Scientists find origin of neuron’s electrical signals

February 7, 2008

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By Marianne Meadahl

A long-standing controversy in scientific circles over where the electrical signal originates in a nerve cell, or neuron – information critical to understanding how nerve cells work and might be modified  - appears to have been solved.

An international research team including SFU kinesiologist Peter Ruben says it has found conclusively that the signal originates in the neuron’s initial segment.
Some scientists previously believed that electrical activity begins in the cell’s axon, a long projection from the body of the cell. The initial segment  is located at the start of the axon, where it emerges from the cell body. The team conducted its research in Germany and Australia and published its findings online Jan. 20 in the journal Nature Neuroscience.

Ruben says the researchers are confident they now know where the cell’s electrical signal begins because the initial segment has the highest density of a protein called the sodium channel, which is responsible for generating signals.

“Knowing that the highest density of sodium channels is in the axon’s initial segment means that it is the site of greatest sensitivity and determines whether or not a neuron will become electrically active,” says Ruben, who studies the biophysical properties of sodium channels.

Ruben says knowing where electrical signals begin sheds a great deal more light on how nerve cells work, particularly in terms of their role in learning and memory, and how they might be modified by pharmaceutical agents to effect such conditions as epilepsy.

“If the sensitivity of these channels is modified then the probability of a neuron being electrically active and generating a signal, either individually to begin a process like movement, or as a link in a chain of events such as a reflex, may be most easily modified at this location.”

The team’s findings are the result of “research at its most basic level,” says Ruben, who is also director of SFU’s School of Kinesiology. “The controversy has gone on for a long time. This puts several nails in the coffin.”

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