Editing Atkinson–Shiffrin memory model (section)

===Capacity and duration===
In this model, as with most models of memory, long-term memory is assumed to be nearly limitless in its duration and capacity. It is most often the case that brain structures begin to deteriorate and fail before any limit of learning is reached. This is not to assume that any item which is stored in long-term memory is accessible at any point in the lifetime.  Rather, it is noted that the connections, cues, or associations to the memory deteriorate; the memory remains intact but unreachable.<ref name=AtkinsonShiffrin1968 />