scholarly journals Respiratory motoneuron properties during the transition from gill to lung breathing in the American bullfrog

2019 ◽  
Vol 316 (3) ◽  
pp. R281-R297 ◽  
Author(s):  
Tara A. Janes ◽  
Stéphanie Fournier ◽  
Simon Chamberland ◽  
Gregory D. Funk ◽  
Richard Kinkead
Keyword(s):  
Action Potential ◽  
Input Resistance ◽  
Type I ◽  
Type Ii ◽  
Excitatory Postsynaptic Currents ◽  
Synaptic Inputs ◽  
Postsynaptic Currents ◽  
American Bullfrog ◽  
Action Potential Threshold ◽  
Potential Threshold

Amphibian respiratory development involves a dramatic metamorphic transition from gill to lung breathing and coordination of distinct motor outputs. To determine whether the emergence of adult respiratory motor patterns was associated with similarly dramatic changes in motoneuron (MN) properties, we characterized the intrinsic electrical properties of American bullfrog trigeminal MNs innervating respiratory muscles comprising the buccal pump. In premetamorphic tadpoles (TK stages IX–XVIII) and adult frogs, morphometric analyses and whole cell recordings were performed in trigeminal MNs identified by fluorescent retrograde labeling. Based on the amplitude of the depolarizing sag induced by hyperpolarizing voltage steps, two MN subtypes (I and II) were identified in tadpoles and adults. Compared with type II MNs, type I MNs had larger sag amplitudes (suggesting a larger hyperpolarization-activated inward current), greater input resistance, lower rheobase, hyperpolarized action potential threshold, steeper frequency-current relationships, and fast firing rates and received fewer excitatory postsynaptic currents. Postmetamorphosis, type I MNs exhibited similar sag, enhanced postinhibitory rebound, and increased action potential amplitude with a smaller-magnitude fast afterhyperpolarization. Compared with tadpoles, type II MNs from frogs received higher-frequency, larger-amplitude excitatory postsynaptic currents. Input resistance decreased and rheobase increased postmetamorphosis in all MNs, concurrent with increased soma area and hyperpolarized action potential threshold. We suggest that type I MNs are likely recruited in response to smaller, buccal-related synaptic inputs as well as larger lung-related inputs, whereas type II MNs are likely recruited in response to stronger synaptic inputs associated with larger buccal breaths, lung breaths, or nonrespiratory behaviors involving powerful muscle contractions.

Serotonin Modulates the Properties of Ascending Commissural Interneurons in the Neonatal Mouse Spinal Cord

2006 ◽  
Vol 95 (3) ◽  
pp. 1545-1555 ◽  
Author(s):  
Guisheng Zhong ◽  
Manuel Díaz-Ríos ◽  
Ronald M. Harris-Warrick
Keyword(s):  
Spinal Cord ◽  
Action Potential ◽  
Critical Role ◽  
Input Resistance ◽  
Pattern Generator ◽  
Neonatal Mouse ◽  
Fictive Locomotion ◽  
Motoneuron Pool ◽  
Action Potential Threshold ◽  
Potential Threshold

The interneuron populations that constitute the central pattern generator (CPG) for locomotion in the mammalian spinal cord are not well understood. We studied the properties of a set of commissural interneurons whose axons cross and ascend in the contralateral cord (aCINs) in the neonatal mouse. During N-methyl-d-aspartate (NMDA) and 5-HT–induced fictive locomotion, a majority of lumbar (L2) aCINs examined were rhythmically active; most of them fired in phase with the ipsilateral motoneuron pool, but some fired in phase with contralateral motoneurons. 5-HT plays a critical role in enabling the locomotor CPG to function. We found that 5-HT increased the excitability of aCINs by depolarizing the membrane potential, reducing the postspike afterhyperpolarization amplitude, broadening the action potential, and decreasing the action potential threshold. Serotonin had no significant effect on the input resistance and sag amplitude of aCINs. These results support the hypothesis that aCINs play important roles in coordinating left–right movements during fictive locomotion and thus may be component neurons in the locomotor CPG in neonatal mice.

Electrophysiology of globus pallidus neurons in vitro

1994 ◽  
Vol 72 (3) ◽  
pp. 1127-1139 ◽  
Author(s):  
A. Nambu ◽  
R. Llinas
Keyword(s):  
Globus Pallidus ◽  
Input Resistance ◽  
Repetitive Firing ◽  
Type I ◽  
Type Ii ◽  
Low Threshold ◽  
Membrane Oscillations ◽  
Neuronal Type ◽  
A Current ◽  
Membrane Level

1. We investigated the electrical properties of globus pallidus neurons intracellularly using brain slices from adult guinea pigs. Three types of neurons were identified according to their intrinsic electrophysiological properties. 2. Type I neurons (59%) were silent at the resting membrane level (-65 +/- 10 mV, mean +/- SD) and generated a burst of spikes, with strong accommodation, to depolarizing current injection. Calcium-dependent low-frequency (1-8 Hz) membrane oscillations were often elicited by membrane depolarization (-53 +/- 8 mV). A low-threshold calcium conductance and an A-current were also identified. The mean input resistance of this neuronal type was 70 +/- 22 M omega. 3. Type II neurons (37%) fired spontaneously at the resting membrane level (-59 +/- 9 mV). Their repetitive firing (< or = 200 Hz) was very sensitive to the amplitude of injected current and showed weak accommodation. Sodium-dependent high-frequency (20-100 Hz) subthreshold membrane oscillations were often elicited by membrane depolarization. This neuronal type demonstrated a low-threshold calcium spike and had the highest input resistance (134 +/- 62 M omega) of the three neuron types. 4. Type III neurons (4%) did not fire spontaneously at the resting membrane level (-73 +/- 5 mV). Their action potentials were characterized by a long duration (2.3 +/- 0.6 ms). Repetitive firing elicited by depolarizing current injection showed weak or no accommodation. This neuronal type had an A-current and showed the lowest input resistance (52 +/- 35 M omega) of the three neuron types. 5. Stimulation of the caudoputamen evoked inhibitory postsynaptic potentials (IPSPs) in Type I and II neurons. In Type II neurons the IPSPs were usually followed by rebound firing. Excitatory postsynaptic potentials and antidromic responses were also elicited in some Type I and II neurons. The estimated conduction velocity of the striopallidal projection was < 1 m/s (Type I neurons, 0.49 +/- 0.37 m/s; Type II neurons, 0.33 +/- 0.13 m/s).

scholarly journals Calcium-induced calcium release activates spontaneous miniature outward currents in newt medullary reticular formation neurons

2018 ◽  
Vol 120 (6) ◽  
pp. 3140-3154 ◽  
Author(s):  
Daniel B. Yaeger ◽  
Emma J. Coddington
Keyword(s):  
Action Potential ◽  
Reticular Formation ◽  
Calcium Release ◽  
Motor Behavior ◽  
Brain Slices ◽  
Medullary Reticular Formation ◽  
Outward Currents ◽  
Decay Times ◽  
Action Potential Threshold ◽  
Potential Threshold

Neurons in the medullary reticular formation are involved in the control of postural and locomotor behaviors in all vertebrates. Reticulospinal neurons in this brain region provide one of the major descending projections to the spinal cord. Although neurons in the newt medullary reticular formation have been extensively studied using in vivo extracellular recordings, little is known of their intrinsic biophysical properties or of the underlying circuitry of this region. Using whole cell patch-clamp recordings in brain slices containing the rostromedial reticular formation from adult male newts, we observed spontaneous miniature outward currents (SMOCs) in ~2/3 of neurons. Although SMOCs superficially resembled inhibitory postsynaptic currents (IPSCs), they had slower risetimes and decay times than spontaneous IPSCs. SMOCs required intracellular Ca2+ release from ryanodine receptors and were also dependent on the influx of extracellular Ca2+. SMOCs were unaffected by apamin but were partially blocked by iberiotoxin and charybdotoxin, indicating that SMOCs were mediated by big-conductance Ca2+-activated K+ channels. Application of the sarco/endoplasmic Ca2+ ATPase inhibitor cyclopiazonic acid blocked the generation of SMOCs and also increased neural excitability. Neurons with SMOCs had significantly broader action potentials, slower membrane time constants, and higher input resistance than neurons without SMOCs. Thus, SMOCs may serve as a mechanism to regulate action potential threshold in a majority of neurons within the newt medullary reticular formation. NEW & NOTEWORTHY The medullary reticular formation exerts a powerful influence on sensorimotor integration and subsequent motor behavior, yet little is known about the neurons involved. In this study, we identify a transient potassium current that regulates action potential threshold in a majority of medullary reticular neurons.

Electrophysiological Characteristics of Classes of Neuron in the HVc of the Zebra Finch

1998 ◽  
Vol 80 (2) ◽  
pp. 914-923 ◽  
Author(s):  
Michinori Kubota ◽  
Ikuo Taniguchi
Keyword(s):  
Action Potential ◽  
Zebra Finch ◽  
Action Potential Duration ◽  
The Other ◽  
Time Dependent ◽  
Inward Rectification ◽  
Type I ◽  
Type Ii ◽  
Type Iii ◽  
Type Iv

Kubota, Michinori and Ikuo Taniguchi. Electrophysiological characteristics of classes of neuron in the HVc of the zebra finch. J. Neurophysiol. 80: 914–923, 1998. Whole cell recordings were made from zebra finch HVc neurons in slice preparations. Four distinct classes of neuron were found on the basis of their electrophysiological properties. The morphological characteristics of some of these neurons were also examined by intracellular injection of Lucifer yellow. Type I neurons (21 of 65 cells) had longer time-to-peak of an afterhyperpolarization following an action potential than the other classes. They exhibited both fast and time-dependent inward rectification and an initial high-frequency firing followed by a slower constant firing. Type I neurons had large somata and thick dendrites with many spines. The axons of some of the neurons in this class projected in the direction of area X of the parolfactory lobe. Type II neurons (30 of 65 cells) had a more negative resting membrane potential than the other classes. They exhibited fast inward rectification. Type II neurons could be divided into two subclasses by the absence (IIa; 22 cells) and the presence (IIb; 8 cells) of a low-threshold transient depolarization. Type IIa neurons had relatively small somata and thin, spiny dendrites. The axons of some of the neurons in this class projected in the direction of the robust nucleus of the archistriatum (RA). Type IIb neurons had relatively large somata and thick dendrites with many spines. Type III neurons (6 of 65 cells) had a shorter action-potential duration than the other classes. They exhibited prominent time-dependent inward rectification and a regular tonic firing with little or no accommodation. Type III neurons had beaded, aspiny dendrites. Type IV neurons (8 of 65 cells) had a longer action-potential duration, a much larger input resistance, and longer membrane time constant than the other classes. Type IV neurons had small somata and thin, short, sparsely spiny dendrites. The axons of some of the neurons in this class projected in the direction of the RA. These classes of neuron may play distinct roles in song production and representation in the HVc.

scholarly journals Mathematical Distinction in Action Potential between Primo-Vessels and Smooth Muscle

2012 ◽  
Vol 2012 ◽  
pp. 1-6 ◽  
Author(s):  
Seong-Jin Cho ◽  
Sang-Hun Lee ◽  
Wenji Zhang ◽  
Sae-Bhom Lee ◽  
Kwang-Ho Choi ◽  
...  
Keyword(s):  
Fourier Transform ◽  
Smooth Muscle ◽  
Action Potential ◽  
Mathematical Analysis ◽  
Action Potentials ◽  
Type I ◽  
Type Ii ◽  
Analysis Method

We studied the action potential of Primo-vessels in rats to determine the electrophysiological characteristics of these structures. We introduced a mathematical analysis method, a normalized Fourier transform that displays the sine and cosine components separately, to compare the action potentials of Primo-vessels with those for the smooth muscle. We found that Primo-vessels generated two types of action potential pulses that differed from those of smooth muscle: (1) Type I pulse had rapid depolarizing and repolarizing phases, and (2) Type II pulse had a rapid depolarizing phase and a gradually slowing repolarizing phase.

Nitric oxide in glutamate-induced compound action potential threshold shifts

2008 ◽  
Vol 239 (1-2) ◽  
pp. 54-59 ◽  
Author(s):  
Mihir R. Patel ◽  
Jocelyn C. Stamat ◽  
Carlton J. Zdanski ◽  
Charles S. Ebert ◽  
Jiri Prazma
Keyword(s):  
Nitric Oxide ◽  
Action Potential ◽  
Compound Action Potential ◽  
Action Potential Threshold ◽  
Potential Threshold ◽  
Compound Action
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