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The Brain - Coggle Diagram
The Brain
Love on the Brain
bartels and zeki 2000 > fMRI brain scans of people in love
- viewing photographs of someone they were in love with or someone they were friends with.
- "truly, madly, deeply in love" > average 2 years.
- in love:
- some overlap with emotion-regulated regions (anterior cingulate and insule)
- makes sense because love can be considered an intense emotion
- some overlap with positive emotion regions related to reward which are dopamine-rich (caudate and putamen)
- amygdala (active when processing fear and sadness) was deactivated in the love confition
- more active when viewing friends compared to partners.
- overall, the combination of brain sites that were activated in the love condition differs from those in previous studies of emotion, suggesting that there's a unique network of areas responsible for evoking the affective states of romantic love
aron et al 2005 > fMRI of early-stage love
- same premise
- early in love > average 7 months
- compared to photo of a friends
- some overlap with positive emotion regions relating to reward which are dopamine-rich (vta and caudate)
- some overlap with emotion-related regions (anterior cingulate and insula)
- suggest that there's a rather unique neural network of love
can love cause more permanent changes in the brain?
- can be studied by examining neural activity in brain regions at rest > resting state fMRI
- activity in a particular region more than surrounding regions
- connectivity with other brain regions
- blood flow in the brain can be examined when people are resting, and at any given time, there's going to be small spikes in how much blood flow there is in any given region.
- connectivity of brain regions can be inferred by spatially remote regions showing a similar pattern or correlation of spontaneous activity.
song et al
- hetero uni students were interviewed > 3 groups
- "in love" group (LG) > intensely in love
- "ended love" group (ELG) > recently ended relationship
- "single" group (SG)
- activation of an emotion-related region (anterior cingulate) in the "in-love" group
- ELG had less activation in the positive reward-related region (caudate) than people in LG or SG.
- suggests that even at rest, the brain shows altered activity in a unique neural network of love.
- implicates caudate as a region signalling breakup.
- even though activity decreases when you break up with someone, findings suggest that with time, the function of this region increases, potentially returning to normal.
- love can fundamentally change the brain, but not permanently.
- people in the LG had increased functional connectivity of the anterior cingulate, insula caudate nucleus, nucleus accumbens, and amygdala.
- may suggest that romantic love alters the function of a neural network of reward motivation, and emotion regulation.
can a brain scan predict relationship longevity?
- Xu et al 2012
- early-stage romance scans of 12 people > VERY small
- follow-up relationship status, happiness, and commitment > 3 years later.
- examine whether brain scans when people were falling in love could predict whether they would still be together 3 years later.
- in those that were still together, deactivation of the medial orbitofrontal cortex at the early time point correlated with scores of relationship happiness at the three-year time point.
- deactivation in a region of the brain involved in judging others negatively (MOFC) might predict relationship happiness.
- suspending negative judgement about their partners
jealousy
- fear of losing something
- fear of abandonment
- involves complex social interactions
- difficult to study in the lab in humans
- socially monogamous animals can display jealousy-like behaviours.
- titi monkey: primate native to Brazil > displays social monogamy in the field and lab
- form long-term pair bonds > grooming together, tail entwining
- often done awake or asleep
- mate-guarding > holding mate back from interacting with strangers
- bonded animals become distressed when separated from their partner
maninger et al 2017
- adult male titi monkeys injected with glucose so that the researchers could monitor which areas of the brain are going to use a lot of energy during a challenge to elicit jealousy.
- those in the jealous condition had an uptake of glucose.
- higher in brain regions associated with emotions (cingulate cortex), including social pain, as well as social bonding/memory (lateral septum)
- dopamine is slow to increase in the lateral septum a few weeks after a pair bond is established.
- activation of this region could be due to memories of the pair bond which is now being threatened.
- no control where the monkeys looked at their partners without a stranger, so the cingulate cortex activation could have just been from the monkeys looking at their partners.
- animals in the jealous condition had higher circulating levels of testosterone and cortisol.
- shows that the monkeys found the stranger next to their partner to be a stressful experience.
- evidence of neural and physiological changes relating to the emotion of jealousy.
Sex on the Brain
background
- the brain is a soft mass of tissue containing around 86 billion neurons, controlling your ability to think, talk, feel, hear, see, remember, walk, breathe, etc.
- some of the nerves in the brain go directly to sensory organs, and other nerves go through the spinal cord and control other areas of the body.
- there are nerves in the spinal cord that detect sensations from out body and bring that information back to the brain.
- some of the nerves in the PNS go to the genitals to control sexual function. a number of physiological responses occur in the body and the brain in preparation for sex and continue during sex.
sexual response cycle
- stages from research by Master and Johnson in the 1960s.
- measured physiological variables such as blood pressure and breathing, as well as measurements of sexual arousal in male and female genitalia.
- stages are fairly similar in men and women.
- many women can repeat the sexual response cycle rather quickly, but men go through a longer refractory period during resolution.
- refractory period: the individual can't experience another orgasm.
- length varies between men > as short as several minutes or as long as a day.
- as men age, their refractory periods tend to last longer.
- some sexual disorders are gender specific, and there is no clear somatic cause > nothing identifiably wrong with the body.
plateau
- men are at full erection (often with pre-ejaculatory fluid)
- women experience further swelling of the vagina and increased blood flow to the labia minora.
orgasm
- women have rhythmic contractions of the pelvis and uterus + increased muscle tension.
- men have pelvic contractions and a build-up of seminal fluid in the urethra that ends up being forced out by contractions of genital muscles (ejaculation)
excitement
- arousal stage
- erection of the penis and clitoris
- expansion and lubrication of the vaginal canal.
resolution
- relatively fast return to an unaroused state
- decreased blood pressure, muscles in the body relax.
comparison between hetero men and women during plateau and orgasm
- tactile genital stimulation in a pet scan
- some regions had higher or lower cerebral flow in both men AND women (blue and orange) compared to when the subjects were resting.
- gender differences in certain brain areas (green and pink).
- suggests that the brains of men and women were functioning somewhat differently when becoming sexually aroused.
- the brains of men and women responded more similarly during orgasm than during plateau.
- areas controlling cardiovascular arousal, respiration, and rhythmic muscle contractions were active in both men and women.
- this could indicate that men and women have different ways to reach orgasm, but the orgasmic experience is largely similar.
hormones
testerone
- touted in public media as being necessary for libido and sexual performance in men.
- signals are set from two hormone-producing regions (hypothalamus and pituitary) to the testes, and these hormones increase testosterone secretion from the testes.
- testosterone levels fluctuate across time in men and there's a difference across men.
- men with low testosterone receive some increase in sexual arousal when testosterone levels are boosted pharmacologically, but those with normal levels don't seem to notice an effect.
- women have testosterone, and there's some evidence that naturally higher levels are linked with vaginal blood flow during sexual arousal.
- evidence supporting testosterone-promoting pills for boosting sexual desire and function in men and women is mixed at best, especially in normal, healthy people
oxytocin
- when blood samples have been taken continuously during sex, and plasma is analysed, it has been shown that oxytocin levels increase during sex and after orgasm in men and women.
- produced in the brain and exerts effects on the body.
- oxytocin correlates with the intensity of orgasmic contractions.
- doesn't get into the brain in humans very well when taken as a pill > nasal sprays work better, but one study has shown that long-term use of oxytocin spray doesn't do anything.
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