You should read the stickied advice threads for applicants. You shouldn't geographically restrict yourself, especially to such a high demand area as SoCal. Even the most competitive applicants will hurt their chances by geographically restricting themselves like that.
You probably would do well to check with the Sepulveda VA facility on Westwood Blvd in West Los Angeles. I believe they have a number of ongoing PTSD research programs.
