April 01, 2007
Trade-Off Between Working Memory And Memory Formation?

Blocking neurogenesis helped mice better use recently acquired information still in working memory.

NEW YORK – New research from Columbia University Medical Center may explain why people who are able to easily and accurately recall historical dates or long-ago events, may have a harder time with word recall or remembering the day’s current events. They may have too much memory – making it harder to filter out information and increasing the time it takes for new short-term memories to be processed and stored.

Published in the Proceedings of the National Academy of Sciences (March 13, 2007 issue), the research reinforces the old adage that too much of anything – even something good for you – can actually be detrimental. In this case, the good thing is the growth of new neurons, a process called neurogenesis, in the hippocampus, the region of the brain responsible for learning and memory.

I just had a conversation with a neuroscientist about neurogenesis and memory formation. He downplayed the need for neurogenesis to form at least some types of memories. A lot of memory formation gets done by protein synthesis and connection formation between existing neurons. Yet this press release implies a role for neurogenesis in longer term memory formation.

Here is the meat of the matter: A cut in neurogenesis allowed mice to use their working memory more efficiently.

Results of the study, conducted with mice, found that the absence of neurogenesis in the hippocampus improves working memory, a specific form of short-term memory that relates to the ability to store task-specific information for a limited timeframe, e.g., where your car is parked in a huge mall lot or remembering a phone number for few seconds before writing it down. Because working memory is highly sensitive to interference from information previously stored in memory, forgetting such information may therefore be necessary for performing everyday working memory tasks, such as balancing your check book or decision making.

“We were surprised to find that halting neurogenesis caused an improvement of working memory, which suggests that too much memory is not always a good thing, and that forgetting is important for normal cognition and behavior,” said Gaël Malleret, Ph.D., a research scientist at the Center for Neurobiology and Behavior at Columbia University Medical Center and the paper’s co-first author. “Altogether, our findings suggest that new neurons in the hippocampus have different, and in some cases, opposite roles in distinct types of memory storage, and that excess neurogenesis can be detrimental to some memory processes.”

Maybe there's a trade-off between better use of memory on a given day versus formation of long term memories. Enhancement of neurogenesis might turn out to boost, for example, the memory formation of a medical student who is trying to memorize all the bones and muscles in the body. Does halting of neurogenesis reduce the formation of long term memories in mice?

Attempts to achieve Artificial Intelligence (AI) will need to avoid excessive memory formation. Also, attempts to boost new memory formation in humans and other animals will need to weigh the costs to working memory function.

“We believe these findings have important implications for diverse disciplines ranging from medicine to artificial intelligence,” said Dr. Malleret. “In medicine, these findings have significant implications for possible therapeutic interventions to improve memory – a careful balance of neurogenesis would need to be struck to improve memory without overwhelming it with too much activity.”

I've love to double or triple my working memory set. This'll probably come much sooner for new babies by use of embryo genetic engineering. We'll probably gain the capability to boost offspring intelligence many years before we gain that same capability to change fully formed and extremely complex adult brains.

Then there are the memories that you don't much want to keep around. Some work is tedious and boring. Do you want to remember every time you did a highly repetitive task on an assembly line or other work setting? I guess you'd want to remember it only well enough to remind you to take steps necessary to avoid the need to work in such a job again.

Share |      Randall Parker, 2007 April 01 08:38 AM  Brain Memory

Jake said at April 1, 2007 9:36 AM:

A sports psychologist told me that you don't forget the way you used to play golf before you received lessons. At each stage in your learning process, the brains stores how you play at that moment in time.

If you think of a past golf experience while you are playing golf, the brain will retrieve the skill level you had at that time and that is skill level you will use to hit the next shot.

Only by refocusing on the present, can your present skill level be retrieved and used.

So a great long term memory for a athlete is a detriment.

dick fuel said at January 28, 2009 11:10 PM:

tradeoff makes little sense to me

working memory is the bottleneck

if you can't put it into working, you can't put it into long-term

the role of neurogenesis in LTM formation is poorly understood, and likely very complex

cannabis markedly enhances neurogenesis, for example.

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