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ENeuro 2016It has been known for a long time that GABAergic Purkinje cells in the cerebellar cortex, as well as their target neurons in the cerebellar nuclei, are spontaneously...
It has been known for a long time that GABAergic Purkinje cells in the cerebellar cortex, as well as their target neurons in the cerebellar nuclei, are spontaneously active. The cerebellar output will, therefore, depend on how input is integrated into this spontaneous activity. It has been shown that input from climbing fibers originating in the inferior olive controls the spontaneous activity in Purkinje cells. While blocking climbing fiber input to the Purkinje cells causes a dramatic increase in the firing rate, increased climbing fiber activity results in reduced Purkinje cell activity. However, the exact calibration of this regulation has not been examined systematically. Here we examine the relation between climbing fiber stimulation frequency and Purkinje cell activity in unanesthetized decerebrated ferrets. The results revealed a gradual suppression of Purkinje cell activity, starting at climbing fiber stimulation frequencies as low as 0.5 Hz. At 4 Hz, Purkinje cells were completely silenced. This effect lasted an average of 2 min after the stimulation rate was reduced to a lower level. We also examined the effect of sustained climbing fiber stimulation on overt behavior. Specifically, we analyzed conditioned blink responses, which are known to be dependent on the cerebellum, while stimulating the climbing fibers at different frequencies. In accordance with the neurophysiological data, the conditioned blink responses were suppressed at stimulation frequencies of ≥4 Hz.
Topics: Action Potentials; Afferent Pathways; Animals; Conditioning, Eyelid; Ferrets; Male; Purkinje Cells
PubMed: 26839917
DOI: 10.1523/ENEURO.0067-15.2015 -
Neuroscience Dec 2006Two vestibular pathways converge at the uvula-nodulus to modulate the discharge of Purkinje cell complex and simple spikes (CSs and SSs). In the mouse, vestibular...
Two vestibular pathways converge at the uvula-nodulus to modulate the discharge of Purkinje cell complex and simple spikes (CSs and SSs). In the mouse, vestibular primary afferent mossy fibers originate from each of the end organs of the ipsilateral labyrinth and terminate in the granule cell layers of folia 9c-10. Vestibular climbing fiber projections originate from the contralateral beta-nucleus and dorsomedial cell column (dmcc) and terminate directly on Purkinje cells. CSs and SSs could be regulated independently or they could be co-dependent. Here we examine how the discharges of CSs and SSs are modulated by sinusoidal and static roll-tilt in the uvula-nodulus of mice anesthetized with either chloralose-urethane or ketamine-xylazine. All vestibularly-driven CSs and SSs were sensitive to static roll-tilt. None were sensitive to horizontal vestibular stimulation. CSs were modulated in phase with ipsilateral roll-tilt. SSs were modulated out of phase. Spontaneous discharges of CSs were followed by a pause in SSs. Phase leads of CSs and SSs with respect to sinusoidal roll-tilt were advanced by ketamine-xylazine anesthesia relative to chloralose-urethane anesthesia by approximately 45 degrees. The antiphasic modulation of CSs and SSs was independent of anesthetic. Chloralose-urethane, but not ketamine-xylazine, induced spontaneous oscillations of CSs and SSs in 16% of Purkinje cells. Optimal planes of CSs in folia 9c-10 Purkinje cells were organized topographically into sagittal zones whose widths were approximately 400 microm. Purkinje cells with optimal planes in the posterior quadrant of the ipsilateral hemi-field were located in a medial zone. Purkinje cells with optimal planes in the anterior quadrant of the ipsilateral hemi-field were located in a lateral zone. The CS-associated pause in SSs establishes a vector-specific SS output. The amplitude of SS modulation may depend on parallel fiber-mediated signals to Purkinje cells as well as on the state of cerebellar interneurons.
Topics: Action Potentials; Analgesics; Analysis of Variance; Animals; Brain Mapping; Cerebellum; Functional Laterality; Mice; Mice, Inbred C57BL; Purkinje Cells; Reflex, Vestibulo-Ocular
PubMed: 16973298
DOI: 10.1016/j.neuroscience.2006.08.006 -
Experimental Neurology Nov 2013Purkinje neurons are a sensitive and specialised cell type important for fine motor movement and coordination. Purkinje cell damage manifests as motor incoordination and...
Purkinje neurons are a sensitive and specialised cell type important for fine motor movement and coordination. Purkinje cell damage manifests as motor incoordination and ataxia - a prominent feature of many human disorders including spinocerebellar ataxia and Huntington's disease. A correlation between Purkinje degeneration and excess cerebellar levels of tissue-type plasminogen activator (tPA) has been observed in multiple genetically-distinct models of ataxia. Here we show that Purkinje loss in a mouse model of Huntington's disease also correlates with a 200% increase in cerebellar tPA activity. That elevated tPA levels arise in a variety of ataxia models suggests that tPA is a common mediator of Purkinje damage. To address the specific contribution of tPA to cerebellar dysfunction we studied the T4 mice line that overexpresses murine tPA in postnatal neurons through the Thy1.2 gene promoter, which directs preferential expression to Purkinje cells within the cerebellum. Here we show that T4 mice develop signs of cerebellar damage within 10 weeks of birth including atrophy of Purkinje cell soma and dendrites, astrogliosis, reduced molecular layer volume and altered gait. In contrast, T4 mice displayed no evidence of microgliosis, nor any changes in interneuron density, nor alteration in the cerebellar granular neuron layer. Thus, excess tPA levels may be sufficient to cause targeted Purkinje cell degeneration and ataxia. We propose that elevated cerebellar tPA levels exert a common pathway of Purkinje cell damage. Therapeutically lowering cerebellar tPA levels may represent a novel means of preserving Purkinje cell integrity and motor coordination across a wide range of neurodegenerative diseases.
Topics: Animals; Ataxia; Extracellular Fluid; Gait; Male; Mice; Mice, Inbred C57BL; Mice, Transgenic; Purkinje Cells; Tissue Plasminogen Activator
PubMed: 23939410
DOI: 10.1016/j.expneurol.2013.08.001 -
Behavioral and Brain Functions : BBF Oct 2012Fear conditioning-induced changes in cerebellar Purkinje cell responses to a conditioned stimulus have been reported in rabbits. It has been suggested that synaptic...
BACKGROUND
Fear conditioning-induced changes in cerebellar Purkinje cell responses to a conditioned stimulus have been reported in rabbits. It has been suggested that synaptic long-term potentiation and the resulting increases in firing rates of Purkinje cells are related to the acquisition of conditioned fear in mammals. However, Purkinje cell activities during acquisition of conditioned fear have not been analysed, and changes in Purkinje cell activities throughout the development of conditioned fear have not yet been investigated. In the present study, we tracked Purkinje cell activities throughout a fear conditioning procedure and aimed to elucidate further how cerebellar circuits function during the acquisition and expression of conditioned fear.
METHODS
Activities of single Purkinje cells in the corpus cerebelli were tracked throughout a classical fear conditioning procedure in goldfish. A delayed conditioning paradigm was used with cardiac deceleration as the conditioned response. Conditioning-related changes of Purkinje cell responses to a conditioned stimulus and unconditioned stimulus were examined.
RESULTS
The majority of Purkinje cells sampled responded to the conditioned stimulus by either increasing or decreasing their firing rates before training. Although there were various types of conditioning-related changes in Purkinje cells, more than half of the cells showed suppressed activities in response to the conditioned stimulus after acquisition of conditioned fear. Purkinje cells that showed unconditioned stimulus-coupled complex-spike firings also exhibited conditioning-related suppression of simple-spike responses to the conditioned stimulus. A small number of Purkinje cells showed increased excitatory responses in the acquisition sessions. We found that the magnitudes of changes in the firing frequencies of some Purkinje cells in response to the conditioned stimulus correlated with the magnitudes of the conditioned responses on a trial-to-trial basis.
CONCLUSIONS
These results demonstrate that Purkinje cells in the corpus cerebelli of goldfish show fear conditioning-related changes in response to a stimulus that had been emotionally neutral prior to conditioning. Unconditioned stimulus-induced climbing fibre inputs to the Purkinje cells may be involved in mediating these plastic changes.
Topics: Animals; Cerebellum; Conditioning, Classical; Electric Stimulation; Fear; Goldfish; Neuronal Plasticity; Purkinje Cells
PubMed: 23114007
DOI: 10.1186/1744-9081-8-52 -
Brain Research Jan 1985Purkinje cell dendritic trees from adult and weanling cerebella were analyzed with an image analysis system following Golgi-Cox impregnation. Measurements of the mean...
Purkinje cell dendritic trees from adult and weanling cerebella were analyzed with an image analysis system following Golgi-Cox impregnation. Measurements of the mean length, number and total length of primary trunks, smooth branches and spiny branchlets were taken to assess the amount of growth between postnatal days 23 and 150. These results revealed a significant post-weanling growth in the length and number of smooth branches and spiny branchlets.
Topics: Animals; Cerebellum; Dendrites; Purkinje Cells; Rats; Weaning
PubMed: 3986587
DOI: 10.1016/0165-3806(85)90143-9 -
The Journal of Neuroscience : the... Nov 2002The cerebellar cortex contains huge numbers of synapses between granule cells and Purkinje cells. These synapses are thought to be a major storage site for information...
The cerebellar cortex contains huge numbers of synapses between granule cells and Purkinje cells. These synapses are thought to be a major storage site for information required to execute coordinated movements. To obtain a quantitative description of this connection, we recorded unitary synaptic responses between granule cell and Purkinje cell pairs in adult rat cerebellar slices. Our results are consistent with parallel fiber-->Purkinje cell synapses having high release probabilities and modest paired pulse facilitation. However, a wide range of response amplitudes was observed. Indeed, we detected many fewer parallel fiber connections (7% of the granule cells that were screened) than expected (54%), leading us to suggest that up to 85% of parallel fiber-->Purkinje cell synapses do not generate detectable electrical responses. We also investigated the possible role of granule cell ascending axons by recording granule cells near the Purkinje cell. A high proportion (up to 50%) of local granule cells generated detectable synaptic responses. However, most of these connections were indistinguishable from parallel fiber connections, suggesting that powerful ascending axon connections are rare. The existence of many very weak synapses would provide a mechanism for Purkinje cells to extract information selectively from the mass provided by parallel fibers.
Topics: Action Potentials; Animals; Axons; Cerebellum; Electric Stimulation; Excitatory Postsynaptic Potentials; In Vitro Techniques; Kinetics; Male; Neurons; Patch-Clamp Techniques; Purkinje Cells; Rats; Rats, Wistar; Sensory Thresholds; Synapses
PubMed: 12427822
DOI: 10.1523/JNEUROSCI.22-22-09668.2002 -
Neuroscience Letters Feb 2014Toluene belongs to a class of psychoactive drugs known as inhalants. Found in common household products such as adhesives, paint products, and aerosols, toluene is...
Toluene belongs to a class of psychoactive drugs known as inhalants. Found in common household products such as adhesives, paint products, and aerosols, toluene is inhaled for its intoxicating and euphoric properties. Additionally, exposure to toluene disrupts motor behaviors in a manner consistent with impairments to cerebellar function. Previous work has suggested a role of GABA in mediating toluene's neurobehavioral effects, but how this manifests in the cerebellar cortex is not yet understood. In the present study, we examined the effects of toluene on cerebellar Purkinje cell action potential output and inhibitory synaptic transmission onto Purkinje cells using patch clamp electrophysiology in acute rat cerebellar slices. Toluene (1mM) reduced the frequency of Purkinje cell action potential output without affecting input resistance. Furthermore, toluene dose-dependently enhanced inhibitory synaptic transmission onto Purkinje cells, increasing the amplitude and frequency of inhibitory postsynaptic currents; no change in the frequency of action potentials from molecular layer interneurons was noted. The observed decreases in Purkinje cell action potential output could contribute to toluene-evoked impairments in cerebellar and motor functions.
Topics: Action Potentials; Animals; Female; In Vitro Techniques; Interneurons; Male; Patch-Clamp Techniques; Psychotropic Drugs; Purkinje Cells; Rats, Long-Evans; Solvents; Synaptic Transmission; Toluene
PubMed: 24345417
DOI: 10.1016/j.neulet.2013.12.010 -
Cellular and Molecular Neurobiology Oct 2018Primary neurons are difficult to cultivate because they are often part of a complex tissue, and synaptically connected to numerous other cell types. These circumstances...
Primary neurons are difficult to cultivate because they are often part of a complex tissue, and synaptically connected to numerous other cell types. These circumstances often prevent us from unveiling molecular and metabolic mechanisms of distinct cells, as functional signals or assays cannot clearly be correlated with them due to interfering signals from other parts of the culture. We therefore present an up-to-date method for obtaining a highly purified neuronal culture of Purkinje cells. In the past, Purkinje cells were successfully isolated from young mouse cerebella, but this protocol was never adapted to other mammals. We therefore provide an updated and adjusted protocol for Purkinje cell isolation from rat instead of mouse cerebella. To purify Purkinje cells, we obtained perinatal rat cerebella, dissociated them and performed a Percoll gradient centrifugation to segregate the smaller and larger cell fractions. In a second step, we performed an immunopanning procedure to enrich only Purkinje cells from the large cell fraction. Based on former protocols, we used a different antibody for the immunopanning procedure and adjusted several aspects from the initial protocol to improve the yield and vitality of Purkinje cells. We provide RT-qPCR-based purity data obtained with this protocol and show the behaviour and the growth of these purified Purkinje cells. We provide a highly reproducible purification protocol for Purkinje cell cultures of high purity that allows functional analysis and downstream assays on living rat Purkinje cells and further morphological growth analysis in future.
Topics: Animals; Animals, Newborn; Cell Proliferation; Cells, Cultured; Cerebellum; Embryo, Mammalian; Mice; Primary Cell Culture; Purkinje Cells; Rats; Rats, Wistar
PubMed: 30066224
DOI: 10.1007/s10571-018-0606-5 -
Journal of Neurobiology Apr 1995The normal development of Purkinje cell dendrites is dependent on afferent innervation. To investigate the role of neuronal activity in Purkinje cell dendritic...
The normal development of Purkinje cell dendrites is dependent on afferent innervation. To investigate the role of neuronal activity in Purkinje cell dendritic development, chick embryos were chronically treated with a potent, selective, and systemically active competitive N-methyl-D-aspartate (NMDA) receptor antagonist, NPC 12626. The NMDA receptor was chosen as a target for pharmacological blockade because of the importance of the NMDA receptor in synaptic plasticity and stabilization in development. Chick embryos were given daily injections of NPC 12626 (25 to 100 mg/kg) from embryonic day 14 (E14) to E17. The initial injections of NPC 12626 dramatically blocked embryo movements, but activity levels partially recovered following subsequent injections. Embryo movements were reduced by 24% at the end of the experiment. Embryos were killed on E18, and their brains processed for Golgi-Cox staining. The morphology of Golgi-stained Purkinje cells in drug-treated embryos was similar to control embryos. Morphometric analysis showed, however, that chronic treatment with NPC 12626 resulted in a 19% reduction in Purkinje cell dendritic tree area and a 13% reduction in the number of dendritic branch points. The overall width and height of the drug-treated dendritic trees were not significantly different from controls, suggesting that NPC 12626 reduced Purkinje cell dendritic area by interfering with branch formation. The volume of the granule cell layer and the heights of the molecular and external granule cell layers was not reduced, suggesting that NPC 12626 treatment did not simply delay development. These results suggest that activation of the NMDA receptor may mediate the afferent-target interactions in the cerebellum that regulate the elaboration of Purkinje cell dendrites.
Topics: Amino Acids; Animals; Chick Embryo; Dendrites; Movement; Purkinje Cells; Receptors, N-Methyl-D-Aspartate; Time Factors
PubMed: 7602317
DOI: 10.1002/neu.480260407 -
Disease Models & Mechanisms Sep 2018Many cerebellar-induced neurological disorders, such as ataxias and cerebellar-induced dystonias, are associated with abnormal Purkinje cell activity. In tottering mice,...
Many cerebellar-induced neurological disorders, such as ataxias and cerebellar-induced dystonias, are associated with abnormal Purkinje cell activity. In tottering mice, a well-established mouse model of episodic ataxia type 2 (EA2), cerebellar Purkinje cells are required for the initiation of motor attacks How Purkinje cells contribute to the initiation of attacks is not known, and to date there are no reports on the activity of Purkinje cells during motor attacks in the tottering mice. Here, we show that tottering Purkinje cells exhibit high-frequency burst firing during attacks, reminiscent of other mouse models of cerebellar-induced motor dysfunction. We recorded the activity of Purkinje cells in awake head-restrained tottering mice at baseline, or during caffeine-induced attacks. During motor attacks, firing of Purkinje cells transformed to high-frequency burst firing. Interestingly, the extent to which the activity of Purkinje cells was erratic was correlated with the severity of the motor dysfunction. In support of a causal role for erratic activity in generating motor dysfunction, we found that direct infusion of the small conductance calcium-activated potassium (SK) channel activator NS309 into the cerebellum of tottering mice in the midst of an attack normalized the firing of Purkinje cells and aborted attacks. Conversely, we found that inducing high-frequency burst firing of Purkinje cells in wild-type animals is sufficient to produce severe motor signs. We report that erratic activity of wild-type Purkinje cells results in ataxia and dystonic postures. Moreover, this aberrant activity is the cause of motor attacks in the tottering mice.
Topics: Action Potentials; Animals; Ataxia; Cadmium; Caffeine; Disease Models, Animal; Female; Ion Channel Gating; Male; Mice, Inbred C57BL; Mice, Neurologic Mutants; Motor Activity; Purkinje Cells; Small-Conductance Calcium-Activated Potassium Channels
PubMed: 30279196
DOI: 10.1242/dmm.034181