POSTSTIMULUS AFTERDISCHARGES OF SPINAL WDR AND NS UNITS IN RATS WITH CHRONIC NERVE CONSTRICTION

FORTY pairs of wide dynamic range (WDR) and nociceptive specific (NS) neurones were simultaneously recorded in the dorsal horn of rats with chronic constriction injury (CCI) of the sciatic nerve. The responses to noxious mechanical stimulation were analysed and the afterdischarges were compared in the two neuronal populations. The number of neurones presenting an afterdischarge was higher in WDR than in NS population. Furthermore afterdischarges had significantly longer duration and greater magnitude with slower time course decays in WDR than in NS neurones. Given the role that afterdischarge may have in the prolonged transmission of nociceptive information, the possibility that WDR neurones could give a major contribute to the abnormal processing of noxious signals in CCI rats is proposed.