FoundationalConceptsNeuroscience

nervous system. Newly stored memories in LTM are initially frail and
may be readily disrupted. It is often easier to remember things that
happened years ago than it is to recall the names of people you just
met at a party. New memories become more stable and robust with
time—a process called consolidation (Latin con = together, solidare =
solid).
Retrieval involves some mechanism of access to the stored
memory. Forgetting can occur because of failure of either storage or
retrieval. An event may have been experienced—for example, some-
body said something to you, sensory processes registered the sounds,
an understanding may have been registered in your WM—but the
information was never retained in LTM. Or, once in LTM, the stored
memory may decay or be lost over time, so that there is less and less to
retrieve. Or, there may be some sort of retrieval failure. This is a com-
mon experience: we know we know something, but just can’t recall it
at the moment, such as someone’s name, or the name of a song or film.
It may even be on the “tip of the tongue.” In such circumstances, pro-
viding a cue, some kind of related information or hint, is often enough
to awaken the memory.
Pathological memory problems are called amnesias, which come
in two major categories: retrograde and anterograde. Retrograde
amnesia (Latin retro = back, gradi = step) refers to an inability to recall
events before the onset of the amnesia. Memories of past experiences
are either lost or unable to be retrieved from LTM. This is the “Holly-
wood view” of what memory loss is: someone gets conked on the head
and looses all memory of who they are. Much more common is antero-
grade amnesia (Latin antero = forward), an inability to recall events
after the onset of the amnesia—such experiences are not retained in
LTM. This is really a problem with learning new information rather
than remembering what is already there.