Neurons communicate using chemical messengers
called NEUROTRANSMITTERS. A neuron sends an
electrical signal that triggers the release of a
neurotransmitter. Like a lock and key, the chemical
attaches to a special receptor on another neuron.
The message is sent.

Some neurotrasmitters tell the next neuron whether
to fire or not, while others may influence how the
neuron responds to other signals. The brain reacts
in different ways depending on the neurotransmitter
and the brain region signaled.

DOPAMINE, among other things, is a key
messenger in the brain' "seeking system,"
which generates desire. When dopamine is
released, it helps motivate you to find the
things you need. Once you achieve your goal
dopamine is released again to strengthen
the memory of what caused the good feeling.

OXYTOCIN plays a key role in the bonding
process. New moms and people in love generally
have high levels of this neurotransmitter in
their brains. Scientists think that oxytocin
may decrease during a period of separation
but increase again during a reunion.
Oxytocin is released by the pituitary gland.

ENDORPHINS are brain chemicals released
by the pituitary gland, the hypothalamus and
many other neurons throughout the brain to
help reduce pain and stress. Endorphins also
activate your pleasure centers when you
accomplish a goal, when you exercise
and even when you eat chocolate!

STRESS-HORMONES include cortisol
and epinephrine. These brain chemicals
are released when something makes you
worried, angry or agitated. Their function
is to get your body and mind ready to defend
yourself if necessary, or to run away.