scholarly journals Activity of Cerebellar Nuclei Neurons Correlates with ZebrinII Identity of Their Purkinje Cell Afferents

Cells ◽  
2021 ◽  
Vol 10 (10) ◽  
pp. 2686
Author(s):  
Gerrit C. Beekhof ◽  
Simona V. Gornati ◽  
Cathrin B. Canto ◽  
Avraham M. Libster ◽  
Martijn Schonewille ◽  
...  
Keyword(s):  
Action Potential ◽  
Bimodal Distribution ◽  
Cerebellar Nuclei ◽  
Firing Frequency ◽  
Action Potential Firing ◽  
Adult Mice ◽  
Electrophysiological Recordings ◽  
Potential Firing

Purkinje cells (PCs) in the cerebellar cortex can be divided into at least two main subpopulations: one subpopulation that prominently expresses ZebrinII (Z+), and shows a relatively low simple spike firing rate, and another that hardly expresses ZebrinII (Z–) and shows higher baseline firing rates. Likewise, the complex spike responses of PCs, which are evoked by climbing fiber inputs and thus reflect the activity of the inferior olive (IO), show the same dichotomy. However, it is not known whether the target neurons of PCs in the cerebellar nuclei (CN) maintain this bimodal distribution. Electrophysiological recordings in awake adult mice show that the rate of action potential firing of CN neurons that receive input from Z+ PCs was consistently lower than that of CN neurons innervated by Z– PCs. Similar in vivo recordings in juvenile and adolescent mice indicated that the firing frequency of CN neurons correlates to the ZebrinII identity of the PC afferents in adult, but not postnatal stages. Finally, the spontaneous action potential firing pattern of adult CN neurons recorded in vitro revealed no significant differences in intrinsic pacemaking activity between ZebrinII identities. Our findings indicate that all three main components of the olivocerebellar loop, i.e., PCs, IO neurons and CN neurons, operate at a higher rate in the Z– modules.

scholarly journals The thalamic low-threshold Ca 2+ potential: a key determinant of the local and global dynamics of the slow (<1 Hz) sleep oscillation in thalamocortical networks

2011 ◽  
Vol 369 (1952) ◽  
pp. 3820-3839 ◽  
Author(s):  
Vincenzo Crunelli ◽  
Adam C. Errington ◽  
Stuart W. Hughes ◽  
Tibor I. Tóth
Keyword(s):  
Action Potential ◽  
Slow Oscillation ◽  
Global Dynamics ◽  
Action Potential Firing ◽  
Local And Global Dynamics ◽  
Up States ◽  
Potential Firing ◽  
Low Threshold

During non-rapid eye movement sleep and certain types of anaesthesia, neurons in the neocortex and thalamus exhibit a distinctive slow (<1 Hz) oscillation that consists of alternating UP and DOWN membrane potential states and which correlates with a pronounced slow (<1 Hz) rhythm in the electroencephalogram. While several studies have claimed that the slow oscillation is generated exclusively in neocortical networks and then transmitted to other brain areas, substantial evidence exists to suggest that the full expression of the slow oscillation in an intact thalamocortical (TC) network requires the balanced interaction of oscillator systems in both the neocortex and thalamus. Within such a scenario, we have previously argued that the powerful low-threshold Ca 2+ potential (LTCP)-mediated burst of action potentials that initiates the UP states in individual TC neurons may be a vital signal for instigating UP states in related cortical areas. To investigate these issues we constructed a computational model of the TC network which encompasses the important known aspects of the slow oscillation that have been garnered from earlier in vivo and in vitro experiments. Using this model we confirm that the overall expression of the slow oscillation is intricately reliant on intact connections between the thalamus and the cortex. In particular, we demonstrate that UP state-related LTCP-mediated bursts in TC neurons are proficient in triggering synchronous UP states in cortical networks, thereby bringing about a synchronous slow oscillation in the whole network. The importance of LTCP-mediated action potential bursts in the slow oscillation is also underlined by the observation that their associated dendritic Ca 2+ signals are the only ones that inform corticothalamic synapses of the TC neuron output, since they, but not those elicited by tonic action potential firing, reach the distal dendritic sites where these synapses are located.

Development of hypersynchrony in the cortical network during chemoconvulsant-induced epileptic seizures in vivo

2012 ◽  
Vol 107 (6) ◽  
pp. 1718-1730 ◽  
Author(s):  
Adi Cymerblit-Sabba ◽  
Yitzhak Schiller
Keyword(s):  
Action Potential ◽  
Early Phase ◽  
Epileptic Seizures ◽  
Firing Frequency ◽  
Cortical Network ◽  
Small Subset ◽  
Action Potential Firing ◽  
Neuronal Synchronization ◽  
Potential Firing

The prevailing view of epileptic seizures is that they are caused by increased hypersynchronous activity in the cortical network. However, this view is based mostly on electroencephalography (EEG) recordings that do not directly monitor neuronal synchronization of action potential firing. In this study, we used multielectrode single-unit recordings from the hippocampus to investigate firing of individual CA1 neurons and directly monitor synchronization of action potential firing between neurons during the different ictal phases of chemoconvulsant-induced epileptic seizures in vivo. During the early phase of seizures manifesting as low-amplitude rhythmic β-electrocorticography (ECoG) activity, the firing frequency of most neurons markedly increased. To our surprise, the average overall neuronal synchronization as measured by the cross-correlation function was reduced compared with control conditions with ∼60% of neuronal pairs showing no significant correlated firing. However, correlated firing was not uniform and a minority of neuronal pairs showed a high degree of correlated firing. Moreover, during the early phase of seizures, correlated firing between 9.8 ± 5.1% of all stably recorded pairs increased compared with control conditions. As seizures progressed and high-frequency ECoG polyspikes developed, the firing frequency of neurons further increased and enhanced correlated firing was observed between virtually all neuronal pairs. These findings indicated that epileptic seizures represented a hyperactive state with widespread increase in action potential firing. Hypersynchrony also characterized seizures. However, it initially developed in a small subset of neurons and gradually spread to involve the entire cortical network only in the later more intense ictal phases.

scholarly journals Zonal variations in K+ currents in vestibular crista calyx terminals

2015 ◽  
Vol 113 (1) ◽  
pp. 264-276 ◽  
Author(s):  
Frances L. Meredith ◽  
Katherine J. Rennie
Keyword(s):  
Action Potential ◽  
Ampa Receptors ◽  
Channel Blocker ◽  
Outward Current ◽  
Firing Frequency ◽  
Action Potential Firing ◽  
Regional Variations ◽  
Electrophysiological Properties ◽  
Kcnq Channels ◽  
Potential Firing

We developed a rodent crista slice to investigate regional variations in electrophysiological properties of vestibular afferent terminals. Thin transverse slices of the gerbil crista ampullaris were made and electrical properties of calyx terminals in central zones (CZ) and peripheral zones (PZ) compared with whole cell patch clamp. Spontaneous action potential firing was observed in 25% of current-clamp recordings and was either regular or irregular in both zones. Firing was abolished when extracellular choline replaced Na+ but persisted when hair cell mechanotransduction channels or calyx AMPA receptors were blocked. This suggests that ion channels intrinsic to the calyx can generate spontaneous firing. In response to depolarizing voltage steps, outward K+ currents were observed at potentials above −60 mV. K+ currents in PZ calyces showed significantly more inactivation than currents in CZ calyces. Underlying K+ channel populations contributing to these differences were investigated. The KCNQ channel blocker XE991 dihydrochloride blocked a slowly activating, sustained outward current in both PZ and CZ calyces, indicating the presence of KCNQ channels. Mean reduction was greatest in PZ calyces. XE991 also reduced action potential firing frequency in CZ and PZ calyces and broadened mean action potential width. The K+ channel blocker 4-aminopyridine (10–50 μM) blocked rapidly activating, moderately inactivating currents that were more prevalent in PZ calyces. α-Dendrotoxin, a selective blocker of KV1 channels, reduced outward currents in CZ calyces but not in PZ calyces. Regional variations in K+ conductances may contribute to different firing responses in calyx afferents.

scholarly journals Nicotine suppresses hyperexcitability of colonic sensory neurons and visceral hypersensivity in mouse model of colonic inflammation

2012 ◽  
Vol 302 (7) ◽  
pp. G740-G747 ◽  
Author(s):  
Galya R. Abdrakhmanova ◽  
Minho Kang ◽  
M. Imad Damaj ◽  
Hamid I. Akbarali
Keyword(s):  
Mouse Model ◽  
Action Potential ◽  
Action Potentials ◽  
Drg Neurons ◽  
Action Potential Firing ◽  
Colonic Inflammation ◽  
Single Action ◽  
Nicotine Administration ◽  
Potential Firing

Recently, we reported that nicotine in vitro at a low 1-μM concentration suppresses hyperexcitability of colonic dorsal root ganglia (DRG; L1-L2) neurons in the dextran sodium sulfate (DSS)-induced mouse model of acute colonic inflammation ( 1 ). Here we show that multiple action potential firing in colonic DRG neurons persisted at least for 3 wk post-DSS administration while the inflammatory signs were diminished. Similar to that in DSS-induced acute colitis, bath-applied nicotine (1 μM) gradually reduced regenerative multiple-spike action potentials in colonic DRG neurons to a single action potential in 3 wk post-DSS neurons. Nicotine (1 μM) shifted the activation curve for tetrodotoxin (TTX)-resistant sodium currents in inflamed colonic DRG neurons (voltage of half-activation changed from −37 to −32 mV) but did not affect TTX-sensitive currents in control colonic DRG neurons. Further, subcutaneous nicotine administration (2 mg/kg b.i.d.) in DSS-treated C57Bl/J6 male mice resulted in suppression of hyperexcitability of colonic DRG (L1-L2) neurons and the number of abdominal constrictions in response to intraperitoneal injection of 0.6% acetic acid. Collectively, the data suggest that neuronal nicotinic acetylcholine receptor-mediated suppression of hyperexcitability of colonic DRG neurons attenuates reduction of visceral hypersensitivity in DSS mouse model of colonic inflammation.

scholarly journals Knockout of Slo2.2 enhances itch, abolishes KNa current, and increases action potential firing frequency in DRG neurons

eLife ◽  
2015 ◽  
Vol 4 ◽  
Author(s):  
Pedro L Martinez-Espinosa ◽  
Jianping Wu ◽  
Chengtao Yang ◽  
Vivian Gonzalez-Perez ◽  
Huifang Zhou ◽  
...  
Keyword(s):  
Action Potential ◽  
Small Diameter ◽  
Firing Frequency ◽  
Drg Neurons ◽  
Action Potential Firing ◽  
Discernible Effect ◽  
Potential Firing ◽  
Mammalian Genes ◽  
Isolectin B4 ◽  
Tools And Methods

Two mammalian genes, Kcnt1 and Kcnt2, encode pore-forming subunits of Na+-dependent K+ (KNa) channels. Progress in understanding KNa channels has been hampered by the absence of specific tools and methods for rigorous KNa identification in native cells. Here, we report the genetic disruption of both Kcnt1 and Kcnt2, confirm the loss of Slo2.2 and Slo2.1 protein, respectively, in KO animals, and define tissues enriched in Slo2 expression. Noting the prevalence of Slo2.2 in dorsal root ganglion, we find that KO of Slo2.2, but not Slo2.1, results in enhanced itch and pain responses. In dissociated small diameter DRG neurons, KO of Slo2.2, but not Slo2.1, abolishes KNa current. Utilizing isolectin B4+ neurons, the absence of KNa current results in an increase in action potential (AP) firing and a decrease in AP threshold. Activation of KNa acts as a brake to initiation of the first depolarization-elicited AP with no discernible effect on afterhyperpolarizations.

scholarly journals A Membrane-Targeted Photoswitch Potently Modulates Neuronal Firing

2019 ◽  
Author(s):  
Mattia L. DiFrancesco ◽  
Francesco Lodola ◽  
Elisabetta Colombo ◽  
Luca Maragliano ◽  
Giuseppe M. Paternò ◽  
...  
Keyword(s):  
Plasma Membrane ◽  
Neural Activity ◽  
Neuronal Firing ◽  
Physiological Effects ◽  
Action Potential Firing ◽  
Polar Groups ◽  
Potential Firing ◽  
Spatio Temporal

ABSTRACTOptical technologies allowing modulation of neuronal activity at high spatio-temporal resolution are becoming paramount in neuroscience. We engineered novel light-sensitive molecules by adding polar groups to a hydrophobic backbone containing azobenzene and azepane moieties. We demonstrate that the probes stably partition into the plasma membrane, with affinity for lipid rafts, and cause thinning of the bilayer through their trans-dimerization in the dark. In neurons pulse-labeled with the compound, light induces a transient hyperpolarization followed by a delayed depolarization that triggers action potential firing. The fast hyperpolarization is attributable to a light-dependent decrease in capacitance due to membrane relaxation that follows disruption of the azobenzene dimers. The physiological effects are persistent and can be evoked in vivo after labeling the mouse somatosensory cortex. These data demonstrate the possibility to trigger neural activity in vitro and in vivo by modulating membrane capacitance, without directly affecting ion channels or local temperature.

scholarly journals Regulation of Action-Potential Firing in Spiny Neurons of the Rat Neostriatum In Vivo

1998 ◽  
Vol 79 (5) ◽  
pp. 2358-2364 ◽  
Author(s):  
J. R. Wickens ◽  
C. J. Wilson
Keyword(s):  
Membrane Potential ◽  
Action Potential ◽  
Action Potentials ◽  
Projection Neurons ◽  
Excitatory Postsynaptic Potential ◽  
Action Potential Firing ◽  
Current Pulses ◽  
Spiny Neurons ◽  
Potential Firing

Wickens, J. R. and C. J. Wilson. Regulation of action-potential firing in spiny neurons of the rat neostriatum in vivo. J. Neurophysiol. 79: 2358–2364, 1998. Both silent and spontaneously firing spiny projection neurons have been described in the neostriatum, but the reason for their differences in firing activity are unknown. We compared properties of spontaneously firing and silent spiny neurons in urethan-anesthetized rats. Neurons were identified as spiny projection neurons after labeling by intracellular injection of biocytin. The threshold for action-potential firing was measured under three different conditions: 1) electrical stimulation of the contralateral cerebral cortex, 2) brief directly applied current pulses, and 3) spontaneous action-potentials occurring during spontaneous episodes of depolarization (up state). The average membrane potential and the amplitude of noiselike fluctuations of membrane potential in the up state were determined by fitting a Gaussian curve to the membrane-potential distribution. All neurons in the sample exhibited spontaneous membrane potential shifts between a hyperpolarized down state and a depolarized up state, but not all fired action potentials while in the up state. The difference between the spontaneously firing and the silent spiny neurons was in the average membrane potential in the up state, which was significantly more depolarized in the spontaneously firing than in the silent spiny neurons. There were no significant differences in the threshold, the amplitude of the noiselike fluctuations of membrane potential in the up state, or in the proportion of time that the membrane potential was in the up state. In both spontaneously firing and silent neurons, the threshold for action potentials evoked by current pulses was significantly higher than for those evoked by cortical stimulation. Application of more intense current pulses that reproduced the excitatory postsynaptic potential rate of rise produced firing at correspondingly lower thresholds. Because the membrane potential in the up state is mainly determined by the balance between the synaptic drive and the outward potassium conductances activated in the subthreshold range of membrane potentials, either or both of these factors may determine whether firing occurs in response to spontaneous afferent activity.

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