How does memory work?
How does memory work?
Memory is the ability to hold onto (retain) and recall information from the past. There are three stages of memory: encoding, storage and retrieval.
- Encoding: The brain receives new information and creates a series of connections to represent that information. Those connections may link to other information already stored in your memory. For many types of information, you have to be paying attention to accurately encode the information.
- Storage: Those previously formed connections are maintained in your brain, even though you may not be using them.
- Retrieval: The brain recreates or activates the connections that represent previously encoded information and you can recall or recognize that information from the past.
This is a simple description of how memory works. Keep in mind that these stages and the processes within them are imperfect. Memory itself is imperfect. The witness to a robbery might remember a blue shirt when the robber was actually wearing green. Such forgetfulness is just that — forgetfulness — not necessarily a sign of amnesia.
There are several types of memory. Here are the two most relevant to understanding amnesia:
- Declarative/Explicit: Knowledge of facts and events in everyday life. Amnesia can erase these memories.
- Nondeclarative/Implicit: Non-conscious knowledge. Amnesia will not erase these “ingrained” memories. If you have amnesia, you should still remember how to walk or ride a bike.
The brain areas involved in memory are different depending on the type of memory you are forming and how long it can be stored.
- Short-term memory: Your short-term memory lasts as long as you have the information ‘in mind’ – usually between five seconds and 30 seconds. During that time you’re able to juggle an average of seven pieces of information – for example, seven letters, seven words or seven numbers. The frontal and parietal lobes are important for this type of memory.
- Long-term memory: Your long-term memory lasts between a minute and a lifetime. In theory, there’s no limit to your long-term memory. However, there is a limit to your ability to recall that information. The hippocampus and surrounding temporal lobes of the brain are important areas for long term storage and retrieval of information. However, long-term memory involves many areas of the brain and damage to many different parts of the brain can cause amnesia.