The activity of VTA DA neurons is inhibited or excited by somatosensory stimuli, such as tactile or noxious stimulation2, 3. Tactile stimulation of the forelimb inhibits DA release in the contralateral striatum4, 5, while noxious stimulation applied to the tail enhances DA release in the NAc6, suggesting that the mesolimbic reward system is modulated by somatosensory input. We and others have shown that sensory stimulation reduces drug craving behaviors through the modulation of the mesolimbic DA systems in rats and humans7–9. The application of acupuncture, widely accepted as a form of peripheral sensory stimulation10, to the ulnar tunnel (also called as HT7 Shenmen Acupoint or Guyon’s Canal) decreases DA release in the NAc by activating GABA neurons in the VTA, resulting in the suppression of cocaine, morphine and ethanol self-administration11–13. We have previously reported that inhibition of drug-seeking behaviors is mediated via activation of specific fiber types in the ulnar nerve. Mechanical stimulation of the ulnar nerve activates peripheral sensory afferents, such as Pacinian and Meissner corpuscles, which are conveyed via large A-fibers within the nerve trunk, and inhibits the locomotor activating effects of cocaine11, providing further evidence that the activation of primary sensory fibers can attenuate the reinforcing effects of drugs of abuse in the reward system. However, the central links between somatosensory and brain reward systems are not completely understood.