I always felt early Voyager has weird and non-sensical titles. Ex Post Facto, Cathexis, Parallax, Prime Factors...
I really liked those titles, and they fit. "EX POST FACTO" is latin for 'after the fact', I think. That suits the situation.
"CATHEXIS" is exactly what happened, with Chakotay focusing his didembodied mind to help the crew, which wasn't revealed until much later in the episode. And the title is eerie enough, as the episode created a paranoid mood, as well.