To gain an idea of the space of Extramental Dimensions containing memories and knowledge (Universal Knowledge), we can borrow from the model of Bohm's Holographic Universe: a hologram can store lots of information in the form of a very fine interference fringes (waves); many more than one could store with neurons, in theory.
In Our Virtual Reality, the waves in which information are stored are "mobile"; that is, they disperse in space over time.
If we hypothesised a Virtual Reality without temporal components, we could imagine "immobile" interference fringes, i.e., interference fringes that do not disperse into any space: that information would then be accessible if one knew how to recover those "immobile" interference fringes.
If that information contained in those "immobile" interference fringes were memories and knowledge, then Universal Knowledge could ("could" being the operative word) be an area of Virtual Reality without temporal components, outside of Our Virtual Reality, where all those "immobile" interference fringes concerning memories and knowledge are accumulated.
Some ways of accessing Universal Knowledge have already been mentioned in this text.