NOCICEPTIVE DETECTION PROBABILITY DEPENDS ON THE TEMPORAL PROPERTIES OF ELECTROCUTANEOUS STIMULI

Electrical stimulation of the skin using a needle-electrode specifically activates nociceptive nerve fibres. The detection of such stimuli by subjects depends on the activation of subsequent nociceptive mechanisms. Activation of these mechanisms depends on the temporal stimulus properties, such as the pulse-width, number of pulses, and inter-pulse interval. This different activation of nociceptive mechanisms is reflected in nociceptive (detection) thresholds [1]. The threshold is a commonly used measure to detect nociceptive malfunctioning and is defined as the stimulus amplitude resulting in a 50 % detection probability in the psychophysical curve [2]. In addition to the threshold, the psychophysical curve is also described by a slope parameter, indicating the steepness of the curve. While the effect of stimulus parameters on the threshold was studied before, the effect on the slope was not studied before. The slope could be dependent on the processing of the stimulus by the underlying mechanisms, and thus on the temporal stimulus properties. Moreover, the combination of threshold and slope estimates could possibly be used to detect malfunctioning of nociceptive mechanisms. Here, we study whether different temporal stimulus properties d