B
As common as it is,scratching to relieve an itch has long been considered a biological mystery:Are cells at the surface of the skin somehow tired in need of outside stimulation (刺激)?Or is the relief of the stimulation centered in the brain?
Perhaps neither one,a new study suggests.Neuroscientists report that specialized cells in the spinal cord (脊髓) appear to be critically involved in producing the feeling of an itch and the feeling of relief after the application of fingernails,at least in healthy individuals.
“It’s a very important study;itching is a major problem for millions of patients,” said Dr.Gil Yosipovitch.
Dr.Yosipovitch cautioned that the findings may not apply to chronic (习惯性的) itches.“But this is the kind of work that should help open this area up to more research.”
The researchers isolated (孤立) in monkeys cellular (细胞的) connections that run from the surface of the foot to the spinal cord and then to the part for feelings in the brain.They caused the feeling of itchiness by injecting something under the skin.They chose some cells at base of spinal cord.Most are sensitive to pain and some to both pain and itchiness.And when the researchers scratched the itchy skin on the monkeys’ feet,it quieted the cell’s activity.
Scientists argue that itching is most likely related to grooming (动物的梳毛),and evolved to protect animals against poisonous plants.But the biology of the itch has been a mystery and ignored for years by researchers who have been far more focused on pain.
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