Stimulus predictability moderates the withdrawal strategy in response to repetitive noxious stimulation in humans

Abstract

Innate defensive behaviors such as reflexes are found across all species, constituting preprogrammed responses to external threats that are not anticipated. Previous studies indicated that the excitability of the reflex arcs like spinal nociceptive withdrawal reflex (NWR) pathways in humans are modulated by several cognitive factors. This study assesses how the predictability of a threat affects the biomechanical pattern of the withdrawal response, showing that distal and proximal muscles are differentially modulated by descending control.

Are changes in nociceptive withdrawal reflex magnitude a viable central sensitization proxy? Implications of a replication attempt

“…Thus, a just comparison could not be made. In the present case, the understanding of CS and of the NWR has greatly advanced over the past two decades (Quesada et al, 2021;Arendt-Nielsen et al, 2018;Sandrini et al, 2005;Andersen, 2007;Jure et al, 2020). Because of these advances, it was worthwhile to re-examine the original results (Ellrich and Treede, 1998) in order not just to confirm or dismiss them but to also put them into context with the new knowledge in the field of CS and NWR studies.…”

“…starting either with the determination of the single or the 3-stimulation threshold, was counterbalanced across subjects. The subsequent six test blocks employed eight single stimulations with a random interstimulation interval of 5 to 15s to avoid predictability, which has been shown to modulate the NWR response (Jure et al, 2020). The eight stimulations were delivered at eight different currents, starting from I 0 -4 mA to I 0 +1 mA in steps of 1 mA followed by one stimulation at 1.5ÁI 0 and one stimulation at 2ÁI 0 , always in that order.…”

“…However, their integration into a multimodal design is more challenging than just combining one stimulation and one recording site. Apart from MP-TA (Meinck et al, 1985), another typical combination uses the sural nerve (SU) dorsal to the lateral malleolus as the stimulation and the biceps femoris muscle (BF) as the recording site (Hugon, 1973;Willer, 1977), although other combinations are used as well, some of which alternatively stimulate free nerve endings instead of trunks (Sandrini et al, 2005;Jensen et al, 2015;Jure et al, 2020).…”