Chapter 8 – General discussion 265 and aversive experience prevails over newly learned positive information, and the uncertainty that comes from this variability of possible outcomes seems to reinforce negative pain expectations 24. This serves an important realistic indicator for learning under specific realworld conditions, where, according to nocebo research, patients are thought to acquire hyperalgesic effects on their symptoms due to a variable mixture of contextual, communicative, and experiential factors 1,26–29. In attenuating nocebo effects in Chapter 4, we compared a typical extinction paradigm, where learning of nocebo associations is simply discontinued, to counterconditioning. In counterconditioning, we reversed the learned associations by pairing the nocebo treatment with a positive, instead of a negative pain outcome. During both attenuation methods, new learning takes place. But our novel counterconditioning method taught participants that instead of increased pain, they would experience reduced pain when a nocebo treatment was applied. Essentially representing a placebo paradigm 21, this attenuation method showed for the first time that counterconditioning is a more potent method than extinction for the attenuation of nocebo hyperalgesia. This finding indicated that new, positive learning may effectively overwrite negative pain expectations, which may open new directions for behavioral treatments for pain symptoms that may be aggravated as a result of prior negative experiences 11. Neuroimaging evidence of multifaceted learning processes Building on this research and on the few existing nocebo neuroimaging studies summarized in chapter 3, in chapter 6 we report an EEG experiment that expands our knowledge of the neurophysiological characteristics of learning in nocebo hyperalgesia. In chapter 3 we described results from EEG studies that are not yet replicated, with each
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