DBS for Parkinson&#x27;s (and dystonia and essential tremor) work reliably well, and the complication rates are considered acceptable.  However, in terms of understanding the mechanisms of how they work on the brain, I would very much characterize it as a black box. So much so that if you look at the different ways different medical centers and practitioners program the devices, it&#x27;s clear we don&#x27;t know how it works; just that it does (and extremely effectively) once you fiddle around with the settings long enough.