• Sry gene causes ….
• Sry gene causes male internal genitalia - testes.
• No Sry gene causes ………..
• No Sry gene causes female internal genitalia - ovaries.
Puberty is initiated by …
Puberty is initiated by the arcuate nucleus of the hypothalamus
kisspeptin causes the anterior hypothalamus to release ,………….
kisspeptin causes the anterior hypothalamus to release Gonadotropin-releasing hormone (GnRH).
• GnRH causes pituitary to release ….
• GnRH causes pituitary to release FSH and LH in both sexes.
• FSH and LH cause testes to release ….
• FSH and LH cause testes to release testosterone and ovaries to release estradiol.
Hypothalamus and pituitary are the ….
Hypothalamus and pituitary are the master controllers of the endocrine system.
The combination of estradiol + progesterone signals …
The combination of estradiol + progesterone signals the fertile phase of the female’s cycle.
different sexual moves in rats>
- Proceptivity – female approach, ear wiggling
- Attractiveness – male engagement/mounting
- Receptivity – female willingness
- Lordos – female posture
what do gonadectomised male rats need for activational effects in adulthood
The Interaction between activational and organization effects is revealed by a series of experiments.
Males and Females are gonadectomised at birth and either given hormones at that time (to study organisational effect) or in adulthood (to study activational effects).
Table shows that gonadectomised males need replacement hormones at birth AND as an adultin order to show activational effects in adulthood.
what did Van Goozen find
Initiation of sexual activity between human partners.
Males initiate sex evenly across the female menstrual cycle.
Females initiate sex more often during ovulation (the fertile phase).
what did
Bagatell et al. find
- Gave males a GnRH hormone antagonist- blocking testosterone
- Measured time in weeks
- From week 4-6, reduced frequency of sexual desire
- In the alternate, there is a testosterone replacement, they have continued sexual desire
- Male sexual behaviour is governed by testosterone
sexual orientations explained
- Male heterosexual = brain masculinized and defeminized
- Female heterosexual = neither masculinized nor defeminized
- Male homosexual = neither masculinized nor defeminized
- Female homosexual = brain masculinized and defeminized
- Male and female bisexual = masculinized but not defeminized
default brain is…
female
what did Balthazart J (2016) atrgue
Individuals who prefer woman (heterosexual males and lesbians) have been masculinised and defeminised, and have a masculine index to ring finger ratio (and longer limbs).
Individuals who prefer males (heterosexual woman and homosexual men) have been feminized and have a feminine index to ring finger ratio (and short limbs).
what is Congenital adrenal hyperplasia (CAH)
- Abnormal androgens in genetic females.
- Produces ambiguous genitalia.
- ≈33.3% genetic females with CAH identify as homosexual or bisexual compared to ≈2% of females as a whole.
what is Androgen insensitivity syndrome
- Testosterone should masculinisation and defeminise morphology.
- Genetic males with androgen insensitivity syndrome develop as females.
- They may be complete or partial females depending on the level of insensitivity.
- Typically female external genitalia, but also with testes (internal) and without uterus or Fallopian tubes.
- Typically favour male partners as do heterosexual females, suggesting neural feminisation.
what is an Androgen insensitivity syndrome example
Joan of Arc - twice intimately examined to verify she was indeed a woman but apparently never menstruated.
What differences are there in the male vs. female brain which are responsible for male sexual behaviour?
Animals: Sexually dimorphic nucleus of the medial preoptic area MPA of the hypothalamus.
Humans: interstitial nucleus of the anterior hypothalamus number 3 INAH3.
Post mortem examination indicates that the INAH3 is …..
Post mortem examination indicates that the INAH3 is 2-3 times larger and has a higher cell density in heterosexual males than homosexual males and females.
what did Balthazart J (2016) find
No difference in heterosexual men with and without AIDS, suggesting this did not cause the INAH3 differences.
MPA in male rats sexual behaviour
o MPA lesions abolish sexual behaviour
o Electrical stimulation increases copulatory behaviour
o Sexual behaviour increases firing rate
o Glutamate (excitatory) infusion increases sexual behaviour
o 3-7 times larger in male than female rats
o Enlargement relies on androgens in the womb and shortly after birth indicating that it is biologically determined rather than socially
o Gonadectomy in males decreases sexual behaviour and can be reinstated by testosterone administered into the MPA showing antinational effect
o MPA contains testosterone receptors
amygdaala in male rats sexual behaviour
o The medial amygdala connects to the MPA
o Medial amygdala also contains testosterone receptors
o Lesions of the medial amygdala disrupt sexual behaviour
o Medial amygdala received input from the vomeronasal organ, detecting pheromones which stimulate sexual behaviour
o Implication is that the amygdala transmits sexual excitation of external sensory sources to stimulate the MPA which then controls behaviour by downstream circuits
• Nucleus paragigantocellularis (nPGI) of the medulla in male rats sexual behaviour
o Spine contains the thrusting and ejaculation reflex and are held under tonic inhibition by the nucleus paragigantocellularis (nPGI)
o Inhibitory GABA projections from the MPA disinhibits these reflexes, stimulating thrusting and ejaculation
o The nPGI send inhibitory serotoninergic connection to the spine to inhibit erection and ejaculation
o Application of serotonin (5-HT) to spinal cord suppresses erection and ejaculation
o Men taking selective serotonin reuptake inhibitors (SSRIs) often report a side effect of difficulty achieving erection and ejaculation, may be mediated by nPGI
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Introduction to animal cognition36
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Exposure Learning17
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Pavlovian Conditioning15
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instrumental learning12
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discrimination and categorisation21
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memory29
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Spatial Representation and Navigation25
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Animal Intelligence & Problem Solving19
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Rescorla Wagner and Blocking12
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Do animals have a Theory of Mind?25
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Origin of behavioural neuroscience23
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comparing intelligence in cog0
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Psychopharmacology32
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Reproductive behaviour29
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emotion25
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Neurological disorders19
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ADHD and Addiction19
