Light touch - the sense that lets musicians find the right notes on a keyboard, a seamstress revel in the feel of cool silk, the artisan feel a curve in material and the blind read Braille – truly depends on the activity of Merkel cells usually found in crescent-shaped clusters in the skin, said researchers from Baylor College of Medicine and colleagues.

"Humans, primates and any animals that rely on hands for dexterity use their Merkel cells to feel texture and shape," said Dr. Ellen Lumpkin, assistant professor of neuroscience, molecular physiology and biophysics and molecular and human genetics at BCM and a senior author of the report. "Merkel cells are not like pain fibres. They exist in special areas of the skin to feel light touch. We have a lot of them on our fingertips and also on our lips."

However, while many scientists thought Merkel cells were key elements of light touch, they could never directly prove the link. The topic has been debated for more than 100 years, since the cells were first described in 1875 by German scientist Friedrich Sigmund Merkel, for whom they are named.

In co-operation with Dr. Huda Zoghbi (another senior author), Lumpkin, first author Dr. Stephen Maricich (now of Case Western Reserve University in Cleveland, Ohio), and colleagues generated mice that lacked a gene called Atoh1 in some areas of the body and, as a result, had no Merkel cells in skin located below the head. Experiments on these mice directly demonstrate the link between Merkel cells and touch in way that can be seen and heard.

That is probably the most significant thing about the paper, said Maricich. While Merkel himself first postulated the link between the cells and light touch, "this is the first direct evidence," said Maricich, who plans to continue working with the cells, determining the progenitor cells from which they arise and determining how they relate to human disease.

Baylor College of Medicine