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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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Aranca TV, Jones TM, Shaw JD, Staffetti JS, Ashizawa T, Kuo SH, Fogel BL, Wilmot GR, Perlman SL, Onyike CU, Ying SH, Zesiewicz TA. Emerging therapies in Friedreich's ataxia. Neurodegener Dis Manag 2016; 6:49-65. [PMID: 26782317 DOI: 10.2217/nmt.15.73] [Citation(s) in RCA: 49] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Friedreich's ataxia (FRDA) is an inherited, progressive neurodegenerative disease that typically affects teenagers and young adults. Therapeutic strategies and disease insight have expanded rapidly over recent years, leading to hope for the FRDA population. There is currently no US FDA-approved treatment for FRDA, but advances in research of its pathogenesis have led to clinical trials of potential treatments. This article reviews emerging therapies and discusses future perspectives, including the need for more precise measures for detecting changes in neurologic symptoms as well as a disease-modifying agent.
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Affiliation(s)
- Tanya V Aranca
- University of South Florida Ataxia Research Center, Department of Neurology, FL, USA
| | - Tracy M Jones
- University of South Florida Ataxia Research Center, Department of Neurology, FL, USA
| | - Jessica D Shaw
- University of South Florida Ataxia Research Center, Department of Neurology, FL, USA
| | - Joseph S Staffetti
- University of South Florida Ataxia Research Center, Department of Neurology, FL, USA
| | - Tetsuo Ashizawa
- McKnight Brain Institute, University of Florida Department of Neurology, FL, USA
| | - Sheng-Han Kuo
- Department of Neurology, Columbia University, NY, USA
| | - Brent L Fogel
- Department of Neurology, Neurogenetics Program, David Geffen School of Medicine, University of California, CA, USA
| | | | - Susan L Perlman
- Ataxia and Huntington Disease Center of Excellence, University of California, CA, US
| | - Chiadi U Onyike
- Department of Psychiatry and Behavioral Sciences, Johns Hopkins University school of Medicine MD, USA
| | - Sarah H Ying
- Department of Neurology, Johns Hopkins University School of Medicine, MD, USA.,Department of Radiology and Radiological Sciences, Johns Hopkins University School of Medicine, MD, USA.,Department of Ophthalmology, Johns Hopkins University School of Medicine, MD, USA
| | - Theresa A Zesiewicz
- University of South Florida Ataxia Research Center, Department of Neurology, FL, USA.,James A. Haley Veterans' Hospital, FL, USA
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3
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Maitre M, Klein C, Mensah-Nyagan AG. Mechanisms for the Specific Properties of γ-Hydroxybutyrate in Brain. Med Res Rev 2016; 36:363-88. [PMID: 26739481 DOI: 10.1002/med.21382] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2015] [Revised: 11/17/2015] [Accepted: 11/25/2015] [Indexed: 12/12/2022]
Abstract
γ-Hydroxybutyrate (GHB) is both a natural brain compound with neuromodulatory properties at central GABAergic synapses (micromolar concentration range) and also a drug (Xyrem(R) ) clinically used for the treatment of various neurological symptoms (millimolar dose range). However, this drug has abuse potential and can be addictive for some patients. Here, we review the basic mechanistic role of endogenous GHB in brain as well as the properties and mechanisms of action for therapeutic clinical doses of exogenous GHB. Several hypotheses are discussed with a preference for a molecular mechanism that conciliates most of the findings available. This conciliatory model may help for the design of GHB-like drugs active at lower doses and devoid of major side effects.
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Affiliation(s)
- Michel Maitre
- Biopathologie de la Myéline, Neuroprotection et Stratégies Thérapeutiques, INSERM U1119, Fédération de Médecine Translationnelle de Strasbourg (FMTS), Université de Strasbourg, Bâtiment 3 de la Faculté de Médecine, 11 rue Humann, 67000, Strasbourg, France
| | - Christian Klein
- Biopathologie de la Myéline, Neuroprotection et Stratégies Thérapeutiques, INSERM U1119, Fédération de Médecine Translationnelle de Strasbourg (FMTS), Université de Strasbourg, Bâtiment 3 de la Faculté de Médecine, 11 rue Humann, 67000, Strasbourg, France
| | - Ayikoe G Mensah-Nyagan
- Biopathologie de la Myéline, Neuroprotection et Stratégies Thérapeutiques, INSERM U1119, Fédération de Médecine Translationnelle de Strasbourg (FMTS), Université de Strasbourg, Bâtiment 3 de la Faculté de Médecine, 11 rue Humann, 67000, Strasbourg, France
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Eucalyptol induces hyperexcitability and epileptiform activity in snail neurons by inhibiting potassium channels. Eur J Pharmacol 2015; 764:70-78. [DOI: 10.1016/j.ejphar.2015.06.050] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2015] [Revised: 05/31/2015] [Accepted: 06/25/2015] [Indexed: 11/18/2022]
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Feng SS, Lin R, Gauck V, Jaeger D. Gain control of synaptic response function in cerebellar nuclear neurons by a calcium-activated potassium conductance. THE CEREBELLUM 2014; 12:692-706. [PMID: 23605187 DOI: 10.1007/s12311-013-0476-9] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Small conductance Ca(2+)-activated potassium (SK) current provides an important modulator of excitatory synaptic transmission, which undergoes plastic regulation via multiple mechanisms. We examined whether inhibitory input processing is also dependent on SK current in the cerebellar nuclei (CN) where inhibition provides the only route of information transfer from the cerebellar cortical Purkinje cells. We employed dynamic clamping in conjunction with computer simulations to address this question. We found that SK current plays a critical role in the inhibitory synaptic control of spiking output. Specifically, regulation of SK current density resulted in a gain control of spiking output, such that low SK current promoted large output signaling for large inhibitory cell input fluctuations due to Purkinje cell synchronization. In contrast, smaller nonsynchronized Purkinje cell input fluctuations were not amplified. Regulation of SK density in the CN therefore would likely lead to important consequences for the transmission of synchronized Purkinje cell activity to the motor system.
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Affiliation(s)
- Steven Si Feng
- Department of Biology, Emory University, 1510 Clifton Rd., Atlanta, GA, 30322, USA
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Ramirez JM, Doi A, Garcia AJ, Elsen FP, Koch H, Wei AD. The cellular building blocks of breathing. Compr Physiol 2013; 2:2683-731. [PMID: 23720262 DOI: 10.1002/cphy.c110033] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
Respiratory brainstem neurons fulfill critical roles in controlling breathing: they generate the activity patterns for breathing and contribute to various sensory responses including changes in O2 and CO2. These complex sensorimotor tasks depend on the dynamic interplay between numerous cellular building blocks that consist of voltage-, calcium-, and ATP-dependent ionic conductances, various ionotropic and metabotropic synaptic mechanisms, as well as neuromodulators acting on G-protein coupled receptors and second messenger systems. As described in this review, the sensorimotor responses of the respiratory network emerge through the state-dependent integration of all these building blocks. There is no known respiratory function that involves only a small number of intrinsic, synaptic, or modulatory properties. Because of the complex integration of numerous intrinsic, synaptic, and modulatory mechanisms, the respiratory network is capable of continuously adapting to changes in the external and internal environment, which makes breathing one of the most integrated behaviors. Not surprisingly, inspiration is critical not only in the control of ventilation, but also in the context of "inspiring behaviors" such as arousal of the mind and even creativity. Far-reaching implications apply also to the underlying network mechanisms, as lessons learned from the respiratory network apply to network functions in general.
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Affiliation(s)
- J M Ramirez
- Center for Integrative Brain Research, Seattle Children's Research Institut, Seattle, Washington, USA.
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Huang JY, Stiefel KM, Protti DA. Implementing dynamic clamp with synaptic and artificial conductances in mouse retinal ganglion cells. J Vis Exp 2013:e50400. [PMID: 23711460 PMCID: PMC3684038 DOI: 10.3791/50400] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/31/2022] Open
Abstract
Ganglion cells are the output neurons of the retina and their activity reflects the integration of multiple synaptic inputs arising from specific neural circuits. Patch clamp techniques, in voltage clamp and current clamp configurations, are commonly used to study the physiological properties of neurons and to characterize their synaptic inputs. Although the application of these techniques is highly informative, they pose various limitations. For example, it is difficult to quantify how the precise interactions of excitatory and inhibitory inputs determine response output. To address this issue, we used a modified current clamp technique, dynamic clamp, also called conductance clamp (1, 2, 3) and examined the impact of excitatory and inhibitory synaptic inputs on neuronal excitability. This technique requires the injection of current into the cell and is dependent on the real-time feedback of its membrane potential at that time. The injected current is calculated from predetermined excitatory and inhibitory synaptic conductances, their reversal potentials and the cell's instantaneous membrane potential. Details on the experimental procedures, patch clamping cells to achieve a whole-cell configuration and employment of the dynamic clamp technique are illustrated in this video article. Here, we show the responses of mouse retinal ganglion cells to various conductance waveforms obtained from physiological experiments in control conditions or in the presence of drugs. Furthermore, we show the use of artificial excitatory and inhibitory conductances generated using alpha functions to investigate the responses of the cells.
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Affiliation(s)
- Jin Y Huang
- Discipline of Biomedical Science, School of Medical Sciences, Sydney Medical School and Bosch Institute, University of Sydney.
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De Zeeuw CI, Hoebeek FE, Bosman LWJ, Schonewille M, Witter L, Koekkoek SK. Spatiotemporal firing patterns in the cerebellum. Nat Rev Neurosci 2011; 12:327-44. [PMID: 21544091 DOI: 10.1038/nrn3011] [Citation(s) in RCA: 278] [Impact Index Per Article: 21.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Neurons are generally considered to communicate information by increasing or decreasing their firing rate. However, in principle, they could in addition convey messages by using specific spatiotemporal patterns of spiking activities and silent intervals. Here, we review expanding lines of evidence that such spatiotemporal coding occurs in the cerebellum, and that the olivocerebellar system is optimally designed to generate and employ precise patterns of complex spikes and simple spikes during the acquisition and consolidation of motor skills. These spatiotemporal patterns may complement rate coding, thus enabling precise control of motor and cognitive processing at a high spatiotemporal resolution by fine-tuning sensorimotor integration and coordination.
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Affiliation(s)
- Chris I De Zeeuw
- Department of Neuroscience, Erasmus Medical Center, Rotterdam, The Netherlands.
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Lin RJ, Jaeger D. Using computer simulations to determine the limitations of dynamic clamp stimuli applied at the soma in mimicking distributed conductance sources. J Neurophysiol 2011; 105:2610-24. [PMID: 21325676 DOI: 10.1152/jn.00968.2010] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
In previous studies we used the technique of dynamic clamp to study how temporal modulation of inhibitory and excitatory inputs control the frequency and precise timing of spikes in neurons of the deep cerebellar nuclei (DCN). Although this technique is now widely used, it is limited to interpreting conductance inputs as being location independent; i.e., all inputs that are biologically distributed across the dendritic tree are applied to the soma. We used computer simulations of a morphologically realistic model of DCN neurons to compare the effects of purely somatic vs. distributed dendritic inputs in this cell type. We applied the same conductance stimuli used in our published experiments to the model. To simulate variability in neuronal responses to repeated stimuli, we added a somatic white current noise to reproduce subthreshold fluctuations in the membrane potential. We were able to replicate our dynamic clamp results with respect to spike rates and spike precision for different patterns of background synaptic activity. We found only minor differences in the spike pattern generation between focal or distributed input in this cell type even when strong inhibitory or excitatory bursts were applied. However, the location dependence of dynamic clamp stimuli is likely to be different for each cell type examined, and the simulation approach developed in the present study will allow a careful assessment of location dependence in all cell types.
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Affiliation(s)
- Risa J Lin
- Department of Biomedical Engineering, Georgia Institute of Technology and Emory University, Atlanta, GA 30322, USA
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Tadayonnejad R, Anderson D, Molineux ML, Mehaffey WH, Jayasuriya K, Turner RW. Rebound discharge in deep cerebellar nuclear neurons in vitro. THE CEREBELLUM 2011; 9:352-74. [PMID: 20396983 PMCID: PMC2949560 DOI: 10.1007/s12311-010-0168-7] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
Neurons of the deep cerebellar nuclei (DCN) play a critical role in defining the output of cerebellum in the course of encoding Purkinje cell inhibitory inputs. The earliest work performed with in vitro preparations established that DCN cells have the capacity to translate membrane hyperpolarizations into a rebound increase in firing frequency. The primary means of distinguishing between DCN neurons has been according to cell size and transmitter phenotype, but in some cases, differences in the firing properties of DCN cells maintained in vitro have been reported. In particular, it was shown that large diameter cells in the rat DCN exhibit two phenotypes of rebound discharge in vitro that may eventually help define their functional roles in cerebellar output. A transient burst and weak burst phenotype can be distinguished based on the frequency and pattern of rebound discharge immediately following a hyperpolarizing stimulus. Work to date indicates that the difference in excitability arises from at least the degree of activation of T-type Ca(2+) current during the immediate phase of rebound firing and Ca(2+)-dependent K(+) channels that underlie afterhyperpolarizations. Both phenotypes can be detected following stimulation of Purkinje cell inhibitory inputs under conditions that preserve resting membrane potential and natural ionic gradients. In this paper, we review the evidence supporting the existence of different rebound phenotypes in DCN cells and the ion channel expression patterns that underlie their generation.
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Affiliation(s)
- Reza Tadayonnejad
- Department of Cell Biology & Anatomy, Hotchkiss Brain Institute, University of Calgary, Calgary, Alberta Canada T2N 4N1
| | - Dustin Anderson
- Department of Cell Biology & Anatomy, Hotchkiss Brain Institute, University of Calgary, Calgary, Alberta Canada T2N 4N1
| | - Michael L. Molineux
- Department of Cell Biology & Anatomy, Hotchkiss Brain Institute, University of Calgary, Calgary, Alberta Canada T2N 4N1
| | - W. Hamish Mehaffey
- Department of Cell Biology & Anatomy, Hotchkiss Brain Institute, University of Calgary, Calgary, Alberta Canada T2N 4N1
| | - Kusala Jayasuriya
- Department of Cell Biology & Anatomy, Hotchkiss Brain Institute, University of Calgary, Calgary, Alberta Canada T2N 4N1
| | - Ray W. Turner
- Department of Cell Biology & Anatomy, Hotchkiss Brain Institute, University of Calgary, Calgary, Alberta Canada T2N 4N1
- Hotchkiss Brain Institute, HRIC 1AA14, University of Calgary, 3330 Hospital Dr. N.W., Calgary, Alberta Canada T2N 4N1
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A small-conductance Ca2+-dependent K+ current regulates dopamine neuron activity: a combined approach of dynamic current clamping and intracellular imaging of calcium signals. Neuroreport 2010; 21:667-74. [PMID: 20508546 DOI: 10.1097/wnr.0b013e32833add56] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
To analyze the small-conductance calcium-dependent K current observed in dopaminergic neurons of the rat midbrain, we have developed a new dynamic current clamping method that incorporates recording of intracellular Ca levels. As reported earlier, blocking the small-conductance current with apamin shifted the firing modes of dopaminergic neurons and changed the firing rate and spike afterhyperpolarization. We modeled the kinetic properties of the current and assessed the model in a real-time computational system. Here, we show that the spike afterhyperpolarization is regulated by the small-conductance current, an effect that is observed in dopaminergic neurons. Thus, this current can effectively shape the autonomous firing patterns of dopaminergic neurons.
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Dynamic clamp: alteration of response properties and creation of virtual realities in neurophysiology. J Neurosci 2010; 30:2407-13. [PMID: 20164323 DOI: 10.1523/jneurosci.5954-09.2010] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
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Vatanparast J, Janahmadi M. Contribution of apamin-sensitive SK channels to the firing precision but not to the slow afterhyperpolarization and spike frequency adaptation in snail neurons. Brain Res 2008; 1255:57-66. [PMID: 19100724 DOI: 10.1016/j.brainres.2008.12.003] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2008] [Revised: 12/01/2008] [Accepted: 12/02/2008] [Indexed: 10/21/2022]
Abstract
Apamin-sensitive small conductance Ca(2+)-dependent K(+)(SK) channels are generally accepted as responsible for the medium afterhyperpolarization (mAHP) after single or train of action potentials. Here, we examined the functional involvement of these channels in the firing precision, post train AHP and spike frequency adaptation (SFA) in neurons of snail Caucasotachea atrolabiata. Apamin, a selective SK channel antagonist, reduced the duration of single-spike AHP and disrupted the spontaneous rhythmic activity. High frequency trains of evoked action potentials showed a time-dependent decrease in the action potential discharge rate (spike frequency adaptation) and followed by a prominent post stimulus inhibitory period (PSIP) as a marker of slow AHP (sAHP). Neither sAHP nor SFA was attenuated by apamin, suggesting that apamin-sensitive SK channels can strongly affect the rhythmicity, but are probably not involved in the SFA and sAHP. Nifedipine, antagonist of L-type Ca(2+) channels, decreased the firing frequency and neuronal rhythmicity. When PSIP was normalized to the background interspike interval, a suppressing effect of nifedipine on PSIP was also observed. Intracellular iontophoretic injection of BAPTA, a potent Ca(2+) chelator, dramatically suppressed PSIP that confirms the intracellular Ca(2+) dependence of the sAHP, but had no discernable effect on the SFA. During train-evoked activity a reduction in the action potential overshoot and maximum depolarization rate was also observed, along with a decrease in the firing frequency, while the action potential threshold increased, which indicated that Na(+) channels, rather than Ca(2+)-dependent K(+) channels, are involved in the SFA.
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Affiliation(s)
- Jafar Vatanparast
- Department of Biology, College of Sciences, Shiraz University, Adabiat Intersection, Shiraz 71454, Iran.
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