Sweet is pleasure after pain: investigating the effect of pain offset on sweet and bitter tastes on brain activity

L. PETRINI; C. PADULO; A. BRANCUCCI; F. G. ARGUISSAIN; J. A. BIURRUN MANRESA; C. D. MØRCH; L. ARENDT-NIELSEN

Yokohama

Congreso; 16th World Congress on Pain; 2016

International Association for the Study of Pain IASP

Aim of Investigation It has been suggested that pain offset relief produces a positive hedonic state. Pain relief is rewarding and activates brain reward/motivation circuits. Furthermore, animal studies have suggested that the activation of the opioid system during pain relief increases the pleasantness of sweetness and decreases the aversive reaction to bitterness. The present study examines if pain offset can produce changes in the processing of taste stimuli of different affective valence (positive and negative) enhancing their intensity and hedonic value.Methods13 healthy young volunteers (9 males, mean age ± SD: 27 ± 3.8 years) participated in the study. Subjects were asked to perform a cold pressure test (CPT) by introducing their hands in a container filled with ice-water (0-2 °C) and a control condition with lukewarm water (30 °C). The order of the conditions was randomized. After completing each condition, subjects were asked to taste two types of chocolate (sweet and bitter) and to rate the intensity and the pleasantness of the stimuli on a Visual Analog Scale (VAS). Prior of the study, subjects were screened to like sweet chocolate and dislike bitter chocolate. Pain detection and tolerance thresholds were also measured. EEG activity was recorded continuously on 32 channels during the study.ResultsSweet taste stimuli produced a significant increase in alpha activity over the left frontal and bilateral medial cortical areas as compared with the bitter taste stimuli (p=0.02). Compared to the control condition, pain offset produced a significant increase of theta activity for sweet taste over the posterior areas in both hemispheres (left hemisphere, p