Rewire Your Brain: Think Your Way to a Better Life

neurotrans-
mitters
across a gap called a
synapse
. This is how one neuron gets 
another neuron to fi re. More than sixty types of neurotransmitters 
exist in the brain. Some make you excited, and some calm you down. 
There are many different shapes and sizes of synapses, and the 
shape and size of a synapse changes as you learn something new. 
Two neurotransmitters account for about 80 percent of the sig-
naling in the brain: glutamate, which is excitatory and stirs activity, 
and gamma - aminobutyric acid (GABA), which is inhibitory and 
quiets down activity. Glutamate is the workhorse in the brain. When 
it delivers a signal between two neurons that previously had no con-
nection, it primes the pump for later activation. The more times this 
connection is activated, the stronger the wiring is between these 
neurons. GABA, in contrast, helps to calm you down when you need 
to be calm. It is the target of drugs like Valium and Ativan, which 
used to be prescribed as a panacea for anxiety. You need optimum 
GABA activity to keep your anxiety down, but you don ’ t need those 
drugs, as I ’ ll explain in chapter 6 . 
Although glutamate and GABA are the principal neurotransmit-
ters, there are scores of others that play important roles in the brain. 
They account for only a fraction of the activity between the neurons, 
but they have a powerful infl uence on those neurons. They are widely 
researched, and many drugs have been designed to affect them. 
The three most researched neurotransmitters are serotonin, 
norepinephrine, and dopamine, and they are sometimes called 
neuromodulators
because they alter the sensitivity of receptors, 
make a neuron more effi cient, or instruct a neuron to make more 
glutamate. They can also help to lower the “ noise ” in the brain by 
working to override other signals that are coming into the synapse. 
Sometimes, however, they intensify those other signals. These three 
neurotransmitters can either act directly, like glutamate and GABA, 
or fi ne - tune the fl ow of information that is being processed in the 
synapses. 
Serotonin has attracted much publicity because of the wide-
spread use of drugs like Prozac. Serotonin plays a role in emotional 
tone and in many different emotional responses. Low serotonin 
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8 Rew i r e
Yo u r
B r a i n
levels are correlated with anxiety, depression, and even obsessive -
compulsive disorder (OCD). 
Serotonin is like a traffi c cop, because it helps to keep brain activ-
ity under control. It ’ s common to hear people who take drugs like 
Prozac say, “ Things don ’ t bother me the way they used to. ” However, 
there is also a downside: these drugs generally provide such an even 
keel that people say, “ I know that the beauty of that sunset would ’ ve 
had a bigger effect on me in the past, but now I ’ m sort of numb to 
things like that. ”
Norepinephrine activates attention. It amplifi es the signals that
infl uence perception, arousal, and motivation. Like serotonin, norepi-
nephrine has been associated with mood and depression. It has been 
targeted by antidepressants such as Ludiomil and Vesta. 
Dopamine sharpens and focuses attention. It has also been associ-
ated with reward, movement, and learning, and it is one of the principal 
neurotransmitters that code pleasure. When registering pleasure, 
dopamine activates an area called the
nucleus accumbens
, some-
times referred to as the pleasure center. Activation of the nucleus 
accumbens has been associated with drug abuse, gambling, and 
other types of addictive behaviors. When this area is frequently 
activated, it becomes hard to stop doing the things that activate it. 
Drugs that activate dopamine, like Ritalin, are used to help peo-
ple with attention - defi cit/hyperactivity disorder (ADHD). People 
(usually children and adolescents) who are given Ritalin or similar 
drugs not only pay attention better but also report feeling calmer.
Cells That Fire Together Wire Together 
In the last twenty years, there has been an overwhelming amount of 
evidence that the synapses are not hardwired but are changing all 
the time. This is what is meant by synaptic plasticity, or
neuroplas-
ticity
. The synapses between the neurons are plastic. 
Neuroplasticity is what makes memory possible. I will devote an 
entire chapter to how you can improve your memory; for now, the 
point is that the brain changes its synapses when you remember 
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F i r i n g t h e R i g h t C e l l s To g e t h e r
9
something new. The brain would not be able to record anything new 
if it were hardwired. Remembering something new is, therefore, 
rewiring the brain. By making connections between ideas or images, 
you also make connections between the neurons that encode those 
ideas and images. 
Neuroplasticity illustrates the phrase “ Use it or lose it. ” When you 
use the synaptic connections that represent a skill, you strengthen 
them, and when you let the skill lie dormant, you weaken those 
connections. It ’ s similar to the way that your muscles will weaken if 
you stop exercising. 
“ Cells that fi re together wire together ” aptly describes the way your 
brain reorganizes when you have new experiences. The more you 
do something in a particular way, use words with a specifi c accent, 
or remember something about your past, the more the neurons that 
fi re together to make this happen will strengthen their connections. 
The more the neurons fi re together, the more likely it is that they 
will fi re together in the future. 
Just as “ Cells that fi re together wire together ” has become a sort 
of mantra in neuroscience, so too has an opposite phrase been 
coined: “ Neurons that fi re apart wire apart. ” This means that neu-
rons that are out of sync will fail to link. It is the neural explanation 
for forgetting. 
In other words, the more you do something, the more likely it is 
that you will do it again in the future. That ’ s why baseball players go 
to batting practice, golfers go to driving ranges, and piano players 
practice for hours on end. The same goes for thinking. The more 
you think about your Aunt Matilda, the more she will pop into your 
mind again and again. Repetition rewires the brain and breeds 
habits. 
When neurons fi re together often, they begin to fi re together at 
a quicker rate. This leads to increased effi ciency, because there is 
more precision in the number of neurons that are required to do a