Amnesia refers to the loss of memory. Memory loss may result
from two-sided (bilateral) damage to parts ofthe brain vital for
memory storage, processing, or recall (the limbic system,
including the hippocampus in the medial temporal lobe). Amnesia
can be a symptom of several neurodegenerative diseases; however,
people whose primary symptom is memory loss (amnesiacs),
typically remain lucid and retain their sense of self. They may
even be aware that they suffer from a memory disorder. People
who experience amnesia have been instrumental in helping brain
researchers determine how the brain processes memory. Until the
early 1970s, researchers viewed memory as a single entity.
Memory of new experiences, motor skills, past events, and
previous conditioning were grouped together in one system that
relied on a specific area of the brain. If all memory were
stored in the same way, it would be reasonable to deduce that
damage to the specific brain area would cause complete memory
loss. However, studies of amnesiacs co