212 In previous research, reduction in LRTC of oscillations has been reported in the alpha and beta bands in patients with cognitive disorders 23,24,38, while other studies link increased LRTC to reduced attention or cognitive performance 22,39–42. LRTC characterize neuronal systems that require rapid reorganization and responsiveness to changing processing demands 25. Previous research indicates that neuronal systems involved in sustained attention may be characterized by a less volatile state with decreased LRTC 25. LRTC changes in the present study may thus be related to reduced attention or cognitive performance. In other words, effective conditioning required sustained attention with a relatively low cognitive load to result in stronger learning and thus larger nocebo hyperalgesia was characterized by reduced complexity of neural dynamics. While on one hand sustained attention (characterized by decreased LRTC) was related to larger nocebo responses, on the other hand strong resting-state LRTC at baseline predict more effective conditioning of nocebo responses. We found that, during rest, before the start of the experimental phases, strong LRTC predicted higher nocebo responses. This finding relates to the above-mentioned studies, that pointed towards an involvement of LRTC in cognitive ability 23,24,38. Stronger LRTC reflect more complex neural dynamics and therefore, it appears that people with more complex baseline brain activity may exhibit higher cognitive functioning (Montez et al., 2009) and are thus more susceptible to the acquisition of nocebo hyperalgesia through learning. Here, the implication of gamma band oscillations is in line with EEG research on (associative) learning, suggesting that memory encoding involves gamma oscillations 12,43,44 potentially in coordination with hippocampal function 45. This links gamma oscillations, which were shown to be involved in nocebo in this study, to a role of the hippocampus in learning and nocebo hyperalgesia 46,47. It is also noteworthy that emotional processes that may play a mediating role in nocebo hyperalgesia, such as fear 48, may engage patterns of gamma coupling in the amygdala 49, a structure
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