The most sensitive area to touch in a human is located at the fingertips. Touch receptors are densely packed with about one hundred per square centimeter. Pain receptors (nocireceptors) occur at lower ratio. The neurons can respond to these two possible stimuli at the same time. What keeps these signals from mixing?

A look at the star-nosed mole (which is not only the fastest eating mammal, but also the animal with the most touch and pain sensitive organ of any mammal) may help. The most sensitive area is not in its fingers (because it has claws) but on its nose. The star shaped portion of its nose has the highest density of nerve endings with over one hundred thousand fibers per square centimeter of skin. Neurons are packed into these nerve endings. More of these neurons respond to touch rather than pain. This translates into several other mammals as well.

This news is important new research because these same types of receptors have been found in the sensory receptors of humans and mice. The sense of touch and pain are closely related, but knowing how these are sensed simultaneously and differentiated in the cells is still being researched. The goal of these studies is to pinpoint certain genes that distinguish which sensation should reported, touch or pain. Further findings in this field may lead to treatments of chronic pain through new medications or types of therapy.

References:

Kimball, John W. “Mechanoreceptors.” Mechanoreceptors. Kimball’s Biology Pages, 19 Feb. 2011. Web. 28 Feb. 2013.     http://users.rcn.com/jkimball.ma.ultranet/BiologyPages/M/Mechanoreceptors.html

Public Library of Science. “Leading by the nose: Star-nosed mole reveals how mammals perceive touch, pain.” ScienceDaily, 30 Jan. 2013. Web. 28 Feb. 2013.             http://www.sciencedaily.com/releases/2013/01/130130184156.htm