Memories have been divided into types based on how the length of time the memory is stored in the brain: sensory memory, short-term memory, and long-term memory. Long-term memory is further divided into types of memories depending upon the kind of information that is stored. Finding ways to turn fleeting thoughts into long-term memories comprises much current neuroscience research. From college students to those diagnosed with Alzheimer's dementia, new research on the storage of memory is exciting.
Sensory Memory and Short-term Memory
The first fleeting thought is termed "sensory memory". Comprised of brief images (icons) or sounds (echoes) these sensory memories persist less than a few seconds. Depending upon the attention given to a sensory memory, it may or may not be turned into a short-term memory.
Short-term memories are often encoded phonetically, that is, by sound. That is why hinting that something "sounds like" something else can trigger recall. We often exclaim, "It's Dolly or Polly or something like that!" Short-term memories do not last beyond eighteen seconds and do not include large amounts of information. Repetition and elaborating on an idea make it more likely to be stored as a long-term memory. Want to remember someone's name at a party? Elaborate on it. "Hank Fitzgerald, that's Irish? Is Hank your given name or is it a nickname?"
Long-term Memory: Procedural, Semantic and Episodic
Memories that make it beyond the short-term designation are more likely to be encoded by meaning. Long-term memories can be pictured as file drawers with information tucked away by topic. While long-term memories last great deal longer than short-term memories, they too fade and change over time. Long-term memories are only "relatively" permanent.
Long-term memories are further subdivided into skills (procedural) memory, facts (semantic memory) and experiences in time (episodic) memories. Episodic memory is the least fixed of the three as it is always changing with the passage of time.
When a memory is stored, it is said to make a memory trace, a chemical change in the brain. But if that memory is not recalled, the trace decays, or fades, over time. Decay is not even. As anyone who has worked with dementia patients will attest, some childhood memories remain vibrant while in dementia newer memories may not be stored, or encoded, at all.
Recent Advances in Memory Research: Engrams and Ampakines
Gary Lynch, neuroscientist at University of California, Irvine, has developed ampakines, a class of drugs meant to increase communication between brain cells by forcing neurons to be more receptive to chemical changes that make the formation of memory trace or engram more likely. In short, receptive neurons are more likely to store long-term memories.
Ampakines help regulate neurotransmitters such as glutamate. Low levels of glutamate have been associated with schizophrenia and Alzheimer's disease. Both enhancing memory and treating stroke may be uses for this class of drugs. The mystery of turning short-term memories into long-term memories is unraveling.
Sources:
Ampakines accessed November 5, 2010
Coon, Dennis. Essentials of Psychology. Ninth edition. United States:Wadsworth, 2003.
McDermott, T. 101 Theory Drive: A Neuroscientist's Quest for Memory. New York: Pantheon Books, 2010.
Gina Barrett Putt - Gina Barrett Putt works in housing, with experience in case management for elders and the mentally ill, and college and K-12 education.
Join the Conversation