YOUR EMOTIONAL BRAIN

Your brain gets information from two
different sources: Your senses tell you
what's going on in the outside world,
while your emotions exist inside your
body to tell you what these events and
circumstances mean to you. Just as hunger motivates you to find food,
emotions motivate you to take care of
other needs—like safety and
companionship—that ultimately
promote survival and reproduction. Emotions are controlled by the levels of
different chemicals in your brain, but
there is no one “love” or “hate”
chemical. At any given moment, dozens
of chemical messengers, or
neurotransmitters, are active. Some of these neurotransmitters go between
individual cells, while others are
broadcast to entire brain regions. By
layering signals on other signals, your
brain can adjust how you respond to
things and can effectively alter your mood. If you're in danger, for example,
your brain releases stress hormones
that make you react faster, flooding
certain regions with the
neurotransmitter epinephrine
(adrenaline). When the danger subsides, your brain sends out a calming signal in
the form of chemicals that dampen the
response of regions that create fear. When you're feeling an emotion, it's
often written all over your face. While all
mammals produce basic emotions like
fear and anger, humans have especially
highly developed social emotions, such
as shame, guilt, and pride, which involve an awareness of what other people
think and feel about us.

BEYOND OUR LIZARD BRAIN

Lizards and humans share similar brain
parts, which they inherited from fish.
These parts handle basic body functions
like breathing, balance, and
coordination, and simple survival urges
like feeding, mating, and defense. Together, these parts—the brain stem,
cerebellum, and basal ganglia—are
casually referred to as your “lizard
brain.” How are mammals different from lizards?

One big difference between mammals
and lizards is that mammals have more
complex emotions. Our emotions are
processed in several regions that
together are loosely called the “limbic
system.” They form a ring around our “lizard brain” regions, which evolved
earlier. Mammal brains also have an
outer layer called a cortex, which helps
us control our emotions and make
complex decisions. Mammals tend to have strong emotional
bonds between family members, and
they generally care for their young after
birth. Instead of responding just by
reflex and instinct—as a lizard does
when it snaps at you if you get too close —they are guided by their emotions,
making their behavior more flexible.
Mammals tend to have good memories,
especially for events that created strong
emotions. Primates—the group of mammals that
includes monkeys, apes, and humans—
can recognize facial expressions,
communicate, maintain social
relationships, and sometimes even lie,
thanks to the front of their cortex, or outer layer of the brain. A monkey's
cortex is more than twice the size of a
comparable mammal's, and in humans,
it is bigger still. All mammals have some
version of basic emotions like fear and
anger, since our limbic systems are very similar. But humans are also especially
sensitive to social emotions like shame,
guilt and pride, which require
understanding what other people think
and feel about us—a specialty of our
advanced prefrontal cortex. The human brain includes many regions
that evolved long ago. Our older “lizard
brain” parts keep our bodies working
and provide basic survival motivations,
while our newer “mammal brain”
regions improve our emotions and memory. Our “primate brain,” with its
large, wrinkly cortex, helps us plan,
predict, and use language. All these
regions work together. So while ancient
urges still drive our behavior, we
constantly think up new strategies for achieving these goals.

FIGHTING DEPRESSION.

Millions of Americans take
antidepressant drugs that alter how the
brain processes serotonin, a
neurotransmitter linked to feelings of
serenity and optimism. These drugs,
called selective serotonin reuptake inhibitors (SSRIs), increase levels of
serotonin in the synapse by blocking its
removal. What happens to the brain when an antidepressant is
introduced? What other practices
can be implemented to combat
depression? While scientists still do not fully
understand how SSRIs relieve
depression, they know that these drugs
increase the serotonin signal and lead to
many long-lasting changes in neurons.
Normally, when serotonin is released into the synapse, some serotonin
reaches receptors in the second cell, but
the remaining serotonin is taken back up
into the first cell. When an
antidepressant is introduced, however,
the drug blocks serotonin from returning to the cell that released it. Excess
serotonin stays in the synapse longer,
allowing for more serotonin to reach
receptors. Antidepressant drugs have helped many
people—but for others they offer no
relief. But any activity that changes your
mood does so by changing your brain
chemistry. Talk therapy, physical
exercise, fulfilling personal relationships, and successful achievements all change
the levels of mood-altering chemicals in
our brains.

LOVE

What is love? Neuroscientists can't
answer that question yet. But they have
learned more about how the feelings
that occur when people “bond” are
produced in the brain. If you look at how
humans bond with their mates and care for their young, you'll see some
surprising similarities between us and
other species. Can family bonds be strengthened and weakened by
chemicals in your brain? Only about 5 percent of mammal species
form exclusive, lifelong bonds with their
mates. One is the prairie vole: Chemicals
in a vole's brain make it link its mate
with good feelings, and pairs tend to
stay together for life. One of these chemicals is the neurotransmitter
oxytocin. Prairie voles with more
oxytocin receptors tend to stay with
their mates. Voles with low levels mate
with new partners. Oxytocin plays a key role in the bonding
process in voles—but what about in
humans? In humans, as in prairie voles,
oxytocin is released during birth,
nursing, and mating—important bonding
moments. Inhaling oxytocin in a nasal spray makes people feel more trusting
in clinical studies. And in studies, men
with naturally low oxytocin levels were
less likely to get married. So is oxytocin the secret of love? No. It is
just one chemical messenger in the
brain—a small part of a very
complicated system. And it's not the
only messenger involved in producing
feelings of love and affection. Dopamine is a key messenger in the brain's
“seeking system” that generates
desire, and endorphin activates your
pleasure centers when you find what
you were looking for.