Constant amplitude of postsynaptic responses for single presynaptic action potentials but not bursting input during growth of an identified neuromuscular junction in the lobster,Homarus americanus

2004 ◽  
Vol 62 (1) ◽  
pp. 47-61 ◽  
Author(s):  
Stefan R. Pulver ◽  
Dirk Bucher ◽  
David J. Simon ◽  
Eve Marder
Keyword(s):  
Neuromuscular Junction ◽  
Action Potentials ◽  
Homarus Americanus ◽  
Constant Amplitude ◽  
Presynaptic Action

Nerve, muscle, and neuromuscular junction

2016 ◽  
Author(s):  
Machiel J. Zwarts
Keyword(s):  
Nervous System ◽  
Ion Channels ◽  
Cell Membrane ◽  
Neuromuscular Junction ◽  
Action Potentials ◽  
Motor Responses ◽  
Selective Permeability ◽  
Nerve Muscle ◽  
Specialized Region ◽  
Human Nervous System

Essential to all living creatures is the ability to convey information. In addition motor responses are required, for example running. This all is possible due to the ability of specialized cells to conduct information along the cell membrane by means of action potentials (AP) made possible by the charged cell membrane, which has selective permeability for different ions. Voltage and ligand sensitive ion channels are responsible for sudden changes in selective permeability of the membrane resulting in local depolarization of the membrane. The neuromuscular junction is a highly specialized region of the distal motor axon that is responsible for the transferring of activation from nerve to muscle. All these systems and subsystems can fail and a thorough understanding is necessary in order to understand the changes a clinical neurophysiologist can encounter while recording from the human nervous system in cases of disorders of brain, nerve and muscle.

scholarly journals Large, stable spikes exhibit differential broadening in excitatory and inhibitory neocortical boutons

2020 ◽  
Author(s):  
Andreas Ritzau-Jost ◽  
Timur Tsintsadze ◽  
Martin Krueger ◽  
Jonas Ader ◽  
Ingo Bechmann ◽  
...  
Keyword(s):  
Patch Clamp ◽  
High Frequency ◽  
Neurotransmitter Release ◽  
Action Potentials ◽  
Pyramidal Neurons ◽  
Cultured Neurons ◽  
Presynaptic Action ◽  
Presynaptic Spike ◽  
Fast Spiking

SUMMARYPresynaptic action potential spikes control neurotransmitter release and thus interneuronal communication. However, the properties and the dynamics of presynaptic spikes in the neocortex remain enigmatic because boutons in the neocortex are small and direct patch-clamp recordings have not been performed. Here we report direct recordings from boutons of neocortical pyramidal neurons and interneurons. Our data reveal rapid and large presynaptic action potentials in layer 5 neurons and fast-spiking interneurons reliably propagating into axon collaterals. For in-depth analyses we validate boutons of mature cultured neurons as models for excitatory neocortical boutons, demonstrating that the presynaptic spike amplitude was unaffected by potassium channels, homeostatic long-term plasticity, and high-frequency firing. In contrast to the stable amplitude, presynaptic spikes profoundly broadened for example during high-frequency firing in layer 5 pyramidal neurons but not in fast-spiking interneurons. Thus, our data demonstrate large presynaptic spikes and fundamental differences between excitatory and inhibitory boutons in the neocortex.

scholarly journals Presynaptic potentials and facilitation of transmitter release in the squid giant synapse.

1978 ◽  
Vol 72 (4) ◽  
pp. 487-511 ◽  
Author(s):  
M P Charlton ◽  
G D Bittner
Keyword(s):  
Transmitter Release ◽  
Action Potentials ◽  
Presynaptic Action ◽  
Squid Giant Synapse ◽  
Giant Synapse ◽  
Pulse Stimulation

Presynaptic potentials were studied during facilitation of transmitter release in the squid giant synapse. Changes in action potentials were found to cause some, but not all, of the facilitation during twin-pulse stimulation. During trains of action potentials, there were no progressive changes in presynaptic action potentials which could account for the growth of facilitation. Facilitation could still be detected in terminals which had undergone conditioning depolarization or hyperpolarization. Facilitation could be produced by small action potentials in low [Ca++]o and by small depolarizations in the presence of tetrodotoxin. Although the production of facilitation varied somewhat with presynaptic depolarization, nevertheless, approximately equal amounts of facilitation could be produced by depolarizations which caused the release of very different amounts of transmitter.

Different VAMP/Synaptobrevin Complexes for Spontaneous and Evoked Transmitter Release at the Crayfish Neuromuscular Junction

1998 ◽  
Vol 80 (6) ◽  
pp. 3233-3246 ◽  
Author(s):  
Shao-Ying Hua ◽  
Dorota A. Raciborska ◽  
William S. Trimble ◽  
Milton P. Charlton
Keyword(s):  
Neuromuscular Junction ◽  
Transmitter Release ◽  
Neurotransmitter Release ◽  
Action Potentials ◽  
Neuromuscular Junctions ◽  
Spontaneous Release ◽  
Intracellular Ca ◽  
Crayfish Neuromuscular Junction ◽  
Evoked Transmitter Release

Hua, Shao-Ying, Dorota A. Raciborska, William S. Trimble, and Milton P. Charlton. Different VAMP/synaptobrevin complexes for spontaneous and evoked transmitter release at the crayfish neuromuscular junction. J. Neurophysiol. 80: 3233–3246, 1998. Although vesicle-associated membrane protein (VAMP/synaptobrevin) is essential for evoked neurotransmitter release, its role in spontaneous transmitter release remains uncertain. For instance, many studies show that tetanus toxin (TeNT), which cleaves VAMP, blocks evoked transmitter release but leaves some spontaneous transmitter release. We used recombinant tetanus and botulinum neurotoxin catalytic light chains (TeNT-LC, BoNT/B-LC, and BoNT/D-LC) to examine the role of VAMP in spontaneous transmitter release at neuromuscular junctions (nmj) of crayfish. Injection of TeNT-LC into presynaptic axons removed most of the VAMP immunoreactivity and blocked evoked transmitter release without affecting nerve action potentials or Ca2+ influx. The frequency of spontaneous transmitter release was little affected by the TeNT-LC when the evoked transmitter release had been blocked by >95%. The spontaneous transmitter release left after TeNT-LC treatment was insensitive to increases in intracellular Ca2+. BoNT/B-LC, which cleaves VAMP at the same site as TeNT-LC but uses a different binding site, also blocked evoked release but had minimal effect on spontaneous release. However, BoNT/D-LC, which cleaves VAMP at a different site from the other two toxins but binds to the same position on VAMP as TeNT, blocked both evoked and spontaneous transmitter release at similar rates. The data indicate that different VAMP complexes are employed for evoked and spontaneous transmitter release; the VAMP used in spontaneous release is not readily cleaved by TeNT or BoNT/B. Because the exocytosis that occurs after the action of TeNT cannot be increased by increased intracellular Ca2+, the final steps in neurotransmitter release are Ca2+ independent.

Excitation of identified serotonergic neurons by escape command neurons in lobsters.

1997 ◽  
Vol 200 (14) ◽  
pp. 2017-2033 ◽  
Author(s):  
M Hörner ◽  
W A Weiger ◽  
D H Edwards ◽  
E A Kravitz
Keyword(s):  
Action Potentials ◽  
Giant Axon ◽  
Homarus Americanus ◽  
Excitatory Input ◽  
Plateau Phase ◽  
Command Neurons ◽  
Substantial Variation ◽  
Giant Fiber ◽  
Neurosecretory Neurons ◽  
Sufficient Magnitude

Serotonin-containing neurosecretory neurons in the first abdominal ganglion (A1 5-HT cells) of the lobster (Homarus americanus) ventral nerve cord have been shown previously to function as 'gain setters' in postural, slow muscle, command neuron circuitries. Here we show that these same amine neurons receive excitatory input from lateral (LG) and medial (MG) giant axons, which are major interneurons in phasic, fast muscle systems. Activation of either LG or MG axons elicits short-latency, non-fatiguing, long-lasting excitatory postsynaptic potentials (EPSPs) in A1 5-HT cells which follow stimulus frequencies of up to 100 Hz in a 1:1 fashion. Single spikes triggered in either giant axon can produce EPSPs in the A1 5-HT cells of sufficient magnitude to cause the cells to spike and to fire additional action potentials after variable latencies; action potentials elicited in this way reset the endogenous spontaneous spiking rhythm of the A1 5-HT neurons. The giant-axon-evoked EPSP amplitudes show substantial variation from animal to animal. In individual preparations, the variation of EPSP size from stimulus to stimulus was small over the first 25 ms of the response, but increased considerably in the later, plateau phase of each response. When tested in the same preparation, EPSPs in A1 5-HT cells evoked by firing the LG axons were larger, longer-lasting and more variable than those triggered by firing the MGs. Firing A1 5-HT cells through an intracellular electrode, prior to activation of the giant fiber pathway, significantly reduced the size of LG-evoked EPSPs in A1 5-HT cells. Finally, morphological and physiological results suggest that similarities exist between giant fiber pathways in lobsters and crayfish. The possible functional significance of an involvement of these large amine-containing neurosecretory neurons in both tonic and phasic muscle circuitries will be discussed.

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