Rhudy JL, et al. - Considering the observation that expectations for pain relief and experience/conditioning are psychological factors that contribute to placebo analgesia, researchers examined the physiological mechanisms underlying their effects. For this work, they examined the influence of placebo analgesia manipulations (that include expectations, conditioning, or both) on the nociceptive flexion reflex (NFR; measure of spinal nociception). Pain inhibition was noted only in relation to the manipulation that involved expectations and conditioning, however, both expectation manipulations facilitated NFR. Findings thereby indicate a complex modulation of spinal neurons by placebo manipulations.