Page 43 - The Memory Program How to Prevent Memory Loss and Enhance Memory Power

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threads of the spider's web have broken because of lack of interest and disuse.

Over time, long-term memory tends to get pushed from consciousness into the subconscious. Then
a simple cue, an odd association, a chance meeting, can activate the sleeping spider's web and fire the
neuronal circuits, resurrecting the long-term memory that had seemingly evaporated from your mind.

Your Brain Is Plastic

If your skin is cut superficially, it heals within a few days. Many other organs in the body can also
repair themselves: new cells are generated by cells that divide and reproduce in response to injury.
Unfortunately, while brain cells do grow and specialize during infancy and childhood, by the time
we become adults nearly all of them lose the capacity to divide and reproduce. And yet we know that
our brains are constantly changing: we learn throughout our lives, we have a range of reactions that
we can modulate in response to other people, places, and even time itself. So how do we explain this
contradiction: the brain creates no new nerve cells but has great flexibility? The answer lies in the
revolutionary new finding of brain plasticity.

Dr. Eric Kandel, a Nobel Prize winner, works a few floors above my office in the same research
institute. For several decades, Kandel has studied a species of snail called aplysia, which looks like a
small black blob with ears. Aplysia has large nerve cells that lend themselves to experiments.
Kandel's groundbreaking studies have shown that many nerve cells in aplysia, and in more complex
species, retain the property of plasticity, which means that they can change their structure or function
over time. The nerve cells do this by sprouting new branches called dendrites and forming contacts
with other nerve cells to compensate for those that have been lost. Using a different approach, Bruce
McEwen's laboratory at Rockefeller University demonstrated what was once thought to be
impossible: plasticity and regeneration of nerve cells in the hippocampus in animal studies.

As an analogy, we know that people who are born blind develop an exquisite sense of touch and
hearing. For those who constantly use Braille and become expert at it, the brain region responsible
for controlling the one finger used for reading physically grows in size. This type of compensation
may also occur following memory loss, depending on the cause.