Acupuncture seems to activate the parts of the brain involved in pain control, say scientists in Taiwan. Jen-Chuen Hseih of the Veterans' General Hospital in Taipei and his colleagues used positron emission tomography (PET) to look at blood flow in the brains of 10 volunteers being given acupuncture between the thumb and the forefinger. PET scans were performed with the needle held still two millimetres (mm) under the skin; with the needle two mm in and rotated; and with the needle inserted three mm or more and being rotated and thrust until the volunteers felt a numb and aching sensation - one that characterises acupuncture. The last condition activated the hypothalamus and the periaqueductal grey matter of the midbrain, the centres of pain control, Jen-Chuen reported.