Burst reset and frequency control of the neuronal oscillators in the cardiac ganglion of the crab, Portunus sanguinolentus

1980 ◽  
Vol 87 (1) ◽  
pp. 285-313
Author(s):  
J. A. Benson
Keyword(s):  
Action Potential ◽  
Current Pulse ◽  
Relaxation Oscillator ◽  
Phase Shifts ◽  
Cardiac Ganglion ◽  
Response Curves ◽  
Pacemaker Potential ◽  
Current Pulses ◽  
Potential Activity ◽  
Driver Potential

1. The five large and four small neurones in the cardiac ganglion of the crab, Portunus, are electrotonically coupled and behave as a single relaxation oscillator, exhibiting periodic bursting activity in vitro. Recorded from the large neurone somata, this activity consists of 200-400 ms slow depolarizations called ‘driver potentials’ (Tazaki & Cooke, 1979a), accompanied by attenuated action potentials and EPSP's from small neurone input. 2. There is a strong positive correlation between the duration of the driver potential and the duration of the following interburst interval in the spontaneously active ganglion. This correlation is preserved during prolonged depolarization and hyperpolarization. 3. When a driver potential is prematurely terminated by an injected current pulse, the following interburst interval is shortened in direct proportion to the decrease in driver potential duration. 4. When a driver potential or a burst of high-frequency action potential activity is evoked by a depolarizing current pulse, the cardiac oscillator resets to the point of maximum hyperpolarization of the burst cycle, and the following interburst interval is of normal duration. Resetting following an evoked driver potential is complete. Partial resetting occurs only after short, evoked action potential bursts in the absence of a driver potential. 5. Reset of the oscillator causes phase shifts in the subsequent cycles of activity, which vary with the phase of application and duration of the injected current pulse. Response curves have been constructed for a comprehensive range of durations and intensities of hyperpolarizing and depolarizing current pulses applied at all phases of the oscillator cycle. 6. The phase shifts are composed of contributions from the duration of the current pulse, from the premature initiation of the slow depolarizing pacemaker potential due to early termination of the burst, and from the change in interburst interval correlated with truncation of the driver potential. 7. Considering the cardiac ganglion as a relaxation oscillator, frequencey control by entrainment to periodically applied current pulses was quantitatively predicted from the phase-response curves and experimentally confirmed. 8. A high concentration (10(−5) M) of octopamine can inhibit driver potential activity in the large neurones. This was used to examine possible frequency modulating effects of electrotonic feedback from the large neurone driver potentials onto the small neurone pacemaker activity. 9. The observations are discussed in relation to the ionic model for driver potentials and slow pacemaker potential activity in the cardiac ganglion, as proposed by Tazaki & Cooke (1979a, b).

Properties of subthreshold response and action potential recorded in layer V neurons from cat sensorimotor cortex in vitro

1984 ◽  
Vol 52 (2) ◽  
pp. 244-263 ◽  
Author(s):  
C. E. Stafstrom ◽  
P. C. Schwindt ◽  
J. A. Flatman ◽  
W. E. Crill
Keyword(s):  
Action Potential ◽  
Current Pulse ◽  
Sensorimotor Cortex ◽  
Sodium Current ◽  
Resting Potential ◽  
Constant Current ◽  
Inward Rectification ◽  
Current Pulses ◽  
Layer V

Properties of the action potential and subthreshold response were studied in large layer V neurons in in vitro slices of cat sensorimotor cortex using intracellular recording and stimulation, application of agents that block active conductances, and a single-microelectrode voltage clamp (SEVC). A variety of measured parameters, including action-potential duration, afterpotentials, input resistance, rheobase, and membrane time constant, were similar to the same parameters reported for large neurons from this region of cortex in vivo. Action-potential amplitudes and resting potentials were greater in vitro. Most measured parameters were distributed unimodally, suggesting that these parameters are similar in all large layer V neurons irrespective of their axonal termination. The voltage response to subthreshold constant-current pulses exhibited both time and voltage dependence in the great majority of cells. Current pulses in either the hyperpolarizing or subthreshold depolarizing direction cause the membrane potential to attain an early peak and then decay (sag) to a steady level. On termination of the pulse, the membrane response transiently overshoots resting potential. Plots of current-voltage relations demonstrate inward rectification during polarization on either side of resting potential. Subthreshold inward rectification in the depolarizing direction is abolished by tetrodotoxin (TTX). The ionic currents responsible for subthreshold rectification and sag were examined using the SEVC. Steady inward rectification in the depolarizing direction is caused by a persistent, subthreshold sodium current (INaP) (54). Sag observed in response to a depolarizing current pulse is due to activation of a slow outward current, which superimposes on and partially counters the persistent sodium current. Both sag in response to hyperpolarizing current pulses and rectification in the hyperpolarizing direction are caused by a slow inward "sag current" that is activated by hyperpolarizing voltage steps. The sag current is unaltered by TTX, tetraethylammonium, (TEA), Co2+, Ba2+, or 4-aminopyridine. Fast-rising, short-duration action potentials can be elicited by an intracellular current pulse or by orthodromic or antidromic stimulation. Spikes are blocked by TTX. The form of the afterpotential following a directly evoked spike varies among cells with similar resting potentials. Biphasic afterhyperpolarizations (AHPs) with fast and slow components were most frequently seen. About 30% of the cells displayed a depolarizing afterpotential (DAP), which was often followed by an AHP. Other cells displayed a purely monophasic AHP.(ABSTRACT TRUNCATED AT 400 WORDS)

scholarly journals General Anaesthesia Shifts the Murine Circadian Clock in a Time-Dependant Fashion

2021 ◽  
Vol 3 (1) ◽  
pp. 87-97
Author(s):  
Nicola M. Ludin ◽  
Alma Orts-Sebastian ◽  
James F. Cheeseman ◽  
Janelle Chong ◽  
Alan F. Merry ◽  
...  
Keyword(s):  
Circadian Clock ◽  
General Anaesthesia ◽  
Wheel Running ◽  
Phase Shifts ◽  
Time Dependent ◽  
Suprachiasmatic Nuclei ◽  
Response Curves ◽  
Inhalational Anaesthetic ◽  
Locomotor Rhythms ◽  
Time Dependent Analysis

Following general anaesthesia (GA), patients frequently experience sleep disruption and fatigue, which has been hypothesized to result at least in part by GA affecting the circadian clock. Here, we provide the first comprehensive time-dependent analysis of the effects of the commonly administered inhalational anaesthetic, isoflurane, on the murine circadian clock, by analysing its effects on (a) behavioural locomotor rhythms and (b) PER2::LUC expression in the suprachiasmatic nuclei (SCN) of the mouse brain. Behavioural phase shifts elicited by exposure of mice (n = 80) to six hours of GA (2% isoflurane) were determined by recording wheel-running rhythms in constant conditions (DD). Phase shifts in PER2::LUC expression were determined by recording bioluminescence in organotypic SCN slices (n = 38) prior to and following GA exposure (2% isoflurane). Full phase response curves for the effects of GA on behaviour and PER2::LUC rhythms were constructed, which show that the effects of GA are highly time-dependent. Shifts in SCN PER2 expression were much larger than those of behaviour (c. 0.7 h behaviour vs. 7.5 h PER2::LUC). We discuss the implications of this work for understanding how GA affects the clock, and how it may inform the development of chronotherapeutic strategies to reduce GA-induced phase-shifting in patients.

Magnification curves of electromagnetic seismographs

1964 ◽  
Vol 54 (5A) ◽  
pp. 1459-1471
Author(s):  
S. K. Chakrabarty ◽  
G. C. Choudhury ◽  
S. N. Roy Choudhury
Keyword(s):  
General Solution ◽  
Frequency Response ◽  
Experimental Method ◽  
Phase Shifts ◽  
Response Curves ◽  
Operating Condition ◽  
Coil Inductance ◽  
The World ◽  
Electromagnetic Seismograph ◽  
Proper Design

Abstract The general solution of the equations connecting the motion of the two coupled components in an electromagnetic seismograph has been obtained in another paper and it shows that the magnification of a seismograph depend on seven instrumental constants. Using these results, equations and curves have been derived in the present paper from which the Magnification as well as Phase shifts in the response of a seismograph and their variations with damping and coil inductance can be easily obtained. Based on these curves a number of magnification curves for different combinations, which are in operation at the different seismological stations of the world, have been derived. Suitable equations and curves have also been obtained which can be used for estimating the absolute Magnification of a Seismograph. An experimental method of obtaining the frequency response curves of seismographs in their operating condition has been described and the results obtained by this method has been given. It has been indicated how the results incorporated in the present paper can be used in the proper design of seismographs required for the different purposes.

scholarly journals Epigenome Interactions with Patterned Neuronal Activity

2018 ◽  
Vol 24 (5) ◽  
pp. 471-485 ◽  
Author(s):  
Jillian Belgrad ◽  
R. Douglas Fields
Keyword(s):  
Gene Expression ◽  
Action Potential ◽  
Neural Development ◽  
Intracellular Signaling ◽  
Regulation Of Gene Expression ◽  
Temporal Coding ◽  
Dna Breaks ◽  
Action Potential Firing ◽  
Potential Activity ◽  
Activity Dependent

The temporal coding of action potential activity is fundamental to nervous system function. Here we consider how gene expression in neurons is regulated by specific patterns of action potential firing, with an emphasis on new information on epigenetic regulation of gene expression. Patterned action potential activity activates intracellular signaling networks selectively in accordance with the kinetics of activation and inactivation of second messengers, phosphorylation and dephosphorylation of protein kinases, and cytoplasmic and nuclear calcium dynamics, which differentially activate specific transcription factors. Increasing evidence also implicates activity-dependent regulation of epigenetic mechanisms to alter chromatin architecture. Changes in three-dimensional chromatin structure, including chromatin compaction, looping, double-stranded DNA breaks, histone and DNA modification, are altered by action potential activity to selectively inhibit or promote transcription of specific genes. These mechanisms of activity-dependent regulation of gene expression are important in neural development, plasticity, and in neurological and psychological disorders.

Effect of electric current pulse type on springback, microstructure, texture, and mechanical properties during V-bending of AA2024 aluminum alloy

2020 ◽  
pp. 1-36
Author(s):  
Nafiseh Mohammadtabar ◽  
Mohammad Bakhshi-jooybari ◽  
Hamid Gorji ◽  
Roohollah Jamaati ◽  
Jerzy A. Szpunar
Keyword(s):  
Mechanical Properties ◽  
Aluminum Alloy ◽  
Electric Current ◽  
Current Pulse ◽  
Fiber Texture ◽  
Electric Current Pulse ◽  
Electric Pulses ◽  
Current Pulses ◽  
Electric Current Pulses ◽  
Pulse Type

Abstract The present work focused on the effect of the electric current pulse type on the springback, microstructure, texture, and mechanical properties during the V-bending process of AA2024 aluminum alloy. In order to investigate this effect, three different forming conditions including conventional V-bending and electrically assisted V-bending with square and sinusoidal pulses were considered. The results indicated that the amount of springback significantly decreased from 45.5° (for the sample formed via conventional V-bending) to 24° by applying the sinusoidal pulse. Microstructural observations revealed lower stored energy in the samples formed by electric current pulses which resulted in larger grain size compared to the samples formed without electric pulses. In addition, the result showed that the intensity of the (111)||BLD (bend line direction) fiber texture reduced after applying electric current pulses whereas it was very strong in the sample formed without electric pulses. It was suggested that the electric current pulses led to change the slip plane of the dislocations from {111} to {110} through cross slip. The applying electric current pulses decrease the ultimate tensile strength (UTS) from 471.1 MPa (for the conventional tensile test) to 448.0 and 426.7 MPa for the square and sinusoidal pulses, respectively. On the other hand, the electric pulses improved the formability of the AA2024 alloy owing to the activation of more slip systems, inhibition of dislocation pinning, the promotion of dislocation movement, and the acceleration of restoration mechanisms.

Afterhyperpolarization Current in Myenteric Neurons of the Guinea Pig Duodenum

2001 ◽  
Vol 85 (5) ◽  
pp. 1941-1951 ◽  
Author(s):  
Fivos Vogalis ◽  
John B. Furness ◽  
Wolf A. A. Kunze
Keyword(s):  
Guinea Pig ◽  
Action Potential ◽  
Dwell Time ◽  
High Probability ◽  
Resting Potential ◽  
Bathing Solution ◽  
Inward Current ◽  
Current Pulses ◽  
Mean Variance ◽  
Small Conductance

Whole cell patch and cell-attached recordings were obtained from neurons in intact ganglia of the myenteric plexus of the guinea pig duodenum. Two classes of neuron were identified electrophysiologically: phasically firing AH neurons that had a pronounced slow afterhyperpolarization (AHP) and tonically firing S neurons that lacked a slow AHP. We investigated the properties of the slow AHP and the underlying current ( I AHP) to address the roles of Ca2+ entry and Ca2+ release in the AHP and the characteristics of the K+channels that are activated. AH neurons had a resting potential of −54 mV and the AHP, which followed a volley of three suprathreshold depolarizing current pulses delivered at 50 Hz through the pipette, averaged 11 mV at its peak, which occurred 0.5–1 s following the stimulus. The duration of these AHPs averaged 7 s. Under voltage-clamp conditions, I AHP's were recorded at holding potentials of −50 to −65 mV, following brief depolarization of AH neurons (20–100 ms) to positive potentials (+35 to +50 mV). The null potential of the I AHP at its peak was −89 mV. The AHP and I AHP were largely blocked by ω-conotoxin GVIA (0.6–1 μM). Both events were markedly decreased by caffeine (2–5 mM) and by ryanodine (10–20 μM) added to the bathing solution. Pharmacological suppression of the I AHP with TEA (20 mM) or charybdotoxin (50–100 nM) unmasked an early transient inward current at −55 mV following step depolarization that reversed at −34 mV and was inhibited by niflumic acid (50–100 μM). Mean-variance analysis performed on the decay of the I AHPrevealed that the AHP K+ channels have a mean chord conductance of ∼10 pS, and there are ∼4,000 per AH neuron. Spectral analysis showed that the AHP channels have a mean open dwell time of 2.8 ms. Cell-attached patch recordings from AH neurons confirmed that the channels that open following action currents have a small unitary conductance (10–17 pS) and open with a high probability (≤0.5) within the first 2 s following an action potential. These results indicate that the AHP is largely a consequence of Ca2+ entry through ω-conotoxin GVIA-sensitive Ca2+ channels during the action potential, Ca2+-triggered Ca2+ release from caffeine-sensitive stores and the opening of Ca2+-sensitive small-conductance K+ channels.

scholarly journals Action-potential broadening and endogenously sustained bursting are substrates of command ability in a feeding neuron of Pleurobranchaea

1980 ◽  
Vol 43 (3) ◽  
pp. 669-685 ◽  
Author(s):  
R. Gillette ◽  
M. U. Gillette ◽  
W. J. Davis
Keyword(s):  
Action Potential ◽  
Action Potentials ◽  
Motor Output ◽  
Buccal Ganglion ◽  
Short Pulses ◽  
Motor Network ◽  
Single Axon ◽  
Network Output ◽  
Bilateral Pair ◽  
Potential Activity

1. The ventral white cells (VWC's) of the buccal ganglion of Pleurobranchaea, so named for their position and color, are a bilateral pair of neuron somata. Each sends a single axon out its contralateral stomatogastric nerve and has a dendritic field originating close to the soma. 2. The vwcs exhibit spontaneous episodes of prolonged depolarization (duration 1--4 min) accompanied by repetitive action-potential activity and separated by regular intervals of 3--30 min. Such prolonged burst episodes can be triggered by short pulses of depolarizing current. During the repetitive activity of the spontaneous bursts or that driven by imposed depolarization, the action potentials progressively broaden to 5--16 times their initial duration. 3. During spontaneous bursting or activity driven by imposed depolarization, the cyclic motor output of the feeding network is initiated or accelerated with a latency corresponding with the development of appreciable VWC spike broadening. When broadening of antidromic VWC spikes is suppressed by imposed hyperpolarization of the soma, the frequency of feeding cycles is significantly lower than when broadened spikes are allowed to develop. When trains of spikes are driven by depolarizing current, the motor output of the feeding network is not initiated until the VWC spikes have broadened to a repeatable "threshold" duration, regardless of the intensity of the depolarizing current. 4. The endogenous production of prolonged burst episodes, triggered by depolarizing current pulses, and progressive spike broadening can be demonstrated in the surgically isolated VWC soma. 5. The paired VWCs are strongly electrically coupled and display highly synchronous activity. They receive synaptic inputs from many previously identified interneurons of the feeding network and are thus reciprocally coupled within the network. 6. These results demonstrate that the capacity of this neuron to generate broadened action potentials during repetitive activity confers the ability to command coordinated motor-network output. The appropriate repetitive activity can be produced endogenously in the form of prolonged bursts of spikes.

Studies on bursting pacemaker potential activity in molluscan neurons. III. Effects of hormones

1975 ◽  
Vol 84 (3) ◽  
pp. 501-513 ◽  
Author(s):  
Jeffery L. Barker ◽  
Mark S. Ifshin ◽  
Harold Gainer
Keyword(s):  
Molluscan Neurons ◽  
Pacemaker Potential ◽  
Potential Activity

scholarly journals The Effect of Intracellular Current Pulses in Smooth Muscle Cells of the Guinea Pig Vas Deferens at Rest and during Transmission

1967 ◽  
Vol 50 (10) ◽  
pp. 2459-2475 ◽  
Author(s):  
M. R. Bennett
Keyword(s):  
Smooth Muscle ◽  
Guinea Pig ◽  
Action Potential ◽  
Smooth Muscle Cells ◽  
Vas Deferens ◽  
Electrical Coupling ◽  
Muscle Cells ◽  
Active Response ◽  
Current Pulses ◽  
Passive Response

The effect of intracellular current pulses on the membrane of smooth muscle cells of the guinea pig vas deferens at rest and during transmission was studied. Two main response types were identified: active response cells, in which a spike was initiated in response to depolarizing currents of sufficient strength and duration; passive response cells, in which depolarizing currents gave only electrotonic potential changes. These cells were three times more numerous than the active response cells. During the crest of the active response the input resistance fell by about 25% of the resting value. Comparison of the active response with the action potential due to stimulating the hypogastric nerve showed that the former was smaller in amplitude and had a slower rate of rise and higher threshold. Electrical coupling occurred between the smooth muscle cells during the propagation of the action potential. Depolarizing current pulses had no effect on the amplitude of the excitatory junction potential (E.J.P.) in passive response cells, but in general did decrease its amplitude in active response cells. These results are discussed with respect to the mechanism of autonomic neuroeffector transmission.

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