INTRODUCTION: Neuroimaging studies indicate that hypnotic suggestions of increased and decreased pain intensity and unpleasantness may modulate somatosensory and cingulate cortex activity, respectively.
METHODS: Using a within subject design and a strict subject selection procedure, we tested in High (Highs) and Low (Lows) hypnotically suggestible individuals whether hypnotic suggestions of sensory and affective hypoalgesia or hyperalgesia differentially affected subjective ratings of laser-induced pain and nociceptive-related brain activity in the time- and time-frequency domain.
RESULTS:Hypnotic modulation of pain intensity and unpleasantness affected subjective ratings of laser-induced pain only in Highs. Such modulation was more specific for unpleasantness manipulation and more evident for suggestions of hyperalgesia. Importantly, Highs and Lows showed increase and decrease of P2a and P2b wave amplitudes and gamma band power, respectively.
CONCLUSIONS: Hypnotic suggestions exerted a top-down modulatory effect on both evoked and induced-cortical brain responses triggered by selective nociceptive laser inputs. Furthermore, correlation analyses indicated that gamma power modulation and suggestions of hyperalgesia may reflect the process of allocating control resources to salient and threatening sensory-affective dimensions of pain.