scholarly journals Membrane potential resonance frequency directly influences network frequency through electrical coupling

2016 ◽  
Vol 116 (4) ◽  
pp. 1554-1563 ◽  
Author(s):  
Yinbo Chen ◽  
Xinping Li ◽  
Horacio G. Rotstein ◽  
Farzan Nadim
Keyword(s):  
Membrane Potential ◽  
Resonance Frequency ◽  
Cell Model ◽  
Electrical Coupling ◽  
Rhythmic Activity ◽  
Biophysical Parameters ◽  
Cancer Borealis ◽  
Resonance Amplitude ◽  
Pyloric Network ◽  
Frequency Relationship

Oscillatory networks often include neurons with membrane potential resonance, exhibiting a peak in the voltage amplitude as a function of current input at a nonzero (resonance) frequency ( f res). Although f res has been correlated to the network frequency ( f net) in a variety of systems, a causal relationship between the two has not been established. We examine the hypothesis that combinations of biophysical parameters that shift f res, without changing other attributes of the impedance profile, also shift f net in the same direction. We test this hypothesis, computationally and experimentally, in an electrically coupled network consisting of intrinsic oscillator (O) and resonator (R) neurons. We use a two-cell model of such a network to show that increasing f res of R directly increases f net and that this effect becomes more prominent if the amplitude of resonance is increased. Notably, the effect of f res on f net is independent of the parameters that define the oscillator or the combination of parameters in R that produce the shift in f res, as long as this combination produces the same impedance vs. frequency relationship. We use the dynamic clamp technique to experimentally verify the model predictions by connecting a model resonator to the pacemaker pyloric dilator neurons of the crab Cancer borealis pyloric network using electrical synapses and show that the pyloric network frequency can be shifted by changing f res in the resonator. Our results provide compelling evidence that f res and resonance amplitude strongly influence fnet, and therefore, modulators may target these attributes to modify rhythmic activity.

Accommodative reactions of medullary respiratory neurons of the cat

1975 ◽  
Vol 38 (5) ◽  
pp. 1172-1180 ◽  
Author(s):  
D. W. Richter ◽  
F. Heyde
Keyword(s):  
Membrane Potential ◽  
Synaptic Input ◽  
Early Period ◽  
Rhythmic Activity ◽  
Respiratory Neurons ◽  
Current Frequency ◽  
Burst Discharge ◽  
Current Pulses ◽  
Medullary Respiratory Neurons ◽  
Frequency Relationship

In most of the bulbospinal respiratory neurons, threshold depolarization increased during the early period of their spontaneous burst discharge but decreased again at the end of a burst. In some vagal respiratory neurons, however, threshold depolarization increased steadily until the very end of their discharge period. These changes generally were accompanied by changes in the rate of depol1rization of the spikes, the amplitude of their overshoot, and their discharge frequency. For a given synaptic input, as indicated by the constancy of the interspike membrane potential trajectories, threshold depolarization of bulbospinal neurons remained constant or even decreased. Only in some vagal neurons was an increase in threshold deplarization observed under these conditions. With the exception of some vagal neurons, most of the respiratory neurons did not show a pronounced accommodative behavior when stimulated with linear rising currents. When stimulating with current pulses, all neurons discharged repetitively with only slight adaptation, which was already complete by the first few spike intervals. The current-frequency relationship was linear and revealed a primary and secondary range. The results support neither accommodation nor adaptation as important mechanisms in the genesis of the rhythmic activity of respiratory neurons.

scholarly journals Minimal model of arterial chaos generated by coupled intracellular and membrane Ca2+oscillators

1999 ◽  
Vol 277 (3) ◽  
pp. H1119-H1144 ◽  
Author(s):  
D. Parthimos ◽  
D. H. Edwards ◽  
T. M. Griffith
Keyword(s):  
Mathematical Model ◽  
Membrane Potential ◽  
Cell Membrane ◽  
Wide Spectrum ◽  
Period Doubling ◽  
Rhythmic Activity ◽  
Vascular Response ◽  
Rabbit Ear ◽  
Dual Action ◽  
Dynamic Variables

We have developed a mathematical model of arterial vasomotion in which irregular rhythmic activity is generated by the nonlinear interaction of intracellular and membrane oscillators that depend on cyclic release of Ca2+ from internal stores and cyclic influx of extracellular Ca2+, respectively. Four key control variables were selected on the basis of the pharmacological characteristics of histamine-induced vasomotion in rabbit ear arteries: Ca2+ concentration in the cytosol, Ca2+ concentration in ryanodine-sensitive stores, cell membrane potential, and the open state probability of Ca2+-activated K+ channels. Although not represented by independent dynamic variables, the model also incorporates Na+/Ca2+exchange, the Na+-K+-ATPase, Cl− fluxes, and Ca2+ efflux via the extrusion ATPase. Simulations reproduce a wide spectrum of experimental observations, including 1) the effects of interventions that modulate the functionality of Ca2+ stores and membrane ion channels, 2) paradoxes such as the apparently unpredictable dual action of Ca2+ antagonists and low extracellular Na+ concentration, which can abolish vasomotion or promote the appearance of large-amplitude oscillations, and 3) period-doubling, quasiperiodic, and intermittent routes to chaos. Nonlinearity is essential to explain these diverse patterns of experimental vascular response.

Nonspiking interneurons in walking system of the cockroach

1975 ◽  
Vol 38 (1) ◽  
pp. 33-52 ◽  
Author(s):  
K. G. Pearson ◽  
C. R. Fourtner
Keyword(s):  
Membrane Potential ◽  
Periplaneta Americana ◽  
Rhythmic Activity ◽  
Synaptic Activity ◽  
Cobalt Sulfide ◽  
Resting Membrane Potential ◽  
Cellular Mechanisms ◽  
Metathoracic Ganglion ◽  
Nonspiking Interneurons ◽  
Leg Movements

Intracellular recordings were made from the neurites of interneurons and motoneurons in the metathoracic ganglion of the cockroach, Periplaneta americana. Many neurons were penetrated which failed to produce action potentials on the application of large depolarizing currents. Nevertheless, some of them strongly excited and/or inhibited slow motoneurons innervating leg musculature, even with weak depolariziing musculature, even with weak depolarizing currents. Cobalt-sulfide-straining of these nonspiking neurons showed them to be interneurons with their neurites contained entirely within the metathoracic ganglion. Two further characteristics of these interneurons were rapid spontaneous fluctuations in membrane potential and a low resting membrane potential. One nonspiking neuron, interneuron I, when depolarized caused a strong excitation of the set of slow levator motoneurons which discharge in bursts during stepping movements of the metathoracic leg. During rhythmic leg movements the membrane potential of interneuron I oscillated with the depolarizing phases occurring at the same time as bursts of activity in the levator motorneurons. No spiking or any other nonspiking neuron was penetrated which could excite these levator motoneurons. From all these observations we conclude that oscillations in the membrane potential of interneuron I are entirely responsible for producing the levator bursts, and thus for producing stepping movements in a walking animal. During rhythmic leg movements, bursts of activity in levator and depressor motoneurons are initiated by slow graded depolarizations. The similarity of the synaptic activity in these two types of motoneurons suggests that burst activity in the depressor motoneurons is also produced by rhythmic activity in nonspiking interneurons. The fact that no spiking neuron was found to excite the depressor motoneurons supports this conclusion. Interneuron I is also an element of the rhythm-generating system, since short depolarizing pulses applied to it during rhythmic activity could reset the thythm. Long-duration current pulses applied to interneuron I in a quiescent animal did not produce rhythmic activity. This observation, together with the finding that during rhythmic activity the slow depolarizations in interneuron I are usually terminated by IPSPs, suggests that interneuron I alone does not generate the rhythm. No spiking interneurons have yet been enccountered which influence the activity in levator motoneurons. Thus, we conclude that the rhythm is generated in a network of nonspiking interneurons. The cellular mechanisms for generating the oscillations in this network are unknown. Continued.

scholarly journals Sensory Regulation of Network Components Underlying Ciliary Locomotion in Hermissenda

2008 ◽  
Vol 100 (5) ◽  
pp. 2496-2506 ◽  
Author(s):  
Terry Crow ◽  
Lian-Ming Tian
Keyword(s):  
Neural Network ◽  
Spike Activity ◽  
Electrical Coupling ◽  
Rhythmic Activity ◽  
Burst Activity ◽  
Type I ◽  
Sensory Regulation ◽  
The Neural Network ◽  
Efferent Neurons ◽  
Ciliary Locomotion

Ciliary locomotion in the nudibranch mollusk Hermissenda is modulated by the visual and graviceptive systems. Components of the neural network mediating ciliary locomotion have been identified including aggregates of polysensory interneurons that receive monosynaptic input from identified photoreceptors and efferent neurons that activate cilia. Illumination produces an inhibition of type Ii (off-cell) spike activity, excitation of type Ie (on-cell) spike activity, decreased spike activity in type IIIi inhibitory interneurons, and increased spike activity of ciliary efferent neurons. Here we show that pairs of type Ii interneurons and pairs of type Ie interneurons are electrically coupled. Neither electrical coupling or synaptic connections were observed between Ie and Ii interneurons. Coupling is effective in synchronizing dark-adapted spontaneous firing between pairs of Ie and pairs of Ii interneurons. Out-of-phase burst activity, occasionally observed in dark-adapted and light-adapted pairs of Ie and Ii interneurons, suggests that they receive synaptic input from a common presynaptic source or sources. Rhythmic activity is typically not a characteristic of dark-adapted, light-adapted, or light-evoked firing of type I interneurons. However, burst activity in Ie and Ii interneurons may be elicited by electrical stimulation of pedal nerves or generated at the offset of light. Our results indicate that type I interneurons can support the generation of both rhythmic activity and changes in tonic firing depending on sensory input. This suggests that the neural network supporting ciliary locomotion may be multifunctional. However, consistent with the nonmuscular and nonrhythmic characteristics of visually modulated ciliary locomotion, type I interneurons exhibit changes in tonic activity evoked by illumination.

scholarly journals Episodic Bouts of Activity Accompany Recovery of Rhythmic Output By a Neuromodulator- and Activity-Deprived Adult Neural Network

2003 ◽  
Vol 90 (4) ◽  
pp. 2720-2730 ◽  
Author(s):  
Jason A. Luther ◽  
Alice A. Robie ◽  
John Yarotsky ◽  
Christopher Reina ◽  
Eve Marder ◽  
...  
Keyword(s):  
Neural Network ◽  
Neuronal Network ◽  
Recovery Process ◽  
Stomatogastric Ganglion ◽  
Cancer Borealis ◽  
Pyloric Network ◽  
Underlying Mechanisms ◽  
Over Time ◽  
Phase Relationships ◽  
Pyloric Rhythm

The pyloric rhythm of the stomatogastric ganglion of the crab, Cancer borealis, slows or stops when descending modulatory inputs are acutely removed. However, the rhythm spontaneously resumes after one or more days in the absence of neuromodulatory input. We recorded continuously for days to characterize quantitatively this recovery process. Activity bouts lasting 40–900 s began several hours after removal of neuromodulatory input and were followed by stable rhythm recovery after 1–4 days. Bout duration was not related to the intervals (0.3–800 min) between bouts. During an individual bout, the frequency rapidly increased and then decreased more slowly. Photoablation of back-filled neuromodulatory terminals in the stomatogastric ganglion (STG) neuropil had no effect on activity bouts or recovery, suggesting that these processes are intrinsic to the STG neuronal network. After removal of neuromodulatory input, the phase relationships of the components of the triphasic pyloric rhythm were altered, and then over time the phase relationships moved toward their control values. Although at low pyloric rhythm frequency the phase relationships among pyloric network neurons depended on frequency, the changes in frequency during recovery did not completely account for the change in phase seen after rhythm recovery. We suggest that activity bouts represent underlying mechanisms controlling the restructuring of the pyloric network to allow resumption of an appropriate output after removal of neuromodulatory input.

scholarly journals Glucose Sensitivity and Metabolism-Secretion Coupling Studied during Two-Year Continuous Culture in INS-1E Insulinoma Cells

Endocrinology ◽  
2004 ◽  
Vol 145 (2) ◽  
pp. 667-678 ◽  
Author(s):  
Arnaud Merglen ◽  
Sten Theander ◽  
Blanca Rubi ◽  
Gaelle Chaffard ◽  
Claes B. Wollheim ◽  
...  
Keyword(s):  
Membrane Potential ◽  
Electrical Activity ◽  
Cell Model ◽  
Cell Voltage ◽  
Resting Potential ◽  
Cell Phenotype ◽  
Similar Degree ◽  
Β Cell ◽  
Patch Clamp Technique ◽  
Insulinoma Cells

Abstract Rat insulinoma-derived INS-1 cells constitute a widely used β-cell surrogate. However, due to their nonclonal nature, INS-1 cells are heterogeneous and are not stable over extended culture periods. We have isolated clonal INS-1E cells from parental INS-1 based on both their insulin content and their secretory responses to glucose. Here we describe the stable differentiated INS-1E β-cell phenotype over 116 passages (no. 27–142) representing a 2.2-yr continuous follow-up. INS-1E cells can be safely cultured and used within passages 40–100 with average insulin contents of 2.30 ± 0.11 μg/million cells. Glucose-induced insulin secretion was dose-related and similar to rat islet responses. Secretion saturated with a 6.2-fold increase at 15 mm glucose, showing a 50% effective concentration of 10.4 mm. Secretory responses to amino acids and sulfonylurea were similar to those of islets. Moreover, INS-1E cells retained the amplifying pathway, as judged by glucose-evoked augmentation of insulin release in a depolarized state. Regarding metabolic parameters, INS-1E cells exhibited glucose dose-dependent elevations of NAD(P)H, cytosolic Ca2+, and mitochondrial Ca2+ levels. In contrast, mitochondrial membrane potential, ATP levels, and cell membrane potential were all fully activated by 7.5 mm glucose. Using the perforated patch clamp technique, 7.5 and 15 mm glucose elicited electrical activity to a similar degree. A KATP current was identified in whole cell voltage clamp using diazoxide and tolbutamide. As in native β-cells, tolbutamide induced electrical activity, indicating that the KATPconductance is important in setting the resting potential. Therefore, INS-1E cells represent a stable and valuable β-cell model.

scholarly journals Electrical coupling and innexin expression in the stomatogastric ganglion of the crabCancer borealis

2014 ◽  
Vol 112 (11) ◽  
pp. 2946-2958 ◽  
Author(s):  
Sonal Shruti ◽  
David J. Schulz ◽  
Kawasi M. Lett ◽  
Eve Marder
Keyword(s):  
Sequence Similarity ◽  
Electrical Coupling ◽  
Homarus Americanus ◽  
Stomatogastric Ganglion ◽  
Electrical Synapse ◽  
Coupling Coefficients ◽  
Cancer Borealis ◽  
Electrophysiological Recordings ◽  
Pyloric Dilator ◽  
Lateral Posterior

Gap junctions are intercellular channels that allow for the movement of small molecules and ions between the cytoplasm of adjacent cells and form electrical synapses between neurons. In invertebrates, the gap junction proteins are coded for by the innexin family of genes. The stomatogastric ganglion (STG) in the crab Cancer borealis contains a small number of identified and electrically coupled neurons. We identified Innexin 1 ( Inx1), Innexin 2 (Inx2), Innexin 3 (Inx3), Innexin 4 ( Inx4), Innexin 5 (Inx5), and Innexin 6 ( Inx6) members of the C. borealis innexin family. We also identified six members of the innexin family from the lobster Homarus americanus transcriptome. These innexins show significant sequence similarity to other arthropod innexins. Using in situ hybridization and reverse transcriptase-quantitative PCR (RT-qPCR), we determined that all the cells in the crab STG express multiple innexin genes. Electrophysiological recordings of coupling coefficients between identified pairs of pyloric dilator (PD) cells and PD-lateral posterior gastric (LPG) neurons show that the PD-PD electrical synapse is nonrectifying while the PD-LPG synapse is apparently strongly rectifying.

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