Neuroscience

Perilous ruptures described in a multiple sclerosis model

The permanent neurological deficits of multiple sclerosis patients largely depend on the extent of degeneration of long nerve fibers. The latter is initiated by ruptures in the cell membrane and the resulting influx of calcium ...

Neuroscience

Nerve-on-a-chip platform makes neuroprosthetics more effective

EPFL scientists have developed a miniaturized electronic platform for the stimulation and recording of peripheral nerve fibers on a chip. By modulating and rapidly recording nerve activity with a high signal-to-noise ratio, ...

Neuroscience

Mouse study supports stem cell therapy for cerebral palsy

Neural stem cells can repair damaged parts of the brain and restore motor impairments in mice that display features of cerebral palsy, according to new research published in eNeuro. These results demonstrate the feasibility ...

Neuroscience

Another step toward the hand prosthesis of the future

Researchers stimulated the nerves of an amputated arm with signals very similar to the natural ones, succeeding in "imitating the colors" of the evoked sensations of the various types of receptors and related nerve fibers ...

Neuroscience

Finding one's way home

The otic placode gives rise to the inner ear in vertebrates. A new study shows that even when it is transplanted to ectopic positions, the nerve cells that grow out of the transplanted ear can form functional connections ...

Neuroscience

Why do paper cuts hurt so much?

Consider, for a moment, the paper cut. It happens suddenly and entirely unexpectedly, usually just as you are finally getting somewhere on that task you had been putting off.

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Axon

An axon or nerve fiber is a long, slender projection of a nerve cell, or neuron, that conducts electrical impulses away from the neuron's cell body or soma.

An axon is one of two types of protoplasmic protrusions that extrude from the cell body of a neuron, the other type being dendrites. Axons are distinguished from dendrites by several features, including shape (dendrites often taper while axons usually maintain a constant radius), length (dendrites are restricted to a small region around the cell body while axons can be much longer), and function (dendrites usually receive signals while axons usually transmit them). All of these rules have exceptions, however.

Some types of neurons have no axon—these are called amacrine cells, and transmit signals from their dendrites. No neuron ever has more than one axon; however in invertebrates such as insects the axon sometimes consists of several regions that function more or less independently of each other. Most axons branch, in some cases very profusely.

Axons make contact with other cells—usually other neurons but sometimes muscle or gland cells—at junctions called synapses. At a synapse, the membrane of the axon closely adjoins the membrane of the target cell, and special molecular structures serve to transmit electrical or electrochemical signals across the gap. Some synaptic junctions appear partway along an axon as it extends—these are called en passant ("in passing") synapses. Other synapses appear as terminals at the ends of axonal branches. A single axon, with all its branches taken together, can innervate multiple parts of the brain and generate thousands of synaptic terminals.

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