Neural activities in human somatosensory cortical areas evoked by acupuncture stimulation

OBJECTIVES: To investigate neural representation evoked by acupuncture from human somatosensory cortices, especially from primary (SI) and secondary (SII) somatosensory areas. DESIGN AND SETTING: Neuroimaging study - Blood-oxygenation-level-dependent (BOLD) functional MRI was performed during acupuncture on LI4 (n=12 healthy participants). Sham acupuncture and innocuous tactile stimulation were also applied on the same acupuncture site as control comparisons. OUTCOME MEASURES: Responsive neural substrates were visualized and identified based on both individual and group-level surface activation maps. RESULTS: Discrete regions within the precentral gyrus (area 4) and the fundus of the central sulcus (area 3a) were selectively activated during the real acupuncture stimulation. In SII, the activation was extended in a postero-inferior direction to the fundus of the lateral sulcus. CONCLUSION: This specific pattern of acupuncture-related activation indicates that deep tissue stimulation (as seen in area 3a activation) and concurrent processing of sensory stimulation (as seen in activation in SII) may mediate neural responses to manual acupuncture.