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We live in the present, but we can recall the past and so use the
results of prior experience to enhance our future. Memory and
prediction are thus central to the maintenance of a current consciously
controlled life. Past. Present. Future.
Past, Present, and Future
Both children and adults learn even though they have little understanding of how a human brain and its memory system work. The detailed workings of our brain’s memory and processing system are not yet well understood even by the leading researchers in this field of study.
Much of our cognitive activity focuses on movement — determining,
activating, and predicting our own movements, and predicting the
movements of objects and others.
Effective movements require efficient memory systems that encompass (1) relevant factual knowledge about our environment and personal experiences, and (2) motor skills that execute complex responsive motor programs. Alzheimer’s and Parkinson’s diseases are examples of maladies that result from a deterioration of the cognitive systems that allow us to easily understand and navigate our time/space environment.
Scientists generally divide memory into a short-term limited-capacity element of our attention system called working memory that has no long-term recall, and a more complex long-term memory of general and personal knowledge. We can thus remember where we put our car keys a few minutes ago, but not every place we’ve ever put them. We do however maintain a long-term factual memory of the recognition and purpose of car keys, and the skill memory of how to use them.
Memory is processed by a variety of related brain modules—each
specialized to process an element of the memory (such as a color,
shape, sound, and smell). The various brain modules that constitute a
memory are linked, so activating one element of a memory will typically
activate others (such as being able to visualize an unseen friend
during a phone conversation).
We don’t store complete discrete memories that exist like photographs, but rather we reconstruct a triggered memory from a huge store of highly interconnected reusable elements developed from our life experiences. For example, the part of our visual system that recognizes red will respond to anything red, such as exit signs, stoplights, and catsup.
If seeing a restored automobile activates the memory of the same model we owned years ago, it may also activate memories of experiences we had with the car. We could thus think of memory as something dynamic that emerges when it’s needed to connect current and previous experiences—and memory loss as the inability to connect the present with our past.
It's adaptive for human memory to focus on information that's currently important. If something in our past was significant enough to be remembered, but is no longer significant, the strength of that memory tends to fade. The phrase “use it or lose it” is thus apt with human memory.
Most people find it easy to understand the idea of learning and
remembering factual information, and that the Web can store factual
information. It is more difficult to understand how a human brain
stores and deals with emotions. Think of factual memory as being more
about remembering what happened, and emotional memory as being about
remembering how you felt about what happened. Both are important, but
our emotional memories are typically the more powerful. For example,
our emotional memories of a childhood experience are often stronger
than our remembrance of its factual details.
Given the complexity of our memory system, the loss of any of its elements may reduce the effectiveness of the entire system. Most of us thus become concerned when we suffer memory lapses, fearful that they may signal the beginning of the disintegration of the complete system.
What Scientists Know About Memory Loss
Sue Halpern is a respected writer for The New Yorker magazine who became professionally interested in memory when her elderly father developed serious memory problems. The result of her search for what researchers know and don’t know about the decline of memory is Can’t Remember What I Forgot: The Good News From The Front Lines Of Memory Research (2008). Although the subtitle suggests a more positive report than the book actually provides, it’s an informative book. It’s basically the report of her fascinating investigation into the difficulty of researching and reversing the increased memory loss we tend to experience as we age.
Halpern takes us on the personal tour of the memory research community that we might all take if we had the time, background, contacts, and determination to discover the current state of knowledge. She participated in many of the research investigations she describes. The book is thus an intriguing combination of anecdotes about the set of important researchers she meets during her quest, and helpful non-technical observations and explanations of the nature and potential of their research. She seasons her discussion of researchers and their discoveries with a dose of skepticism that is an expression of her realization that researchers must truly believe in and promote what they’re attempting to do, even when the odds are against them—given that they must constantly seek grant support for their research and commit to long frustrating laboratory hours.
Since no current cure exists for the dementias, the research has tended to focus on delaying the onset. Dementia tends to be a malady of aging, and so delaying its onset means that potential patients and their families won’t suffer as long, or that the person might die of something less destructive to personal dignity and family relationships. Still, some researchers are currently focused on potential cures, and the level of understanding of dementia is considerably advanced over that of a few years ago. That’s the Good News of the book’s subtitle.
Halpern focuses on two research approaches that hope to reduce memory loss. The first seeks to identify a chemical abnormality that a drug could ameliorate. For example, the hippocampus is a structure that plays a central role in memory. It has long been implicated in Alzheimer’s disease, but researcher Scott Small discovered that memory loss associated with normal aging occurs in a hippocampal area called the dentate gyrus, and memory loss associated with Alzheimer’s disease occurs in a hippocampal area called the entorhinal cortex. This discovery allows researchers to focus their search for abnormalities in a specific area.
The second approach focuses on brain plasticity, the ability to improve brain network connections through intensive practice in related activities. For example, right-handed violin players increase left-hand digital competence through violin practice, and chess players increase their knowledge of effective strategies by playing a lot of matches with good players. One fascinating study traced the documented lives of 678 elderly Roman Catholic nuns to discover the reasons for their much lower than normal incidence of dementias (http://brainfitnessforseniors.com/2009/04/29/the-nun-study-2/).
Since stimulating activities that enhance memory capabilities can actually improve our mental capabilities, computerized brain training programs are emerging that purport to enhance networks that regulate memory. One problem with these programs is that most purchasers don’t know how effective they are. Memory enhancing drugs must pass stringent federal research guidelines before they can be sold, but no such oversight exists for brain training computer programs.
One approach to credibility for such programs is through independent
studies of their effectiveness. For example, Posit Science’s Brain
Fitness Program was investigated by researchers at University of
Southern California and the Mayo Clinic, and the positive results were
published in a peer-reviewed journal, The Journal of the American
Geriatrics Society. See http://www.positscience.com/science/detailed-information/studies-results.
Halpern, S. (2008) Can’t remember what I forgot: The good news from the front lines of memory research. New York: Harmony Books.
Sylwester, Robert (2010). Fading memories, emerging understanding. Retrieved 2/10/2010 from http://iae-pedia.org/Fading_Memories,_Emerging_Understanding.
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