Supraspinal modulation of trigeminal pain and nociception

Headaches afflict at least half the population; however, few paradigms exist to study modulation of experimental head pain. Supraspinal modulation of nociception has been studied with two procedures, emotional controls of nociception (ECON) and diffuse noxious inhibitory controls (DNIC). ECON examines the influence of emotion on nociception. DNIC assesses for nociceptive inhibition during presentation of a heterotopic pain stimulus. Research suggests different neurological circuitries are involved in these modulation procedures. The present study assessed the influence of ECON and DNIC on subjective (pain report) and physiological (nociceptive blink reflex, NBR; skin conductance response, SCR; heart rate acceleration, HR) reactions to painful electrical stimulation of the supraorbital branch of the trigeminal nerve. A concentric stimulating electrode was used to enhance nociceptive specificity of stimulations. ECON were assessed by delivering stimulations during emotionally evocative pictures (attack, neutral, erotic). Picture content modulated subjective pain, the NBR, and autonomic reactions to stimulations (heart rate acceleration, skin conductance response), with larger reactions during unpleasant pictures than pleasant pictures. DNIC were assessed by delivering stimulations during forearm ischemia. DNIC inhibited subjective pain, the NBR, and autonomic reactions to stimulations, with smaller nociceptive reactions generally being observed during and after ischemia compared to baseline. These results indicate ECON and DNIC circuitry can influence modulation of head pain. Future research can use this paradigm to study the functioning of supraspinal modulation circuits in persons with headache disorders.