Communicating and moving are now things to sniff at

Movement of air through the nostrils can be translated by electronics engineers into electrical signals that can operate electrical devices.

July 31, 2011 04:23
4 minute read.
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Pharmacist pouring something 311. (photo credit: NATI SHOHAT/FLASH90)

For the disabled who have difficulty getting around even in a wheelchair, even sniffing will be enough to become mobile, according to Weizmann Institute of Science and Beit Loewenstein Rehabilitation researchers. They have invented a device that enables the severely handicapped to maneuver their wheelchair, write and perform other necessary tasks.

The hospital’s latest newsletter notes that Dr. Nahum Soroker, head of the neurology B rehabilitation department, has explained that the movement of air through the nostrils can be translated by electronics engineers into electrical signals that can operate electrical devices (which in this case were also invented by Weizmann scientists). Four writing systems using inhaling and exhaling were given to four patients at the Ra’anana rehabilitation hospital, and the institute’s Yeda Research and Development Ltd. is looking into marketing the technology Sniffing an object by inhaling and exhaling is an exact motor activity controlled, among other things, by its location on the soft palate in the mouth.

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This mechanism is usually preserved even if a person suffers severe neurological damage. Using functional MRI (fMRI) scans, the team strengthened their hypothesis that brain regions controlling the movement of the soft palate are almost identical with areas connected to language. Thus the scientists hoped that this natural connection would make possible the intuitive use of such a device to communicate.

To examine the hypothesis, they created a device that measures changes in air pressure in the nose (thorough a non-invasive device attached to the nostrils) and translates them into electrical signals. For patients who are connected to a respirator, a passive sniffing version of the device was devised. In this case, the user must learn to move the soft palate, which 75% of this population is able to do.

Tests on healthy volunteers who played a computer game showed that the sniffing mechanism is similar to using a computer mouse or joystick. Then they used a text writing program, and it worked with sniffing as well.

Soroker tried it on Beit Loewenstein patients suffering from “locked-in syndrome” – who suffer from paralysis in all four limbs. One woman who has been paralyzed for seven months after a stroke learned to manipulate the new device in a few days and sent her first e-mail message to her family since becoming disabled. Another patient who has had locked-in syndrome for 18 years due to a road accident said the Weizmann mechanism is much easier to use than batting his eyelids. Now Prof. Stephen Hawking, the British scientist who has locked-in syndrome from Lou Gehrig’s disease and uses an eyelid-batting device, is invited to contact the Weizmann Institute and Beit Loewenstein.

GPS FOR BAT-TEETH RESEARCH Using global-positioning systems – most commonly employed for finding your way around town – for mapping the topography of bat molars sounds like an odd application, but that is what biologists at the University of Massachusetts-Amherst are doing. They tried the technology to better understand how ridges, peaks and valleys on the teeth have evolved to allow different species to eat everything from hard-shelled insects to blood and nectar.

Researchers Sharlene Santana and Betsy Dumont and colleagues calculated a measure of dental complexity that reflects how “rugged” the surface of the tooth is and illustrates a trend from relative simplicity of the shearing molars in insect eaters and omnivores to high complexity of the crushing molars in fruit eaters. Their study was recently published in the journal Functional Ecology.

Working with field-collected bat skulls, they compared the structure of molars across 17 species of New World leaf-nosed bats that specialize in a variety of diets, such as insects, fruits and a combination).

It’s well known that mammalian tooth structure and function are strongly related to diet, the authors explain, but this study goes further to directly measure trends in the relationships among diet, tooth structure and feeding behavior.

They found that the molars of fruiteating species had sharp outer edges that likely allow them to pierce tough fruit skin and pulp, plus large surfaces with tiny indentations that may help them grind fruit pulp efficiently. By contrast, the molars of insect-eating species were less complex, possibly because of their smoother shearing surfaces. The more simply-shaped teeth would presumably be good for cutting through hard insect exoskeletons.

Santana and colleagues further tested if, within insect-eating species, higher molar complexity was related to a greater ability to crush prey. They fed beetles to field-caught bats, recorded their feeding behavior, then collected fecal samples to measure how well the beetles had been broken down. “We found that insect-eating bats with more complex molars were better at breaking down prey, but how much bats chewed their prey was also important,” Santana and colleagues say.

Like any specialized tool, teeth are designed to match the task at hand, in this case breaking down food. Tooth shapes are very specialized to fulfill specific functions, Santana explains.

“However, little is known about how the structure of teeth in bats from this family evolved in relation to the types of food they eat. Across mammals, there’s also little information about how differences in tooth structure relate to how well they perform.

“Our study highlights the functional significance of tooth structure and chewing behavior in breaking down natural prey, and provides the basis for future studies relating 3D tooth structure to an animal’s ability to break down food, how species divide up food resources and how these divisions evolve,” they point out.

This work provides a major step forward in understanding mammalian feeding systems.

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