Human sexuality

1. HOMONES AND SEXUAL RESPONSE
MOENGA FREDRICK
0717268348
moengafredrick@gmail.com
YOUR BRAIN AND
SEX

2. INTRODUCTION
 the sensation of orgasm actually originates
between your ears, in the form of neurochemical
changes.
 These neurochemical changes take place in the
limbic system, or "primitive brain.
 " The primitive brain controls almost all bodily
functions.
 It’s the seat of emotions, desires, drives and
impulses. It’s where you fall in and out of
love…or lust.

3.  The primitive brain is largely the same in all
mammals. It has been around for well over
100,000,000 years, lurking right beneath your
large, rational neo-cortex
 you cannot will your feelings, emotions,
falling in love, or staying in love, anymore
than you can will your heart to beat, or
yourself to digest a meal or sleep.
 For every biological event in your body, there
is a biological cause. In this case, the cause
is neurochemicals.

4. Neurochemical Commands
 Dopamine is the neurochemical that activates your
reward center (more accurately, "reward circuitry").
 The reward center is a small portion of the limbic
system, but it drives nearly all of your behaviors.
 This center is activated when you engage in
activities that further your survival, or the
continuation of your genes.
 Whether it’s sex, eating, taking risks, achieving
goals, or drinking water, all increase dopamine, and
dopamine turns on your reward center. You can
think of dopamine as the "I’ve got to have it"
neurochemical, whatever "it" is. It’s the "craving"
neurochemical.

5.  The more dopamine you release and the more your
reward center is activated, the more "reward" you
experience. A good example is food. We get a much
bigger blast of dopamine eating high-calorie foods than
we do low-calorie foods.
 Our reward center is programmed that "calories equal
survival." You’re not actually craving ice cream, or a
winning lotto ticket, or even a romp in the sack. You’re
craving the dopamine that is released with these
activities. Dopamine is your reward, not the item or
activity.
 All addictive drugs and all addictions increase
dopamine; that is why they are addictive. Money,
power, gambling, shopping, computer games…if
something increases your dopamine, then it’s addictive

6.  Dopamine is absolutely necessary for your survival.
Yet when it’s too low or too high it can cause real
problems.
 Researchers placed electrodes in rats’ reward centers
to stimulate them, just as dopamine does. The rats
could then press a lever to stimulate the reward center.
That’s all those rats did; they ignored food, and even
female rats. They just sat there pressing the lever over
and over, wasting away…not unlike crack addicts.
 In a second experiment, scientists blocked dopamine
so the reward center could not be stimulated. What
happened? The rats just sat there, again ignoring food,
receptive mates, and the opportunity to explore their
environment

7. Changes with Dopamine levels
 Dopamine Levels Excess Deficient
"Normal"
 Addictions Addictions
Motivated
 Anxiety Depression Feelings of well-being,
satisfaction
 Compulsions Anhedonia - no pleasure, world looks
colorless Pleasure, reward in
accomplishing tasks
 Sexual fetishes Lack of ambition and drive Healthy libido
 Sexual addiction Inability to "love" Good feelings toward
others
 Unhealthy risk-taking Low libido Healthy bonding
 Gambling Erectile dysfunction Healthy risk taking

8.  Orgasm is the biggest blast of dopamine
(legally) available to us. A Dutch scientist
recently scanned the brains of people having
orgasm. He said they resembled scans of
heroin rushes.
 He saw visions of an "orgasm pill" and lots of
money. We saw visions of one of the most
addictive substance ever produced.
 Orgasm is the biggest blast of dopamine
(legally) available to us. A Dutch scientist
recently scanned the brains of people having
orgasm. He said they resembled scans of
heroin rushes. He saw visions of an "orgasm
pill" and lots of money. We saw visions of one of

9.  The highs and lows of dopamine are only half of
the "orgasm hangover" story. At orgasm,
dopamine drops like a lead balloon, and we lose
interest, at least temporarily. However, if
dopamine’s not kept in check, it could rapidly
shoot up again and we’d be back in the sack.
Biology’s mission is now to stop us from
screwing around and place our attention
elsewhere - like on hunting and gathering,
feeding the babies, going to our job, taking out
the trash and so forth. Otherwise we’d end up
like those rats, working our levers over and

10.  Suppressing dopamine is so important that
nature uses an additional neurochemical to
curtail our sexual desire. It’s called prolactin. If
dopamine is the "foot on the gas," then prolactin
is the "foot on the brake.“
 Research shows that prolactin surges
immediately after orgasm in both men and
women. Men may experience this prolactin
surge as the "roll over and snore" phenomenon.
In women, the effects may be delayed for days.
 There’s an inverse relationship between the
levels of prolactin and dopamine; when one is
up the other is down. This rise and fall produces

11.  What do couples complain of as their honeymoons end?
The very symptoms associated with high prolactin:
weight gain, drop in libido, mood changes, depression.
Notice that in women excess prolactin is also associated
with anxiety and hostility. Sound familiar?
Women Men
• Loss of libido Loss of libido
 Mood changes / depression Mood changes / depression
 Hostility, anxiety Impotence
 HeadacheHeadache
 Menopausal symptoms,
 even when estrogen is sufficient Infertility
 Signs of increased testosterone levels Decreased
testosterone levels
 Weight gain Weight gain

12.  Dopamine restrains prolactin production, so the
more dopamine there is, the less prolactin is released
 It is well-known that dopamine constitutively
inhibits prolactin (PRL) secretion via
the dopamine receptor 2 (DR2D). If dopamine is
increased or if dopamine receptors
hyperfunction, PRL may be reduced. During the first SCZ
episode, low PRL levels are associated with worse
symptoms.

13.  Although research hasn’t shown how long prolactin
surges continue in humans after sex, in rats surges of
prolactin continue for up to two weeks. This may help
to explain how great sex last week could lead to
relationship friction now.
 And it’s no wonder we don’t make the link between
cause and effect.
 There’s also evidence that prolactin acts as a stress
hormone. Unlike the "fight or flight" stress hormones,
prolactin seems to be associated with "giving up," or
"despair-type" stress.
When a wild monkey is first caged, "fight or flight" stress
hormones rise. As time goes by and despair sets in,
"fight or flight" hormones fall and prolactin rises. Could
these surges of prolactin explain relationship despair?

14.  orgasm leads to a drop in dopamine and a rise in prolactin.
Both of these lead to multiple behavioral and emotional
symptoms, which, in our experience, can arise over the
next two weeks. During this time, our behavior may change
for the worse.
 More importantly, our perception of each other can shift
dramatically for the worse. If we feel depleted, our partner
will seem overly demanding; if we feel needy, our partner
will seem selfish and uncaring. Of course, few people ever
avoid orgasm for two weeks. Most of us ride this roller
coaster over and over, never really experiencing balanced
brain chemistry.

15.  Orgasm’s high dopamine/low dopamine pattern
actually encourages addictions of many kinds
because people attempt to use artificial means
to manipulate their dopamine levels
 Most addictions kick in during teen years, when
we become sexually active. A recent Columbia
University study found that sexually active teens
use more drugs. One might think social factors
alone lead to this correlation between drugs and
sex, but when scientists studied hamsters, they
found that sexually-active hamsters were much
more susceptible to amphetamine addiction
than their virgin counterparts

16.  Children, or pre-teens have yet to activate this dopamine
roller coaster, and they possess a cheerful, optimistic
enthusiasm for the simplest activities. Perhaps this is due
to balanced dopamine. Low Testosterone and the Coolidge
Effect
 Sexually-satiated male rats take up to seven days to
recover their full desire for sex, although there is one
way to jumpstart them, which we’ll get to in a moment.
Research shows they experience a reduction in
testosterone receptors for up to a week, which may
decrease that "manly feeling." If this happens in
females, it would also reduce their sexual desire. Low
testosterone is associated with irritability and anger.
Serotonin and endorphin levels also rise in sexually-
satiated rats, which decrease dopamine and raise
prolactin, respectively. Remember, in humans, any

17.  Your primitive brain is not equipped to "get" that. It just
keeps rewarding you to do the same unrewarding things. A
"fix" just positions you for a continuous addictive cycle of
highs, more lows, and a search for more highs. Many of us
spend much of our sex lives caught in this cycle - with no
obvious way out.
N/B: We have talked about how dopamine can break
couples apart, but there’s also something holding couples
together…at least at first

18. The Power of Oxytocin

19.  The neurochemical that binds couples together
is oxytocin, the "cuddle hormone" or "bonding
hormone." Without it, we could not fall in love.
 Falling in love is associated with a soup of
neurochemicals - like adrenaline, which makes
your heart race, and dopamine, which makes
you crave your beloved. But the heartwarming,
loving, "gushy" aspects of love are due to
oxytocin.
 It is the "unconditional love" hormone
associated with nurturing and generous
affection.

20.  Oxytocin has various functions in the body,
such as inducing labor contractions and milk
ejection, but from evolutionary biology’s
perspective, its main evolutionary function is to
bond us to our children for life. It also serves
to bond us to our mate…at least long enough
to produce a child and (if we're lucky) get it on
its feet.
 Friendships are also built on oxytocin, and can
be quite deep bonds. Yet, what happens to
friendships that turn into sexual relationships?
Often things change for the worse. This
change is an excellent example of the

21.  Making love with lots of affection, without the
dopamine-driven highs and lows of conventional
sex, seems to keep oxytocin levels high. The
more oxytocin you produce, the more receptive
you are to it. This is the opposite of dopamine.
 Addicts need more and more of a drug, which,
of course, which actually means they need more
and more dopamine. Luckily you don’t need an
ever-increasing "fix" of oxytocin to maintain the
same gushy feeling. In fact, your partner just
looks better and better…at least to you.
 This is why this practice can strengthen your
bond with your mate.

22.  When researchers injected oxytocin into the
brain of a promiscuous breed of rodent, it
preferred familiar partners to unfamiliar
partners. Dopamine and its hangover are the
keys to promiscuity, whereas oxytocin is the key
to monogamy.
 Oxytocin has huge benefits, both emotionally
and physically. Oxytocin is the answer to the
question, "What is the mechanism by which love
and affection positively affect our health?"
 Oxytocin reduces cravings. When scientists
administered it to rodents who were addicted to
cocaine, morphine, or heroin, the rats opted for

23.  Oxytocin calms. A single rat injected with
oxytocin has a calming effect on a cage full of
anxious rats. (Agren, 2002)
 This quality of oxytocin explains why
companionship can increase longevity - even
among those who are HIV positive (Young,
2004).
 Or speed recovery: wounded hamsters heal
twice as fast when they are paired with a sibling,
rather than left in isolation (DeVries, 2004).
 It may also explain why, among various species
of primates, care-giving parents (whether male
or female) live significantly longer. (Cal Tech,

24.  Oxytocin appears be a major reason that SSRI’s
[Prozac-type drugs] ease depression, perhaps
because high levels of cortisol are the chief culprits in
depression and anxiety disorders. (Uvnas-Moberg,
1999)
 Oxytocin increases sexual receptivity and counteracts
impotence, which is why this other way of making love
remains pleasurable. (Pedersen, C.A., 2002), (Arletti,
1997)
 Again, notice that oxytocin reduces cravings and
increases sexual receptivity. This allows making love
without orgasm to be completely satisfying. The
affection is always there, flowing between you and
your partner. When we tiptoe around dopamine’s highs
and lows, we encourage more oxytocin receptors and

25.  The Karezza Method by J. William Lloyd, MD (1931)
 Male Continence by John Humphrey Noyes (1872)
 Karezza: Ethics of Marriage by Alice Bunker Stockham,
MD (1903)
 Sex Perfection and Marital Happiness by Rudolf von
Urban, MD (1949)

26. SEXUAL RESPONSE CYCLE