Baroreceptor cortical effects, emotions and pain.

The specificity of baroreceptor-dependent inhibition of pain reactions to electrical stimuli was investigated during induction of different emotional states in 27 subjects. Baroreceptors were stimulated through the PRES (Phase Related External Suction) technique, while emotions were induced by means of pleasant, neutral and unpleasant slides. The dependent variables were pain ratings, somatic evoked potentials (N150 and P260) recorded from Fz, Cz and Pz, and skin conductance response (SCR), while heart rate was recorded as a PRES requirement. Valence and arousal ratings were obtained in front of each slide. During suction (external baroreceptor activation) reduced pain ratings, cortical disfacilitation (from Pz, as revealed by N150) and lower SCR were found as compared to pressure (baroreceptor deactivation). Moreover, brain evoked potentials (N150 and P260) reflecting cortical inhibition were found under condition of baroreceptor stimulation during unpleasant slides, but not during pleasant or neutral ones: this result was found in the high blood pressure subjects only. Data showed also a valence effect on pain ratings: pain was evaluated to be higher during unpleasant slides, than neutral and pleasant ones. Results are discussed in the light of "baroreceptor reward" hypothesis, which proposes a learning mechanism for the development of essential hypertension.