All I remember is that there was a huge structure (not planet-size huge but like a large building), some kind of brain or something similar (neural structure).
Then there was a young boy, IIRC the protagonist, and a recurring older man. Later in the show it turned out that the older man is a version of the young boy from the future.
That's really all I can recall but I distinctly remember that I loved that show and would be insanely happy to rediscover it! Thanks.