Long Term Memory - What Is Memory: Improving Memory Understanding Age Related Memory Loss

Content provided by the Faculty of the Harvard Medical School

Long-term memory

Although the brain quickly purges most unimportant short-term memories, it stores the important ones — those that are emotionally compelling or personally meaningful. That stored information is long-term memory. It is the total of what you know: a compendium of data ranging from your name, address, and phone number and the names of friends and relatives to more complex information, such as the sounds and images of important events that happened decades ago. It also includes the routine information you use every day, like how to make coffee, operate your computer, and carry out all of the intricate behavioral sequences involved in performing your job or running your household.

Unimportant details stay in the brain only briefly as short-term memories, but more meaningful experiences tend to remain for the long term.

Your long-term memory and short-term memory are not distinguished merely by how long the memories last. Another difference is the amount of information each memory system and its associated brain regions can handle. Although the brain can juggle only a relatively small number of short-term memories at a time, it can store a virtually unlimited number of long-term memories. Barring disease or injury, you can always learn and retain something new. Furthermore, long-term memories are less fragile than short-term memories, which means they're not lost when something interrupts your train of thought. Previously learned long-term memories even tend to remain intact in the early stages of dementia, when patients have trouble learning new information.

Maintaining a long-term memory often requires that you periodically "revisit" it. Some long-term memories that go unused or become irrelevant fade or become distorted over time. Have you ever read a book that you loved, but years later found yourself unable to recall much more than the title? That's probably because you hadn't thought of the plot and characters in a long time. On the other hand, some long-term memories are amazingly persistent, no matter how infrequently you use them. For example, many adults are surprised by their ability to remember minute details of their youth — an unjustified punishment they received, a fifth-grade science project, their first date. Interestingly, research demonstrates that although long-term memory is more durable than short-term memory, it is also changeable. For example, the way you remember your first romance can evolve over time in response to experiences and information you acquire years later.

Long-term memory can be divided into two categories: declarative memory and procedural memory.

Last updated:	January 23, 2007