Brain Functions: Memory Processes, Amnesia and Forgetting

In addition to these categories, memory is composed of various processes.  You would not be satisfied if your memory could only store the many types of information you want it to save.  You also want your memory to enable you to retrieve this information at the right time.

The ability to memorize new information is completely different from the ability to retrieve this information from your store of memories.  When information is sent to your memory, it must first be encoded into memory.  At this stage, a specific piece of information, such as the image of the Eiffel Tower glistening under soft white spotlights, will be associated to other related information such as the weather, the people around you or the emotions you felt at the time.  If the encoding is strong enough and your brain considers the information relevant, the data will be consolidated.  In other words, you will store a memory of the event.  Your memory of the Eiffel Tower and the information relating to it will eventually be permanently stored in your cerebral cortex.  When you are telling others about your trip a few years later, recovery processes will enable you to retrieve this event from your explicit memory and make it accessible to your conscious mind.

If you have a head injury or an illness resulting in brain damage that hinders one of these processes, a memory disorder known as amnesia may occur.  If the affected brain circuit is involved in encoding and consolidating information, you will no longer be able to store new memories—a condition known as anterograde amnesia. This is in contrast with retrograde amnesia which is the loss of recent memories or the inability to access memories already stored in long-term memory.  This type of amnesia is consistent with impaired consolidation or recovery processes.  Depending on the type of brain damage, the amnesia may or may not be permanent.  Even if there is no brain damage, certain psychological conditions can cause retrograde amnesia which is generally temporary.

It is important to carefully distinguish between amnesia and forgetting.  The fact that you can no longer retrieve a piece of information does not necessarily mean that a medical or psychological pathology is disrupting your memory processes.  Forgetting is a normal process which provides a way for the brain to erase less relevant memories.