December 10, 2012
Fruit Flies Shed Light On The Mechanisms Behind Response To Gentle Touch
redOrbit Staff & Wire Reports - Your Universe Online
A team of University of California, San Francisco (UCSF) researchers has reportedly discovered the group of nerve cells responsible for communicating the sensation of gentle touch in fruit flies -- and possibly in humans and other organisms as well -- potentially shedding light on one of most mysterious senses in all of biology.In their research, which has been published online by the journal Nature, the UCSF researchers studied newborn fruit flies. The insect larvae were gently stroked with a freshly plucked eyelash, the university explained in a Sunday press statement, and they responded by altering their movements.
That observation helped the research team to discover that a subset of nerve cells known as class III neurons were responsible for that reaction, and that the ends of those nerves contained large amounts of a protein known as NOMPC, which "appears to be critical for sensing gentle touch in flies," the researchers said.
Without that molecule, the flies do not respond to the eyelash stroking, and if the protein is added to other neurons, then those nerves gain the ability to sense gentle touch, study leader Dr. Yuh Nung Jan, a professor of physiology, biochemistry and biophysics at the university, explained.
According to UCSF, the study "sheds light on a poorly understood yet fundamental sense through which humans experience the world and derive pleasure and comfort." However, Jan warns that despite the team's findings, "many unanswered questions remain, including the exact mechanism through which NOMPC detects mechanical force and the identity of the analogous human molecules that confer gentle touch sensitivity in people."
"Though it is fundamental to our experience of the world, our sense of gentle touch has been the least well understood of our senses scientifically, because, unlike with vision or taste, scientists have not known the identity of the molecules that mediate it.," the university added. "Scientists generally feel that, like those other senses, the sense of touch is governed by peripheral nerve fibers stretching from the spine to nerve endings all over the body."
Scientists were aware that there were special molecules in nerve endings that detected when skin around them is touched, and respond by allowing ions to enter en masse. That response is observed by the nerve cell, and provided the signal was strong enough, it notified the brain about the gentle contact. The discovery of NOMPC's role in the process -- at least in fruit flies -- is a "milestone" that helps fill in some of the details, the university said.