The LIGHT Center, T-90, College of the Redwoods (476-4290)

One of the most complicated and least understood mechanisms that we as humans rely on is memory. The area of memory has been studied for many years, with few major advances in what it is and how it works. Early neurological study of memory focused on brain mapping and trying to locate specific brain areas responsible for memory. Studies stemming from brain injury and amnesia research suggest that the hippocampus and the limbic system are essential to the functioning of memory. However, there are other theories out there competing with the brain localization theories. Biochemical studies suggest that there is an implication of neurotransmitters and the actual measurable changes in brain chemistry when memory is impaired. For example, studies of individuals with Alzheimer’s show a depletion of acetylcholine and glutamate, suggesting their involvement in memory function. Other theories suggest the development of neural pathways being established. For example, when first learning information there are new neural pathways being forged. As that pathway is used more and more to access the newly learned information, it becomes more definitive and accessible. Some studies actually suggest growth in the portions of cells that allow information to be transmitted.

Regardless of what theory one adopts, there are some commonalties across the most accepted ones. For anyone who has taken Introduction to Normal Psychology, they will be familiar with the three component model. The three components are:

Sensory Store – This is a mechanism believed to hold the sensory image for only a millisecond, long enough to form a perception. It is thought to be automatic rather than operating under command.

Short Term Store – This retains the information for about 30 seconds without rehearsal. It has a capacity of 7-8 pieces of information and tends to maintain meaningful information more easily than nonsense. It is within this stage of processing that one can enhance recall by using memory enhancement strategies. Short Term Store is vulnerable to decay due to lack of rehearsal, retroactive interference (interfered with by information following that to be learned) or proactive interference (interfered with by previously learned information).

Long Term Store – This is like a filing cabinet. It is thought that nothing is actually lost from LTS unless brain damage occurs. When cells die, so does information. "Forgetting" is thought to be an inability to "locate" where the information was filed. How the information is filed is dependent upon the individual. There are complex schemas and hierarchies which come into play. Most people tend to either be visual, semantic or auditory/phonemic encoders. The first involves the recall of what the information looked like. The second refers to filing the information related to its meaning. The auditory/phonemic encoder tends to file based on the sounds of the words used. To efficiently recall information, one needs to use retrieval strategies that match the way they filed the information in the first place.

Comments? Mailto:trish-blair@redwoods.edu

-Norman Cousins

January 31, 2000

"Retrieval" is the process involved in accessing the learned information in one’s memory. People’s names are a good way to determine how you file information for later usage. If when trying to recall a person’s name, if you

picture their face in your head, you are likely a visual encoder and decoder. If you try to determine what situation you last met that person in, or try to determine where you last saw them, you are likely semantically coding material. If you go through the alphabet to determine the first letter of their name, and go from there, or determine how many syllables the name has, you are likely an auditory/phonemic decoder.

There are a number of conditions in which memory is severely impaired:

• Dementias

There are a number of progressive dementias which methodically decay the memory system. Alzheimer’s is the best known of these.

• Stroke or TIA

Stroke or mini-strokes (Transient Eschemic Attacks) destroy brain cells which then result in memory degradation. In many cases, retrieval is severely impaired, with the person "forgetting" how to search their memory system for information. Most common is Anomia, the forgetting of names of things.

• Substance Abuse

Korsakoff’s disease due to chronic alcoholism significantly affects memory. New research suggests that cocaine usage has similar affects on the memory system.