Some characteristics of ephaptic transmission of action potentials were investigated with squid giant axons. For these studies two isolated axons were placed. Thus, the secondary peaks must represent the orthodromic impulses generated by ephaptic transmission. An average inter-peak interval of ms between the. Ephaptic transmission was implied. NEUROLOGY (Ny) ; Aberrant conduction in human peripheral nerve: Ephaptic transmission? Richard A.

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In a preoperative study of 21 patients, we delivered a series of stimuli, in short increments, successively distally along the temporal branch of the facial nerve to record abnormal muscle responses from the orbicularis oculi and mentalis muscles.

Ephaptic transmission in squid giant axons.

Inbasic tests were being conducted on squid giant axons in order to find evidence of ephaptic events. Resources for ephaptic Time Traveler! While these manipulations do ephaptix reflect normal conditions, they do highlight the mechanisms behind ephaptic excitation.

It was found that rhythmic electrical discharge associated with fetal neurons in the rat spinal cord and medulla was still sustained.

Ephaptic transmission is the origin of the abnormal muscle response seen in hemifacial spasm.

For example, the currents that caused the depolarization excitation of the active nerve caused a corresponding hyperpolarization depression of the adjacent resting fiber. These findings support a model in which ephaptic coupling works alongside canonical synapses to propagate signals across neuronal networks. A hypothesis or explanation behind the mechanism is “one-way”, “master-slave”, or “unidirectional synchronization” effect as mathematical and fundamental property of non-linear dynamic systems oscillators like neurons to synchronize under certain criteria.

Studies of ephaptic coupling have also focused on its role in the synchronization and timing of action potentials in neurons. Synchronization of neurons is in principle unwanted behavior, as brain would have zero information or be simply a bulb if all neurons would synchronize. How to use a word that literally drives some people nuts.


We tested the hypothesis that this anomaly results from lateral spread of impulses from one motor axon to another at the site of the nerve compression by the offending artery.

Extracellular potentials measured adjacent to axons surrounded by a very restricted volume of liquid ranged up to 80 mV in magnitude and had a shape similar to that of the membrane current.

Ephaptic transmission is the origin of the abnormal muscle response seen in hemifacial spasm.

It has been observed that local field potentials in cortical neurons can serve to synchronize neuronal activity. Test your visual vocabulary with our question challenge! More recent research, however, has focused on the more general case of electric fields that affect a variety of neurons. Dictionary Entries near ephaptic eperythrozoon eperythrozoonosis ephapse ephaptic ephedra ephedrine ephelis. Comments on ephaptic What made you want to look up ephaptic?

Due to the very small electrical fields produced by neurons, mathematical models are often used transmssion order to test a number of manipulations.

Although the exact functional role of this inhibition is still unclear, it may well have a synchronizing effect in the Purkinje cells as the ephaptic effect will limit the firing time. And is one way more correct than the others? Take the quiz Name That Thing Test your visual vocabulary with our question challenge! Early experiments, like those by du Bois-Reymond, [3] demonstrated that the firing of a primary nerve may induce the firing of an adjacent secondary nerve termed “secondary excitation”.

In one study, newly excited neighboring neurons interfered with already sustained currents, thus lowering the extracellular potential and depolarizing the neuron in relation to its surrounding environment, effectively inhibiting the action potential’s propagation.


The nerve action potentials recorded during surgery comprised the initial antidromic signal followed by one or more additional peaks. In patients with hemifacial spasm, stimulation of a branch of the affected facial nerve elicits an abnormal response in the muscles innervated by another branch.

Myelination is thought to inhibit ephaptic interactions. Test Your Knowledge – and learn some interesting things along the way. Explore the year a word first appeared. One study suggested that cortical cells represent an ideal place to observe ephaptic coupling due to the tight packing of axons, which allows for interactions between their electrical fields.

A number of studies have shown how inhibition among neurons in the olfactory system work to fine tune integration of signals in response to odor. Is Singular ‘They’ a Better Choice? However, newer research has been challenging some of the previously accepted models.

Ephaptic transmission | definition of ephaptic transmission by Medical dictionary

For these studies two isolated axons were placed side by side or, on occasion, a single long axon was looped to form an “ephapse” between the axon trunk and one of its main branches. Published by Elsevier Ireland Ltd. Need even more definitions?

Whether it is a true lack of evidence or simply obstinance in the face of change, many ephapfic the field are still not entirely convinced there is unambiguous evidence of ephaptic coupling.

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