The human sensory experience may be far more complex and nuanced than previously thought, according to a new report: Researchers say they found a sensory network located throughout our blood vessels and sweat glands, for most people largely imperceptible. "It is only when we shift focus away from the nerve endings associated with normal skin sensation that we can appreciate the sensation hidden in the background," said senior author Frank Rice.
The research team found indications of this hidden sensory system by studying two unique patients who were diagnosed with a previously unknown abnormality. These patients had an extremely rare condition called congenital insensitivity to pain, meaning that they were born with very little ability to feel pain. Other rare individuals with this condition have excessively dry skin, often mutilate themselves accidentally and usually have severe mental handicaps. "What made these two patients unique was that they led normal lives. Excessive sweating brought them to the clinic, where we discovered their severe lack of pain sensation," said lead author David Bowsher. "Our tests revealed that all their skin sensation was severely impaired, including their response to different temperatures and mechanical contact. But they had adequate sensation for daily living and could tell what is warm and cold, what is touching them, and what is rough and smooth."
Bowsher sent skin biopsies to a laboratory: To the researchers’ surprise, the skin lacked all the nerve endings that are normally associated with skin sensation. So how were these individuals feeling anything?
The answer appeared to be in the presence of sensory nerve endings on the small blood vessels and sweat glands embedded in the skin. "We did not think they could contribute to conscious sensation. However, while all the other sensory endings were missing in this unusual skin, the blood vessels and sweat glands still had the normal types of nerve endings. Apparently, these unique individuals are able to 'feel things' through these remaining nerve endings," assumes Rice.
MEDICA.de; Source: Integrated Tissue Dynamics (INTIDYN)