13.6 Brain mechanisms of sexual behaviour Flashcards
what are the four brain structures have a well established role I sexual behaviour
cortex, amygdala, hypthal and ventral striatum
what are the 2 main source of info for brain mechanisms of sex behaviour
- human volunteers, correlational and focussed on arousal and orgasm triggered by sexual images or masturbatio - no real sex
- nonhuman subjects - only way to get solid causal info bc we can’t scan human brains during sex for a few reasons
how does the study of lab rats circumvent the problems with studying humans (2)
- can use invasive techniques
2. can study natural patterns of copulatory activity
what are some of the problems with using lab animals to study sexual behaviours
can’t study some important aspects, like sexual imagery, delayed orgasm, female orgasm, feelings of love
what are the areas of the Cortex often associated with sexual arousal in the human brain (8)
- occipitotemporal
- inferotemporal
- parietal
- orbitofrontal
- medial prefrontal
- insular
- cingulate
8 premotor
what are the two interesting pieces of information concerning cortical activity during sexual behaviours?
- activity of the secondary visual cortex (occipitotemporal and innferotemporal cortexes) occurs during arousal even if the eyes are closed
- prefrontal cortex is suppressed during orgasm
what is the assumption about the role of the cortex in sexual experience
controls the most complex aspects, like the feelings of release of control, changes inn self awareness, disturbances In perceptions of space and time, love
What did Gorski and colleagues find in the hypothalamus that relates to sexual activity?
the medial preoptic area, which is several times larger I males and tf called the sexually dimorphic nucleus
Explain the development of the sexually dimorphic nuclei in rats
same size in both sexes at birth
first few days after, the male nuclei grow at fast pace and the females dont
growth of the male nuclei is triggered by estradiol aromatized from T
what are the other sex differences in the hypthal? (4)
what are they all influenced by?
- volume of various nuclei
- cell number, connectivity, morphology,
- neural activity
- neurotransmitter type
- prenatal exposure to estradiol
what area plays a massive role in male sexual behaviour? what doest his include
the medial prepotic area, includes the sexually dimorphic nucleus
What evidence proves that the preoptic area plays a major role in male sexual behaviours? (4)
- destruction of the area abolishes sexual behaviour in males in all mammalians species studied
- lesions do not eliminate he female sex behaviours of males, do eliminate the male behaviours in females
- stimulation elicits copulatory behaviours in male rats
- copulatory behaviour can be reinstated In castraed male rats by medial prep-tic implants of testosterone
What does the medial preoptic area control sexual beahviour in males through
through a tract that projects to an area of the midbrain called the lateral Tegmental field
what is the evidence for the role of the tract from the medial preoptic area to the lateral segmental field (2)
- destruction of the tract disrupts sexual behaviour in male rats
- activity of individual neurons in the lateral tegmental field is correlated with male copulatory acts
- for example, some only fire a lot during intromission
what area of the rat hypthal is relevant in female sexual behaviour? is it the whole thing?
the ventromedial nucleus, only certain circuits
what occurs to female rats with bilateral lesions of the ventromedial nucleus (VMN)?
do not display lordosis, likely to attack ardent suitors
what mediates the influence of the VMN on female rat sex behaviour
how do we know? (2)
the tract descending to the periaqueductal Gray (PAG) of the tegmentum
- destruction of the tract eliminates female sexual behaviour
- lesions to the PAG itself also eliminate female sexual behaviour
what does the amygdala mediate?
identification of potential mating patners based on sensory and social signals (visual in humans, olfactory in rats)
what is Kulver Busy syndrome and how does it support the influence of the amygdala in sex behaviours?
disorder caused by bilateral lesions to the amygdala in primates, causes flat affect, hyper sexuality, complete inability to limit sexual advances to appropriate partners or locations
explain everitts study of bilateral amygdalae lesions in male rats.
- destroyed copulatory behaviour
- not bc they had trouble copulating,
- incapable of responding to the olfactory ad visual cues of receptive females
how does male and female arousal to sexual images support the role of amygdala in sex behaviours
males are more likely to be aroused by images, difference is reflected in amygdala activation
- erotic images produced greater amygdala activation in males
is sex a reinforcer?
yes. rats prefer partners, locations and odors associated with copulation
what is the activity in the ventral striatum associated with in sex behaviours
anticipation and experience of sex and other forms of pleasure