Chapter 6 – EEG imaging 191 Introduction The experience of pain varies widely between and within individuals and can be shaped by cognitive processes such as learning. Nocebo hyperalgesia, a worsening in perceived pain attributed to negative expectations, demonstrates that learning can be detrimental for the experience of pain 1–3. Memories and negative expectations may directly impact pain processing 4,5, yet it remains unclear which specific processes are involved in cognitive pain reappraisal and how negative expectations may shape physiological characteristics of pain. Electroencephalography (EEG) can be used to identify physiological markers of phenomena that include cognitive components 6,7 such as nocebo effects. EEG has been used in cognitive and pain research and has largely focused on spectral characteristics of brain oscillations, with evidence indicating that expectations 8,9 and cognitive pain regulation 10,11 are reflected through alterations in the alpha and beta power bands. Concurrently, EEG research has shown that gamma oscillations are involved in associative learning 12 and encoding of ongoing pain 13. Alpha and gamma oscillations may also act in synergy during the cognitive stages of nociceptive processing 14. How EEG measures within these frequency bands relate to pain and cognitive processing under hyperalgesic conditions remains unclear. Electrophysiological research into nocebo effects has been scarce and has mainly focused on the power spectrum of oscillations 15–19. However, in order to more precisely pinpoint cognitive processes involved in nocebo, it may be valuable to utilize sophisticated EEG biomarkers such as Detrended Fluctuation Analysis (DFA), a component that quantifies long-range temporal correlations (LRTC) between oscillating groups of neurons and determines how oscillation
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