does the ps4 gpu have its own dedicated RAM?
Both the PS4 and Xbox One will have one massive pool of RAM.
having them have very similar specs, allows developers to more easily create games and regulate the data flow.
They have tools that allow them to analize the data stream and processes of RAM and CPU cycles/cores to better efficiently create games.
Uncharted 3 has a bonus video that shows a little glimpe about this software, and they briefly talk about how they utilize that information to keep the game running smoothly.
This way, with games, you can pick and choose the bare minumum of RAM and CPU/GPU power needed to each different element.
IIRC, on Last of Us, Naughty Dog engineers dictated that only 4MB of RAM was allowed for animations. (Which explains why the animations when you strangle someone, or stealth kill a Clikcer, is all the same, every time)