Action potential initiation and propagation: Upstream influences on neurotransmission

Abstract

Axonal action potentials initiate the cycle of inter-neuronal, synaptic communication that is key to our understanding of nervous system functioning. The field has accumulated vast knowledge of the signature action potential waveform, firing patterns, and underlying channel properties of many cell types, but in most cases this information comes from somatic intracellular/whole-cell recordings, which necessarily measure a mixture of the currents compartmentalized in the soma, dendrites, and axon. Because the axon in many neuron types appears to be the site of lowest threshold for action potential initiation, the channel constellation in the axon is of particular interest. However, the axon is more experimentally inaccessible than the soma or dendrites. Recent studies have developed and applied single-fiber extracellular recording, direct intracellular recording, and optical recording techniques from axons toward understanding the behavior of the axonal action potential. We are starting to understand better how specific channels and other cellular properties shape action potential threshold, waveform, and timing: key elements contributing to downstream transmitter release. From this increased scrutiny emerges a theme of axons with more computational power than in traditional conceptualizations.

Activity-dependent Phosphorylation of Neuronal Kv2.1 Potassium Channels by CDK5

“…ability and of the input-output relationships in mammalian neurons (34). A number of recent studies have provided valuable insights into the role of specific Kv channel subtypes in the processing and integration of synaptic input within the somatodendritic domain (35), initiation and propagation of axonal action potentials (36), and regulation of neurotransmitter release (37). Modulation of the abundance, subcellular distribution, and gating of Kv channels through reversible multisite phosphorylation has emerged as a common theme for dynamic regulation of neuronal function (34,38,39) by allowing for integration between cell signaling pathways impacting the activity of specific neuronal PKs and PPs and the ion channels crucial for regulating neuronal excitability.…”

Influence of the Circulating Current on the Propagation of the Change in Membrane Potential

“…The results indicate that the existence of the threshold potential on the nerve transmission can be elucidated by the magnitude of the influx at the active site. [1][2][3][4][5][6] The reason why the nerve cell has a unique structure can be considered to be due to the circulating current.…”

“…On the other hand, ilim, W1|M at the W1|M interface of the potential-receiving cell (ilim, W1|M (pr)) can be described by Eq. (6).…”

“…[1][2][3][4][5][6] When neurotransmitters bind to a specific channel-type receptor at the synapse, Na + is mainly transported from the outside to the inside by opening the channels. When the current due to the transport of Na + from the outside to the inside exceeds the threshold, the membrane potential changes from the rest potential to the action potential regulated by the ratio of the inside Na + concentration to that of the outside.…”

Non-thermal Influence of A Weak Microwave on Nerve Fiber Activity

“…[7,8,9] are expressed in the peripheral nervous system. Nav1.6 is expressed at the action potential initiation site [29][30][31] A few years ago, it has been proposed to increase the frequency of the electromagnetic radiation used for telecommunications up to 30-300 GHz. [33,34].…”