Remembering the dynamic changes in pain intensity and unpleasantness: A psychophysical study

Abstract

This study investigated the short-term memory of dynamic changes in acute pain using psychophysical methods. Pain intensity or unpleasantness induced by painful contact-heat stimuli of 8, 9, or 10s was rated continuously during the stimulus or after a 14-s delay using an electronic visual analog scale in 10 healthy volunteers. Because the continuous visual analog scale time courses contained large amounts of redundant information, a principal component analysis was applied to characterize the main features inherent to both the concurrent rating and retrospective evaluations. Three components explained about 90% of the total variance across all trials and subjects, with the first component reflecting the global perceptual profile, and the second and third components explaining finer perceptual aspects (eg, changes in slope at onset and offset and shifts in peak latency). We postulate that these 3 principal components may provide some information about the structure of the mental representations of what one perceives, stores, and remembers during the course of few seconds. Analysis performed on the components confirmed significant memory distortions and revealed that the discriminative information about pain dimensions in concurrent ratings was partly or completely lost in retrospective ratings. Importantly, our results highlight individual differences affecting these memory processes. These results provide further evidence of the important transformations underlying the processing of pain in explicit memory and raise fundamental questions about the conversion of dynamic nociceptive signals into a mental representation of pain in perception and memory.

The delayed reproduction of long time intervals defined by innocuous thermal sensation

“…The underestimation of duration in delayed reproduction that we previously reported with continuous heat pain stimuli (Khoshnejad et al 2014) is hereby shown to generalize to innocuous cool sensation. Interestingly, this underestimation effect was not found with the segmented stimuli for which the duration of the delayed reproduction of the dynamic sensation matched the duration of the concurrent rating of the sensation (Fig.…”

“…Another factor adding some complexity to the interpretation of the present results in relation to the time perception literature is the delay between the stimulus offset and the interval reproduction. The inclusion of this delay was motivated by our previous observation that both the intensity and duration of heat pain sensations appear to be distorted in short-term memory (Rainville et al 2004;Khoshnejad et al 2014). Some of the effects reported here may be associated with memory processes that might have less impact in the immediate reproduction or discrimination tasks typically used in prospective time perception studies.…”

“…However, this does not preclude from the investigation of multi-seconds intervals. In a recent study on the memory of thermal pain, we observed that the delayed reproduction of the temporal dynamics of the sensation was characterized by an underestimation of the latency of the maximum pain and of the overall duration of the pain experienced (Khoshnejad et al 2014). This finding is consistent with the earlier observation of Hellström and Carlsson (1997) that time is underestimated during a cold pressor test compared to a non-painful control condition.…”

“…The goals of this study are (1) to test the replicability of our previous results (Khoshnejad et al 2014), showing an underestimation of the duration of painful thermal stimuli in delayed reports, using innocuous cool stimuli, (2) to assess how variations in thermal sensation within a long time interval affect the delayed reproduction of interval duration and (3) to examine how the (top-down) monitoring and delayed reproduction of sensory intensity over time (dynamic condition), as opposed to onset-to-offset duration only, might affect the reproduction of the interval duration. Two stimulation conditions are compared where (a) a continuous thermal stimulation fills the interval and (b) additional variations in thermal intensity (bottom-up sensory events) are intercalated in the interval, thereby creating segmented stimuli.…”

A standard for terminology in chronic pelvic pain syndromes: A report from the chronic pelvic pain working group of the international continence society

“…b.Location of pain: Pelvis, lower abdomen, low back, medial aspect of thigh, inguinal area, perineum. c.Perception of pain: Patients may describe the pain as sharp, burning, aching, shooting, stabbing, pressure or discomfort, sexual pain (dyspareunia) d.Modality of pain (7): Persistent and/or continuous, recurrent and/or episodic and/or cyclic (related to menstrual cycle). …”