14 Unit 1 Reaching Your Potential
decline as nerve cells die off. This healthy removal
of unused cells allows the often-used brain con-
nections to strengthen, which speeds their signals.
Thus, your choices can make a physical difference
in the structure of your brain.
The most effi cient time for learning to take
place is called a window of opportunity. If the
window is missed, nerve cells often die off and
the related development may take longer or not
take place at all. For example, you are born with
the capacity to learn any language. The brain
connections that are used to learn the language
you speak continue to develop, but the parts you
could use to learn other languages die off because
of nonuse. After age 10, you are still able to learn
another language, but it may take you more time
or effort to master that new language than if you
had learned it earlier.
Although your heredity determines the number
of brain cells you start with, your environment
affects the number of connections made among
them. Good nutrition and plenty of rest are
important for brain development. As you will see
in the next lesson, a stimulating environment is
just as important. To reach your full intellectual
potential, both hereditary and environmental factors
need to come together.
extensions that look like fi ngers or tentacles. Their
job is to receive information from other cells. The
axon is a long fi ber that carries information away
from the cell body to the dendrites of other nerve
cells or to other cells in the body. The myelin
sheath is a coating along the axon that helps transmit
information along the neuron.
Each neuron connects with thousands of other
neurons in the brain. Each new experience you
have results in new connections made between
neurons. As more signals are sent and received
between neurons, these connections grow stronger.
The result is that information can be transmitted
between neurons faster. This speeds thinking and
reaction time.
The space between the axon of a sending neuron
and the dendrite of a receiving neuron is called a
synapse. The body makes chemicals in the syn-
apses that allow messages to be carried from one
neuron to another. These chemicals are called
neurotransmitters.
Different neurotransmitters result in different
types of messages. For example, some messages
speed up a body response; others slow it down.
Some chemicals produce a positive feeling, while
others help information fl ow to different parts of the
brain. The way your body responds is controlled
by the neurotransmitters.
The chemicals that are produced in your
synapses can be affected by both your heredity
and your environment. For example, your body
produces certain chemicals when you sleep and
others when you are awake. Other chemicals are
produced when you are in danger or in a stressful
situation. These responses are genetic. Environmental
factors—like the food you eat and how physically
active you are—can also affect which chemicals
are produced in the synapses.
How Your Brain Grows and Develops
As you grow and develop, your brain continues
to strengthen the pathways that are used. The
more you use a pathway, the quicker and stronger
the neural connections become. You can see these
results when, for example, your performance
steadily improves by practicing a skill over and over
(Figure 1.9). Parts of the brain that are not used
©iStock.com/monkeybusinessimages
Figure 1.9 With practice, your neural connections for
a task become stronger, improving your performance.
In what areas have you improved your performance
through practice?
Copyright Goodheart-Willcox Co., Inc.