I send email... with my mind

Science fiction, meet science fact.

Surgeons drilled a hole in Nagle's skull and inserted a pill-sized chip covered with 96 protruding electrodes into his motor cortex, an area at the centre of his brain that normally controls bodily movement. The operation carries the risk of infection and brain damage, an especially chilling prospect for someone already quadriplegic.

The motor cortex is made up of billions of neurons that constantly produce electrical signals, known as "spikes". Activity in different parts of the motor cortex was already known to correspond to different limbs, but Donoghue's team was able to identify signals related to different movements of the same limb.

To do this, they asked Nagle to imagine moving a limb and recorded the corresponding electrical signals. They found that the same small clusters of neurons produced different numbers of spikes when imagined moving a limb in different ways. For example, the same cluster might produce 15 spikes when he thought about moving the left arm to the left and only six when he thought about moving it to the right.

Donoghue's team built a list of spike patterns and corresponding movements. By automatically matching these together, a connected computer allows Nagle to control his computer or robot arm.