Valentine's Day tidbits: Our brain is the key

Where to we find enduring love? Answer: Oxytocin. Infidelity? Testosterone.
Heartbreak? Low serotonin and endorphins. In fact, our loved ones are actually
present in our brains - neurochemically - and when we lose them, it results in
chemical trauma for the brain:

"An American study of over four thousand men found that husbands with high
testosterone levels were 43 percent more likely to get divorced and 38 percent
more likely to have extramarital affairs than men with lower levels. They were
also 50 percent less likely to get married at all. Men with the least amounts of
testosterone were more likely to get married and to stay married, maybe because
low testosterone levels make men calmer, less aggressive, less intense, and more
cooperative.

"The desire to commit to someone is strongly linked to ... oxytocin. ...
Oxytocin is released by the pituitary gland and acts on the ovaries and testes
to regulate reproduction. Researchers suspect that this hormone is important for
forming close social bonds. The levels of this chemical rise when couples watch
romantic movies, hug, or hold hands. Prairie voles [mammals related to the
mouse], when injected with oxytocin, pair much faster than normally. Blocking
oxytocin prevents them from bonding in a normal way. This is similar in humans,
because couples bond to certain characteristics in each other. This is why you
are attracted to the same type of man or woman repeatedly. In general, levels of
oxytocin are lower in men, except after an orgasm, where they are raised more
than 500 percent. This may explain why men feel very sleepy after an orgasm.
This is the same hormone released in babies during breast-feeding, which makes
them sleepy as well.

"Oxytocin is also related to the feelings of closeness and being 'in love' when
you have regular sex for several reasons. First, the skin is sensitized by
oxytocin, encouraging affection and touching behavior. Then, oxytocin levels
rise during subsequent touching and eventually even with the anticipation of
being touched. Oxytocin increases during sexual activity, peaks at orgasm, and
stays elevated for a period of time after intercourse. ... In addition, there is
an amnesic effect created by oxytocin during sex and orgasm that blocks negative
memories people have about each other for a period of time. The same amnesic
effect occurs from the release of oxytocin during childbirth, while a mother is
nursing to help her forget the labor pain, and during long, stressful nights
spent with a newborn so that she can bond to her baby with positive feelings and
love.

"Higher oxytocin levels are also associated with an increased feeling of trust.
In a landmark study by Michael Kosfeld and colleagues from Switzerland published
in the journal Nature, intranasal oxytocin was found to increase trust. Men who
inhale a nasal spray spiked with oxytocin give more money to partners in a risky
investment game than do men who sniff a spray containing a placebo. This
substance fosters the trust needed for friendship, love, families, economic
transactions, and political networks. According to the study's authors,
'Oxytocin specifically affects an individual's willingness to accept social
risks arising through interpersonal interactions.' ...

"What happens in the brain when you lose someone you love? Why do we hurt, long,
even obsess about the other person? When we love someone, they come to live in
the emotional or limbic centers of our brains. He or she actually occupies
nerve-cell pathways and physically lives in the neurons and synapses of the
brain. When we lose someone, either through death, divorce, moves, or breakups,
our brain starts to get confused and disoriented. Since the person lives in the
neuronal connections, we expect to see her, hear her, feel her, and touch her.
When we cannot hold her or talk to her as we usually do, the brain centers where
she lives becomes inflamed looking for her. Overactivity in the limbic brain has
been associated with depression and low serotonin levels, which is why we have
trouble sleeping, feel obsessed, lose our appetites, want to isolate ourselves,
and lose the joy we have about life. A deficit in endorphins, which modulate
pain and pleasure pathways in the brain, also occurs, which may be responsible
for the physical pain we feel during a breakup."