The influence of semantic priming on event-related potentials to painful laser-heat stimuli in migraine patients.

We investigated the effects of different semantic primes on the processing of painful stimuli in migraine patients. For prime stimuli, descriptors of three categories were used: somatosensory pain-related, affective pain-related, and neutral adjectives. While migraine patients (n = 17) processed these primes, a painful laser-heat stimulus was applied to the dorsum of the left hand. Laser-evoked potentials (LEPs) were recorded and pain intensity ratings were obtained after each single laser stimulus. Pain thresholds were significantly lower in patients than in control subjects. LEP amplitudes were also significantly smaller in patients than in controls, but this effect could be explained by differences in applied stimulus intensity. Within the group of migraine patients, LEP amplitudes at 300 ms post laser stimulus and N2-P2 peak-to-peak amplitudes were significantly enlarged when applied while subjects processed pain-related as compared to non-pain-related primes, i.e. patients showed a pattern of priming effect similar to that of the control group. Additionally, patients recognised more affective words than control subjects, and affective pain-related primes tended to enhance the P2 amplitude of LEP more than somatosensory pain-related primes. It is suggested that pain-related semantic primes might pre-activate neural networks subserving pain memory and pain processing. Copyright 2003 Elsevier Science Ireland Ltd.