13.6 Brain mechanisms of sexual behaviour

Question 1

what are the four brain structures have a well established role I sexual behaviour

Answer 1

cortex, amygdala, hypthal and ventral striatum

Question 2

what are the 2 main source of info for brain mechanisms of sex behaviour

Answer 2

1. human volunteers, correlational and focussed on arousal and orgasm triggered by sexual images or masturbatio - no real sex
2. nonhuman subjects - only way to get solid causal info bc we can’t scan human brains during sex for a few reasons

Question 3

how does the study of lab rats circumvent the problems with studying humans (2)

Answer 3

1. can use invasive techniques

2. can study natural patterns of copulatory activity

Question 4

what are some of the problems with using lab animals to study sexual behaviours

Answer 4

can’t study some important aspects, like sexual imagery, delayed orgasm, female orgasm, feelings of love

Question 5

what are the areas of the Cortex often associated with sexual arousal in the human brain (8)

Answer 5

1. occipitotemporal
2. inferotemporal
3. parietal
4. orbitofrontal
5. medial prefrontal
6. insular
7. cingulate
   8 premotor

Question 6

what are the two interesting pieces of information concerning cortical activity during sexual behaviours?

Answer 6

1. activity of the secondary visual cortex (occipitotemporal and innferotemporal cortexes) occurs during arousal even if the eyes are closed
2. prefrontal cortex is suppressed during orgasm

Question 7

what is the assumption about the role of the cortex in sexual experience

Answer 7

controls the most complex aspects, like the feelings of release of control, changes inn self awareness, disturbances In perceptions of space and time, love

Question 8

What did Gorski and colleagues find in the hypothalamus that relates to sexual activity?

Answer 8

the medial preoptic area, which is several times larger I males and tf called the sexually dimorphic nucleus

Question 9

Explain the development of the sexually dimorphic nuclei in rats

Answer 9

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

Question 10

what are the other sex differences in the hypthal? (4)

what are they all influenced by?

Answer 10

1. volume of various nuclei
2. cell number, connectivity, morphology,
3. neural activity
4. neurotransmitter type
   - prenatal exposure to estradiol

Question 11

what area plays a massive role in male sexual behaviour? what doest his include

Answer 11

the medial prepotic area, includes the sexually dimorphic nucleus

Question 12

What evidence proves that the preoptic area plays a major role in male sexual behaviours? (4)

Answer 12

• 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

Question 13

What does the medial preoptic area control sexual beahviour in males through

Answer 13

through a tract that projects to an area of the midbrain called the lateral Tegmental field

Question 14

what is the evidence for the role of the tract from the medial preoptic area to the lateral segmental field (2)

Answer 14

1. destruction of the tract disrupts sexual behaviour in male rats
2. activity of individual neurons in the lateral tegmental field is correlated with male copulatory acts
   - for example, some only fire a lot during intromission

Question 15

what area of the rat hypthal is relevant in female sexual behaviour? is it the whole thing?

Answer 15

the ventromedial nucleus, only certain circuits

Question 16

what occurs to female rats with bilateral lesions of the ventromedial nucleus (VMN)?

Answer 16

do not display lordosis, likely to attack ardent suitors

Question 17

what mediates the influence of the VMN on female rat sex behaviour
how do we know? (2)

Answer 17

the tract descending to the periaqueductal Gray (PAG) of the tegmentum

1. destruction of the tract eliminates female sexual behaviour
2. lesions to the PAG itself also eliminate female sexual behaviour

Question 18

what does the amygdala mediate?

Answer 18

identification of potential mating patners based on sensory and social signals (visual in humans, olfactory in rats)

Question 19

what is Kulver Busy syndrome and how does it support the influence of the amygdala in sex behaviours?

Answer 19

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

Question 20

explain everitts study of bilateral amygdalae lesions in male rats.

Answer 20

• destroyed copulatory behaviour
• not bc they had trouble copulating,
• incapable of responding to the olfactory ad visual cues of receptive females

Question 21

how does male and female arousal to sexual images support the role of amygdala in sex behaviours

Answer 21

males are more likely to be aroused by images, difference is reflected in amygdala activation
- erotic images produced greater amygdala activation in males

Question 22

is sex a reinforcer?

Answer 22

yes. rats prefer partners, locations and odors associated with copulation

Question 23

what is the activity in the ventral striatum associated with in sex behaviours

Answer 23

anticipation and experience of sex and other forms of pleasure