My question is: as the mapping happens in 1-to-1 manner, then is it logical to assume that the brain loses the ability to map space anymore when it already has each suitable neuron assigned to a place?
From these articles, it is clear that the space unit is not very big, and is a sphere of some size not significantly bigger than the body. If the answer to the question is "yes", then what is the approximate size of the world we can map? (any metric would do, be it a volume in liters or surface area in square meters).
Other than that, if the observations described in the articles are lab simplifications, and in real life the mapping mechanism is more complex, then what is it like?