1
|
González-Tapia D, Vázquez-Hernández N, Urmeneta-Ortiz F, Navidad-Hernandez N, Lazo-Yepez M, Tejeda-Martínez A, Flores-Soto M, González-Burgos I. 3-Acetylpyridine-induced ataxic-like motor impairments are associated with plastic changes in the Purkinje cells of the rat cerebellum. Neurologia 2024; 39:408-416. [PMID: 38830720 DOI: 10.1016/j.nrleng.2021.09.015] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2021] [Accepted: 09/18/2021] [Indexed: 06/05/2024] Open
Abstract
Ataxias are characterized by aberrant movement patterns closely related to cerebellar dysfunction. Purkinje cell axons are the sole outputs from the cerebellar cortex, and dysfunctional activity of Purkinje cells has been associated with ataxic movements. However, the synaptic characteristics of Purkinje cells in cases of ataxia are not yet well understood. The nicotinamide antagonist 3-acethylpyridine (3-AP) selectively destroys inferior olivary nucleus neurons so it is widely used to induce cerebellar ataxia. Five days after 3-AP treatment (65mg/kg) in adult male Sprague-Dawley rats, motor incoordination was revealed through BBB and Rotarod testing. In addition, in Purkinje cells from lobules V-VII of the cerebellar vermis studied by the Golgi method, the density of dendritic spines decreased, especially the thin and mushroom types. Western blot analysis showed a decrease in AMPA and PSD-95 content with an increase of the α-catenin protein, while GAD-67 and synaptophysin were unchanged. Findings suggest a limited capacity of Purkinje cells to acquire and consolidate afferent excitatory inputs and an aberrant, rigid profile in the movement-related output patterns of Purkinje neurons that likely contributes to the motor-related impairments characteristic of cerebellar ataxias.
Collapse
Affiliation(s)
- D González-Tapia
- Centro Universitario de Tlajomulco, Universidad de Guadalajara, Tlajomulco de Zúñiga, Jal., Mexico
| | - N Vázquez-Hernández
- División de Neurociencias, Centro de Investigación Biomédica de Occidente, IMSS, Guadalajara, Jal., Mexico
| | - F Urmeneta-Ortiz
- División de Neurociencias, Centro de Investigación Biomédica de Occidente, IMSS, Guadalajara, Jal., Mexico
| | - N Navidad-Hernandez
- Universidad Politécnica de la Zona Metropolitana de Guadalajara, Tlajomulco de Zúñiga, Jal., Mexico
| | - M Lazo-Yepez
- Universidad Politécnica de la Zona Metropolitana de Guadalajara, Tlajomulco de Zúñiga, Jal., Mexico
| | - A Tejeda-Martínez
- División de Neurociencias, Centro de Investigación Biomédica de Occidente, IMSS, Guadalajara, Jal., Mexico
| | - M Flores-Soto
- División de Neurociencias, Centro de Investigación Biomédica de Occidente, IMSS, Guadalajara, Jal., Mexico
| | - I González-Burgos
- División de Neurociencias, Centro de Investigación Biomédica de Occidente, IMSS, Guadalajara, Jal., Mexico.
| |
Collapse
|
2
|
González-Tapia D, Vázquez-Hernández N, Urmeneta-Ortiz F, Navidad-Hernandez N, Lazo-Yepez M, Tejeda-Martínez A, Flores-Soto M, González-Burgos I. 3-Acetylpyridine-induced ataxic-like motor impairments are associated with plastic changes in the Purkinje cells of the rat cerebellum. Neurologia 2021. [DOI: 10.1016/j.nrl.2021.09.005] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
|
3
|
Barmack NH, Pettorossi VE. Adaptive Balance in Posterior Cerebellum. Front Neurol 2021; 12:635259. [PMID: 33767662 PMCID: PMC7985352 DOI: 10.3389/fneur.2021.635259] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2020] [Accepted: 02/16/2021] [Indexed: 11/26/2022] Open
Abstract
Vestibular and optokinetic space is represented in three-dimensions in vermal lobules IX-X (uvula, nodulus) and hemisphere lobule X (flocculus) of the cerebellum. Vermal lobules IX-X encodes gravity and head movement using the utricular otolith and the two vertical semicircular canals. Hemispheric lobule X encodes self-motion using optokinetic feedback about the three axes of the semicircular canals. Vestibular and visual adaptation of this circuitry is needed to maintain balance during perturbations of self-induced motion. Vestibular and optokinetic (self-motion detection) stimulation is encoded by cerebellar climbing and mossy fibers. These two afferent pathways excite the discharge of Purkinje cells directly. Climbing fibers preferentially decrease the discharge of Purkinje cells by exciting stellate cell inhibitory interneurons. We describe instances adaptive balance at a behavioral level in which prolonged vestibular or optokinetic stimulation evokes reflexive eye movements that persist when the stimulation that initially evoked them stops. Adaptation to prolonged optokinetic stimulation also can be detected at cellular and subcellular levels. The transcription and expression of a neuropeptide, corticotropin releasing factor (CRF), is influenced by optokinetically-evoked olivary discharge and may contribute to optokinetic adaptation. The transcription and expression of microRNAs in floccular Purkinje cells evoked by long-term optokinetic stimulation may provide one of the subcellular mechanisms by which the membrane insertion of the GABAA receptors is regulated. The neurosteroids, estradiol (E2) and dihydrotestosterone (DHT), influence adaptation of vestibular nuclear neurons to electrically-induced potentiation and depression. In each section of this review, we discuss how adaptive changes in the vestibular and optokinetic subsystems of lobule X, inferior olivary nuclei and vestibular nuclei may contribute to the control of balance.
Collapse
Affiliation(s)
- Neal H. Barmack
- Department of Physiology & Pharmacology, Oregon Health & Science University, Portland, OR, United States
| | - Vito Enrico Pettorossi
- Section of Human Physiology and Biochemistry, Department of Experimental Medicine, University of Perugia, Perugia, Italy
| |
Collapse
|
4
|
Luck B, Engevik MA, Ganesh BP, Lackey EP, Lin T, Balderas M, Major A, Runge J, Luna RA, Sillitoe RV, Versalovic J. Bifidobacteria shape host neural circuits during postnatal development by promoting synapse formation and microglial function. Sci Rep 2020; 10:7737. [PMID: 32385412 PMCID: PMC7210968 DOI: 10.1038/s41598-020-64173-3] [Citation(s) in RCA: 60] [Impact Index Per Article: 15.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2019] [Accepted: 04/12/2020] [Indexed: 12/17/2022] Open
Abstract
We hypothesized that early-life gut microbiota support the functional organization of neural circuitry in the brain via regulation of synaptic gene expression and modulation of microglial functionality. Germ-free mice were colonized as neonates with either a simplified human infant microbiota consortium consisting of four Bifidobacterium species, or with a complex, conventional murine microbiota. We examined the cerebellum, cortex, and hippocampus of both groups of colonized mice in addition to germ-free control mice. At postnatal day 4 (P4), conventionalized mice and Bifidobacterium-colonized mice exhibited decreased expression of synapse-promoting genes and increased markers indicative of reactive microglia in the cerebellum, cortex and hippocampus relative to germ-free mice. By P20, both conventional and Bifidobacterium-treated mice exhibited normal synaptic density and neuronal activity as measured by density of VGLUT2+ puncta and Purkinje cell firing rate respectively, in contrast to the increased synaptic density and decreased firing rate observed in germ-free mice. The conclusions from this study further reveal how bifidobacteria participate in establishing functional neural circuits. Collectively, these data indicate that neonatal microbial colonization of the gut elicits concomitant effects on the host CNS, which promote the homeostatic developmental balance of neural connections during the postnatal time period.
Collapse
Affiliation(s)
- Berkley Luck
- Department of Pathology, Texas Children's Hospital, Houston, Texas, United States of America
- Department of Pathology & Immunology, Baylor College of Medicine, Houston, Texas, United States of America
- Integrative Molecular and Biomedical Sciences (IMBS), Baylor College of Medicine, Houston, Texas, United States of America
| | - Melinda A Engevik
- Department of Pathology, Texas Children's Hospital, Houston, Texas, United States of America.
- Department of Pathology & Immunology, Baylor College of Medicine, Houston, Texas, United States of America.
| | - Bhanu Priya Ganesh
- Department of Neurology, University of Texas Health Science Center, Houston, Texas, United States of America
| | - Elizabeth P Lackey
- Department of Pathology & Immunology, Baylor College of Medicine, Houston, Texas, United States of America
- Department of Neuroscience, Baylor College of Medicine, Houston, Texas, United States of America
| | - Tao Lin
- Department of Pathology, Texas Children's Hospital, Houston, Texas, United States of America
- Department of Pathology & Immunology, Baylor College of Medicine, Houston, Texas, United States of America
| | - Miriam Balderas
- Department of Pathology & Immunology, Baylor College of Medicine, Houston, Texas, United States of America
- Texas Children's Microbiome Center, Texas Children's Hospital, Houston, Texas, United States of America
| | - Angela Major
- Department of Pathology & Immunology, Baylor College of Medicine, Houston, Texas, United States of America
| | - Jessica Runge
- Department of Pathology & Immunology, Baylor College of Medicine, Houston, Texas, United States of America
- Program in Developmental Biology, Baylor College of Medicine, Houston, Texas, United States of America
| | - Ruth Ann Luna
- Department of Pathology & Immunology, Baylor College of Medicine, Houston, Texas, United States of America
- Program in Developmental Biology, Baylor College of Medicine, Houston, Texas, United States of America
| | - Roy V Sillitoe
- Department of Pathology, Texas Children's Hospital, Houston, Texas, United States of America
- Department of Pathology & Immunology, Baylor College of Medicine, Houston, Texas, United States of America
- Department of Neuroscience, Baylor College of Medicine, Houston, Texas, United States of America
- Program in Developmental Biology, Baylor College of Medicine, Houston, Texas, United States of America
| | - James Versalovic
- Department of Pathology, Texas Children's Hospital, Houston, Texas, United States of America
- Department of Pathology & Immunology, Baylor College of Medicine, Houston, Texas, United States of America
- Texas Children's Microbiome Center, Texas Children's Hospital, Houston, Texas, United States of America
| |
Collapse
|
5
|
Rasmussen A. Graded error signals in eyeblink conditioning. Neurobiol Learn Mem 2020; 170:107023. [DOI: 10.1016/j.nlm.2019.04.011] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2019] [Revised: 04/15/2019] [Accepted: 04/23/2019] [Indexed: 01/06/2023]
|
6
|
Luque NR, Naveros F, Carrillo RR, Ros E, Arleo A. Spike burst-pause dynamics of Purkinje cells regulate sensorimotor adaptation. PLoS Comput Biol 2019; 15:e1006298. [PMID: 30860991 PMCID: PMC6430425 DOI: 10.1371/journal.pcbi.1006298] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2018] [Revised: 03/22/2019] [Accepted: 01/08/2019] [Indexed: 11/25/2022] Open
Abstract
Cerebellar Purkinje cells mediate accurate eye movement coordination. However, it remains unclear how oculomotor adaptation depends on the interplay between the characteristic Purkinje cell response patterns, namely tonic, bursting, and spike pauses. Here, a spiking cerebellar model assesses the role of Purkinje cell firing patterns in vestibular ocular reflex (VOR) adaptation. The model captures the cerebellar microcircuit properties and it incorporates spike-based synaptic plasticity at multiple cerebellar sites. A detailed Purkinje cell model reproduces the three spike-firing patterns that are shown to regulate the cerebellar output. Our results suggest that pauses following Purkinje complex spikes (bursts) encode transient disinhibition of target medial vestibular nuclei, critically gating the vestibular signals conveyed by mossy fibres. This gating mechanism accounts for early and coarse VOR acquisition, prior to the late reflex consolidation. In addition, properly timed and sized Purkinje cell bursts allow the ratio between long-term depression and potentiation (LTD/LTP) to be finely shaped at mossy fibre-medial vestibular nuclei synapses, which optimises VOR consolidation. Tonic Purkinje cell firing maintains the consolidated VOR through time. Importantly, pauses are crucial to facilitate VOR phase-reversal learning, by reshaping previously learnt synaptic weight distributions. Altogether, these results predict that Purkinje spike burst-pause dynamics are instrumental to VOR learning and reversal adaptation. Cerebellar Purkinje cells regulate accurate eye movement coordination. However, it remains unclear how cerebellar-dependent oculomotor adaptation depends on the interplay between Purkinje cell characteristic response patterns: tonic, high frequency bursting, and post-complex spike pauses. We explore the role of Purkinje spike burst-pause dynamics in VOR adaptation. A biophysical model of Purkinje cell is at the core of a spiking network model, which captures the cerebellar microcircuit properties and incorporates spike-based synaptic plasticity mechanisms at different cerebellar sites. We show that Purkinje spike burst-pause dynamics are critical for (1) gating the vestibular-motor response association during VOR acquisition; (2) mediating the LTD/LTP balance for VOR consolidation; (3) reshaping synaptic efficacy distributions for VOR phase-reversal adaptation; (4) explaining the reversal VOR gain discontinuities during sleeping.
Collapse
Affiliation(s)
- Niceto R. Luque
- Sorbonne Université, INSERM, CNRS, Institut de la Vision, Paris, France
- * E-mail: (NRL); (AA)
| | - Francisco Naveros
- Department of Computer Architecture and Technology, CITIC-University of Granada, Granada, Spain
| | - Richard R. Carrillo
- Department of Computer Architecture and Technology, CITIC-University of Granada, Granada, Spain
| | - Eduardo Ros
- Department of Computer Architecture and Technology, CITIC-University of Granada, Granada, Spain
| | - Angelo Arleo
- Sorbonne Université, INSERM, CNRS, Institut de la Vision, Paris, France
- * E-mail: (NRL); (AA)
| |
Collapse
|
7
|
Abstract
The climbing fiber-Purkinje cell circuit is one of the most powerful and highly conserved in the central nervous system. Climbing fibers exert a powerful excitatory action that results in a complex spike in Purkinje cells and normal functioning of the cerebellum depends on the integrity of climbing fiber-Purkinje cell synapse. Over the last 50 years, multiple hypotheses have been put forward on the role of the climbing fibers and complex spikes in cerebellar information processing and motor control. Central to these theories is the nature of the interaction between the low-frequency complex spike discharge and the high-frequency simple spike firing of Purkinje cells. This review examines the major hypotheses surrounding the action of the climbing fiber-Purkinje cell projection, discussing both supporting and conflicting findings. The review describes newer findings establishing that climbing fibers and complex spikes provide predictive signals about movement parameters and that climbing fiber input controls the encoding of behavioral information in the simple spike firing of Purkinje cells. Finally, we propose the dynamic encoding hypothesis for complex spike function that strives to integrate established and newer findings.
Collapse
Affiliation(s)
- Martha L Streng
- Department of Neuroscience, University of Minnesota, Lions Research Building, Room 421, 2001 Sixth Street S.E, Minneapolis, MN, 55455, USA
| | - Laurentiu S Popa
- Department of Neuroscience, University of Minnesota, Lions Research Building, Room 421, 2001 Sixth Street S.E, Minneapolis, MN, 55455, USA
| | - Timothy J Ebner
- Department of Neuroscience, University of Minnesota, Lions Research Building, Room 421, 2001 Sixth Street S.E, Minneapolis, MN, 55455, USA.
| |
Collapse
|
8
|
Ransdell JL, Nerbonne JM. Voltage-gated sodium currents in cerebellar Purkinje neurons: functional and molecular diversity. Cell Mol Life Sci 2018; 75:3495-3505. [PMID: 29982847 PMCID: PMC6123253 DOI: 10.1007/s00018-018-2868-y] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2017] [Revised: 06/28/2018] [Accepted: 07/03/2018] [Indexed: 01/09/2023]
Abstract
Purkinje neurons, the sole output of the cerebellar cortex, deliver GABA-mediated inhibition to the deep cerebellar nuclei. To subserve this critical function, Purkinje neurons fire repetitively, and at high frequencies, features that have been linked to the unique properties of the voltage-gated sodium (Nav) channels expressed. In addition to the rapidly activating and inactivating, or transient, component of the Nav current (INaT) present in many types of central and peripheral neurons, Purkinje neurons, also expresses persistent (INaP) and resurgent (INaR) Nav currents. Considerable progress has been made in detailing the biophysical properties and identifying the molecular determinants of these discrete Nav current components, as well as defining their roles in the regulation of Purkinje neuron excitability. Here, we review this important work and highlight the remaining questions about the molecular mechanisms controlling the expression and the functioning of Nav currents in Purkinje neurons. We also discuss the impact of the dynamic regulation of Nav currents on the functioning of individual Purkinje neurons and cerebellar circuits.
Collapse
Affiliation(s)
- Joseph L Ransdell
- Department of Developmental Biology, Washington University School of Medicine, St. Louis, MO, 63110, USA
- Department of Medicine, Washington University School of Medicine, Box 8086, 660 South Euclid Avenue, St. Louis, MO, 63110, USA
| | - Jeanne M Nerbonne
- Department of Developmental Biology, Washington University School of Medicine, St. Louis, MO, 63110, USA.
- Department of Medicine, Washington University School of Medicine, Box 8086, 660 South Euclid Avenue, St. Louis, MO, 63110, USA.
| |
Collapse
|
9
|
Jin XH, Wang HW, Zhang XY, Chu CP, Jin YZ, Cui SB, Qiu DL. Mechanisms of Spontaneous Climbing Fiber Discharge-Evoked Pauses and Output Modulation of Cerebellar Purkinje Cell in Mice. Front Cell Neurosci 2017; 11:247. [PMID: 28878623 PMCID: PMC5572406 DOI: 10.3389/fncel.2017.00247] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2017] [Accepted: 08/04/2017] [Indexed: 11/16/2022] Open
Abstract
Climbing fiber (CF) afferents modulate the frequency and patterns of cerebellar Purkinje cell (PC) simple spike (SS) activity, but its mechanism is unclear. In the present study, we investigated the mechanisms of spontaneous CF discharge-evoked pauses and the output modulation of cerebellar PCs in urethane-anesthetized mice using in vivo whole-cell recording techniques and pharmacological methods. Under voltage-clamp recording conditions, spontaneous CF discharge evoked strong inward currents followed by small conductance calcium-activated potassium (SK) channels that mediated outward currents. The application of a GABAA receptor antagonist did not significantly alter the spontaneous SS firing rate, although an AMPA receptor blocker abolished complex spike (CS) activity and induced significantly increased SS firing rates and a decreased coefficient of variation (CV) SS value. Either removal of extracellular calcium or chelated intracellular calcium induced a decrease in amplitude of CS-evoked after-hyperpolarization (AHP) potential accompanied by an increase in SS firing rate. In addition, blocking SK channels activity with a selective antagonist, dequalinium decreased the amplitude of AHP and increased SS firing rate. Moreover, we found repeated CF stimulation at 1 Hz induced a significant decrease in the spontaneous firing rate of SS, and accompanied with an increase in CV of SS in cerebellar slices, which was also abolished by dequalinium. These results indicated that the spontaneous CF discharge contributed to decreasing SS firing rate via activation of SK channels in the cerebellar PCs in vivo in mice.
Collapse
Affiliation(s)
- Xian-Hua Jin
- Key Laboratory of Cellular Function and Pharmacology of Jilin Province, Yanbian UniversityYanji, China.,Department of Neurology, Affiliated Hospital of Yanbian UniversityYanji, China
| | - Hong-Wei Wang
- Key Laboratory of Cellular Function and Pharmacology of Jilin Province, Yanbian UniversityYanji, China.,Department of Endocrinology and Metabolism, Affiliated Zhongshan Hospital of Dalian UniversityDalian, China
| | - Xin-Yuan Zhang
- Key Laboratory of Cellular Function and Pharmacology of Jilin Province, Yanbian UniversityYanji, China.,Department of Physiology and Pathophysiology, College of Medicine, Yanbian UniversityYanji, China
| | - Chun-Ping Chu
- Key Laboratory of Cellular Function and Pharmacology of Jilin Province, Yanbian UniversityYanji, China
| | - Yuan-Zhe Jin
- Key Laboratory of Cellular Function and Pharmacology of Jilin Province, Yanbian UniversityYanji, China.,Department of Physiology and Pathophysiology, College of Medicine, Yanbian UniversityYanji, China
| | - Song-Biao Cui
- Department of Neurology, Affiliated Hospital of Yanbian UniversityYanji, China
| | - De-Lai Qiu
- Key Laboratory of Cellular Function and Pharmacology of Jilin Province, Yanbian UniversityYanji, China.,Department of Physiology and Pathophysiology, College of Medicine, Yanbian UniversityYanji, China
| |
Collapse
|
10
|
Climbing Fibers Control Purkinje Cell Representations of Behavior. J Neurosci 2017; 37:1997-2009. [PMID: 28077726 DOI: 10.1523/jneurosci.3163-16.2017] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2016] [Revised: 12/13/2016] [Accepted: 01/06/2017] [Indexed: 11/21/2022] Open
Abstract
A crucial issue in understanding cerebellar function is the interaction between simple spike (SS) and complex spike (CS) discharge, the two fundamentally different activity modalities of Purkinje cells. Although several hypotheses have provided insights into the interaction, none fully explains or is completely consistent with the spectrum of experimental observations. Here, we show that during a pseudo-random manual tracking task in the monkey (Macaca mulatta), climbing fiber discharge dynamically controls the information present in the SS firing, triggering robust and rapid changes in the SS encoding of motor signals in 67% of Purkinje cells. The changes in encoding, tightly coupled to CS occurrences, consist of either increases or decreases in the SS sensitivity to kinematics or position errors and are not due to differences in SS firing rates or variability. Nor are the changes in sensitivity due to CS rhythmicity. In addition, the CS-coupled changes in encoding are not evoked by changes in kinematics or position errors. Instead, CS discharge most often leads alterations in behavior. Increases in SS encoding of a kinematic parameter are associated with larger changes in that parameter than are decreases in SS encoding. Increases in SS encoding of position error are followed by and scale with decreases in error. The results suggest a novel function of CSs, in which climbing fiber input dynamically controls the state of Purkinje cell SS encoding in advance of changes in behavior.SIGNIFICANCE STATEMENT Purkinje cells, the sole output of the cerebellar cortex, manifest two fundamentally different activity modalities, complex spike (CS) discharge and simple spike (SS) firing. Elucidating cerebellar function will require an understanding of the interactions, both short- and long-term, between CS and SS firing. This study shows that CSs dynamically control the information encoded in a Purkinje cell's SS activity by rapidly increasing or decreasing the SS sensitivity to kinematics and/or performance errors independent of firing rate. In many cases, the CS-coupled shift in SS encoding leads a change in behavior. These novel findings on the interaction between CS and SS firing provide for a new hypothesis in which climbing fiber input adjusts the encoding of SS information in advance of a change in behavior.
Collapse
|
11
|
Kuo SH, Lin CY, Wang J, Sims PA, Pan MK, Liou JY, Lee D, Tate WJ, Kelly GC, Louis ED, Faust PL. Climbing fiber-Purkinje cell synaptic pathology in tremor and cerebellar degenerative diseases. Acta Neuropathol 2017; 133:121-138. [PMID: 27704282 DOI: 10.1007/s00401-016-1626-1] [Citation(s) in RCA: 61] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2016] [Revised: 09/26/2016] [Accepted: 09/28/2016] [Indexed: 12/19/2022]
Abstract
Changes in climbing fiber-Purkinje cell (CF-PC) synaptic connections have been found in the essential tremor (ET) cerebellum, and these changes are correlated with tremor severity. Whether these postmortem changes are specific to ET remains to be investigated. We assessed CF-PC synaptic pathology in the postmortem cerebellum across a range of degenerative movement disorders [10 Parkinson's disease (PD) cases, 10 multiple system atrophy (MSA) cases, 10 spinocerebellar ataxia type 1 (SCA1) cases, and 20 ET cases] and 25 controls. We observed differences in terms of CF pathological features across these disorders. Specifically, PD cases and ET cases both had more CFs extending into the parallel fiber (PF) territory, but ET cases had more complex branching and increased length of CFs in the PF territory along with decreased CF synaptic density compared to PD cases. MSA cases and SCA1 cases had the most severely reduced CF synaptic density and a marked paucity of CFs extending into the PF territory. Furthermore, CFs in a subset of MSA cases formed collateral branches parallel to the PC layer, a feature not seen in other diagnostic groups. Using unsupervised cluster analysis, the cases and controls could all be categorized into four clusters based on the CF pathology and features of PC pathology, including counts of PCs and their axonal torpedoes. ET cases and PD cases co-segregated into two clusters, whereas SCA1 cases and MSA cases formed another cluster, separate from the control cluster. Interestingly, the presence of resting tremor seemed to be the clinical feature that separated the cases into the two ET-PD clusters. In conclusion, our study demonstrates that these degenerative movement disorders seem to differ with respect to the pattern of CF synaptic pathology they exhibit. It remains to be determined how these differences contribute to the clinical presentations of these diseases.
Collapse
|
12
|
Cheron G, Márquez-Ruiz J, Dan B. Oscillations, Timing, Plasticity, and Learning in the Cerebellum. THE CEREBELLUM 2016; 15:122-38. [PMID: 25808751 DOI: 10.1007/s12311-015-0665-9] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
Abstract
The highly stereotyped, crystal-like architecture of the cerebellum has long served as a basis for hypotheses with regard to the function(s) that it subserves. Historically, most clinical observations and experimental work have focused on the involvement of the cerebellum in motor control, with particular emphasis on coordination and learning. Two main models have been suggested to account for cerebellar functioning. According to Llinás's theory, the cerebellum acts as a control machine that uses the rhythmic activity of the inferior olive to synchronize Purkinje cell populations for fine-tuning of coordination. In contrast, the Ito-Marr-Albus theory views the cerebellum as a motor learning machine that heuristically refines synaptic weights of the Purkinje cell based on error signals coming from the inferior olive. Here, we review the role of timing of neuronal events, oscillatory behavior, and synaptic and non-synaptic influences in functional plasticity that can be recorded in awake animals in various physiological and pathological models in a perspective that also includes non-motor aspects of cerebellar function. We discuss organizational levels from genes through intracellular signaling, synaptic network to system and behavior, as well as processes from signal production and processing to memory, delegation, and actual learning. We suggest an integrative concept for control and learning based on articulated oscillation templates.
Collapse
Affiliation(s)
- G Cheron
- Laboratory of Electrophysiology, Université de Mons, 7000, Mons, Belgium. .,Laboratory of Neurophysiology and Movement Biomechanics, ULB Neuroscience Institute, Université Libre de Bruxelles, CP640, 1070, Brussels, Belgium.
| | - J Márquez-Ruiz
- División de Neurociencias, Universidad Pablo de Olavide, 41013, Seville, Spain
| | - B Dan
- Laboratory of Neurophysiology and Movement Biomechanics, ULB Neuroscience Institute, Université Libre de Bruxelles, CP640, 1070, Brussels, Belgium.,Department of Neurology, Hôpital Universitaire des Enfants Reine Fabiola, Université Libre de Bruxelles, 1020, Brussels, Belgium
| |
Collapse
|
13
|
Barmack NH, Yakhnitsa V. Climbing fibers mediate vestibular modulation of both "complex" and "simple spikes" in Purkinje cells. THE CEREBELLUM 2016; 14:597-612. [PMID: 26424151 DOI: 10.1007/s12311-015-0725-1] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Climbing and mossy fibers comprise two distinct afferent paths to the cerebellum. Climbing fibers directly evoke a large multispiked action potential in Purkinje cells termed a "complex spike" (CS). By logical exclusion, the other class of Purkinje cell action potential, termed "simple spike" (SS), has often been attributed to activity conveyed by mossy fibers and relayed to Purkinje cells through granule cells. Here, we investigate the relative importance of climbing and mossy fiber pathways in modulating neuronal activity by recording extracellularly from Purkinje cells, as well as from mossy fiber terminals and interneurons in folia 8-10. Sinusoidal roll-tilt vestibular stimulation vigorously modulates the discharge of climbing and mossy fiber afferents, Purkinje cells, and interneurons in folia 9-10 in anesthetized mice. Roll-tilt onto the side ipsilateral to the recording site increases the discharge of both climbing fibers (CSs) and mossy fibers. However, the discharges of SSs decrease during ipsilateral roll-tilt. Unilateral microlesions of the beta nucleus (β-nucleus) of the inferior olive blocks vestibular modulation of both CSs and SSs in contralateral Purkinje cells. The blockage of SSs occurs even though primary and secondary vestibular mossy fibers remain intact. When mossy fiber afferents are damaged by a unilateral labyrinthectomy (UL), vestibular modulation of SSs in Purkinje cells ipsilateral to the UL remains intact. Two inhibitory interneurons, Golgi and stellate cells, could potentially contribute to climbing fiber-induced modulation of SSs. However, during sinusoidal roll-tilt, only stellate cells discharge appropriately out of phase with the discharge of SSs. Golgi cells discharge in phase with SSs. When the vestibularly modulated discharge is blocked by a microlesion of the inferior olive, the modulated discharge of CSs and SSs is also blocked. When the vestibular mossy fiber pathway is destroyed, vestibular modulation of ipsilateral CSs and SSs persists. We conclude that climbing fibers are primarily responsible for the vestibularly modulated discharge of both CSs and SSs. Modulation of the discharge of SSs is likely caused by climbing fiber-evoked stellate cell inhibition.
Collapse
Affiliation(s)
- N H Barmack
- Department of Physiology and Pharmacology, Oregon Health & Science University, 3181 SW Sam Jackson Park Road, Portland, OR, 97239, USA.
| | - V Yakhnitsa
- Department of Physiology and Pharmacology, Oregon Health & Science University, 3181 SW Sam Jackson Park Road, Portland, OR, 97239, USA
| |
Collapse
|
14
|
Burroughs A, Wise AK, Xiao J, Houghton C, Tang T, Suh CY, Lang EJ, Apps R, Cerminara NL. The dynamic relationship between cerebellar Purkinje cell simple spikes and the spikelet number of complex spikes. J Physiol 2016; 595:283-299. [PMID: 27265808 PMCID: PMC5199739 DOI: 10.1113/jp272259] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2016] [Accepted: 05/27/2016] [Indexed: 11/08/2022] Open
Abstract
Key points Purkinje cells are the sole output of the cerebellar cortex and fire two distinct types of action potential: simple spikes and complex spikes. Previous studies have mainly considered complex spikes as unitary events, even though the waveform is composed of varying numbers of spikelets. The extent to which differences in spikelet number affect simple spike activity (and vice versa) remains unclear. We found that complex spikes with greater numbers of spikelets are preceded by higher simple spike firing rates but, following the complex spike, simple spikes are reduced in a manner that is graded with spikelet number. This dynamic interaction has important implications for cerebellar information processing, and suggests that complex spike spikelet number may maintain Purkinje cells within their operational range.
Abstract Purkinje cells are central to cerebellar function because they form the sole output of the cerebellar cortex. They exhibit two distinct types of action potential: simple spikes and complex spikes. It is widely accepted that interaction between these two types of impulse is central to cerebellar cortical information processing. Previous investigations of the interactions between simple spikes and complex spikes have mainly considered complex spikes as unitary events. However, complex spikes are composed of an initial large spike followed by a number of secondary components, termed spikelets. The number of spikelets within individual complex spikes is highly variable and the extent to which differences in complex spike spikelet number affects simple spike activity (and vice versa) remains poorly understood. In anaesthetized adult rats, we have found that Purkinje cells recorded from the posterior lobe vermis and hemisphere have high simple spike firing frequencies that precede complex spikes with greater numbers of spikelets. This finding was also evident in a small sample of Purkinje cells recorded from the posterior lobe hemisphere in awake cats. In addition, complex spikes with a greater number of spikelets were associated with a subsequent reduction in simple spike firing rate. We therefore suggest that one important function of spikelets is the modulation of Purkinje cell simple spike firing frequency, which has implications for controlling cerebellar cortical output and motor learning. Purkinje cells are the sole output of the cerebellar cortex and fire two distinct types of action potential: simple spikes and complex spikes. Previous studies have mainly considered complex spikes as unitary events, even though the waveform is composed of varying numbers of spikelets. The extent to which differences in spikelet number affect simple spike activity (and vice versa) remains unclear. We found that complex spikes with greater numbers of spikelets are preceded by higher simple spike firing rates but, following the complex spike, simple spikes are reduced in a manner that is graded with spikelet number. This dynamic interaction has important implications for cerebellar information processing, and suggests that complex spike spikelet number may maintain Purkinje cells within their operational range.
Collapse
Affiliation(s)
- Amelia Burroughs
- School of Physiology, Pharmacology and Neuroscience, University of Bristol, Bristol, UK
| | - Andrew K Wise
- Bionics Institute, East Melbourne, Victoria, Australia
| | - Jianqiang Xiao
- Department of Neuroscience and Physiology, New York University School of Medicine, New York, NY, USA
| | - Conor Houghton
- Department of Computer Science, University of Bristol, Bristol, UK
| | - Tianyu Tang
- Department of Neuroscience and Physiology, New York University School of Medicine, New York, NY, USA
| | - Colleen Y Suh
- Department of Neuroscience and Physiology, New York University School of Medicine, New York, NY, USA
| | - Eric J Lang
- Department of Neuroscience and Physiology, New York University School of Medicine, New York, NY, USA
| | - Richard Apps
- School of Physiology, Pharmacology and Neuroscience, University of Bristol, Bristol, UK
| | - Nadia L Cerminara
- School of Physiology, Pharmacology and Neuroscience, University of Bristol, Bristol, UK
| |
Collapse
|
15
|
Liu H, Lan Y, Bing YH, Chu CP, Qiu DL. N-methyl-D-Aspartate Receptors Contribute to Complex Spike Signaling in Cerebellar Purkinje Cells: An In vivo Study in Mice. Front Cell Neurosci 2016; 10:172. [PMID: 27445699 PMCID: PMC4928496 DOI: 10.3389/fncel.2016.00172] [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: 05/31/2016] [Accepted: 06/16/2016] [Indexed: 11/13/2022] Open
Abstract
N-methyl-D-aspartate receptors (NMDARs) are post-synaptically expressed at climbing fiber-Purkinje cell (CF-PC) synapses in cerebellar cortex in adult mice and contributed to CF-PC synaptic transmission under in vitro conditions. In this study, we investigated the role of NMDARs at CF-PC synapses during the spontaneous complex spike (CS) activity in cerebellar cortex in urethane-anesthetized mice, by in vivo whole-cell recording technique and pharmacological methods. Under current-clamp conditions, cerebellar surface application of NMDA (50 μM) induced an increase in the CS-evoked pause of simple spike (SS) firing accompanied with a decrease in the SS firing rate. Under voltage-clamp conditions, application of NMDA enhanced the waveform of CS-evoked inward currents, which expressed increases in the area under curve (AUC) and spikelet number of spontaneous CS. NMDA increased the AUC of spontaneous CS in a concentration-dependent manner. The EC50 of NMDA for increasing AUC of spontaneous CS was 33.4 μM. Moreover, NMDA significantly increased the amplitude, half-width and decay time of CS-evoked after-hyperpolarization (AHP) currents. Blockade of NMDARs with D-(-)-2-amino-5-phosphonopentanoic acid (D-APV, 250 μM) decreased the AUC, spikelet number, and amplitude of AHP currents. In addition, the NMDA-induced enhancement of CS activity could not be observed after α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptors were blocked. The results indicated that NMDARs of CF-PC synapses contributed to the spontaneous CS activity by enhancing CS-evoked inward currents and AHP currents.
Collapse
Affiliation(s)
- Heng Liu
- Cellular Function Research Center, Yanbian UniversityYanji, China; Department of Physiology and Pathophysiology, College of Medicine, Yanbian UniversityYanji, China
| | - Yan Lan
- Cellular Function Research Center, Yanbian UniversityYanji, China; Department of Physiology and Pathophysiology, College of Medicine, Yanbian UniversityYanji, China
| | - Yan-Hua Bing
- Cellular Function Research Center, Yanbian UniversityYanji, China; Department of Physiology and Pathophysiology, College of Medicine, Yanbian UniversityYanji, China
| | - Chun-Ping Chu
- Cellular Function Research Center, Yanbian University Yanji, China
| | - De-Lai Qiu
- Cellular Function Research Center, Yanbian UniversityYanji, China; Department of Physiology and Pathophysiology, College of Medicine, Yanbian UniversityYanji, China; Key Laboratory of Natural Resource of the Changbai Mountain and Functional Molecular of the Ministry of Education, Yanbian UniversityYanji, China
| |
Collapse
|
16
|
Christophersen P, Wulff H. Pharmacological gating modulation of small- and intermediate-conductance Ca(2+)-activated K(+) channels (KCa2.x and KCa3.1). Channels (Austin) 2015. [PMID: 26217968 DOI: 10.1080/19336950.2015.1071748] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023] Open
Abstract
This short review discusses pharmacological modulation of the opening/closing properties (gating) of small- and intermediate-conductance Ca(2+)-activated K(+) channels (KCa2 and KCa3.1) with special focus on mechanisms-of-action, selectivity, binding sites, and therapeutic potentials. Despite KCa channel gating-modulation being a relatively novel field in drug discovery, efforts in this area have already revealed a surprising plethora of pharmacological sites-of-actions and channel subtype selectivity exerted by different chemical classes. The currently published positive modulators show that such molecules are potentially useful for the treatment of various neurodegenerative disorders such as ataxia, alcohol dependence, and epilepsy as well as hypertension. The negative KCa2 modulators are very effective agents for atrial fibrillation. The prediction is that further unraveling of the molecular details of gating pharmacology will allow for the design of even more potent and subtype selective KCa modulators entering into drug development for these indications.
Collapse
Affiliation(s)
| | - Heike Wulff
- b Department of Pharmacology ; University of California, Davis ; Davis , CA USA
| |
Collapse
|
17
|
Barmack NH, Qian Z, Yakhnitsa V. Long-term climbing fibre activity induces transcription of microRNAs in cerebellar Purkinje cells. Philos Trans R Soc Lond B Biol Sci 2015; 369:rstb.2013.0508. [PMID: 25135969 DOI: 10.1098/rstb.2013.0508] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Abstract
Synaptic activation of central neurons is often evoked by electrical stimulation leading to post-tetanic potentiation, long-term potentiation or long-term depression. Even a brief electrical tetanus can induce changes in as many as 100 proteins. Since climbing fibre activity is often associated with cerebellar behavioural plasticity, we used horizontal optokinetic stimulation (HOKS) to naturally increase synaptic input to floccular Purkinje cells in mice for hours, not minutes, and investigated how this activity influenced the transcription of microRNAs, small non-coding nucleotides that reduce transcripts of multiple, complementary mRNAs. A single microRNA can reduce the translation of as many as 30 proteins. HOKS evoked increases in 12 microRNA transcripts in floccular Purkinje cells. One of these microRNAs, miR335, increased 18-fold after 24 h of HOKS. After HOKS stopped, miR335 transcripts decayed with a time constant of approximately 2.5 h. HOKS evoked a 28-fold increase in pri-miR335 transcripts compared with an 18-fold increase in mature miR335 transcripts, confirming that climbing fibre-evoked increases in miR335 could be attributed to increases in transcription. We used three screens to identify potential mRNA targets for miR335 transcripts: (i) nucleotide complementarity, (ii) detection of increased mRNAs following microinjection of miR335 inhibitors into the cerebellum, and (iii) detection of decreased mRNAs following HOKS. Two genes, calbindin and 14-3-3-θ, passed these screens. Transfection of N2a cells with miR335 inhibitors or precursors inversely regulated 14-3-3-θ transcripts. Immunoprecipitation of 14-3-3-θ co-immunoprecipitated PKC-γ and GABAAγ2. Knockdown of either 14-3-3-θ or PKC-γ decreased the serine phosphorylation of GABAAγ2, suggesting that 14-3-3-θ and PKC-γ under the control of miR335 homeostatically regulate the phosphorylation and insertion of GABAAγ2 into the Purkinje cell post-synaptic membrane.
Collapse
Affiliation(s)
- Neal H Barmack
- Department of Physiology and Pharmacology, Oregon Health and Science University, 3181 SW Sam Jackson Park Road, Portland, OR 97239, USA
| | - Zuyuan Qian
- Department of Physiology and Pharmacology, Oregon Health and Science University, 3181 SW Sam Jackson Park Road, Portland, OR 97239, USA
| | - Vadim Yakhnitsa
- Department of Physiology and Pharmacology, Oregon Health and Science University, 3181 SW Sam Jackson Park Road, Portland, OR 97239, USA
| |
Collapse
|
18
|
Forrest MD. Simulation of alcohol action upon a detailed Purkinje neuron model and a simpler surrogate model that runs >400 times faster. BMC Neurosci 2015; 16:27. [PMID: 25928094 PMCID: PMC4417229 DOI: 10.1186/s12868-015-0162-6] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2014] [Accepted: 04/10/2015] [Indexed: 11/16/2022] Open
Abstract
BACKGROUND An approach to investigate brain function/dysfunction is to simulate neuron circuits on a computer. A problem, however, is that detailed neuron descriptions are computationally expensive and this handicaps the pursuit of realistic network investigations, where many neurons need to be simulated. RESULTS We confront this issue; we employ a novel reduction algorithm to produce a 2 compartment model of the cerebellar Purkinje neuron from a previously published, 1089 compartment model. It runs more than 400 times faster and retains the electrical behavior of the full model. So, it is more suitable for inclusion in large network models, where computational power is a limiting issue. We show the utility of this reduced model by demonstrating that it can replicate the full model's response to alcohol, which can in turn reproduce experimental recordings from Purkinje neurons following alcohol application. CONCLUSIONS We show that alcohol may modulate Purkinje neuron firing by an inhibition of their sodium-potassium pumps. We suggest that this action, upon cerebellar Purkinje neurons, is how alcohol ingestion can corrupt motor co-ordination. In this way, we relate events on the molecular scale to the level of behavior.
Collapse
Affiliation(s)
- Michael D Forrest
- Department of Computer Science, University of Warwick, Coventry, West Midlands, UK.
| |
Collapse
|
19
|
Forrest MD. Intracellular calcium dynamics permit a Purkinje neuron model to perform toggle and gain computations upon its inputs. Front Comput Neurosci 2014; 8:86. [PMID: 25191262 PMCID: PMC4138505 DOI: 10.3389/fncom.2014.00086] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2013] [Accepted: 07/17/2014] [Indexed: 01/29/2023] Open
Abstract
Without synaptic input, Purkinje neurons can spontaneously fire in a repeating trimodal pattern that consists of tonic spiking, bursting and quiescence. Climbing fiber input (CF) switches Purkinje neurons out of the trimodal firing pattern and toggles them between a tonic firing and a quiescent state, while setting the gain of their response to Parallel Fiber (PF) input. The basis to this transition is unclear. We investigate it using a biophysical Purkinje cell model under conditions of CF and PF input. The model can replicate these toggle and gain functions, dependent upon a novel account of intracellular calcium dynamics that we hypothesize to be applicable in real Purkinje cells.
Collapse
|
20
|
Alviña K, Sawtell NB. Sensory processing and corollary discharge effects in posterior caudal lobe Purkinje cells in a weakly electric mormyrid fish. J Neurophysiol 2014; 112:328-39. [PMID: 24790163 DOI: 10.1152/jn.00016.2014] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Although it has been suggested that the cerebellum functions to predict the sensory consequences of motor commands, how such predictions are implemented in cerebellar circuitry remains largely unknown. A detailed and relatively complete account of predictive mechanisms has emerged from studies of cerebellum-like sensory structures in fish, suggesting that comparisons of the cerebellum and cerebellum-like structures may be useful. Here we characterize electrophysiological response properties of Purkinje cells in a region of the cerebellum proper of weakly electric mormyrid fish, the posterior caudal lobe (LCp), which receives the same mossy fiber inputs and projects to the same target structures as the electrosensory lobe (ELL), a well-studied cerebellum-like structure. We describe patterns of simple spike and climbing fiber activation in LCp Purkinje cells in response to motor corollary discharge, electrosensory, and proprioceptive inputs and provide evidence for two functionally distinct Purkinje cell subtypes within LCp. Protocols that induce rapid associative plasticity in ELL fail to induce plasticity in LCp, suggesting differences in the adaptive functions of the two structures. Similarities and differences between LCp and ELL are discussed in light of these results.
Collapse
Affiliation(s)
- Karina Alviña
- Department of Neuroscience, Columbia University, New York, New York
| | | |
Collapse
|
21
|
Cheron G, Prigogine C, Cheron J, Márquez-Ruiz J, Traub RD, Dan B. Emergence of a 600-Hz buzz UP state Purkinje cell firing in alert mice. Neuroscience 2014; 263:15-26. [PMID: 24440752 DOI: 10.1016/j.neuroscience.2014.01.007] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2013] [Revised: 12/19/2013] [Accepted: 01/03/2014] [Indexed: 12/25/2022]
Abstract
Purkinje cell (PC) firing represents the sole output from the cerebellar cortex onto the deep cerebellar and vestibular nuclei. Here, we explored the different modes of PC firing in alert mice by extracellular recording. We confirm the existence of a tonic and/or bursting and quiescent modes corresponding to UP and DOWN state, respectively. We demonstrate the existence of a novel 600-Hz buzz UP state of firing characterized by simple spikes (SS) of very small amplitude. Climbing fiber (CF) input is able to switch the 600-Hz buzz to the DOWN state, as for the classical UP-to-DOWN state transition. Conversely, the CF input can initiate a typical SS pattern terminating into 600-Hz buzz. The 600-Hz buzz was transiently suppressed by whisker pad stimulation demonstrating that it remained responsive to peripheral input. It must not be mistaken for a DOWN state or the sign of PC inhibition. Complex spike (CS) frequency was increased during the 600-Hz buzz, indicating that this PC output actively contributes to the cerebello-olivary loop by triggering a disinhibition of the inferior olive. During the 600-Hz buzz, the first depolarizing component of the CS was reduced and the second depolarizing component was suppressed. Consistent with our experimental observations, using a 559-compartment single-PC model - in which PC UP state (of about -43mV) was obtained by the combined action of large tonic AMPA conductances and counterbalancing GABAergic inhibition - removal of this inhibition produced the 600-Hz buzz; the simulated buzz frequency decreased following an artificial CS.
Collapse
Affiliation(s)
- G Cheron
- Laboratory of Electrophysiology, Université de Mons, 7000 Mons, Belgium; Laboratory of Neurophysiology and Movement Biomechanics, CP601, ULB Neurosciences Institut, Université Libre de Bruxelles, 1070 Brussels, Belgium.
| | - C Prigogine
- Laboratory of Electrophysiology, Université de Mons, 7000 Mons, Belgium; Laboratory of Neurophysiology and Movement Biomechanics, CP601, ULB Neurosciences Institut, Université Libre de Bruxelles, 1070 Brussels, Belgium
| | - J Cheron
- Laboratory of Electrophysiology, Université de Mons, 7000 Mons, Belgium; Laboratory of Neurophysiology and Movement Biomechanics, CP601, ULB Neurosciences Institut, Université Libre de Bruxelles, 1070 Brussels, Belgium
| | - J Márquez-Ruiz
- División de Neurociencias, Universidad Pablo de Olavide, 41013 Sevilla, Spain
| | - R D Traub
- Department of Physical Sciences, IBM T.J. Watson Research Center, Yorktown Heights, NY 10598, USA; Department of Neurology, Columbia University, New York, NY 10032, USA
| | - B Dan
- Laboratory of Neurophysiology and Movement Biomechanics, CP601, ULB Neurosciences Institut, Université Libre de Bruxelles, 1070 Brussels, Belgium
| |
Collapse
|
22
|
Shabani M, Mahnam A, Sheibani V, Janahmadi M. Alterations in the Intrinsic Burst Activity of Purkinje Neurons in Offspring Maternally Exposed to the CB1 Cannabinoid Agonist WIN 55212-2. J Membr Biol 2013; 247:63-72. [DOI: 10.1007/s00232-013-9612-1] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2013] [Accepted: 10/25/2013] [Indexed: 11/28/2022]
|
23
|
Cheron G, Dan B, Márquez-Ruiz J. Translational approach to behavioral learning: lessons from cerebellar plasticity. Neural Plast 2013; 2013:853654. [PMID: 24319600 PMCID: PMC3844268 DOI: 10.1155/2013/853654] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2013] [Accepted: 09/18/2013] [Indexed: 11/17/2022] Open
Abstract
The role of cerebellar plasticity has been increasingly recognized in learning. The privileged relationship between the cerebellum and the inferior olive offers an ideal circuit for attempting to integrate the numerous evidences of neuronal plasticity into a translational perspective. The high learning capacity of the Purkinje cells specifically controlled by the climbing fiber represents a major element within the feed-forward and feedback loops of the cerebellar cortex. Reciprocally connected with the basal ganglia and multimodal cerebral domains, this cerebellar network may realize fundamental functions in a wide range of behaviors. This review will outline the current understanding of three main experimental paradigms largely used for revealing cerebellar functions in behavioral learning: (1) the vestibuloocular reflex and smooth pursuit control, (2) the eyeblink conditioning, and (3) the sensory envelope plasticity. For each of these experimental conditions, we have critically revisited the chain of causalities linking together neural circuits, neural signals, and plasticity mechanisms, giving preference to behaving or alert animal physiology. Namely, recent experimental approaches mixing neural units and local field potentials recordings have demonstrated a spike timing dependent plasticity by which the cerebellum remains at a strategic crossroad for deciphering fundamental and translational mechanisms from cellular to network levels.
Collapse
Affiliation(s)
- Guy Cheron
- Laboratory of Electrophysiology, Université de Mons, 7000 Mons, Belgium
- Laboratory of Neurophysiology and Movement Biomechanics, CP640, ULB Neuroscience Institut, Université Libre de Bruxelles, 1070 Brussels, Belgium
| | - Bernard Dan
- Laboratory of Neurophysiology and Movement Biomechanics, CP640, ULB Neuroscience Institut, Université Libre de Bruxelles, 1070 Brussels, Belgium
- Department of Neurology, Hôpital Universitaire des Enfants Reine Fabiola, Université Libre de Bruxelles, 1020 Brussels, Belgium
| | - Javier Márquez-Ruiz
- División de Neurociencias, Universidad Pablo de Olavide, 41013 Sevilla, Spain
| |
Collapse
|
24
|
Barmack NH, Yakhnitsa V. Modulated discharge of Purkinje and stellate cells persists after unilateral loss of vestibular primary afferent mossy fibers in mice. J Neurophysiol 2013; 110:2257-74. [PMID: 23966673 DOI: 10.1152/jn.00352.2013] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Cerebellar Purkinje cells are excited by two afferent pathways: climbing and mossy fibers. Climbing fibers evoke large "complex spikes" (CSs) that discharge at low frequencies. Mossy fibers synapse on granule cells whose parallel fibers excite Purkinje cells and may contribute to the genesis of "simple spikes" (SSs). Both afferent systems convey vestibular information to folia 9c-10. After making a unilateral labyrinthectomy (UL) in mice, we tested how the discharge of CSs and SSs was changed by the loss of primary vestibular afferent mossy fibers during sinusoidal roll tilt. We recorded from cells identified by juxtacellular neurobiotin labeling. The UL preferentially reduced vestibular modulation of CSs and SSs in folia 8-10 contralateral to the UL. The effects of a UL on Purkinje cell discharge were similar in folia 9c-10, to which vestibular primary afferents project, and in folia 8-9a, to which they do not project, suggesting that vestibular primary afferent mossy fibers were not responsible for the UL-induced alteration of SS discharge. UL also induced reduced vestibular modulation of stellate cell discharge contralateral to the UL. We attribute the decreased modulation to reduced vestibular modulation of climbing fibers. In summary, climbing fibers modulate CSs directly and SSs indirectly through activation of stellate cells. Whereas vestibular primary afferent mossy fibers cannot account for the modulated discharge of SSs or stellate cells, the nonspecific excitation of Purkinje cells by parallel fibers may set an operating point about which the discharges of SSs are sculpted by climbing fibers.
Collapse
Affiliation(s)
- N H Barmack
- Department of Physiology and Pharmacology, Oregon Health & Science University, Portland, Oregon
| | | |
Collapse
|
25
|
Abstract
Climbing fiber (CF) input to the cerebellum is thought to instruct associative motor memory formation through its effects on multiple sites within the cerebellar circuit. We used adeno-associated viral delivery of channelrhodopsin-2 (ChR2) to inferior olivary neurons to selectively express ChR2 in CFs, achieving nearly complete transfection of CFs in the caudal cerebellar lobules of rats. As expected, optical stimulation of ChR2-expressing CFs generates complex spike responses in individual Purkinje neurons (PNs); in addition we found that such stimulation recruits a network of inhibitory interneurons in the molecular layer. This CF-driven disynaptic inhibition prolongs the postcomplex spike pause observed when spontaneously firing PNs receive direct CF input; such inhibition also elicits pauses in spontaneously firing PNs not receiving direct CF input. Baseline firing rates of PNs are strongly suppressed by low-frequency (2 Hz) stimulation of CFs, and this suppression is partly relieved by blocking synaptic inhibition. We conclude that CF-driven, disynaptic inhibition has a major influence on PN excitability and contributes to the widely observed negative correlation between complex and simple spike rates. Because they receive input from many CFs, molecular layer interneurons are well positioned to detect the spatiotemporal patterns of CF activity believed to encode error signals. Together, our findings suggest that such inhibition may bind together groups of Purkinje neurons to provide instructive signals to downstream sites in the cerebellar circuit.
Collapse
|
26
|
Forrest MD, Wall MJ, Press DA, Feng J. The sodium-potassium pump controls the intrinsic firing of the cerebellar Purkinje neuron. PLoS One 2012; 7:e51169. [PMID: 23284664 PMCID: PMC3527461 DOI: 10.1371/journal.pone.0051169] [Citation(s) in RCA: 51] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2012] [Accepted: 10/30/2012] [Indexed: 11/18/2022] Open
Abstract
In vitro, cerebellar Purkinje cells can intrinsically fire action potentials in a repeating trimodal or bimodal pattern. The trimodal pattern consists of tonic spiking, bursting, and quiescence. The bimodal pattern consists of tonic spiking and quiescence. It is unclear how these firing patterns are generated and what determines which firing pattern is selected. We have constructed a realistic biophysical Purkinje cell model that can replicate these patterns. In this model, Na(+)/K(+) pump activity sets the Purkinje cell's operating mode. From rat cerebellar slices we present Purkinje whole cell recordings in the presence of ouabain, which irreversibly blocks the Na(+)/K(+) pump. The model can replicate these recordings. We propose that Na(+)/K(+) pump activity controls the intrinsic firing mode of cerbellar Purkinje cells.
Collapse
Affiliation(s)
- Michael D Forrest
- Department of Computer Science, University of Warwick, Coventry, West Midlands, United Kingdom.
| | | | | | | |
Collapse
|
27
|
Almajan ER, Richter R, Paeger L, Martinelli P, Barth E, Decker T, Larsson NG, Kloppenburg P, Langer T, Rugarli EI. AFG3L2 supports mitochondrial protein synthesis and Purkinje cell survival. J Clin Invest 2012; 122:4048-58. [PMID: 23041622 DOI: 10.1172/jci64604] [Citation(s) in RCA: 83] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2012] [Accepted: 08/13/2012] [Indexed: 12/11/2022] Open
Abstract
Mutations in the AFG3L2 gene have been linked to spinocerebellar ataxia type 28 and spastic ataxia-neuropathy syndrome in humans; however, the pathogenic mechanism is still unclear. AFG3L2 encodes a subunit of the mitochondrial m-AAA protease, previously implicated in quality control of misfolded inner mitochondrial membrane proteins and in regulatory functions via processing of specific substrates. Here, we used a conditional Afg3l2 mouse model that allows restricted deletion of the gene in Purkinje cells (PCs) to shed light on the pathogenic cascade in the neurons mainly affected in the human diseases. We demonstrate a cell-autonomous requirement of AFG3L2 for survival of PCs. Examination of PCs prior to neurodegeneration revealed fragmentation and altered distribution of mitochondria in the dendritic tree, indicating that abnormal mitochondrial dynamics is an early event in the pathogenic process. Moreover, PCs displayed features pointing to defects in mitochondrially encoded respiratory chain subunits at early stages. To unravel the underlying mechanism, we examined a constitutive knockout of Afg3l2, which revealed a decreased rate of mitochondrial protein synthesis associated with impaired mitochondrial ribosome assembly. We therefore propose that defective mitochondrial protein synthesis, leading to early-onset fragmentation of the mitochondrial network, is a central causative factor in AFG3L2-related neurodegeneration.
Collapse
Affiliation(s)
- Eva R Almajan
- Institute of Zoology, University of Cologne, Cologne, Germany
| | | | | | | | | | | | | | | | | | | |
Collapse
|
28
|
Engbers JDT, Fernandez FR, Turner RW. Bistability in Purkinje neurons: ups and downs in cerebellar research. Neural Netw 2012; 47:18-31. [PMID: 23041207 DOI: 10.1016/j.neunet.2012.09.006] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2012] [Revised: 09/07/2012] [Accepted: 09/08/2012] [Indexed: 10/27/2022]
Abstract
The output of cerebellar Purkinje cells has been characterized extensively and theories regarding the role of simple spike (SS) and complex spike (CS) patterns have evolved through many different studies. A bistable pattern of SS output can be observed in vitro; however, differing views exist regarding the occurrence of bistable SS output in vivo. Bistability in Purkinje cell output is characterized by abrupt transitions between tonic firing and quiescence, usually evoked by synaptic inputs to the neuron. This is in contrast to the trimodal pattern of activity which has been found in vitro and in vivo when climbing fiber input to Purkinje cells is removed. The mechanisms underlying bistable membrane properties in Purkinje cells have been determined through in vitro studies and computational analysis. In vitro studies have further established that Purkinje cells possess the ability to toggle between firing states, but in vivo studies in both awake and anesthetized animals have found conflicting results as to the presence of toggling in the intact circuit. Here, we provide an overview of the current state of research on bistability, examining the mechanisms underlying bistability and current findings from in vivo studies. We also suggest possible reasons for discrepancies between in vivo studies and propose future studies which would aid in clarifying the role of bistability in the cerebellar circuit.
Collapse
Affiliation(s)
- Jordan D T Engbers
- Hotchkiss Brain Institute, University of Calgary, Calgary, Alberta, Canada T2N 4N1
| | | | | |
Collapse
|
29
|
Dendritic calcium signaling in cerebellar Purkinje cell. Neural Netw 2012; 47:11-7. [PMID: 22985934 DOI: 10.1016/j.neunet.2012.08.001] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2012] [Revised: 07/30/2012] [Accepted: 08/09/2012] [Indexed: 11/24/2022]
Abstract
The Purkinje cells in the cerebellum are unique neurons that generate local and global Ca(2+) signals in response to two types of excitatory inputs, parallel fiber and climbing fiber, respectively. The spatiotemporal distribution and interaction of these synaptic inputs produce complex patterns of Ca(2+) dynamics in the Purkinje cell dendrites. The Ca(2+) signals originate from Ca(2+) influx through voltage-gated Ca(2+) channels and Ca(2+) release from intracellular stores that are mediated by the metabotropic glutamate receptor signaling pathway. These Ca(2+) signals are essential for the induction of various forms of synaptic plasticity and for controlling the input-output relationship of Purkinje cells. In this article we review Ca(2+) signaling in Purkinje cell dendrites.
Collapse
|
30
|
Abrams ZR, Warrier A, Wang Y, Trauner D, Zhang X. Tunable oscillations in the Purkinje neuron. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2012; 85:041905. [PMID: 22680496 DOI: 10.1103/physreve.85.041905] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/27/2011] [Revised: 01/18/2012] [Indexed: 06/01/2023]
Abstract
In this paper, we experimentally study the dynamics of slow oscillations in Purkinje neurons in vitro, and derive a strong association with a forced parametric oscillator model. We observed the precise rhythmicity of these oscillations in Purkinje neurons, as well as a dynamic tunability of this oscillation using a photoswitchable compound. We found that this slow oscillation can be induced in every Purkinje neuron measured, having periods ranging between 10 and 25 s. Starting from a Hodgkin-Huxley model, we demonstrate that this oscillation can be externally modulated, and that the neurons will return to their intrinsic firing frequency after the forced oscillation is concluded. These findings signify an additional timing functional role of tunable oscillations within the cerebellum, as well as a dynamic control of a time scale in the brain in the range of seconds.
Collapse
Affiliation(s)
- Ze'ev R Abrams
- NSF Nanoscale Science and Engineering Center, 3112 Etcheverry Hall, University of California, Berkeley, California 94720, USA
| | | | | | | | | |
Collapse
|
31
|
Engbers JDT, Anderson D, Tadayonnejad R, Mehaffey WH, Molineux ML, Turner RW. Distinct roles for I(T) and I(H) in controlling the frequency and timing of rebound spike responses. J Physiol 2011; 589:5391-413. [PMID: 21969455 PMCID: PMC3240880 DOI: 10.1113/jphysiol.2011.215632] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2011] [Accepted: 09/26/2011] [Indexed: 12/22/2022] Open
Abstract
The ability for neurons to generate rebound bursts following inhibitory synaptic input relies on ion channels that respond in a unique fashion to hyperpolarization. Inward currents provided by T-type calcium channels (I(T)) and hyperpolarization-activated HCN channels (I(H)) increase in availability upon hyperpolarization, allowing for a rebound depolarization after a period of inhibition. Although rebound responses have long been recognized in deep cerebellar nuclear (DCN) neurons, the actual extent to which I(T) and I(H) contribute to rebound spike output following physiological levels of membrane hyperpolarization has not been clearly established. The current study used recordings and simulations of large diameter cells of the in vitro rat DCN slice preparation to define the roles for I(T) and I(H) in a rebound response. We find that physiological levels of hyperpolarization make only small proportions of the total I(T) and I(H) available, but that these are sufficient to make substantial contributions to a rebound response. At least 50% of the early phase of the rebound spike frequency increase is generated by an I(T)-mediated depolarization. An additional frequency increase is provided by I(H) in reducing the time constant and thus the extent of I(T) inactivation as the membrane returns from a hyperpolarized state to the resting level. An I(H)-mediated depolarization creates an inverse voltage-first spike latency relationship and produces a 35% increase in the precision of the first spike latency of a rebound. I(T) and I(H) can thus be activated by physiologically relevant stimuli and have distinct roles in the frequency, timing and precision of rebound responses.
Collapse
Affiliation(s)
- Jordan D T Engbers
- Hotchkiss Brain Institute, University of Calgary, 3330 Hospital Drive N.W., Calgary, AB, Canada T2N 4N1.
| | | | | | | | | | | |
Collapse
|
32
|
Dendritic calcium signaling triggered by spontaneous and sensory-evoked climbing fiber input to cerebellar Purkinje cells in vivo. J Neurosci 2011; 31:10847-58. [PMID: 21795537 DOI: 10.1523/jneurosci.2525-10.2011] [Citation(s) in RCA: 79] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Cerebellar Purkinje cells have one of the most elaborate dendritic trees in the mammalian CNS, receiving excitatory synaptic input from a single climbing fiber (CF) and from ∼200,000 parallel fibers. The dendritic Ca(2+) signals triggered by activation of these inputs are crucial for the induction of synaptic plasticity at both of these synaptic connections. We have investigated Ca(2+) signaling in Purkinje cell dendrites in vivo by combining targeted somatic or dendritic patch-clamp recording with simultaneous two-photon microscopy. Both spontaneous and sensory-evoked CF inputs triggered widespread Ca(2+) signals throughout the dendritic tree that were detectable even in individual spines of the most distal spiny branchlets receiving parallel fiber input. The amplitude of these Ca(2+) signals depended on dendritic location and could be modulated by membrane potential, reflecting modulation of dendritic spikes triggered by the CF input. Furthermore, the variability of CF-triggered Ca(2+) signals was regulated by GABAergic synaptic input. These results indicate that dendritic Ca(2+) signals triggered by sensory-evoked CF input can act as associative signals for synaptic plasticity in Purkinje cells in vivo and may differentially modulate plasticity at parallel fiber synapses depending on the location of synapses, firing state of the Purkinje cell, and ongoing GABAergic synaptic input.
Collapse
|
33
|
Abrams ZR, Zhang X. Signals and circuits in the purkinje neuron. Front Neural Circuits 2011; 5:11. [PMID: 21980311 PMCID: PMC3180174 DOI: 10.3389/fncir.2011.00011] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2011] [Accepted: 09/05/2011] [Indexed: 11/23/2022] Open
Abstract
Purkinje neurons (PN) in the cerebellum have over 100,000 inputs organized in an orthogonal geometry, and a single output channel. As the sole output of the cerebellar cortex layer, their complex firing pattern has been associated with motor control and learning. As such they have been extensively modeled and measured using tools ranging from electrophysiology and neuroanatomy, to dynamic systems and artificial intelligence methods. However, there is an alternative approach to analyze and describe the neuronal output of these cells using concepts from electrical engineering, particularly signal processing and digital/analog circuits. By viewing the PN as an unknown circuit to be reverse-engineered, we can use the tools that provide the foundations of today’s integrated circuits and communication systems to analyze the Purkinje system at the circuit level. We use Fourier transforms to analyze and isolate the inherent frequency modes in the PN and define three unique frequency ranges associated with the cells’ output. Comparing the PN to a signal generator that can be externally modulated adds an entire level of complexity to the functional role of these neurons both in terms of data analysis and information processing, relying on Fourier analysis methods in place of statistical ones. We also re-describe some of the recent literature in the field, using the nomenclature of signal processing. Furthermore, by comparing the experimental data of the past decade with basic electronic circuitry, we can resolve the outstanding controversy in the field, by recognizing that the PN can act as a multivibrator circuit.
Collapse
Affiliation(s)
- Zéev R Abrams
- Applied Science and Technology, Graduate Program University of California Berkeley Berkeley, CA, USA
| | | |
Collapse
|
34
|
Microlesions of the inferior olive reduce vestibular modulation of Purkinje cell complex and simple spikes in mouse cerebellum. J Neurosci 2011; 31:9824-35. [PMID: 21734274 DOI: 10.1523/jneurosci.1738-11.2011] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
Cerebellar Purkinje cells have two distinct action potentials: complex spikes (CSs) are evoked by single climbing fibers that originate from the contralateral inferior olive. Simple spikes (SSs) are often ascribed to mossy fiber-granule cell-parallel fiber inputs to Purkinje cells. Although generally accepted, this view lacks experimental support. Vestibular stimulation independently activates primary afferent mossy fibers and tertiary afferent climbing fibers that project to the uvula-nodulus (folia 8-10). CSs and SSs normally discharge antiphasically during sinusoidal roll-tilt. When CSs increase, SSs decrease. We tested the relative independence of these pathways in mice by making electrolytic microlesions of the two inferior olivary nuclei from which vestibular climbing fibers originate; the β-nucleus and dorsomedial cell column. This reduced vestibular climbing fiber signaling to the contralateral folia 8-10, while leaving intact vestibular primary and secondary afferent mossy fibers. We recorded from Purkinje cells and interneurons in folia 8-10, identified by juxtacellular labeling with Neurobiotin. Microlesions of the inferior olive increased the spontaneous discharge of SSs in contralateral folia 8-10, but blocked their modulation during vestibular stimulation. The vestibularly evoked discharge of excitatory cerebellar interneurons (granule cells and unipolar brush cells) was not modified by olivary microlesions. The modulated discharge of stellate cells, but not Golgi cells, was reduced by olivary microlesions. We conclude that vestibular modulation of CSs and SSs depends on intact climbing fibers. The absence of vestibularly modulated SSs following olivary microlesions reflects the loss of climbing fiber-evoked stellate cell discharge.
Collapse
|
35
|
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: 277] [Impact Index Per Article: 21.3] [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.
Collapse
Affiliation(s)
- Chris I De Zeeuw
- Department of Neuroscience, Erasmus Medical Center, Rotterdam, The Netherlands.
| | | | | | | | | | | |
Collapse
|
36
|
Kaffashian M, Shabani M, Goudarzi I, Behzadi G, Zali A, Janahmadi M. Profound alterations in the intrinsic excitability of cerebellar Purkinje neurons following neurotoxin 3-acetylpyridine (3-AP)-induced ataxia in rat: new insights into the role of small conductance K+ channels. Physiol Res 2010; 60:355-65. [PMID: 21114365 DOI: 10.33549/physiolres.932032] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
Abstract
Alterations in the intrinsic properties of Purkinje cells (PCs) may contribute to the abnormal motor performance observed in ataxic rats. To investigate whether such changes in the intrinsic neuronal excitability could be attributed to the role of Ca(2+)-activated K(+) channels (K(Ca)), whole cell current clamp recordings were made from PCs in cerebellar slices of control and ataxic rats. 3-AP induced profound alterations in the intrinsic properties of PCs, as evidenced by a significant increase in both the membrane input resistance and the initial discharge frequency, along with the disruption of the firing regularity. In control PCs, the blockade of small conductance K(Ca) channels by UCL1684 resulted in a significant increase in the membrane input resistance, action potential (AP) half-width, time to peak of the AP and initial discharge frequency. SK channel blockade also significantly decreased the neuronal discharge regularity, the peak amplitude of the AP, the amplitude of the afterhyperpolarization and the spike frequency adaptation ratio. In contrast, in ataxic rats, both the firing regularity and the initial firing frequency were significantly increased by the blockade of SK channels. In conclusion, ataxia may arise from alterations in the functional contribution of SK channels, to the intrinsic properties of PCs.
Collapse
Affiliation(s)
- M Kaffashian
- Neuroscience Research Centre and Department of Physiology, Medical School, Shahid Beheshti University of Medical Sciences, Tehran, Iran
| | | | | | | | | | | |
Collapse
|
37
|
Intrinsic plasticity complements long-term potentiation in parallel fiber input gain control in cerebellar Purkinje cells. J Neurosci 2010; 30:13630-43. [PMID: 20943904 DOI: 10.1523/jneurosci.3226-10.2010] [Citation(s) in RCA: 107] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Synaptic gain control and information storage in neural networks are mediated by alterations in synaptic transmission, such as in long-term potentiation (LTP). Here, we show using both in vitro and in vivo recordings from the rat cerebellum that tetanization protocols for the induction of LTP at parallel fiber (PF)-to-Purkinje cell synapses can also evoke increases in intrinsic excitability. This form of intrinsic plasticity shares with LTP a requirement for the activation of protein phosphatases 1, 2A, and 2B for induction. Purkinje cell intrinsic plasticity resembles CA1 hippocampal pyramidal cell intrinsic plasticity in that it requires activity of protein kinase A (PKA) and casein kinase 2 (CK2) and is mediated by a downregulation of SK-type calcium-sensitive K conductances. In addition, Purkinje cell intrinsic plasticity similarly results in enhanced spine calcium signaling. However, there are fundamental differences: first, while in the hippocampus increases in excitability result in a higher probability for LTP induction, intrinsic plasticity in Purkinje cells lowers the probability for subsequent LTP induction. Second, intrinsic plasticity raises the spontaneous spike frequency of Purkinje cells. The latter effect does not impair tonic spike firing in the target neurons of inhibitory Purkinje cell projections in the deep cerebellar nuclei, but lowers the Purkinje cell signal-to-noise ratio, thus reducing the PF readout. These observations suggest that intrinsic plasticity accompanies LTP of active PF synapses, while it reduces at weaker, nonpotentiated synapses the probability for subsequent potentiation and lowers the impact on the Purkinje cell output.
Collapse
|
38
|
Shabani M, Hosseinmardi N, Haghani M, Shaibani V, Janahmadi M. Maternal exposure to the CB1 cannabinoid agonist WIN 55212-2 produces robust changes in motor function and intrinsic electrophysiological properties of cerebellar Purkinje neurons in rat offspring. Neuroscience 2010; 172:139-52. [PMID: 20969930 DOI: 10.1016/j.neuroscience.2010.10.031] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2010] [Revised: 10/07/2010] [Accepted: 10/09/2010] [Indexed: 01/18/2023]
Abstract
The cerebellum, which controls coordinated and rapid movements, is a potential target for the deleterious effects of drugs of abuse including cannabis (i.e. marijuana, cannabinoids). Prenatal exposure to cannabinoids has been documented to cause abnormalities in motor and cognitive development, but the exact mechanism of this effect at the cellular level has not been fully elucidated. Previous studies indicate that cannabinoids are capable of modulating synaptic neurotransmission. In addition to altering synaptic activity, cannabinoid exposure may also change intrinsic neuronal properties. In the present study several different approaches including behavioral assays, extracellular field potential recordings and whole-cell patch clamp recordings, were used to address whether maternal exposure to the CB1 cannabinoid receptor agonist WIN 55-212-2 (WIN) affects the intrinsic electrophysiological properties of Purkinje neurons. WIN treatment of pregnant rats produced a significant decrease in the rearing frequency, total distance moved and mobility of the offspring, but significantly increased the time of the righting reflex, the grooming frequency and immobility. Neuromotor function, as assessed in the grip test and balance beam test, was also significantly impaired in prenatally WIN-treated group. Prenatal exposure to WIN increased the amplitude of population spikes (PS) recorded from the cerebellar Purkinje cell layer of offspring following synaptic blockage. WIN treatment of pregnant rats also profoundly affected the intrinsic properties of Purkinje neurons in offspring. This treatment increased the firing regularity, firing frequency, amplitude of afterhyperpolarization (AHP), the peak amplitude of action potential and the first spike latency, but decreased significantly the time to peak and duration of action potentials, the instantaneous firing frequency, the rate of rebound action potential and the voltage "sag" ratio. These results raise the possibility that maternal exposure to cannabinoids may profoundly affect the intrinsic membrane properties of cerebellar Purkinje neurons of offspring by altering the membrane excitability through modulation of intrinsic ion channels.
Collapse
Affiliation(s)
- M Shabani
- Neuroscience Research Centre and Department of Physiology, Medical School, Shahid Beheshti University of Medical Sciences, Evin, Tehran, Islamic Republic of Iran
| | | | | | | | | |
Collapse
|
39
|
Urbanski M, Kovacs F, Szabo B. Endocannabinoid-mediated synaptically evoked suppression of GABAergic transmission in the cerebellar cortex. Neuroscience 2010; 169:1268-78. [DOI: 10.1016/j.neuroscience.2010.05.036] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2009] [Revised: 04/23/2010] [Accepted: 05/16/2010] [Indexed: 11/29/2022]
|
40
|
Goudarzi I, Kaffashian M, Shabani M, Haghdoost-Yazdi H, Behzadi G, Janahmadi M. In vivo 4-aminopyridine treatment alters the neurotoxin 3-acetylpyridine-induced plastic changes in intrinsic electrophysiological properties of rat cerebellar Purkinje neurones. Eur J Pharmacol 2010; 642:56-65. [DOI: 10.1016/j.ejphar.2010.05.031] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2009] [Revised: 04/29/2010] [Accepted: 05/25/2010] [Indexed: 12/30/2022]
|
41
|
Bower JM. Model-founded explorations of the roles of molecular layer inhibition in regulating purkinje cell responses in cerebellar cortex: more trouble for the beam hypothesis. Front Cell Neurosci 2010; 4:27. [PMID: 20877427 PMCID: PMC2944648 DOI: 10.3389/fncel.2010.00027] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2010] [Accepted: 07/04/2010] [Indexed: 11/17/2022] Open
Abstract
For most of the last 50 years, the functional interpretation for inhibition in cerebellar cortical circuitry has been dominated by the relatively simple notion that excitatory and inhibitory dendritic inputs sum, and if that sum crosses threshold at the soma the Purkinje cell generates an action potential. Thus, inhibition has traditionally been relegated to a role of sculpting, restricting, or blocking excitation. At the level of networks, this relatively simply notion is manifest in mechanisms like "surround inhibition" which is purported to "shape" or "tune" excitatory neuronal responses. In the cerebellum, where all cell types except one (the granule cell) are inhibitory, these assumptions regarding the role of inhibition continue to dominate. Based on our recent series of modeling and experimental studies, we now suspect that inhibition may play a much more complex, subtle, and central role in the physiological and functional organization of cerebellar cortex. This paper outlines how model-based studies are changing our thinking about the role of feed-forward molecular layer inhibition in the cerebellar cortex. The results not only have important implications for continuing efforts to understand what the cerebellum computes, but might also reveal important features of the evolution of this large and quintessentially vertebrate brain structure.
Collapse
Affiliation(s)
- James M. Bower
- Research Imaging Center, University of Texas Health Science CenterSan Antonio, TX, USA
| |
Collapse
|
42
|
Zhang Y, Magnus G, Han VZ. Electrophysiological characteristics of cells in the anterior caudal lobe of the mormyrid cerebellum. Neuroscience 2010; 171:79-91. [PMID: 20732390 DOI: 10.1016/j.neuroscience.2010.08.033] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2010] [Revised: 07/21/2010] [Accepted: 08/18/2010] [Indexed: 11/19/2022]
Abstract
We have examined the basic electrophysiology and pharmacology of cells in the anterior caudal lobe (CLa) of the mormyrid cerebellum. Intracellular recordings were performed in an in vitro slice preparation using the whole-cell patch recording method. The responses of cells to parallel fiber (PF) and climbing fiber (CF) stimulation and to somatic current injection were recorded, and then characterized by bath application of receptor and ion channel blockers. Using biocytin or neurobiotin, these cells were also morphologically identified after recording to ensure their classification. Efferent cells and two subtypes of Purkinje cells were identified on the basis of their physiology and morphology. While the majority of Purkinje cells fire a single type of spike that is mediated by Na(+), some fire a large broad spike mediated by Ca(2+) and a narrow spike mediated by Na(+) at resting potential levels. By patching one recording electrode to the soma and another to one of the proximal dendrites of the same cell simultaneously, it was found that the Na(+) spike has an axonal origin and the Ca(2+) spike is generated in the soma-dendritic region of Purkinje cells. Efferent cells fire a single type of Na(+) spike only. Despite variations in their physiology and morphology, all cell types responded to PF stimulation with graded excitatory postsynaptic potentials (EPSPs) mediated by AMPA receptors. However, none of the efferent cells and only some of the Purkinje cells responded to CF activation with a large, AMPA receptor-mediated all-or-none EPSPs. We conclude that the functional circuitry of the CLa resembles that of other regions of the mormyrid cerebellum and is largely similar to that of the mammalian cerebellum.
Collapse
Affiliation(s)
- Y Zhang
- Center for Integrative Brain Research, Seattle Children's Hospital Research Institute, Seattle, WA 98101, USA
| | | | | |
Collapse
|
43
|
Abrams ZR, Warrier A, Trauner D, Zhang X. A Signal Processing Analysis of Purkinje Cells in vitro. Front Neural Circuits 2010; 4:13. [PMID: 20508748 PMCID: PMC2876879 DOI: 10.3389/fncir.2010.00013] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2009] [Accepted: 04/12/2010] [Indexed: 11/13/2022] Open
Abstract
Cerebellar Purkinje cells in vitro fire recurrent sequences of Sodium and Calcium spikes. Here, we analyze the Purkinje cell using harmonic analysis, and our experiments reveal that its output signal is comprised of three distinct frequency bands, which are combined using Amplitude and Frequency Modulation (AM/FM). We find that the three characteristic frequencies – Sodium, Calcium and Switching – occur in various combinations in all waveforms observed using whole-cell current clamp recordings. We found that the Calcium frequency can display a frequency doubling of its frequency mode, and the Switching frequency can act as a possible generator of pauses that are typically seen in Purkinje output recordings. Using a reversibly photo-switchable kainate receptor agonist, we demonstrate the external modulation of the Calcium and Switching frequencies. These experiments and Fourier analysis suggest that the Purkinje cell can be understood as a harmonic signal oscillator, enabling a higher level of interpretation of Purkinje signaling based on modern signal processing techniques.
Collapse
Affiliation(s)
- Ze'ev R Abrams
- Applied Science and Technology, University of California Berkeley, CA, USA
| | | | | | | |
Collapse
|
44
|
Roš H, Sachdev RNS, Yu Y, Šestan N, McCormick DA. Neocortical networks entrain neuronal circuits in cerebellar cortex. J Neurosci 2009; 29:10309-20. [PMID: 19692605 PMCID: PMC3137973 DOI: 10.1523/jneurosci.2327-09.2009] [Citation(s) in RCA: 87] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2009] [Accepted: 06/28/2009] [Indexed: 11/21/2022] Open
Abstract
Activity in neocortex is often characterized by synchronized oscillations of neurons and networks, resulting in the generation of a local field potential (LFP) and electroencephalogram. Do the neuronal networks of the cerebellum also generate synchronized oscillations and are they under the influence of those in the neocortex? Here we show that, in the absence of any overt external stimulus, the cerebellar cortex generates a slow oscillation that is correlated with that of the neocortex. Disruption of the neocortical slow oscillation abolishes the cerebellar slow oscillation, whereas blocking cerebellar activity has no overt effect on the neocortex. We provide evidence that the cerebellar slow oscillation results in part from the activation of granule, Golgi, and Purkinje neurons. In particular, we show that granule and Golgi cells discharge trains of single spikes, and Purkinje cells generate complex spikes, during the "up" state of the slow oscillation. Purkinje cell simple spiking is weakly related to the cerebellar and neocortical slow oscillation in a minority of cells. Our results indicate that the cerebellum generates rhythmic network activity that can be recorded as an LFP in the anesthetized animal, which is driven by synchronized oscillations of the neocortex. Furthermore, we show that correlations between neocortical and cerebellar LFPs persist in the awake animal, indicating that neocortical circuits modulate cerebellar neurons in a similar manner in natural behavioral states. Thus, the projection neurons of the neocortex collectively exert a driving and modulatory influence on cerebellar network activity.
Collapse
Affiliation(s)
- Hana Roš
- Department of Neurobiology, School of Medicine, and
- Kavli Institute for Neuroscience, Yale University, New Haven, Connecticut 06520
| | - Robert N. S. Sachdev
- Department of Neurobiology, School of Medicine, and
- Kavli Institute for Neuroscience, Yale University, New Haven, Connecticut 06520
| | - Yuguo Yu
- Department of Neurobiology, School of Medicine, and
- Kavli Institute for Neuroscience, Yale University, New Haven, Connecticut 06520
| | - Nenad Šestan
- Department of Neurobiology, School of Medicine, and
- Kavli Institute for Neuroscience, Yale University, New Haven, Connecticut 06520
| | - David A. McCormick
- Department of Neurobiology, School of Medicine, and
- Kavli Institute for Neuroscience, Yale University, New Haven, Connecticut 06520
| |
Collapse
|
45
|
Abstract
Many current models of the cerebellar cortical microcircuit are equivalent to an adaptive filter using the covariance learning rule. The adaptive filter is a development of the original Marr-Albus framework that deals naturally with continuous time-varying signals, thus addressing the issue of 'timing' in cerebellar function, and it can be connected in a variety of ways to other parts of the system, consistent with the microzonal organization of cerebellar cortex. However, its computational capacities are not well understood. Here we summarise the results of recent work that has focused on two of its intrinsic properties. First, an adaptive filter seeks to decorrelate its (mossy fibre) inputs from a (climbing fibre) teaching signal. This procedure can be used both for sensory processing, e.g. removal of interference from sensory signals, and for learning accurate motor commands, by decorrelating an efference copy of those commands from a sensory signal of inaccuracy. As a model of the cerebellum the adaptive filter thus forms a natural link between events at the cellular level, such as forms of synaptic plasticity and the learning rules they embody, and intelligent behaviour at the system level. Secondly, it has been shown that the covariance learning rule enables the filter to handle input and intrinsic noise optimally. Such optimality may underlie the recently described role of the cerebellum in producing accurate smooth pursuit eye movements in the face of sensory noise. Moreover, it has the consequence of driving most input weights to very small values, consistent with experimental data that many parallel-fibre synapses are normally silent. The effectiveness of silent synapses can only be altered by LTP, so learning tasks depending on a reduction of Purkinje cell firing require the synapses to be embedded in a second, inhibitory pathway from parallel fibre to Purkinje cell. This pathway and the appropriate climbing-fibre related plasticity have been described experimentally, and its presence has implications for asymmetries and hysteresis in behavioural learning rates that are also consistent with experimental observations. These computational properties of the adaptive filter suggest that it is both powerful and realistic enough to be a suitable candidate model of the cerebellar cortical microcircuit.
Collapse
|
46
|
Janahmadi M, Goudarzi I, Kaffashian MR, Behzadi G, Fathollahi Y, Hajizadeh S. Co-treatment with riluzole, a neuroprotective drug, ameliorates the 3-acetylpyridine-induced neurotoxicity in cerebellar Purkinje neurones of rats: Behavioural and electrophysiological evidence. Neurotoxicology 2009; 30:393-402. [DOI: 10.1016/j.neuro.2009.02.014] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2008] [Revised: 01/03/2009] [Accepted: 02/18/2009] [Indexed: 01/22/2023]
|
47
|
Abstract
Activation of the climbing fiber input powerfully excites cerebellar Purkinje cells via hundreds of widespread dendritic synapses, triggering dendritic spikes as well as a characteristic high-frequency burst of somatic spikes known as the complex spike. To investigate the relationship between dendritic spikes and the spikelets within the somatic complex spike, and to evaluate the importance of the dendritic distribution of climbing fiber synapses, we made simultaneous somatic and dendritic patch-clamp recordings from Purkinje cells in cerebellar slices. Injection of large climbing fiber-like synaptic conductances at the soma using dynamic clamp was sufficient to reproduce the complex spike, independently of dendritic spikes, indicating that neither a dendritic synaptic distribution nor dendritic spikes are required. Furthermore, we found that dendritic spikes are not directly linked to spikelets in the complex spike, and that each dendritic spike is associated with only 0.24 +/- 0.09 extra somatic spikelets. Rather, we demonstrate that dendritic spikes regulate the pause in firing that follows the complex spike. Finally, using dual somatic and axonal recording, we show that all spikelets in the complex spike are axonally generated. Thus, complex spike generation proceeds relatively independently of dendritic spikes, reflecting the dual functional role of climbing fiber input: triggering plasticity at dendritic synapses and generating a distinct output signal in the axon. The encoding of dendritic spiking by the post-complex spike pause provides a novel computational function for dendritic spikes, which could serve to link these two roles at the level of the target neurons in the deep cerebellar nuclei.
Collapse
|
48
|
Cheron G, Servais L, Dan B. Cerebellar network plasticity: From genes to fast oscillation. Neuroscience 2008; 153:1-19. [DOI: 10.1016/j.neuroscience.2008.01.074] [Citation(s) in RCA: 80] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2007] [Revised: 01/24/2008] [Accepted: 01/25/2008] [Indexed: 11/30/2022]
|
49
|
Ovsepian SV, Friel DD. The leaner P/Q-type calcium channel mutation renders cerebellar Purkinje neurons hyper-excitable and eliminates Ca2+-Na+ spike bursts. Eur J Neurosci 2007; 27:93-103. [PMID: 18093175 DOI: 10.1111/j.1460-9568.2007.05998.x] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The leaner mouse mutation of the Cacna1a gene leads to a reduction in P-type Ca2+ current, the dominant Ca2+ current in Purkinje cells (PCs). Here, we compare the electro-responsiveness and structure of PCs from age-matched leaner and wild-type (WT) mice in pharmacological isolation from synaptic inputs in cerebellar slices. We report that compared with WT, leaner PCs exhibit lower current threshold for Na+ spike firing, larger subthreshold membrane depolarization, rapid adaptation followed by complete block of Na+ spikes upon strong depolarization, and fail to generate Ca2+-Na+ spike bursts. The Na+ spike waveforms in leaner PCs have slower kinetics, reduced spike amplitude and afterhyperpolarization. We show that a deficit in the P-type Ca2+ current caused by the leaner mutation accounts for most but not all of the changes in mutant PC electro-responsiveness. The selective P-type Ca2+ channel blocker, omega-agatoxin-IVA, eliminated differences in subthreshold membrane depolarization, adaptation of Na+ spikes upon strong current-pulse stimuli, Na+ spike waveforms and Ca2+-Na+ burst activity. In contrast, a lower current threshold for eliciting repetitive Na+ spikes in leaner PCs was still observed after blockade of the P-type Ca2+ current, suggesting secondary effects of the mutation that render PCs hyper-excitable. Higher input resistance, reduced whole-cell capacitance and smaller dendritic size accompanied the enhanced excitability in leaner PCs, indicative of developmental retardation in these cells caused by P/Q-type Ca2+ channel malfunction. Our data indicate that a deficit in P-type Ca2+ current leads to complex functional and structural changes in PCs, impairing their intrinsic and integrative properties.
Collapse
Affiliation(s)
- Saak V Ovsepian
- Department of Neurosciences, School of Medicine, Case Western Reserve University, 10900 Euclid Avenue, Cleveland, OH 44106, USA.
| | | |
Collapse
|
50
|
Kimpo RR, Raymond JL. Impaired motor learning in the vestibulo-ocular reflex in mice with multiple climbing fiber input to cerebellar Purkinje cells. J Neurosci 2007; 27:5672-82. [PMID: 17522312 PMCID: PMC6672772 DOI: 10.1523/jneurosci.0801-07.2007] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
A unique feature of the cerebellar architecture is that Purkinje cells in the cerebellar cortex each receive input from a single climbing fiber. In mice deficient in the gamma isoform of protein kinase C (PKCgamma-/- mice), this normal architecture is disrupted so that individual Purkinje cells receive input from multiple climbing fibers. These mice have no other known abnormalities in the cerebellar circuit. Here, we show that PKCgamma-/- mice are profoundly impaired in vestibulo-ocular reflex (VOR) motor learning. The PKCgamma-/- mice exhibited no adaptive increases or decreases in VOR gain at training frequencies of 2 or 0.5 Hz. This impairment was present across a broad range of peak retinal slip speeds during training. We compare the results for VOR motor learning with previous studies of the performance of PKCgamma-/- mice on other cerebellum-dependent learning tasks. Together, the results suggest that single climbing fiber innervation of Purkinje cells is critical for some, but not all, forms of cerebellum-dependent learning, and this may depend on the region of the cerebellum involved, the organization of the relevant neural circuits downstream of the cerebellar cortex, as well as the timing requirements of the learning task.
Collapse
Affiliation(s)
- Rhea R. Kimpo
- Department of Neurobiology, Stanford University, Stanford, California 94305-5125
| | - Jennifer L. Raymond
- Department of Neurobiology, Stanford University, Stanford, California 94305-5125
| |
Collapse
|