STABILITY AND PLASTICITY OF NOCICEPTOR FUNCTION AND THEIR RELATIONSHIP TO PROVOKED AND ONGOING PAIN

The peripheral nociceptive nervous system is very malleable and following tissue injury, nociceptors often increase their sensitivity. They accomplish this by a leftward-shift of their stimulus response functions to heat stimuli, the acquisition of responses to new modalities, notably algesic mediators or the expansion of mechanosensitive receptive fields. Moreover, a recently discovered class of nociceptors which is unresponsive to transient noxious stimuli in healthy tissue starts to discharge specifically at the onset of tissue inflammatian. Persistent increases of nociceptor excitability can occur after nerve lesion and contribute significantly neuropathic pain states in humans.