Elephant's nerve tested for speed

June 09, 2005, vol. 33, no. 4
By Marianne Meadahl

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How fast are the nerves in large animals like elephants? Preliminary results of an SFU-lead study at the Edmonton Valley Zoo show that elephant nerves are only slightly faster than those of mice, even though the signals have to go about 50 times further as they travel the length of the leg.

In a bid to better understand how the neural control of movement is affected by body size, SFU kinesiologist Max Donelan and University of Alberta researchers Steven Aung, David Collins and Doug Weber conducted tests on a female Asian elephant at the zoo named Lucy.

The researchers measured the speed of signals travelling along the elephant's nerves and came up with the surprising results, which could also help shed light on how large dinosaurs moved.

"Time delays in neuromuscular control systems can be substantial," Donelan explains. "The most significant contributor to reflex delay in large animals is the time it takes for signals to travel up the nerves in the leg and back down again. When compared to the copper wires which transmit our email messages at nearly light-speed, nerves appear dreadfully slow.

"We become acutely aware of the speed of our nerves whenever we trip and fall. Our preliminary results suggest that delay due to nerve speed is a much bigger problem for elephants - perhaps to a degree that it limits how fast they can move."

Measurements were taken from Lucy's hind leg using procedures the researchers usually use on human subjects.

Muscle activity was recorded using electrodes placed on her skin and the nerve to those muscles was stimulated at the back of the knee. The 8,600 pound Lucy feasted on sugar cane and watermelon throughout the experiment.

"We anticipate that in future years this research may aid veterinarians and zoos in the care and treatment of elephants," says Donelan, noting that while these experiments are the first of their kind carried out on elephants, similar measurements in humans are commonly used to diagnose neurological dysfunction and may prove similarly useful for elephants.

Researchers had strong support from the zoo to undertake their work. "Lucy has been fantastic, considering that she is about 60 times more massive than the human subjects we usually work with," says Collins.

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