Pain wind-up is the increase in
pain intensity over time when a given stimulus is delivered repeatedly above a critical rate. It is caused by repeated stimulation of
group C peripheral nerve fibers, leading to progressively increasing electrical response in the corresponding spinal cord (
posterior horn) neurons due to priming of the NMDA receptor based response.
[{{cite book, author1=Feng Xu, author2=Tianjian Lu, title=Introduction to Skin Biothermomechanics and Thermal Pain, url=https://books.google.com/books?id=fMggKzt8ofoC&pg=PA347, accessdate=25 April 2012, date=29 May 2011, publisher=Springer, isbn=978-3-642-13201-8, page=347][Pitcher and Henry (2000). ''Eur. J. Neurosci.'', 12:2006–2020.] It describes an exponentially progressive increase in firing of WDR neurons with repeated stimulation.
References
Pain