International Handbook of Clinical Hypnosis - E-Lib FK UWKS

NEUROPSYCHOPHYSIOLOGY OF HYPNOSIS 69
will permit us to understand how hypnotic analgesia affects both cortical and
subcortical processes.For instance, the ®rst fMRI study Crawford et al., 1998;
Crawford, Horton, Harrington, Hirsh-Downs, Fox, Daugherty & Downs, 2000) that
examined hypnotic analgesia in highly hypnotizable individuals showed dramatic
activation shifts between attend and hypnotic analgesia in response to noxious
stimuli presented to the left middle ®nger.In the cingulate cortex, there was
bilateral or right hemisphere activation during attend, whereas in hypnotic analgesia
only left hemisphere activation remained.Among other ®ndings, we also
observed reductions of insular and shifts in thalamic activity during hypnotic
analgesia.
Human pain responses have been successfully studied through the analysis of
brain somatosensory event-related potentials SEPs).Hypnotically suggested analgesia
results in signi®cant decreases in the later SEP components 100 msec or
later after stimulus) at certain scalp leads using painful electrical e.g., Crawford,
1994a; Crawford, Clarke & Kitner-Triolo, 1996; De Pascalis, Crawford & Marucci,
1992; Meszaros, BaÂnyai & Greguss, 1978; Spiegel, Bierre & Rootenberg, 1989;
but see Meier, Klucken, Soyka & Bromm, 1993), laser heat e.g., Arendt-Nielsen,
Zachariae & Bjerring, 1990; Zacharie & Bjerring, 1994) or tooth pulp Sharav &
Tal, 1989) stimulation.Earlier studies, often plagued by methodological ¯aws,
provide mixed evidence for reviews, see Crawford & Gruzelier, 1992; Spiegel,
Bierre & Rootenberg, 1989).
Multiple intracranial electrodes temporarily implanted in the anterior cingulate
cortex, amygdala, temporal cortex and parietal cortex of two patients undergoing
evaluation and treatment of obsessive-compulsive disorder permitted Kropotov,
Crawford & Polyakov 1997) to conduct a unique evaluation of pain processes.We
investigated changes in SEPs accompanying electrical stimulations to the right ®nger
during conditions of attention and hypnotically suggested analgesia.Only in the
hypnotically responsive patient was reduced pain perception during suggested
hypnotic analgesia accompanied by a signi®cant reduction of the positive SEP
component within the range of 120±140 msec.In the left anterior temporal cortex, a
signi®cant enhancement of the negative SEP component in the range of 210±
260 msec was observed.Enhancement of the N200 component is thought to be
indicative of increased active and controlled inhibitory processing.No signi®cant
changes were observed at the amygdala or at Fz.Rainville, Duncan, Price, Carrier
and Bushnell 1997), using hypnotically suggested reduction of affective but sensory
pain to cold pressor pain during PET recordings, reported a relationship between the
degree of affective pain experienced and activation of the anterior cingulate cortex.
Considered together, Crawford et al.1998), Kropotov et al.1997) and Rainville et
al.1997) demonstrate changes in the activation of the anterior cingulate during
hypnotic analgesia, a region known to show increased activation during attention to
pain e.g., Bromm & Chen, 1995; Jones et al., 1991; Talbot et al., 1991).
In our laboratory, we evaluated SEPs in two populations: a) normal college
undergraduates who were either low or `virtuoso' highs, the latter of whom could