Emotional modulation of pain perception in experimental and clinical neuropathy: an fMRI study.

Neuroimaging studies of neuropathic pain qualities referred to as allodynia and
hyperalgesia suggest that (a) no specific substrates in addition to known
structures in the pain neuromatrix are engaged, but that (b) these specific
pain qualities are represented in the affective circuit of the pain matrix.

It is therefore planned to study pain perception in peripheral neuropathy in
the context of positive and negative emotional stimulation. Although there is a
recent plea for the study of emotional modulation of pain, only one study has
as yet done so for visceral enteroception. The present study aims at
contrasting sensory and affective circuits of the pain neuromatrix in
neuropathy to controls according to emotional context type. These results will
be linked to self-report and genetic data.

Clinical group comparison between neuropathy and normal control subjects.
Event-related fMRI design with 1 neutral pain level, 3 individually established
pain levels, and one visual emotional (positive or negative) stimulus class.
Four experimental runs of each 20 minutes duration will enable 2 x 2 factorial
analysis: Limb-right, limb-left, emotion-positive, emotion-negative. Per
experimental run of 20 minutes, a total of 100 heat/cold or visual emotional
stimuli will be presented; subjects rate subjective stimulus intensity.

Risks are minimal. Burden is to tolerate and rate pain application to a limb
and stay in an MRI scanner. The subjects will receive monetary compensation;
they contribute to better understanding of brain circuitry involved in abnormal
pain perception in neuropathy.