KEEP YOUR BRAIN ALIVE: HOW THE BRAIN WORKS

The brain receives action, organizes and also, store and distributes
important information information for future use. The problems we associate
with getting older—forgetfulness, not feeling “sharp,” or having difficulty learning
new things—involve the cerebral cortex and the hippocampus.

The cortex is the part of the brain that is responsible for our
unique human abilities of memory, language, and abstract
thought. The hippocampus coordinates incoming sensory information
from the cortex and organizes it into memories. The
wiring of the cortex and hippocampus is designed to form links
(or associations) between different sensory representations of
the same object, event, or behavior.

THE CEREBRAL CORTEX AND HIPPOCAMPUS
Most pictures of the brain usually show the deeply grooved
and folded cerebral cortex: a thin sheet of cells (no thicker
than twenty pages of this book) wrapped around the other
“core” parts of the brain like a rind on a grapefruit. Although
thin, the cortex is very large (spread out it would cover the
front page of a newspaper) and contains an astounding number of
nerve cells—about one hundred million in every square
inch. And while the cortex may look like a uniform sheet, it
actually consists of dozens, perhaps hundreds, of smaller, specialized
regions (some as small as a fingernail, others as large
as a credit card). Each of the senses has its own dedicated
portions of cortical real estate—for example, there are at least
thirty specialized areas just for vision.
Processing information as it comes in from the senses involves
a network of many smaller regions. In addition, other regions of the cortex specialize in integrating information fromtwo or more different senses (so, for example, when you hear a
sound you know where to look).
These hundreds of regions are linked together by the
brains equivalent of wires: thin threads called axons (each only
one hundredth the thickness of a human hair) that extend from nerve cells and
conduct electrical impulses from one part of
the brain to another.
Every cortical region
sends and receives millions of impulses via
these axons to and from
dozens of other cortical
regions. The brain contains literally hundreds
of miles of such wires.
Thus, the cortex resembles an intricate web, VISUAL AREAS OF THE CORTEX
with each region linked directly or indirectly
to many other regions. Some of these connections are between
areas that process similar information, such as the thirty
involving vision, while other connections are between dissimilar
areas, such as touch and smell. The network of pathways
between cortical regions that do many different things is what
allows the cortex to be so adept at forming associations.
Like the cortex, the hippocampus plays an important role
in forming associations. The senses continually flood the brain
with information, some of it vital but much of it unimportant.
You don’t need to remember the face of everyone you pass on
the street, but you do want to recognize someone you just met
at your boss’s party! To prevent the information overload that
would accompany having to remember too much, the hippocampus sifts
through the barrage of incoming information
from the cortex and picks out what to store or discard. In other
words, the hippocampus acts like a central clearinghouse, deciding
what will be placed into long-term memory, and then,
when called upon, retrieving it. The hippocampus’s decision to
store a memory is believed to hinge on two factors: whether
the information has emotional significance, or whether it relates
to something we already know.
The hippocampus is also vital for making mental maps,
allowing us to remember things like where our car is parked
or how to get from home to work. Animals in which the hippocampus has
been removed cannot learn or remember
simple mazes. Most problems that cause mental deficiencies involve the
cerebral cortex or the hippocampus. So keeping mentally fit really
means exercising these parts of our brain so they function
at their best. And what they do best is to form associations between
different kinds of information they receive.

ASSOCIATIONS: How WE LEARN
Associations are representations of events, people, and places
that form when the brain decides to link different kinds of information,
especially if the link is likely to be useful in the future. The raw material
for associations originates primarily
from the five senses but also can be emotional or social cues.
The brain takes several different things into account in deciding
whether to forge these mental connections. For example, if
something provides inputs to two or more senses close together in time,
like the sight, smell, and taste of a cheeseburger, the brain will
almost automatically link the sensations.
In essence, this is our basic learning process.
The classic example of associative linking, often taught in
introductory psychology courses, is Dr. Ivan Pavlov’s experiments
with dogs. Dogs normally salivate at the sight of food.
Every day when Pavlov fed the dogs, he rang a bell. After a
few days, just ringing a bell made the dogs salivate, even if no
food was presented.
These dogs made an association—a connection within
their brains—that a certain sensory stimulus (the bell) meant
food. Consequently, the sound of the bell alone made the
brain instruct the salivary glands to get ready for food. Humans
and animals can form similar links between almost any
kind of sensory inputs.
Obviously, humans are capable of much more sophisticated
and abstract learning that isn’t as closely tied to external stimuli
(like bells) or external rewards (like food). Take learning a language, for example. An infant learns language by associating a
particular set of sounds with a certain behavior, person, or object.
(An explicit reward may or may not be present.)
Once such associations are formed, they reside in the
brain as a long-term memory, which can be accessed just by
experiencing the original stimulus. It’s rather astounding
when you think about it: A certain kind of sensory experience
can permanently change the wiring in part of your brain!
Most of what we learn and remember relies on the ability
of the brain to form and retrieve associations in much the
same way as Pavlov’s dogs learned that a bell meant food. For
example, you pick up a rose, and its smell activates the olfactory
(smelling) parts of the cortex, its image activates the visual
areas, and the soft petals or sharp thorns activate the feeling
sections. All these different sensations cause nerve cells in
very different areas of the cortex to be activated at the same
time in a particular pattern, strengthening some of the linkages between these areas.
Once that happens, anything that activates just part of the
network will activate all the areas of the brain that have representations
of rose events. Someone hands you a rose, and as you
hold it, you may remember your first wedding anniversary
when you received a dozen roses, which reminds you of your
first apartment in that awful building with the broken elevator.
Or the smell of roses reminds you of Aunt Harriet’s rose garden
in late summer where you had picnics with your cousin Arnie
who is now living in California and whom you keep meaning to
call—all sorts of memories result from a single stimulus.

MEMORY
Existing programs for brain exercise have ignored this powerful
associative route to forming and retrieving memories.
Neurobics seeks to access it by providing the cortex with the
raw material that will create new and potent associations.
Because each memory is represented in many different cortical areas,
the stronger and richer the network of associations
or representations you have built into your brain, the more your
brain is protected from the loss of any one representation. 1
Take the common problem of remembering names.
When you meet a new person, your brain links a name to a
few sensory inputs, such as his appearance (visual). When the
brain is younger, these few associations are strong enough so
that the next time you see this person, you recall his name.
But the more you age, the more people you’ve met, leaving
fewer unique visual characteristics available to represent each
new person, so the associative links between visual characteristics
and names are more tenuous. Now, imagine closing
your eyes in the course of meeting someone. Sensory inputs,
other than vision, become much more important as the basis
for forming associations necessary for recalling a name: the
feel of his hand, his smell, the quality of his voice.
You have now tagged someone’s name with not just one or
two associations, but at least four. If access to one associative
pathway is partly blocked (“Gosh, he looks familiar”), you can
tap into associations based on other senses and do an end run
around the obstruction. Adopting the strategies of forming
multisensory associations when the brain is still at or near its
peak performance—in the forties and fifties—builds a bulwark
against some of the inevitable loss of processing power later in
life. If your network of associations is very large, it’s like having
a very tightly woven net, and the loss of a few threads isn’t
going to let much fall through.
These multisensory representations for tasks like remembering names
were always available to you, but early on, your
brain established an effective routine for meeting people that
relied primarily on visual cues. An important part of the Neurobic strategy is to help you “see” in other ways—to use other
senses to increase the number and range of associations you
make. The larger your “safety net,” the better your chances of
solving a problem or meeting a challenge because you simply
have more pathways available to reach a conclusion.
More often than not, adults don’t exploit the brain’s rich potential for
multisensory associations. Think of a baby encountering a rattle. She’ll
look at it closely, pick it up, and run her
fingers around it, shake it, listen to whether it makes a sound,
and then most likely stick it in her mouth to taste and feel it
with her tongue and lips. The child’s rapidly growing brain uses
all of her senses to develop the network of associations that will
become her memory of a rattle.
Now think of yourself finding a rattle on the floor.
Most likely, you’ll just look at it and instantly catalog it:
“It’s a rattle.” The point is that a child is constantly tapping
into the brain’s ability to strengthen and increase connections
between its many regions—for smelling, touching, hearing,
tasting, and seeing—to produce an ever-growing tapestry of associations…and neural activity.

ROUTINES CAN BE BRAIN-DEADENING
You may be reading this and thinking, “I lead a fairly active
life and my brain seems pretty stimulated. Sure, I have my
routines, but it’s not like I don’t see new movies, listen to new
songs on the radio, watch TV, or meet new people.”
The truth, however, is that most of us go through our adult
lives engaged in a series of remarkably fixed routines. Think
about your average week.. .or day-to-day life. Really, how different
are your commutes, your breakfasts, lunches, and dinners, week in and
week out? And what about things like shopping and laundry? It’s startling
to realize just how predictable
and free from surprises our everyday lives really are and, as a
consequence, how little we tap into our brain’s ability to make
new associations. Now, routines are not necessarily bad. People created routines because
until recent times, the world was unpredictable,
and finding food and shelter was filled with risk and
danger. Once reliable sources of food, water, and shelter were
discovered, it made sense to continue in the same patterns
that allowed them to be obtained with a minimum of risk.
Discovering and practicing successful routines in an
unpredictable world ensured survival.
But in our late-twentieth-century, middle-class American
lives, such unpredictability is largely gone. Food is readily
available at the local supermarket; water flows from the tap;
weather-resistant, heated and cooled houses shrug off the climate.
Modern medicines ward off most common diseases.
We even count on the fact that our favorite TV shows air
each week at the same time.2
What consequences does this predictability have on the
brain? Because routine behaviors are almost subconscious,
they are carried out using a minimum of brain energy—and
provide little brain exercise. The power of the cortex to form
new associations is vastly underutilized.
If you drive or walk to work via the same route every day,
you use the same brain pathways. The neural links between
brain areas required to perform that trip become strong. But
other links to areas that were initially activated when the
route was novel—such as a new smell, sight, or sound when
you rounded a certain corner—get weaker as the trip becomes routine.
So you become very efficient at getting from
point A to point B, but at a cost to the brain. You lose out on
opportunities for novelty and the kind of diverse, multi sensory
associations that give the brain a good workout.

THE BRAIN HUNGERS FOR NOVELTY
The human brain is evolutionarily primed to seek out and respond to
what is unexpected or novel—new information coming in from the outside
world that is different from what it
expects. It’s what turns the brain on. In response to novelty, cortical
activity is increased in more and varied brain areas.3 This
strengthens synaptic connections, links different areas together
in new patterns, and pumps up production of neurotrophins.
But if it is simply more activity in the brain that leads to increased
neurotrophin production, then listening to more music
(even noise), or watching more TV, or getting a massage—all of
which stimulate the sense organs—would lead to better brain
health. Such passive stimulation of the senses, however, doesn’t
work as a brain exercise and neither does repeatedly doing the
same routine activities. Neurobics is neither passive nor routine.
It uses the senses in novel ways to break out of everyday routines.

OUR UNDERUSED SENSES
Our five senses are the portals, or gateways, through which
the brain gets its entire contact with the outside world. We
rely primarily on our senses of vision and hearing because
they quickly tell us a lot about our environment. Our other
senses—smell, taste, and touch—are less frequently and obviously
called upon. To understand this better, close your eyes
and try walking through a room. Instantly, the world around
you changes radically. Sounds, smells, and spatial memories
of your physical surroundings leap into consciousness. With
vision gone, your sense of touch suddenly becomes paramount. Navigating
even a familiar environment is a real challenge, and your brain goes into high alert.
The brain has a huge network of pathways based on visual
information. That’s why so many everyday experiences are
geared to visual appeal. In magazine, television, and billboard
ads, businesses use visual associations to encourage purchasing
decisions. In a world increasingly dominated by shrinkwrapped, plastic-packaged,
and deodorized items, the efforts
demanded of our other senses, such as touch and smell, are
diminished—far more than we’re consciously aware of.
Information and associations based on smell used to be far more relevant than
they are today. A keen sense of smell
was often vital to survival. Native Americans could track animals by their
smell; farmers could smell when a change in the
weather was about to happen; smell was important in making
sure that foods were safe to eat; doctors even used their sense
of smell to diagnose illness. Today, unless you have a very special job,
such as creating perfumes, aromas usually function as
masks (that’s why we use deodorants and fragrances).
Despite its diminished role in our daily lives, however, the
sense of smell plays an important role in memory. Associations
based on odors form rapidly and persist for a very long time,
unlike those based on the other
senses. The olfactory system is the
only sense that has direct connections to the cortex, hippocampus,
and other parts of the limbic system involved in processing emotions and
storing memories (see
illustration, page 10). That’s why
certain aromas like fresh-baked
bread or a particular flower, spice,
or perfume can trigger an abundance of emotional responses that stimulate
the memory of events associated with them. (For example, realtors often
advise you to have something delicious
baking in the oven when you’re showing your house for sale.
And if you saw Scent of a Woman, you’ll remember how Al Pacino’s blind
character could call up complex associations based
on smell alone.)

THE SIXTH SENSE: EMOTION
Researchers are finding that brain circuits for emotions are
just as tangible as circuits for the senses, and advanced imaging
techniques can now observe this.4 It is also clear from a
number of studies that one’s ability to remember something is
largely dependent on its emotional context.5 As we discussed
earlier, the hippocampus is more apt to tag information for
long-term memory if it has emotional significance. That’s why
engaging emotions through social interactions is a key strategy of Neurobics.
Interactions with other people are an important trigger of
emotional responses. Also, since social situations are generally
unpredictable, they are more likely to result in nonroutine activities.
Most people have a strong, built-in need for these interactions, and in
their absence, mental performance declines.As we age, our social circles
tend to shrink, so an important aspect of Neurobic exercise is to find
opportunities to interact with others. Not only does this engage our interest,
which directly helps us to remember things, but as the MacArthur
Foundation’s studies on aging have clearly demonstrated, social interactions
themselves have positive effects on overallbrain health.
The pace and structure of modern life has reduced the
number and intensity of our ordinary, day-to-day social interactions,
just as modern conveniences have deprived us of
the richness of many sensory stimulations. Remember when
buying gas meant talking with an attendant instead of
swiping a card at a gas pump? Or getting cash involved dealing
with a bank teller instead of pushing buttons on an ATM
machine? Or a night out involved going to the movies with a
crowd rather than renting a video and sitting alone in front of
your VCR? And the computer and the Internet have isolated
us even further from any number of personal transactions.
There’s ample evidence today that being out in the real
world, where you’re engaging all the senses, including the
important emotional and social “senses,” is essential to a healthy
brain and an active memory—especially as you age.
The aim of Neurobics and the exercises that follow is to provide you
with a balanced, comfortable, and enjoyable way to
stimulate your brain.
As we have shown, Neurobics is a scientifically based
program that helps you modify your behavior by introducing
the unexpected to your brain and enlisting the aid of all your
senses as you go through your day. An active brain is a
healthy brain, while inaction leads to reduced brain fitness.
Or, in simpler words—”Use it or lose it.”