon KS, Keene CD, Zweifel LS, Carlson ES. Dopamine D 1 Receptor-Positive Neurons in the Lateral Nucleus of the Cerebellum Contribute to Cognitive Behavior. Biol Psychiatry 2018; 84:401-412. [PMID: 29478701 PMCID: PMC6072628 DOI: 10.1016/j.biopsych.2018.01.019] [Citation(s) in RCA: 47] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/10/2017] [Revised: 01/08/2018] [Accepted: 01/12/2018] [Indexed: 12/28/2022]
Abstract
BACKGROUND Studies in humans and nonhuman primates have identified a region of the dentate nucleus of the cerebellum, or the lateral cerebellar nucleus (LCN) in rodents, activated during performance of cognitive tasks involving complex spatial and sequential planning. Whether such a subdivision exists in rodents is not known. Dopamine and its receptors, which are implicated in cognitive function, are present in the cerebellar nuclei, but their function is unknown. METHODS Using viral and genetic strategies in mice, we examined cellular phenotypes of dopamine D1 receptor-positive (D1R+) cells in the LCN with whole-cell patch clamp recordings, messenger RNA profiling, and immunohistochemistry to examine D1R expression in mouse LCN and human dentate nucleus of the cerebellum. We used chemogenetics to inhibit D1R+ neurons and examined behaviors including spatial navigation, social recognition memory, prepulse inhibition of the acoustic startle reflex, response inhibition, and working memory to test the necessity of these neurons in these behaviors. RESULTS We identified a population of D1R+ neurons that are localized to an anatomically distinct region of the LCN. We also observed D1R+ neurons in human dentate nucleus of the cerebellum, which suggests an evolutionarily conserved population of dopamine-receptive neurons in this region. The genetic, electrophysiological, and anatomical profile of mouse D1R neurons is consistent with a heterogeneous population of gamma-aminobutyric acidergic, and to a lesser extent glutamatergic, cell types. Selective inhibition of D1R+ LCN neurons impairs spatial navigation memory, response inhibition, working memory, and prepulse inhibition of the acoustic startle reflex. CONCLUSIONS Collectively, these data demonstrate a functional link between genetically distinct neurons in the LCN and cognitive behaviors.
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Affiliation(s)
- Timothy M. Locke
- University of Washington, Department of Psychiatry and Behavioral Sciences
| | | | | | - Avery Hunker
- University of Washington, Department of Pharmacology
| | - Cerise Knakal
- University of Washington, Department of Pharmacology
| | | | - Karn S. Dhillon
- University of Washington, Department of Biological Chemistry
| | | | - Larry S. Zweifel
- University of Washington, Department of Psychiatry and Behavioral Sciences,University of Washington, Department of Pharmacology
| | - Erik S. Carlson
- University of Washington, Department of Psychiatry and Behavioral Sciences,Correspondence: Erik Sean Carlson M.D., Ph.D. Department of Psychiatry and Behavioral Sciences University of Washington 1959 NE Pacific Street, Box 356560 Seattle, WA, 98195-6560 Telephone: 612-387-7304 Fax: 206-543-9520
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27
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Grzesiak L, Meganck V. Spiking signal processing: Principle and applications in control system. Neurocomputing 2018. [DOI: 10.1016/j.neucom.2018.03.054] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
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28
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Lackey EP, Heck DH, Sillitoe RV. Recent advances in understanding the mechanisms of cerebellar granule cell development and function and their contribution to behavior. F1000Res 2018; 7. [PMID: 30109024 PMCID: PMC6069759 DOI: 10.12688/f1000research.15021.1] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 07/20/2018] [Indexed: 12/20/2022] Open
Abstract
The cerebellum is the focus of an emergent series of debates because its circuitry is now thought to encode an unexpected level of functional diversity. The flexibility that is built into the cerebellar circuit allows it to participate not only in motor behaviors involving coordination, learning, and balance but also in non-motor behaviors such as cognition, emotion, and spatial navigation. In accordance with the cerebellum’s diverse functional roles, when these circuits are altered because of disease or injury, the behavioral outcomes range from neurological conditions such as ataxia, dystonia, and tremor to neuropsychiatric conditions, including autism spectrum disorders, schizophrenia, and attention-deficit/hyperactivity disorder. Two major questions arise: what types of cells mediate these normal and abnormal processes, and how might they accomplish these seemingly disparate functions? The tiny but numerous cerebellar granule cells may hold answers to these questions. Here, we discuss recent advances in understanding how the granule cell lineage arises in the embryo and how a stem cell niche that replenishes granule cells influences wiring when the postnatal cerebellum is injured. We discuss how precisely coordinated developmental programs, gene expression patterns, and epigenetic mechanisms determine the formation of synapses that integrate multi-modal inputs onto single granule cells. These data lead us to consider how granule cell synaptic heterogeneity promotes sensorimotor and non-sensorimotor signals in behaving animals. We discuss evidence that granule cells use ultrafast neurotransmission that can operate at kilohertz frequencies. Together, these data inspire an emerging view for how granule cells contribute to the shaping of complex animal behaviors.
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Affiliation(s)
- Elizabeth P Lackey
- Department of Pathology & Immunology, Baylor College of Medicine, Houston, TX, USA.,Department of Neuroscience, Baylor College of Medicine, Houston, TX, USA.,Jan and Dan Duncan Neurological Research Institute at Texas Children's Hospital, 1250 Moursund Street, Suite 1325, Houston, TX, 77030, USA
| | - Detlef H Heck
- Department of Anatomy and Neurobiology, University of Tennessee Health Science Center, 855 Monroe Avenue, Memphis, TN, 38163, USA
| | - Roy V Sillitoe
- Department of Pathology & Immunology, Baylor College of Medicine, Houston, TX, USA.,Department of Neuroscience, Baylor College of Medicine, Houston, TX, USA.,Jan and Dan Duncan Neurological Research Institute at Texas Children's Hospital, 1250 Moursund Street, Suite 1325, Houston, TX, 77030, USA.,Program in Developmental Biology, Baylor College of Medicine, Houston, TX, USA
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29
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Beckinghausen J, Sillitoe RV. Insights into cerebellar development and connectivity. Neurosci Lett 2018; 688:2-13. [PMID: 29746896 DOI: 10.1016/j.neulet.2018.05.013] [Citation(s) in RCA: 59] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/26/2017] [Revised: 05/04/2018] [Accepted: 05/06/2018] [Indexed: 02/06/2023]
Abstract
The cerebellum has a well-established role in controlling motor functions such coordination, balance, posture, and skilled learning. There is mounting evidence that it might also play a critical role in non-motor functions such as cognition and emotion. It is therefore not surprising that cerebellar defects are associated with a wide array of diseases including ataxia, dystonia, tremor, schizophrenia, dyslexia, and autism spectrum disorder. What is intriguing is that a seemingly uniform circuit that is often described as being "simple" should carry out all of these behaviors. Analyses of how cerebellar circuits develop have revealed that such descriptions massively underestimate the complexity of the cerebellum. The cerebellum is in fact highly patterned and organized around a series of parasagittal stripes and transverse zones. This topographic architecture partitions all cerebellar circuits into functional modules that are thought to enhance processing power during cerebellar dependent behaviors. What are arguably the most remarkable features of cerebellar topography are the developmental processes that produce them. This review is concerned with the genetic and cellular mechanisms that orchestrate cerebellar patterning. We place a major focus on how Purkinje cells control multiple aspects of cerebellar circuit assembly. Using this model, we discuss evidence for how "zebra-like" patterns in Purkinje cells sculpt the cerebellum, how specific genetic cues mediate the process, and how activity refines the patterns into an adult map that is capable of executing various functions. We also discuss how defective Purkinje cell patterning might impact the pathogenesis of neurological conditions.
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Affiliation(s)
- Jaclyn Beckinghausen
- Department of Pathology and 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 TX Children's Hospital, 1250 Moursund Street, Suite 1325, Houston, TX, 77030, USA
| | - Roy V Sillitoe
- Department of Pathology and 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 TX Children's Hospital, 1250 Moursund Street, Suite 1325, Houston, TX, 77030, USA.
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30
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Beiderbeck B, Myoga MH, Müller NIC, Callan AR, Friauf E, Grothe B, Pecka M. Precisely timed inhibition facilitates action potential firing for spatial coding in the auditory brainstem. Nat Commun 2018; 9:1771. [PMID: 29720589 PMCID: PMC5932051 DOI: 10.1038/s41467-018-04210-y] [Citation(s) in RCA: 38] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2017] [Accepted: 04/10/2018] [Indexed: 01/06/2023] Open
Abstract
The integration of excitatory and inhibitory synaptic inputs is fundamental to neuronal processing. In the mammalian auditory brainstem, neurons compare excitatory and inhibitory inputs from the ipsilateral and contralateral ear, respectively, for sound localization. However, the temporal precision and functional roles of inhibition in this integration process are unclear. Here, we demonstrate by in vivo recordings from the lateral superior olive (LSO) that inhibition controls spiking with microsecond precision throughout high frequency click trains. Depending on the relative timing of excitation and inhibition, neuronal spike probability is either suppressed or-unexpectedly-facilitated. In vitro conductance-clamp LSO recordings establish that a reduction in the voltage threshold for spike initiation due to a prior hyperpolarization results in post-inhibitory facilitation of otherwise sub-threshold synaptic events. Thus, microsecond-precise differences in the arrival of inhibition relative to excitation can facilitate spiking in the LSO, thereby promoting spatial sensitivity during the processing of faint sounds.
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Affiliation(s)
- Barbara Beiderbeck
- Department Biology II, Division of Neurobiology, Ludwig-Maximilians-Universitaet Munich, Planegg-Martinsried, D-82152, Germany.,Graduate School of Systemic Neurosciences, Ludwig-Maximilians-Universitaet Munich, Planegg-Martinsried, D-82152, Germany
| | - Michael H Myoga
- Department Biology II, Division of Neurobiology, Ludwig-Maximilians-Universitaet Munich, Planegg-Martinsried, D-82152, Germany.,Max Planck Institute of Neurobiology, Am Klopferspitz 18, Martinsried, 82152, Germany
| | - Nicolas I C Müller
- Department of Biology, Animal Physiology Group, University of Kaiserslautern, Kaiserslautern, D-67653, Germany
| | - Alexander R Callan
- Department Biology II, Division of Neurobiology, Ludwig-Maximilians-Universitaet Munich, Planegg-Martinsried, D-82152, Germany.,Graduate School of Systemic Neurosciences, Ludwig-Maximilians-Universitaet Munich, Planegg-Martinsried, D-82152, Germany
| | - Eckhard Friauf
- Department of Biology, Animal Physiology Group, University of Kaiserslautern, Kaiserslautern, D-67653, Germany
| | - Benedikt Grothe
- Department Biology II, Division of Neurobiology, Ludwig-Maximilians-Universitaet Munich, Planegg-Martinsried, D-82152, Germany. .,Max Planck Institute of Neurobiology, Am Klopferspitz 18, Martinsried, 82152, Germany.
| | - Michael Pecka
- Department Biology II, Division of Neurobiology, Ludwig-Maximilians-Universitaet Munich, Planegg-Martinsried, D-82152, Germany.
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31
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Sarnaik R, Raman IM. Control of voluntary and optogenetically perturbed locomotion by spike rate and timing of neurons of the mouse cerebellar nuclei. eLife 2018; 7:29546. [PMID: 29659351 PMCID: PMC5902160 DOI: 10.7554/elife.29546] [Citation(s) in RCA: 45] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2017] [Accepted: 03/30/2018] [Indexed: 11/13/2022] Open
Abstract
Neurons of the cerebellar nuclei (CbN), which generate cerebellar output, are inhibited by Purkinje cells. With extracellular recordings during voluntary locomotion in head-fixed mice, we tested how the rate and coherence of inhibition influence CbN cell firing and well-practiced movements. Firing rates of Purkinje and CbN cells were modulated systematically through the stride cycle (~200–300 ms). Optogenetically stimulating ChR2-expressing Purkinje cells with light steps or trains evoked either asynchronous or synchronous inhibition of CbN cells. Steps slowed CbN firing. Trains suppressed CbN cell firing less effectively, but consistently altered millisecond-scale spike timing. Steps or trains that perturbed stride-related modulation of CbN cell firing rates correlated well with irregularities of movement, suggesting that ongoing locomotion is sensitive to alterations in modulated CbN cell firing. Unperturbed locomotion continued more often during trains than steps, however, suggesting that stride-related modulation of CbN spiking is less readily disrupted by synchronous than asynchronous inhibition.
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Affiliation(s)
- Rashmi Sarnaik
- Department of Neurobiology, Northwestern University, Evanston, United States
| | - Indira M Raman
- Department of Neurobiology, Northwestern University, Evanston, United States
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32
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Modulation of sensory prediction error in Purkinje cells during visual feedback manipulations. Nat Commun 2018; 9:1099. [PMID: 29545572 PMCID: PMC5854574 DOI: 10.1038/s41467-018-03541-0] [Citation(s) in RCA: 33] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2017] [Accepted: 02/21/2018] [Indexed: 11/09/2022] Open
Abstract
It is hypothesized that the cerebellum implements a forward internal model that transforms motor commands into predictions about upcoming movements. The predictions are compared with sensory feedback to generate sensory prediction errors critical to controlling movements. The simple spike firing of cerebellar Purkinje cells both lead and lag movement consistent with representations of motor predictions and sensory feedback. This study tests whether this leading and lagging modulation provides the prediction and sensory feedback necessary to compute sensory prediction errors. Two manipulations of the visual feedback are used in rhesus monkeys performing pseudo-random tracking. Consistent with a forward model, delaying the visual feedback demonstrates that the leading simple spike modulation with position error is time-locked to the hand movement. Reducing the feedback shows that the lagged modulation is directly driven by visual inputs. Therefore, Purkinje cell discharge carries both the motor predictions and sensory feedback required of a forward internal model.
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33
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Abstract
Purkinje cells (PC) control deep cerebellar nuclei (DCN), which in turn inhibit inferior olive nucleus, closing a positive feedback loop via climbing fibers. PC highly express potassium BK channels but their contribution to the olivo-cerebellar loop is not clear. Using multiple-unit recordings in alert mice we found in that selective deletion of BK channels in PC induces a decrease in their simple spike firing with a beta-range bursting pattern and fast intraburst frequency (~200 Hz). To determine the impact of this abnormal rhythm on the olivo-cerebellar loop we analyzed simultaneous rhythmicity in different cerebellar structures. We found that this abnormal PC rhythmicity is transmitted to DCN neurons with no effect on their mean firing frequency. Long term depression at the parallel-PC synapses was altered and the intra-burst complex spike spikelets frequency was increased without modification of the mean complex spike frequency in BK-PC−/− mice. We argue that the ataxia present in these conditional knockout mice could be explained by rhythmic disruptions transmitted from mutant PC to DCN but not by rate code modification only. This suggests a neuronal mechanism for ataxia with possible implications for human disease.
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34
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Barron T, Saifetiarova J, Bhat MA, Kim JH. Myelination of Purkinje axons is critical for resilient synaptic transmission in the deep cerebellar nucleus. Sci Rep 2018; 8:1022. [PMID: 29348594 PMCID: PMC5773691 DOI: 10.1038/s41598-018-19314-0] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2017] [Accepted: 12/29/2017] [Indexed: 11/08/2022] Open
Abstract
The roles of myelin in maintaining axonal integrity and action potential (AP) propagation are well established, but its role in synapse maintenance and neurotransmission remains largely understudied. Here, we investigated how Purkinje axon myelination regulates synaptic transmission in the Purkinje to deep cerebellar nuclei (DCN) synapses using the Long Evans Shaker (LES) rat, which lacks compact myelin and thus displays severe locomotion deficits. DCN neurons fired spontaneous action potentials (APs), whose frequencies were dependent on the extent of myelin. In the LES cerebellum with severe myelin deficiency, DCN neurons were hyper-excitable, exhibiting spontaneous AP firing at a much higher frequency compared to those from wild type (LE) and heterozygote (LEHet) rats. The hyper-excitability in LES DCN neurons resulted from reduced inhibitory GABAergic inputs from Purkinje cells to DCN neurons. Corresponding with functional alterations including failures of AP propagation, electron microscopic analysis revealed anatomically fewer active zones at the presynaptic terminals of Purkinje cells in both LEHet and LES rats. Taken together, these studies suggest that proper axonal myelination critically regulates presynaptic terminal structure and function and directly impacts synaptic transmission in the Purkinje cell-DCN cell synapse in the cerebellum.
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Affiliation(s)
- Tara Barron
- Department of Cellular and Integrative Physiology, University of Texas Health Science Center, San Antonio, Texas, 78229, USA
| | - Julia Saifetiarova
- Department of Cellular and Integrative Physiology, University of Texas Health Science Center, San Antonio, Texas, 78229, USA
| | - Manzoor A Bhat
- Department of Cellular and Integrative Physiology, University of Texas Health Science Center, San Antonio, Texas, 78229, USA
| | - Jun Hee Kim
- Department of Cellular and Integrative Physiology, University of Texas Health Science Center, San Antonio, Texas, 78229, USA.
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35
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Convergence of Primary Sensory Cortex and Cerebellar Nuclei Pathways in the Whisker System. Neuroscience 2018; 368:229-239. [DOI: 10.1016/j.neuroscience.2017.07.036] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2017] [Revised: 07/07/2017] [Accepted: 07/16/2017] [Indexed: 01/23/2023]
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36
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Kros L, Lindeman S, Eelkman Rooda OHJ, Murugesan P, Bina L, Bosman LWJ, De Zeeuw CI, Hoebeek FE. Synchronicity and Rhythmicity of Purkinje Cell Firing during Generalized Spike-and-Wave Discharges in a Natural Mouse Model of Absence Epilepsy. Front Cell Neurosci 2017; 11:346. [PMID: 29163057 PMCID: PMC5671558 DOI: 10.3389/fncel.2017.00346] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2017] [Accepted: 10/17/2017] [Indexed: 11/13/2022] Open
Abstract
Absence epilepsy is characterized by the occurrence of generalized spike and wave discharges (GSWDs) in electrocorticographical (ECoG) recordings representing oscillatory activity in thalamocortical networks. The oscillatory nature of GSWDs has been shown to be reflected in the simple spike activity of cerebellar Purkinje cells and in the activity of their target neurons in the cerebellar nuclei, but it is unclear to what extent complex spike activity is implicated in generalized epilepsy. Purkinje cell complex spike firing is elicited by climbing fiber activation and reflects action potential firing in the inferior olive. Here, we investigated to what extent modulation of complex spike firing is reflected in the temporal patterns of seizures. Extracellular single-unit recordings in awake, head-restrained homozygous tottering mice, which suffer from a mutation in the voltage-gated CaV2.1 calcium channel, revealed that a substantial proportion of Purkinje cells (26%) showed increased complex spike activity and rhythmicity during GSWDs. Moreover, Purkinje cells, recorded either electrophysiologically or by using Ca2+-imaging, showed a significant increase in complex spike synchronicity for both adjacent and remote Purkinje cells during ictal events. These seizure-related changes in firing frequency, rhythmicity and synchronicity were most prominent in the lateral cerebellum, a region known to receive cerebral input via the inferior olive. These data indicate profound and widespread changes in olivary firing that are most likely induced by seizure-related activity changes in the thalamocortical network, thereby highlighting the possibility that olivary neurons can compensate for pathological brain-state changes by dampening oscillations.
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Affiliation(s)
- Lieke Kros
- Department of Neuroscience, Erasmus MC, Rotterdam, Netherlands
| | - Sander Lindeman
- Department of Neuroscience, Erasmus MC, Rotterdam, Netherlands
| | - Oscar H J Eelkman Rooda
- Department of Neuroscience, Erasmus MC, Rotterdam, Netherlands.,Department of Neurosurgery, Erasmus MC, Rotterdam, Netherlands
| | | | - Lorenzo Bina
- Department of Neuroscience, Erasmus MC, Rotterdam, Netherlands
| | | | - Chris I De Zeeuw
- Department of Neuroscience, Erasmus MC, Rotterdam, Netherlands.,Netherlands Institute for Neuroscience, Royal Dutch Academy for Arts and Sciences, Amsterdam, Netherlands
| | - Freek E Hoebeek
- Department of Neuroscience, Erasmus MC, Rotterdam, Netherlands
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37
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Cao Y, Liu Y, Jaeger D, Heck DH. Cerebellar Purkinje Cells Generate Highly Correlated Spontaneous Slow-Rate Fluctuations. Front Neural Circuits 2017; 11:67. [PMID: 28979195 PMCID: PMC5611370 DOI: 10.3389/fncir.2017.00067] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2017] [Accepted: 09/05/2017] [Indexed: 11/30/2022] Open
Abstract
Cerebellar Purkinje cells (PC) fire action potentials at high, sustained rates. Changes in spike rate that last a few tens of milliseconds encode sensory and behavioral events. Here we investigated spontaneous fluctuations of PC simple spike rate at a slow time scale of the order of 1 s. Simultaneous recordings from pairs of PCs that were aligned either along the sagittal or transversal axis of the cerebellar cortex revealed that simple spike rate fluctuations at the 1 s time scale were highly correlated. Each pair of PCs had either a predominantly positive or negative slow-rate correlation, with negative correlations observed only in PC pairs aligned along the transversal axis. Slow-rate correlations were independent of faster rate changes that were correlated with fluid licking behavior. Simultaneous recordings from PCs and cerebellar nuclear (CN) neurons showed that slow-rate fluctuations in PC and CN activity were also highly correlated, but their correlations continually alternated between periods of positive and negative correlation. The functional significance of this new aspect of cerebellar spike activity remains to be determined. Correlated slow-rate fluctuations seem too slow to be involved in the real-time control of ongoing behavior. However, slow-rate fluctuations of PCs converging on the same CN neuron are likely to modulate the excitability of the CN neuron, thus introduce a possible slow modulation of cerebellar output activity.
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Affiliation(s)
- Ying Cao
- Department of Anatomy and Neurobiology, University of Tennessee Health Science CenterMemphis, TN, United States
| | - Yu Liu
- Department of Anatomy and Neurobiology, University of Tennessee Health Science CenterMemphis, TN, United States
| | - Dieter Jaeger
- Department of Biology, Emory UniversityAtlanta, GA, United States
| | - Detlef H Heck
- Department of Anatomy and Neurobiology, University of Tennessee Health Science CenterMemphis, TN, United States
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38
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Wu Y, Raman IM. Facilitation of mossy fibre-driven spiking in the cerebellar nuclei by the synchrony of inhibition. J Physiol 2017; 595:5245-5264. [PMID: 28513836 PMCID: PMC5538193 DOI: 10.1113/jp274321] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2017] [Accepted: 05/11/2017] [Indexed: 11/08/2022] Open
Abstract
KEY POINTS Large premotor neurons of the cerebellar nuclei (CbN cells) integrate synaptic inhibition from Purkinje neurons and synaptic excitation from mossy fibres to generate cerebellar output. We find that mossy fibre inputs to CbN cells generate unitary AMPA receptor EPSCs of ∼1 nS that decay in ∼1 ms and mildly voltage-dependent NMDA receptor EPSCs of ∼0.6 nS that decay in ∼7 ms. A few hundred mossy fibres active at a few tens of spikes s-1 must converge on CbN cells to generate physiological CbN spike rates (∼60 spikes s-1 ) during convergent inhibition from spontaneously active Purkinje cells. Dynamic clamp studies in cerebellar slices from weanling mice demonstrate that synaptic excitation from mossy fibres becomes more effective at increasing the rate of CbN cell spiking when the coherence (synchrony) of convergent inhibition is increased. ABSTRACT Large projection neurons of the cerebellar nuclei (CbN cells), whose activity generates movement, are inhibited by Purkinje cells and excited by mossy fibres. The high convergence, firing rates and strength of Purkinje inputs predict powerful suppression of CbN cell spiking, raising the question of what activity patterns favour excitation over inhibition. Recording from CbN cells at near-physiological temperatures in cerebellar slices from weanling mice, we measured the amplitude, kinetics, voltage dependence and short-term plasticity of mossy fibre-mediated EPSCs. Unitary EPSCs were small and brief (AMPA receptor, ∼1 nS, ∼1 ms; NMDA receptor, ∼0.6 nS, ∼7 ms) and depressed moderately. Using these experimentally measured parameters, we applied combinations of excitation and inhibition to CbN cells with dynamic clamp. Because Purkinje cells can fire coincident simple spikes during cerebellar behaviours, we varied the proportion (0-20 of 40) and precision (0-4 ms jitter) of synchrony of inhibitory inputs, along with the rates (0-100 spikes s-1 ) and number (0-800) of excitatory inputs. Even with inhibition constant, when inhibitory synchrony was higher, excitation increased CbN cell firing rates more effectively. Partial inhibitory synchrony also dictated CbN cell spike timing, even with physiological rates of excitation. These effects were present with ≥10 inhibitory inputs active within 2-4 ms of each other. Conversely, spiking was most effectively suppressed when inhibition was maximally asynchronous. Thus, the rate and relative timing of Purkinje-mediated inhibition set the rate and timing of cerebellar output. The results suggest that increased coherence of Purkinje cell activity can facilitate mossy fibre-driven spiking by CbN cells, in turn driving movements.
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Affiliation(s)
- Yeechan Wu
- Interdepartmental Neuroscience Program, Northwestern University, Evanston, IL, 60208, USA
- Department of Neurobiology, Northwestern University, Evanston, IL, 60208, USA
| | - Indira M Raman
- Interdepartmental Neuroscience Program, Northwestern University, Evanston, IL, 60208, USA
- Department of Neurobiology, Northwestern University, Evanston, IL, 60208, USA
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39
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Yarden-Rabinowitz Y, Yarom Y. In vivo analysis of synaptic activity in cerebellar nuclei neurons unravels the efficacy of excitatory inputs. J Physiol 2017; 595:5945-5963. [PMID: 28618000 DOI: 10.1113/jp274115] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2017] [Accepted: 06/07/2017] [Indexed: 11/08/2022] Open
Abstract
KEY POINTS Cerebellar nuclei (CN) neurons can be classified into four groups according to their action potential (AP) waveform, corresponding to four types of neurons previously characterized. Half of the APs are generated by excitatory events, suggesting that excitatory inputs play a key role in generating CN outputs. Analysis of post-synaptic potentials reveals that the probability of excitatory inputs generating an AP is 0.1. The input from climbing fibre collaterals is characterized by a pair of synaptic potentials with a distinct interpair interval of 4.5 ms. The probability of climbing fibre collaterals initiating an AP in CN neurons is 0.15. ABSTRACT It is commonly agreed that the main function of the cerebellar system is to provide well-timed signals used for the execution of motor commands or prediction of sensory inputs. This function is manifested as a temporal sequence of spiking that should be expressed in the cerebellar nuclei (CN) projection neurons. Whether spiking activity is generated by excitation or release from inhibition is still a hotly debated issue. In an attempt to resolve this debate, we recorded intracellularly from CN neurons in anaesthetized mice and performed an analysis of synaptic activity that yielded a number of important observations. First, we demonstrate that CN neurons can be classified into four groups. Second, shape-index plots of the excitatory events suggest that they are distributed over the entire dendritic tree. Third, the rise time of excitatory events is linearly related to amplitude, suggesting that all excitatory events contribute equally to the generation of action potentials (APs). Fourth, we identified a temporal pattern of spontaneous excitatory events that represent climbing fibre inputs and confirm the results by direct stimulation and analysis on harmaline-evoked activity. Finally, we demonstrate that the probability of excitatory inputs generating an AP is 0.1 yet half of the APs are generated by excitatory events. Moreover, the probability of a presumably spontaneous climbing fibre input generating an AP is higher, reaching a mean population value of 0.15. In view of these results, the mode of synaptic integration at the level of the CN should be re-considered.
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Affiliation(s)
- Yasmin Yarden-Rabinowitz
- Department of Neurobiology, Silberman Institute of Life Sciences and Edmond & Lily Safra Center for Brain Sciences (ELSC), The Hebrew University, 91904, Jerusalem, Israel
| | - Yosef Yarom
- Department of Neurobiology, Silberman Institute of Life Sciences and Edmond & Lily Safra Center for Brain Sciences (ELSC), The Hebrew University, 91904, Jerusalem, Israel
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40
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El-Shamayleh Y, Kojima Y, Soetedjo R, Horwitz GD. Selective Optogenetic Control of Purkinje Cells in Monkey Cerebellum. Neuron 2017. [PMID: 28648497 DOI: 10.1016/j.neuron.2017.06.002] [Citation(s) in RCA: 60] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
Purkinje cells of the primate cerebellum play critical but poorly understood roles in the execution of coordinated, accurate movements. Elucidating these roles has been hampered by a lack of techniques for manipulating spiking activity in these cells selectively-a problem common to most cell types in non-transgenic animals. To overcome this obstacle, we constructed AAV vectors carrying the channelrhodopsin-2 (ChR2) gene under the control of a 1 kb L7/Pcp2 promoter. We injected these vectors into the cerebellar cortex of rhesus macaques and tested vector efficacy in three ways. Immunohistochemical analyses confirmed selective ChR2 expression in Purkinje cells. Neurophysiological recordings confirmed robust optogenetic activation. Optical stimulation of the oculomotor vermis caused saccade dysmetria. Our results demonstrate the utility of AAV-L7-ChR2 for revealing the contributions of Purkinje cells to circuit function and behavior, and they attest to the feasibility of promoter-based, targeted, genetic manipulations in primates.
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Affiliation(s)
- Yasmine El-Shamayleh
- Department of Physiology & Biophysics, University of Washington, 1959 NE Pacific St., HSB I-728, UW Mailbox 357290, Seattle, WA 98195, USA; Washington National Primate Research Center, University of Washington, 1959 NE Pacific St., HSB I-728, UW Mailbox 357290, Seattle, WA 98195, USA
| | - Yoshiko Kojima
- Department of Physiology & Biophysics, University of Washington, 1959 NE Pacific St., HSB I-728, UW Mailbox 357290, Seattle, WA 98195, USA; Washington National Primate Research Center, University of Washington, 1959 NE Pacific St., HSB I-728, UW Mailbox 357290, Seattle, WA 98195, USA
| | - Robijanto Soetedjo
- Department of Physiology & Biophysics, University of Washington, 1959 NE Pacific St., HSB I-728, UW Mailbox 357290, Seattle, WA 98195, USA; Washington National Primate Research Center, University of Washington, 1959 NE Pacific St., HSB I-728, UW Mailbox 357290, Seattle, WA 98195, USA
| | - Gregory D Horwitz
- Department of Physiology & Biophysics, University of Washington, 1959 NE Pacific St., HSB I-728, UW Mailbox 357290, Seattle, WA 98195, USA; Washington National Primate Research Center, University of Washington, 1959 NE Pacific St., HSB I-728, UW Mailbox 357290, Seattle, WA 98195, USA.
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41
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Abbasi S, Hudson AE, Maran SK, Cao Y, Abbasi A, Heck DH, Jaeger D. Robust transmission of rate coding in the inhibitory Purkinje cell to cerebellar nuclei pathway in awake mice. PLoS Comput Biol 2017; 13:e1005578. [PMID: 28617798 PMCID: PMC5491311 DOI: 10.1371/journal.pcbi.1005578] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2016] [Revised: 06/29/2017] [Accepted: 05/15/2017] [Indexed: 11/18/2022] Open
Abstract
Neural coding through inhibitory projection pathways remains poorly understood. We analyze the transmission properties of the Purkinje cell (PC) to cerebellar nucleus (CN) pathway in a modeling study using a data set recorded in awake mice containing respiratory rate modulation. We find that inhibitory transmission from tonically active PCs can transmit a behavioral rate code with high fidelity. We parameterized the required population code in PC activity and determined that 20% of PC inputs to a full compartmental CN neuron model need to be rate-comodulated for transmission of a rate code. Rate covariance in PC inputs also accounts for the high coefficient of variation in CN spike trains, while the balance between excitation and inhibition determines spike rate and local spike train variability. Overall, our modeling study can fully account for observed spike train properties of cerebellar output in awake mice, and strongly supports rate coding in the cerebellum. Detailed computer simulations of biological neurons can make an important contribution to our understanding of how the brain works. In this paper we use such a model of a neuron that represents the output from the cerebellum. We can show that the inhibition this neuron type receives from Purkinje cells in the cerebellar cortex is well suited to pass a detailed time course of movement control to the output of the cerebellum. Importantly we find that this type of coding requires a population of Purkinje cells that pass the same temporal coding of spike rate to the output neurons in the cerebellar nuclei.
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Affiliation(s)
- Samira Abbasi
- Department of Biology, Emory University, Atlanta, GA, United States of America
- Department of Biomedical Engineering, Hamedan University of Technology, Hamedan, Iran
| | - Amber E. Hudson
- Department of Biology, Emory University, Atlanta, GA, United States of America
| | - Selva K. Maran
- Department of Biology, Emory University, Atlanta, GA, United States of America
| | - Ying Cao
- Department of Anatomy and Neurobiology, University of Tennessee Health Science Center, Memphis, Tennessee, United States of America
| | - Ataollah Abbasi
- Computational Neuroscience Laboratory, Department of Biomedical Engineering, Faculty of Electrical Engineering, Sahand University of Technology, Tabriz, Iran
| | - Detlef H. Heck
- Department of Anatomy and Neurobiology, University of Tennessee Health Science Center, Memphis, Tennessee, United States of America
| | - Dieter Jaeger
- Department of Biology, Emory University, Atlanta, GA, United States of America
- * E-mail:
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Ransdell JL, Dranoff E, Lau B, Lo WL, Donermeyer DL, Allen PM, Nerbonne JM. Loss of Navβ4-Mediated Regulation of Sodium Currents in Adult Purkinje Neurons Disrupts Firing and Impairs Motor Coordination and Balance. Cell Rep 2017; 19:532-544. [PMID: 28423317 PMCID: PMC5473293 DOI: 10.1016/j.celrep.2017.03.068] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2016] [Revised: 02/16/2017] [Accepted: 03/22/2017] [Indexed: 11/28/2022] Open
Abstract
The resurgent component of voltage-gated Na+ (Nav) currents, INaR, has been suggested to provide the depolarizing drive for high-frequency firing and to be generated by voltage-dependent Nav channel block (at depolarized potentials) and unblock (at hyperpolarized potentials) by the accessory Navβ4 subunit. To test these hypotheses, we examined the effects of the targeted deletion of Scn4b (Navβ4) on INaR and on repetitive firing in cerebellar Purkinje neurons. We show here that Scn4b-/- animals have deficits in motor coordination and balance and that firing rates in Scn4b-/- Purkinje neurons are markedly attenuated. Acute, in vivo short hairpin RNA (shRNA)-mediated "knockdown" of Navβ4 in adult Purkinje neurons also reduced spontaneous and evoked firing rates. Dynamic clamp-mediated addition of INaR partially rescued firing in Scn4b-/- Purkinje neurons. Voltage-clamp experiments revealed that INaR was reduced (by ∼50%), but not eliminated, in Scn4b-/- Purkinje neurons, revealing that additional mechanisms contribute to generation of INaR.
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Affiliation(s)
- Joseph L Ransdell
- Departments of Developmental Biology and Internal Medicine , Washington University School of Medicine, St. Louis, MO 63110, USA
| | - Edward Dranoff
- Departments of Developmental Biology and Internal Medicine , Washington University School of Medicine, St. Louis, MO 63110, USA
| | - Brandon Lau
- Departments of Developmental Biology and Internal Medicine , Washington University School of Medicine, St. Louis, MO 63110, USA
| | - Wan-Lin Lo
- Department of Pathology and Immunology , Washington University School of Medicine, St. Louis, MO 63110, USA
| | - David L Donermeyer
- Department of Pathology and Immunology , Washington University School of Medicine, St. Louis, MO 63110, USA
| | - Paul M Allen
- Department of Pathology and Immunology , Washington University School of Medicine, St. Louis, MO 63110, USA
| | - Jeanne M Nerbonne
- Departments of Developmental Biology and Internal Medicine , Washington University School of Medicine, St. Louis, MO 63110, USA.
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Turecek J, Jackman SL, Regehr WG. Synaptic Specializations Support Frequency-Independent Purkinje Cell Output from the Cerebellar Cortex. Cell Rep 2016; 17:3256-3268. [PMID: 28009294 PMCID: PMC5870134 DOI: 10.1016/j.celrep.2016.11.081] [Citation(s) in RCA: 43] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2016] [Revised: 11/14/2016] [Accepted: 11/28/2016] [Indexed: 11/23/2022] Open
Abstract
The output of the cerebellar cortex is conveyed to the deep cerebellar nuclei (DCN) by Purkinje cells (PCs). Here, we characterize the properties of the PC-DCN synapse in juvenile and adult mice and find that prolonged high-frequency stimulation leads to steady-state responses that become increasingly frequency independent within the physiological firing range of PCs in older animals, resulting in a linear relationship between charge transfer and activation frequency. We used a low-affinity antagonist to show that GABAA-receptor saturation occurs at this synapse but does not underlie frequency-invariant transmission. We propose that PC-DCN synapses have two components of release: one prominent early in trains and another specialized to maintain transmission during prolonged activation. Short-term facilitation offsets partial vesicle depletion to produce frequency-independent transmission.
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Affiliation(s)
- Josef Turecek
- Department of Neurobiology, Harvard Medical School, 220 Longwood Ave., Boston, MA 02115, USA
| | - Skyler L Jackman
- Department of Neurobiology, Harvard Medical School, 220 Longwood Ave., Boston, MA 02115, USA
| | - Wade G Regehr
- Department of Neurobiology, Harvard Medical School, 220 Longwood Ave., Boston, MA 02115, USA.
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Canto CB, Witter L, De Zeeuw CI. Whole-Cell Properties of Cerebellar Nuclei Neurons In Vivo. PLoS One 2016; 11:e0165887. [PMID: 27851801 PMCID: PMC5112928 DOI: 10.1371/journal.pone.0165887] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2016] [Accepted: 10/19/2016] [Indexed: 11/22/2022] Open
Abstract
Cerebellar nuclei neurons integrate sensorimotor information and form the final output of the cerebellum, projecting to premotor brainstem targets. This implies that, in contrast to specialized neurons and interneurons in cortical regions, neurons within the nuclei encode and integrate complex information that is most likely reflected in a large variation of intrinsic membrane properties and integrative capacities of individual neurons. Yet, whether this large variation in properties is reflected in a heterogeneous physiological cell population of cerebellar nuclei neurons with well or poorly defined cell types remains to be determined. Indeed, the cell electrophysiological properties of cerebellar nuclei neurons have been identified in vitro in young rodents, but whether these properties are similar to the in vivo adult situation has not been shown. In this comprehensive study we present and compare the in vivo properties of 144 cerebellar nuclei neurons in adult ketamine-xylazine anesthetized mice. We found regularly firing (N = 88) and spontaneously bursting (N = 56) neurons. Membrane-resistance, capacitance, spike half-width and firing frequency all widely varied as a continuum, ranging from 9.63 to 3352.1 MΩ, from 6.7 to 772.57 pF, from 0.178 to 1.98 ms, and from 0 to 176.6 Hz, respectively. At the same time, several of these parameters were correlated with each other. Capacitance decreased with membrane resistance (R2 = 0.12, P<0.001), intensity of rebound spiking increased with membrane resistance (for 100 ms duration R2 = 0.1503, P = 0.0011), membrane resistance decreased with membrane time constant (R2 = 0.045, P = 0.031) and increased with spike half-width (R2 = 0.023, P<0.001), while capacitance increased with firing frequency (R2 = 0.29, P<0.001). However, classes of neuron subtypes could not be identified using merely k-clustering of their intrinsic firing properties and/or integrative properties following activation of their Purkinje cell input. Instead, using whole-cell parameters in combination with morphological criteria revealed by intracellular labelling with Neurobiotin (N = 18) allowed for electrophysiological identification of larger (29.3-50 μm soma diameter) and smaller (< 21.2 μm) cerebellar nuclei neurons with significant differences in membrane properties. Larger cells had a lower membrane resistance and a shorter spike, with a tendency for higher capacitance. Thus, in general cerebellar nuclei neurons appear to offer a rich and wide continuum of physiological properties that stand in contrast to neurons in most cortical regions such as those of the cerebral and cerebellar cortex, in which different classes of neurons operate in a narrower territory of electrophysiological parameter space. The current dataset will help computational modelers of the cerebellar nuclei to update and improve their cerebellar motor learning and performance models by incorporating the large variation of the in vivo properties of cerebellar nuclei neurons. The cellular complexity of cerebellar nuclei neurons may endow the nuclei to perform the intricate computations required for sensorimotor coordination.
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Affiliation(s)
- Cathrin B. Canto
- Netherlands Institute for Neuroscience, Royal Dutch Academy of Arts & Sciences, Amsterdam, The Netherlands
| | - Laurens Witter
- Netherlands Institute for Neuroscience, Royal Dutch Academy of Arts & Sciences, Amsterdam, The Netherlands
| | - Chris I. De Zeeuw
- Netherlands Institute for Neuroscience, Royal Dutch Academy of Arts & Sciences, Amsterdam, The Netherlands
- Department of Neuroscience, Erasmus Medical Center, Rotterdam, The Netherlands
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45
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Hong S, Negrello M, Junker M, Smilgin A, Thier P, De Schutter E. Multiplexed coding by cerebellar Purkinje neurons. eLife 2016; 5. [PMID: 27458803 PMCID: PMC4961467 DOI: 10.7554/elife.13810] [Citation(s) in RCA: 41] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2015] [Accepted: 06/13/2016] [Indexed: 01/05/2023] Open
Abstract
Purkinje cells (PC), the sole output neurons of the cerebellar cortex, encode sensorimotor information, but how they do it remains a matter of debate. Here we show that PCs use a multiplexed spike code. Synchrony/spike time and firing rate encode different information in behaving monkeys during saccadic eye motion tasks. Using the local field potential (LFP) as a probe of local network activity, we found that infrequent pause spikes, which initiated or terminated intermittent pauses in simple spike trains, provide a temporally reliable signal for eye motion onset, with strong phase-coupling to the β/γ band LFP. Concurrently, regularly firing, non-pause spikes were weakly correlated with the LFP, but were crucial to linear encoding of eye movement kinematics by firing rate. Therefore, PC spike trains can simultaneously convey information necessary to achieve precision in both timing and continuous control of motion. DOI:http://dx.doi.org/10.7554/eLife.13810.001 The cerebellum is a part of the brain that uses information from the senses to coordinate movement. Cells called Purkinje neurons in the cerebellum produce the final ‘output’ of its cortex. Therefore, Purkinje neurons have to communicate precise information about different aspects of the movement, such as its speed and timing. This information is likely to be represented by patterns of electrical activity within Purkinje neurons, but these patterns are still not fully understood. Hong et al. recorded and analyzed electrical ‘spikes’, the output activity of Purkinje neurons, while monkeys made rapid eye movements. The recordings showed that occasional pauses in the otherwise regularly firing spikes of Purkinje neurons signaled the start of the eye movements. The pauses were accompanied by a sharp change in the local field potential, another electrical signal that comes from many neurons in the neighborhood. In the same cells, the rate of regularly firing spikes increased and decreased with the direction and speed of eye movements, following a simple relationship and independently of the local field potential. Purkinje neurons therefore appear to use both the timing and the rate of their spiking activity to represent movement. This resolves conflicting reports in the literature claiming that either rates of spiking or their timing code essential information about movements: both are important. This way of representing information by combining more than one source is known as multiplexed coding. Next, experiments recording electrical activity from many cells in the cerebellum at the same time are needed to find out how multiple Purkinje neurons can pause their spiking activity at the same time. Future experiments should also uncover how pauses in spiking and firing rates change with learning. DOI:http://dx.doi.org/10.7554/eLife.13810.002
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Affiliation(s)
- Sungho Hong
- Computational Neuroscience Unit, Okinawa Institute of Science and Technology, Okinawa, Japan
| | - Mario Negrello
- Computational Neuroscience Unit, Okinawa Institute of Science and Technology, Okinawa, Japan.,Department of Neuroscience, Erasmus Medical Center, Rotterdam, The Netherlands
| | - Marc Junker
- Department of Cognitive Neurology, Hertie Institute for Clinical Brain Research, University of Tübingen, Tübingen, Germany
| | - Aleksandra Smilgin
- Department of Cognitive Neurology, Hertie Institute for Clinical Brain Research, University of Tübingen, Tübingen, Germany
| | - Peter Thier
- Department of Cognitive Neurology, Hertie Institute for Clinical Brain Research, University of Tübingen, Tübingen, Germany
| | - Erik De Schutter
- Computational Neuroscience Unit, Okinawa Institute of Science and Technology, Okinawa, Japan
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Del Rio-Bermudez C, Plumeau AM, Sattler NJ, Sokoloff G, Blumberg MS. Spontaneous activity and functional connectivity in the developing cerebellorubral system. J Neurophysiol 2016; 116:1316-27. [PMID: 27385801 DOI: 10.1152/jn.00461.2016] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2016] [Accepted: 06/30/2016] [Indexed: 12/13/2022] Open
Abstract
The development of the cerebellar system depends in part on the emergence of functional connectivity in its input and output pathways. Characterization of spontaneous activity within these pathways provides insight into their functional status in early development. In the present study we recorded extracellular activity from the interpositus nucleus (IP) and its primary downstream target, the red nucleus (RN), in unanesthetized rats at postnatal days 8 (P8) and P12, a period of dramatic change in cerebellar circuitry. The two structures exhibited state-dependent activity patterns and age-related changes in rhythmicity and overall firing rate. Importantly, sensory feedback (i.e., reafference) from myoclonic twitches (spontaneous, self-generated movements that are produced exclusively during active sleep) drove neural activity in the IP and RN at both ages. Additionally, anatomic tracing confirmed the presence of cerebellorubral connections as early as P8. Finally, inactivation of the IP and adjacent nuclei using the GABAA receptor agonist muscimol caused a substantial decrease in neural activity in the contralateral RN at both ages, as well as the disappearance of rhythmicity; twitch-related activity in the RN, however, was preserved after IP inactivation, indicating that twitch-related reafference activates the two structures in parallel. Overall, the present findings point to the contributions of sleep-related spontaneous activity to the development of cerebellar networks.
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Affiliation(s)
| | - Alan M Plumeau
- Interdisciplinary Graduate Program in Neuroscience, University of Iowa, Iowa City, Iowa
| | - Nicholas J Sattler
- Department of Psychological & Brain Sciences, University of Iowa, Iowa City, Iowa
| | - Greta Sokoloff
- Department of Psychological & Brain Sciences, University of Iowa, Iowa City, Iowa; DeLTA Center, University of Iowa, Iowa City, Iowa
| | - Mark S Blumberg
- Department of Psychological & Brain Sciences, University of Iowa, Iowa City, Iowa; Interdisciplinary Graduate Program in Neuroscience, University of Iowa, Iowa City, Iowa; Department of Biology, University of Iowa, Iowa City, Iowa; and DeLTA Center, University of Iowa, Iowa City, Iowa
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47
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Purkinje Cell Collaterals Enable Output Signals from the Cerebellar Cortex to Feed Back to Purkinje Cells and Interneurons. Neuron 2016; 91:312-9. [PMID: 27346533 DOI: 10.1016/j.neuron.2016.05.037] [Citation(s) in RCA: 56] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2015] [Revised: 03/30/2016] [Accepted: 05/23/2016] [Indexed: 10/21/2022]
Abstract
Purkinje cells (PCs) provide the sole output from the cerebellar cortex. Although PCs are well characterized on many levels, surprisingly little is known about their axon collaterals and their target neurons within the cerebellar cortex. It has been proposed that PC collaterals transiently control circuit assembly in early development, but it is thought that PC-to-PC connections are subsequently pruned. Here, we find that all PCs have collaterals in young, juvenile, and adult mice. Collaterals are restricted to the parasagittal plane, and most synapses are located in close proximity to PCs. Using optogenetics and electrophysiology, we find that in juveniles and adults, PCs make synapses onto other PCs, molecular layer interneurons, and Lugaro cells, but not onto Golgi cells. These findings establish that PC output can feed back and regulate numerous circuit elements within the cerebellar cortex and is well suited to contribute to processing in parasagittal zones.
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Benedetti B, Benedetti A, Flucher BE. Loss of the calcium channel β4 subunit impairs parallel fibre volley and Purkinje cell firing in cerebellum of adult ataxic mice. Eur J Neurosci 2016; 43:1486-98. [PMID: 27003325 PMCID: PMC4949674 DOI: 10.1111/ejn.13241] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2016] [Revised: 03/17/2016] [Accepted: 03/18/2016] [Indexed: 01/08/2023]
Abstract
The auxiliary voltage-gated calcium channel subunit β4 supports targeting of calcium channels to the cell membrane, modulates ionic currents and promotes synaptic release in the central nervous system. β4 is abundant in cerebellum and its loss causes ataxia. However, the type of calcium channels and cerebellar functions affected by the loss of β4 are currently unknown. We therefore studied the structure and function of Purkinje cells in acute cerebellar slices of the β4 (-/-) ataxic (lethargic) mouse, finding that loss of β4 affected Purkinje cell input, morphology and pacemaker activity. In adult lethargic cerebellum evoked postsynaptic currents from parallel fibres were depressed, while paired-pulse facilitation and spontaneous synaptic currents were unaffected. Because climbing fibre input was spared, the parallel fibre/climbing fibre input ratio was reduced. The dendritic arbor of adult lethargic Purkinje cells displayed fewer and shorter dendrites, but a normal spine density. Accordingly, the width of the molecular and granular layers was reduced. These defects recapitulate the impaired cerebellar maturation observed upon Cav 2.1 ataxic mutations. However, unlike Cav 2.1 mutations, lethargic Purkinje cells also displayed a striking decrease in pacemaker firing frequency, without loss of firing regularity. All these deficiencies appear in late development, indicating the importance of β4 for the normal differentiation and function of mature Purkinje cells networks. The observed reduction of the parallel fibre input, the altered parallel fibre/climbing fibre ratio and the reduced Purkinje cell output can contribute to the severe motor impairment caused by the loss of the calcium channel β4 subunit in lethargic mice.
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Affiliation(s)
- Bruno Benedetti
- Department of Physiology and Medical Physics, Medical University of Innsbruck, Schöpfstraße 41, Innsbruck, A-6020, Austria
| | - Ariane Benedetti
- Department of Physiology and Medical Physics, Medical University of Innsbruck, Schöpfstraße 41, Innsbruck, A-6020, Austria
| | - Bernhard E Flucher
- Department of Physiology and Medical Physics, Medical University of Innsbruck, Schöpfstraße 41, Innsbruck, A-6020, Austria
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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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50
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Sudhakar SK, Torben-Nielsen B, De Schutter E. Cerebellar Nuclear Neurons Use Time and Rate Coding to Transmit Purkinje Neuron Pauses. PLoS Comput Biol 2015; 11:e1004641. [PMID: 26630202 PMCID: PMC4668013 DOI: 10.1371/journal.pcbi.1004641] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2015] [Accepted: 11/03/2015] [Indexed: 11/29/2022] Open
Abstract
Neurons of the cerebellar nuclei convey the final output of the cerebellum to their targets in various parts of the brain. Within the cerebellum their direct upstream connections originate from inhibitory Purkinje neurons. Purkinje neurons have a complex firing pattern of regular spikes interrupted by intermittent pauses of variable length. How can the cerebellar nucleus process this complex input pattern? In this modeling study, we investigate different forms of Purkinje neuron simple spike pause synchrony and its influence on candidate coding strategies in the cerebellar nuclei. That is, we investigate how different alignments of synchronous pauses in synthetic Purkinje neuron spike trains affect either time-locking or rate-changes in the downstream nuclei. We find that Purkinje neuron synchrony is mainly represented by changes in the firing rate of cerebellar nuclei neurons. Pause beginning synchronization produced a unique effect on nuclei neuron firing, while the effect of pause ending and pause overlapping synchronization could not be distinguished from each other. Pause beginning synchronization produced better time-locking of nuclear neurons for short length pauses. We also characterize the effect of pause length and spike jitter on the nuclear neuron firing. Additionally, we find that the rate of rebound responses in nuclear neurons after a synchronous pause is controlled by the firing rate of Purkinje neurons preceding it. Neurons can transmit information by two different coding strategies: Rate coding, where the firing rate of the neuron is vital, and time coding where timing of individual spikes carries relevant information. In this study we analyze the importance of brief cessations in firing of the presynaptic neuron (pauses) on the spiking of the postsynaptic neuron. We perform this analysis on the inhibitory synaptic connection between Purkinje neurons (presynaptic) and nuclear neurons (postsynaptic) of the cerebellum. We employ a computational model of nuclear neurons and “synthetic” Purkinje neuron spike trains to study the effect of synchronous pauses on the spiking responses of nuclear neurons. We find that synchronous pauses can cause both well-timed spikes and increased firing rate in the nuclear neuron. In addition, we characterize the effect of pause length, amount and type of pause synchrony, and spike jitter. As such, we conclude that nuclear cells use both rate and time coding to relay upstream spiking information.
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Affiliation(s)
- Shyam Kumar Sudhakar
- Computational Neuroscience Unit, Okinawa Institute of Science and Technology, Onna-son, Okinawa, Japan
- Laboratory of Theoretical Neurobiology and Neuro-engineering, University of Antwerp, Wilrijk, Belgium
| | - Benjamin Torben-Nielsen
- Computational Neuroscience Unit, Okinawa Institute of Science and Technology, Onna-son, Okinawa, Japan
- Biocomputation Research Group, University of Hertfordshire, Hertfordshire, United Kingdom
| | - Erik De Schutter
- Computational Neuroscience Unit, Okinawa Institute of Science and Technology, Onna-son, Okinawa, Japan
- Laboratory of Theoretical Neurobiology and Neuro-engineering, University of Antwerp, Wilrijk, Belgium
- * E-mail:
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