ÎçÒ¹¸£Àû1000¼¯ºÏ

Imagine if there were a major highway into the brain that could be safely accessed from elsewhere in the body. That’s what vagus nerve stimulation is tapping into.

The vagus nerve is a bundle of neurons connecting the brain to many of the major organs, with nerves running both from the organ to the brain and vice versa. It does a multitude of jobs, including helping to control heart rate, breathing and appetite.

It is possible to wrap electrodes around the nerve in the lower neck and connect these to a small power source implanted in the chest, programmed to turn on and off at regular intervals. Trial and error has shown that altering the frequency and timing of stimulation can affect the brain in different ways.

A stimulator made by US firm Cyberonics is approved in that country for treating severe forms of epilepsy and depression. However, exactly how it works and which parts of the brain it targets is still unclear.

As the Cyberonics device is commercially available and fairly easy to implant, it is being investigated for many different uses. Some people who have had a device implanted have lost weight as a side effect, possibly because stimulation is mimicking the normal messages from our gut to our brain that signal when we are full. Research on pigs published last year showed that vagus nerve stimulation stopped the animals overeating and even made them select healthy food options (, vol 55, p 245).

If the effects extend to people who are obese, vagus nerve stimulation would look a good option next to stomach stapling, as the operation to do this carries a 0.5 per cent risk of death.

VERDICT Looks fairly safe but how it works is still unclear.

Read more:

Mind controls: Eight new tools to boost your brain
From electric currents to beams of sound, could new ways to treat mental illness ever be used to enhance our brain power? We look at eight routes to a better brain

Mind controls: Wires in the brain
Deep brain stimulation gives a direct line to areas where electric current can ease conditions from Parkinson’s to obsessive compulsive disorder

Mind controls: Running electricity through the skull
Transcranial direct current stimulation helps people recover from stroke – and boosts learning of both manual and mathematical skills

Mind controls: Electrodes sitting on the brain’s surface
Epidural cortical stimulation is a halfway house: you do get a hole in your head, but no wires in the brain, and it has helped severely depressed people

Mind controls: Good vibrations reach deep in the brain
Ultrasound focused within the skull can trigger movement in animals – could it give us a safe way to plug technology into the brain?

Mind controls: Magnetic relief for depression
Transcranial magnetic stimulation lets us turn parts of the brain on or off at will. It can ease depression too, and a handheld device may be on the way

Mind controls: Putting a light switch in the brain
With optogenetics, researchers can implant optical fibres to control genetically modified animals – could gene therapy bring it to humans?

Mind controls: How magnets make the worm turn
Magnetogenetics is a new spin on optogenetics, using magnets instead of fibre optics to turn nerve cells on and off