Just come back from an appointment with my Chiropractic Neurologist. Asked him about why I would benefit from supplementing Gaba. I may not be quoting him correctly but he said something to the effect with my brain injury , there is inflammation and thus an excess of Glutamate which keeps attacking the injured area thus making it more susceptible to pain and thus the need for Gaba supplementation.

Here's a link to an intersting article.

http://www.ncbi.nlm.nih.gov/pmc/articles/PMC155411/