Amnesiacs are people who have sustained some kind of brain injury, traumatic experience or illness that has left them with the inability to remember things. Most amnesia is only temporary, but there are some who will never be able to retrieve their memory — and a few who can only remember things for a few seconds or minutes, including the people they love.
Most people with amnesia are able to function as normally as they did before they lost their memory, but are not able to retrieve memory that is still stored there. It’s as if the connection has been cut completely to their personal information memory storage area, they are still able to walk and talk, and even do complex math problems. In other words, the portion of the brain that processes your actions and cognitive skills is still intact, but memory (usually long-term memory) is not accessible.
The brain is so fascinating. It protects us just as much as it helps us to function. If we undergo something that is harmful, or too hard to handle, it puts up a defense mechanism that separates the good from the bad. It has been found that there are several different areas of the brain that store memory, but the limbic system, which includes the hippocampus, the amygdala and parts of the cerebral cortex, is involved in the retrieval of it. The limbic system is also responsible for the coordination of motivation and emotions, and for some of the functions of the endocrine system.
Amnesia can affect both types of memory — short-term (working) memory and long-term memory. Single functions, like riding a bicycle, remain intact. This could explain why amnesiacs can often remember basic skills and motor functions, while losing personal memories.
The odd aspect to amnesia is that, although some memories may be hard to retrieve, the person can have excellent memory function in other areas. That could mean that an individual with amnesia may have good childhood memories, and remember the years before their injury, but remember little or nothing from then on.
Why the brain reacts this way is not certain. A study using rats suggested that memory loss is probably due to an error in memory retrieval. It could also be due to swelling in the brain, which would explain why some amnesiacs get their memory back after the brain swelling has subsided.
It can’t be easy, for an amnesiac or their loved ones, to not be able to remember things that happened to you before or after a trauma. Memory is a complex part of the brain, and requires a lot of different areas. Fortunately, many of them work independently of each other so not all other functions are affected.
Wikipedia – Anterograde amnesia: http://en.wikipedia.org/wiki/Anterograde_amnesia
Memory Loss and the Brain – Anterograde Amnesia: http://www.memorylossonline.com/glossary/anterogradeamnesia.html
Life Extension — Amnesia and Memory Loss: http://www.lef.org/protocols/neurological/amnesia_01.htm