Newborns are hypersensitive to pain
Discovered the receptorial basis
Newborns feel pain generated by mechanoreceptors in the skin more than adults. This characteristic, according new studies, is not mediated through the activation of low-threshold mechanoreceptors (LTMRs). Woodbury and Koerber (Widespread projections from myelinated nociceptors throught the substantia gelatinosa provide novel insights into neonatal hypersensitivity, J. Neurosci. 23, 601-610, 2003) provide strong evidences that a particular kind of high threshold mechanoreceptors (HTMRs) morphologically characterized are responsible for the newborns hypersensitivity to pain. Woodbury and Koerber identified two subset of HTMRs one of which generates projections for the whole dorsal horn laminae and becomes increasingly active as the intensity of painful stimuli increases.
Suzanne Farley wrote a brief discussion of the Woodbury and Koerber work in the current issue of Nature Reviews Neuroscience, comparing the present paper with the previous one published by the authors two years ago: J. Comp. Neurol. 436, 304-323 (2001).