Long-term potentiation in single wide dynamic range neurons induced by noxious stimulation in intact and spinalized rats

Abstract

Publisher Summary This chapter discusses the long-term potentiation (LTP) in single wide dynamic range (WDR) neurons induced by noxious stimulation in intact and spinalized rats. The wind-up phenomenon shows that neurons respond dynamically to stimulation. Spinal nociceptive neurons increase their responses during a low-frequency constant-intensity train of stimulus pulses (0.8 Hz, C-fiber strength). The wind-up was shown to be most prominent in WDR neurons and natural stimulation of nociceptive C-fibers. Mechanisms of LTP measured in WDR neurons is shown to be segmental but they may be both mono- and polysynaptic. However, there is an indication of a tonic supraspinal descending inhibition preventing the development of an even larger LTP, which were seen in neurons after spinalization. For a quarter of a century, LTP experiments have been done in the hippocampus without confirming the hypothesis that LTP and long-term depression are cellular mechanisms underlying memory. It indicated that long-term memory of neural sensitization, according to Hebb's paradigm, in that WDR neurons strengthen their responses to nociceptive signals after strong nociceptive stimulation.