Medicine is as much the quest to control our cells (and their signalling mechanisms) as anything else. Here is a small step on the way to both controlling errant cells in our brains, and ultimately learning how to replace them with something more durable: "The methods that are currently used to stimulate nerve signals in the nervous system are based on electrical stimulation. Examples of this are cochlear implants, which are surgically inserted into the cochlea in the inner ear, and electrodes that are used directly in the brain. One problem with this method is that all cell types in the vicinity of the electrode are activated, which gives undesired effects. Scientists have now used an electrically conducting plastic to create a new type of 'delivery electrode' that instead releases the neurotransmitters that brain cells use to communicate naturally. The advantage of this is that only neighbouring cells that have receptors for the specific neurotransmitter, and that are thus sensitive to this substance, will be activated. ... The ability to deliver exact doses of neurotransmitters opens completely new possibilities for correcting the signalling systems that are faulty in a number of neurological disease conditions."

Link: http://www.physorg.com/news166109773.html