V. De Pascalis et al., Somatosensory event-related potential and autonomic activity to varying pain reduction cognitive strategies in hypnosis, CLIN NEU, 112(8), 2001, pp. 1475-1485
Objectives: The issues of differential effects among cognitive strategies d
uring hypnosis in the control of human pain are under active debate. This s
tudy, which employs measures of pain perception, electrocortical and autono
mic responses, was aimed at determining these pain-related modulations.
Methods: Somatosensory event-related potentials (SERPs) to noxious stimuli
under an odd-ball paradigm were recorded at the frontal, temporal and parie
tal regions in 10 high, 9 mid, and 10 low hypnotizable right-handed young w
omen, at waking baseline, varying cognitive strategies (deep relaxation, di
ssociative imagery, focused analgesia) in hypnosis and placebo conditions.
The phasic heart rate (HR) and skin conductance response were also recorded
. The analysis was focused on the frequent standard trials of the odd-ball
SER-Ps. Repeated measures analysis of variance was conducted to examine the
experimental effects.
Results: Focused analgesia induced the largest reduction in pain rating, mo
re in the high than low hypnotizable subjects. In high hypnotizable subject
s, the N2 amplitude was greater over frontal and temporal scalp sites than
over parietal and central sites, whereas in moderately and low hypnotizable
subjects, N2 was greater over temporal sites than over frontal, parietal,
and central sites. These subjects also displayed a larger N2 peak over temp
oral sites during focused analgesia than in the other conditions. The P3 am
plitude was smaller under deep relaxation, dissociative imagery and focused
analgesia in the high hypnotizable subjects. For these subjects, the small
est P3 peaks were obtained for dissociated imagery and focused analgesia ov
er frontal and temporal sites. In contrast, for the P3 peak, low hypnotizab
le subjects failed to show significant condition effects. In all of the sub
jects, the skin conductance and HR were smaller during hypnotic suggestions
than in the waking state.
Conclusions: The effect of pain modulation is limited to high hypnotizable
subjects rather than low hypnotizable ones. Fligher frontal-temporal N2 and
smaller posterior parietal P3 may indicate active inhibitory processes dur
ing cognitive strategies in hypnotic analgesia. These inhibitory processes
also regulate the autonomic activities in pain perception. (C) 2001 Elsevie
r Science Ireland Ltd. All rights reserved.