This research is ongoing.
Some areas of the brain have overlapping and they are noted as cortical areas. The dorsolateral prefrontal cortex has been confirmed to decrease cortex band gamma activity. A lower end control hub, but a motion receiver of the parahippocampal for loudness of tinnitus. The parahippocampal area has been confirmed beyond any doubts that it alone controls tinnitus perception. They believe that now they will be able to decrease loudness by targeting the hippocampal, the control center over the DPC that will direct tinnitus suppression.
So now they are trying to figure out if they can use a drug to target, instead of implantation which my neuro has performed for other conditions.