
known as the temporal lobes control new learning, and are particularly vulnerable to the effects of
aging. This means that, as we get older, we take longer to learn a new language, and slower to
master new routines and technologies at work, and we have to rely more on diaries and other
mental aids.
“Working memory” is the third brain system which is vulnerable to the effects of aging.
Working memory is the brain's “blackboard”, where we juggle from moment to moment
the things we have to keep in mind when solving problems, planning tasks and generally
organizing our day-to-day life. Absent-mindedness occurs at all ages because of imperfections in
the working memory system - so, for instance, you may continually lose your glasses, or find
yourself walking into a room of your house only to find that you cannot remember what you came
for.
Such absent-mindedness tends to creep up on us as we age and occurs because our
plans and intentions, which are chalked up on the mental blackboard, are easily wiped out by stray
thoughts and other distractions. Stress and preoccupation can also cause such
absent-mindedness, in addition to age-related changes in the brain. The frontal lobes of the brain -
located behind the forehead and above the eyes - are where the working memory system is located.
Like the temporal lobes, which handle new learning, the frontal lobes are more vulnerable to the
aging process than other parts of the brain.
The news, however, is not all bleak. Although neurons reduce in number with age, the
remaining neurons send out new and longer connection fibers (dendrites) to maintain connections
and allow us to function reasonably well with only relatively small drops in ability.
This and other evidence suggests that the principle “use it or lost it” might apply to the
aging brain. Professor Shimamura studied a group of university professors who were still
intellectually active, and compared their performance on neuropsychological tests with that of
others of their age group, as well as with younger people. He found that on several tests of
memory, the mentally active professors in their sixties and early seventies were superior to their
contemporaries, and as good as the younger people.
Research on animals provide even stronger evidence of the effects of stimulation on the brain
structure. Professor Bryan Kolb, of the University of Lethbridge in Canada, has shown that
animals kept in stimulating environments show sprouting (生长) and lengthening of the
connecting nerve fibers in comparison with animals kept in unstimulating environments.
The beneficial effects of continued mental activity are shown by the fact that older
contestants in quiz shows are just as fast and accurate in responding to general knowledge
questions as younger competitors, suggesting that at least part of their intellectual apparatus is
spared the effects of aging because of practice and skill.
Such findings lead to the intriguing possibility of “mental fitness training” to accompany
jogging and workouts for the health conscious. Research in Stockholm by Professor Lars