An experiment conducted in the BBC TV series Alternative Medicine: The Evidence (tx BBC 2, 9pm, 24 January 2006) presented by scientist Professor Kathy Sykes from Bristol University, shows that acupuncture has a powerful and measurable effect on the human brain. The effect is surprising, because scientists have previously predicted that parts of the cortex would be activated during acupuncture. This unique experiment suggests that, on the contrary, parts of the brain, beyond the cortex, are actually deactivated.

The first programme in the three part series brings together a group of leading scientists including neuro-scientist Mark Lythgoe (UCL); neuro-physiologist Dr Aziz Asghar (Hull York Medical School); academic Dr George Lewith (Southampton University); and acupuncturist Dr Hugh McPherson (York University). Together they devise a rigorous scientific test to assess the neurological effect of acupuncture. Volunteers were subjected to a process acupuncturists call 'deep needling' and the findings were compared with a control group undergoing 'superficial needling'. 'Deep needling' involves having needles inserted approximately one centimetre into the back of the hand at a well known acupuncture point and the needles are then rotated by the practitioner until the effect acupuncturists call de chi is experienced - the subjects feeling a tingling sensation. Those undergoing 'superficial needling' have needles only inserted approximately one millimetre into a similar point. During these two procedures the volunteers underwent brain scans to see what, if any, effect there was in the brain.

The most up-to-date functional magnetic resonance imager at York University was used, and continuous real time images were obtained with the latest Magnetoencephelography (MEG) scanning equipment. MEG is a new technology that measures the very faint magnetic fields that emanate from the head as a result of brain activity. As we see in this programme, when the results are analysed the scientists discover that 'superficial needling' results in activation of the motor areas of the cortex, a normal response to touch or pain. With 'deep needling' and de chi effect, a deeper part of the brain is affected. This is within what is often known as the limbic system, and is a part of the pain matrix. Surprisingly, this part of the brain is deactivated with 'deep needling'; neuroscientists are more familiar with interventions causing activations. This result seems to support anecdotal accounts of acupuncture (and some experimental studies) which indicate that the therapy is particularly effective in the management of pain, and suggests a mechanism.

Professor Sykes said: "I'm just thrilled that we managed to do a real scientific experiment, shaped and run by scientists and acupuncturists together, where we found something quite unexpected; that acupuncture is having a measurable effect on the human brain."

Dr Mark Lythgoe said: "This finding permits the team to suggest a novel neurobiological mechanism for the action of acupuncture, which may account for its therapeutic benefits."