Monday, March 05, 2012

Does Amnesia Erase Memories?

Image Source:
During the 1940's and 1950's, when severe epileptic disorders were treated by surgically removing part of the brain, doctors found that electrical stimulation of the hippocampus provoked a flood of memories in their patients. Removal of or damage to the hippocampus made it impossible for patients to learn anything new, and at the same time erased memories of events within the past three years. Only older memories were left intact. This kind of amnesia (loss of memory) has proved to be permanent.

Progressive loss of memory is the dire result of Alzheimer's disease, a degeneration of the brain that generally strikes in old age. This, too, is an irreversible loss.

A head injury can also cause amnesia, but often the effect is temporary. For example, the victim of a car crash may lose memories of events just prior to the accident. Scientists call this retrograde amnesia.

Severe emotional stress is another cause of amnesia. Victims of crime and battle-scarred soldiers may protect themselves from the horrors they have experienced by blotting out the memory.. Such a mechanism may seem merciful, but can result in deeper emotional trouble, for, it seems, these memories are not lost. Unless the past is retrieved and faced, the stress may fester.

No comments: