My thanks go to DavidInFife on the Parkinson's UK forum for bringing this article to my attention from the MIT Technology Review, 13 October, 2016. [1]

It's still early days yet, but scientists at MIT are developing a very thin mesh that can deliver to the brain electrical current in a more focussed and less invasive way than present methods.

This overcomes the problems with today's DBS which "involves implanting rigid, dense electrodes in the brain... [where] after about four weeks, scar tissue begins to build up... [requiring the need] to keep upping the voltage used to excite the neurons... [S]ometimes another surgery is required to replace the implant."

Reference:

[1] https://www.technologyreview.com/s/6...rce=features_1

John