There we have it; every incarnation of the Doctor so far, tucked away inside his brain, not forgotten. I think that's how human beings work too. We're emotional creatures, that don't forget our pasts.
If that scene was the brain of Anthony, not Matt Smith's Doctor, then I think you'd see the people who influenced me the most mixed in there. Family. Old friends. Old girlfriends. The 'headliners' in my life, those that may have left me, but have left their mark.
(I don't believe in Heaven, but when I imagine my much-missed dead granddad, it's OK to picture him somewhere like this - this unreal fantasy, that I can escape to when I sleep and dream, to be reunited with the man I knew and loved)
I like to think that they've all contributed to who I am today; perhaps some in bigger ways than others. Still, I am the man I am now, in part, due to their involvement.