In a ground-breaking research, scientists have resolved the age-old mystery of touch - how cells just beneath the skin surface enable us to feel fine details and textures.
Till date, almost nothing is known about the cells and molecules responsible for initiating our sense of touch.
Using optogenetics - a new method that uses light as a signalling system to turn neurons on and off on demand - on skin cells, scientists have discovered how these cells function and communicate.
The team showed that skin cells called Merkel cells can sense touch and that they work virtually hand in glove with the skin's neurons to create what we perceive as fine details and textures.
"These experiments are the first direct proof that Merkel cells can encode touch into neural signals that transmit information to the brain about the objects in the world around us," explained Ellen Lumpkin, an associate professor of somatosensory biology at Columbia University medical centre.
Touch is the last frontier of sensory neuroscience.
"No one has tested whether the loss of Merkel cells causes loss of function with aging - it could be a coincidence - but it is a question we are interested in pursuing," Lumpkin added.
Several conditions - including diabetes and some cancer chemotherapy treatments, as well as normal aging - are known to reduce sensitive touch.
The new findings should open up the field of skin biology and reveal how sensations are initiated, Lumpkin noted.
Other types of skin cells may also play a role in sensations of touch, as well as less pleasurable skin sensations, such as itch.
The same optogenetics techniques can now be applied to other skin cells to answer these questions.
In the future, these findings could inform the design of new "smart" prosthetics that restore touch sensation to limb amputees, as well as introduce new targets for treating skin diseases such as chronic itch, the researchers said in a paper published in the journal Nature.
