Biology 202

2006 First Web Paper

On Serendip

Memory loss occurs for a variety of reasons: Alzheimer's disease, strokes, head injuries, and prolonged alcohol abuse are only a few (1). In some instances memory loss may be slowed, prevented, or regained. These cases provide insight into how memory and certain aspects of the brain in general work.

Beginning with the more physical aspects of memory loss, each of the examples of memory loss cause listed above can be traced to physical problems. A stroke occurs when too much or too little blood is in a part of the brain, damaging cells (2). Excessive alcohol consumption changes the balance of molecules in many parts of the body, including the brain. Head injuries that produce memory loss such as concussions are maybe the most tangible example of a physical source for memory loss problems.

Even diseases like Alzheimer's can be traced to specific molecules within the brain-either too many of the wrong molecules or too few of the right ones. The use of medications with cholinesterase inhibitors and research on new Alzheimer's drugs highlight this connection. Cholinesterase inhibitors are the only drugs approved for middle stages of Alzheimer's disease. They are part of a chain of enzymes that determines how many of certain molecules are present in the brain. Cholinesterase inhibitors slow the molecules that break down acetylcholine, allowing more acetylcholine to accumulate. The related studies suggest that a decrease in acetylcholine is part of many memory problems. (3)

In addition to the effects of molecules, the destruction and re-growth of nervous system cells, called neurogenesis, accounts for changes in memory. Former alcoholics were found to have adult neurogenesis in areas of the hippocampus (4). However, although short term memory improves as the length of abstinence increases, long term memory remaines impaired. This suggests that the parts of the brain responsible for short term memory can resume their activities after re-growing, but that either long-term memory cells are harder to re-grow or that the damage to the long-term memory requires more than the right kind of cells. (5)

The physical, tangible aspects of the nervous system -parts of the brain, cells and molecules- are one part of the explanation for memory and memory loss. Culture, behavior and other less tangible factors add to that explanation. Memory impaired individuals can take mental notes more carefully, write notes, practice memorization with clues, and compensate with less damaged areas of the brain. These behavior changes can increase independence for dementia patients early on through learning to use the memory capacity they have in all situations. (6)

Similar to making a conscious effort to remember small details, in "The Culture of Memory" the researchers explored the impact of culture in what individuals remember (7). They found that in cultures that emphasize the individual, people remember farther back in than those from more community based cultures. Also the types of memories vary from personal, single event memories to memories of routine and group activities. Finally this effect was paralleled in familial influences within the same culture. Children whose mothers encourage them to tell personal stores are more likely to remember events and details of those events than children whose mothers place less emphasis on personal story telling.

Besides restructuring and paying more attention to what is remembered, practice can also help. A smaller working memory –the number of ideas that can be held simultaneously in one's thoughts- may be part of the problem in ADHD. While the human brain seems to reach a limit of thinking about four different items at once, individuals with smaller working memory capacities can increase their working memories up to four items through practice. (8)

These studies together highlight some aspects of how memory works. First, there is a difference between short term and long term memory, and probably a difference between immediate or working memory, short term memory, and long term memory (5), (8). Somewhere in the process, the nervous system decides to move certain bits of information, or memories, from shorter term storage to longer term storage or to forget them. These are partially distinct operations because shorter term and longer term operations are not uniformly affected by memory losses and memory recoveries. This means that individuals, like those in the Cognitive Loss and Recovery study may recover short term memory without equivalent long term memory improvements (5). At the same time, children in different cultures with identical short term memory abilities may have farther or shorter-reaching long term memories (7). Related to short-term/long-term distinction, memory works in different parts of the brain, and some processes and places can be trained to do the job of other parts (6). Also, taking in information, storing information, and then recalling the information are distinct though connected processes.

Secondly, memory works within a biological system and, just like the muscles that allow a person to walk, depend on biological, physical, and chemical processes. When cells die or the wrong molecules are present memory suffers. Furthermore, these problems are sometimes treatable or curable and sometimes permanent. (1), (3), (4)

However there are just as important social and cultural elements that affect the nervous system. Although they may at some level affect physical processes, the solutions that these elements provide for memory loss are not applied with pills or surgeries. Individuals make conscious and unconscious decisions about if, where, and how to store memories (6), (7). These influences are manifested in individuals without memory loss and can be usefully applied to help those with less severe memory loss problems cope with, work around, or fight their memory loss.

Finally, these pieces to the puzzle of memory, memory loss, and memory recovery parallel many aspects of nervous system problems that are more traditionally called mental illnesses. Depression, for example, also has physical, biological causes as well as cultural and behavioral influences. It changes the ways people are able to interact with others and to think. This similarity raises questions about why and if there is a distinction between memory problems and other problems that appear in parallel ways, but are more commonly labeled illnesses.

WWW Sources

1) Poor memory's multiple causes, R. Adleson

2) NINDS Stroke Information Page

3) Brain study sheds light on anti-Alzheimer's drugs, R. Adelson

4) Temporally Specific Burst in Cell Proliferation Increases Hippocampal Neurogenesis in Protracted Abstinence from Alcohol, Kimberly Nixon and Fulton T. Crews

5) Cognitive loss and recovery in long-term alcohol abusers, J. Brandt, et. al.

6) Mending memory, Rachel Adelson

7) he culture of memory, Lea Winerman

8) A workout for working memory, Sadie F. Dingfelder


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