A rift between implicit and explicit conditioned valence in human pain relief learning

Abstract

Pain is aversive, but does the cessation of pain (‘relief’) have a reward-like effect? Indeed, fruitflies avoid an odour previously presented before a painful event, but approach an odour previously presented after a painful event. Thus, event-timing may turn punishment to reward. However, is event-timing also crucial in humans who can have explicit cognitions about associations? Here, we show that stimuli associated with pain-relief acquire positive implicit valence but are explicitly rated as aversive. Specifically, the startle response, an evolutionarily conserved defence reflex, is attenuated by stimuli that had previously followed a painful event, indicating implicit positive valence of the conditioned stimulus; nevertheless, participants explicitly evaluate these stimuli as ‘emotionally negative’. These results demonstrate a rift between the implicit and explicit conditioned valence induced by pain relief. They might explain why humans in some cases are attracted by conditioned stimuli despite explicitly judging them as negative.

Onset and offset of aversive events establish distinct memories requiring fear and reward networks

“…Paralleling the situation in Drosophila, training humans with first shock and then the conditioned stimulus leads to a decrease in the amplitude of the startle response in the presence of this stimulus, in contrast to the increase in startle amplitude observed after fear conditioning (Andreatta et al 2010). Thus, one and the same shock episode presumably leaves two kinds of memory with opponent implicit valences indicated by startle potentiation and startle attenuation: conditioned fear and conditioned relief, respectively.…”

“…Thus, one and the same shock episode presumably leaves two kinds of memory with opponent implicit valences indicated by startle potentiation and startle attenuation: conditioned fear and conditioned relief, respectively. Interestingly, humans explicitly report a negative valence in both cases, despite the opponency of the implicit valences (Andreatta et al 2010). Notably, this human paradigm, similar to the fly paradigm (Tanimoto et al 2004;Yarali et al 2008), enables assaying conditioned fear and conditioned relief directly and within the same behavioral setting.…”

“…Then, event-related fMRI registered during the following test phase was analyzed for activations by CS SHOCK and SHOCK CS as compared to a CS that had been presented without shock during training (CS CONTROL ) or to a CS that had not been presented during training at all (CS NOVEL ). As we (Andreatta et al 2010) have previously found that CS SHOCK potentiates startle (indicating implicit negative valence), whereas SHOCK CS attenuates startle (indicating implicit positive valence), we hypothesized that fear and/or reward networks may be activated by these stimuli, respectively, and we therefore examined the activity in amygdala and striatum as regions of interest (ROIs).…”

“…An overall analysis revealed significant effects of the different ISIs in the learning phase (Kruskal-Wallis test: H ¼ 68.46, P , 0.001). As depicted in Figure 3A, we observed a weak, nonsignificant attenuation of the startle magnitude by the light cue in the two control conditions (Wilcoxon Signed Rank test; , e.g., circle) was presented before the shock and thus was to be associated with shock-onset, or relief conditioning, in which a shape ( SHOCK CS) was presented after the shock, to be associated with shock-offset; such training endows the CS SHOCK and the SHOCK CS with the capacity to respectively potentiate or attenuate startle in humans (Andreatta et al 2010). In both cases, another shape (CS CONTROL , e.g., square) was presented alone, thus not to be associated with shock.…”

Effects of context preexposure and delay until anxiety retrieval on generalization of contextual anxiety

“…The intensity of the US was individually assessed at the beginning of the experiment. The pain threshold procedure consisted of two ascending and two descending series of electric shocks in steps of 0.5 mA (for details, see Andreatta et al 2010). Participants rated the shock on a visual analog scale ranging from 0 (no pain at all) to 10 (unbearable pain), with 4 ( just noticeable pain) as the anchor for the threshold.…”