He began developing a non-invasive surgical method that involved a more natural approach.

CNN: Health

But the vagus nerve doesn't target all areas of the brain, so some severe disorders, such as advanced Parkinson's, may require Medtronic's more invasive deep-brain stimulation method.

FORBES: Rewiring the brain

However, the researchers said that despite a lower number of invasive tests, the heavier reliance of this method on chorionic villus sampling earlier in pregnancy could actually mean an increase in the number of healthy babies lost if the miscarriage rate using this method was closer to 2%.

BBC: Down's test miscarriage warning