Principles of Neuroscience Lecture 22 Sexuality Flashcards Preview

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Flashcards in Principles of Neuroscience Lecture 22 Sexuality Deck (23)

What are the genetic determinants of gender?
Describe how this leads to gender
Where is this gene located?

The SRY (sex determining region Y)
It codes for testosterone producing cells in early development

It is located on the Y chromosome, of which males have 1 copy


What does mutation of the SRY gene lead to?

It leads to a female phenotype
No testosterone is produced because we don't have e testosterone secreting cells


Which is the "default" gender? How is this changed?

Female is the default gender

The male gender is produced when there is the SRY gene present in the genome (ie a Y chromosome)


Differentiate between the sex hormones

Testosterone: male sex hormone

Estrogen (estradiol) and progesterone: female sex hormones


Describe the sex hormone synthesis pathway



Why is aromatase important?

It converts testosterone to estradiol


Describe the presence of testosterone throughout the lifetime

It is present during foetal development and then the levels drop at birth

Levels rise again during puberty, and eventually drop off after middle age


Describe the presence of estrogen throughout the lifetime

Levels rise during puberty
Levels fall during menopause


Where do sex hormones act?

In the brain:
1. Synapses
2. Cell body receptors


What is ER?
Where is it often located?
How does it function?

ER is Estrogen Receptor
It is often located in the cell body
Estrogen binds here, and the receptor-ligand complex alters gene expression


Describe the hypothalamus' role in sex hormones

It stimulates the pituitary to release LH & FSH

These two hormones bring abo the production of the sex hormones


Where are LH and FSH released from?

The pituitary gland


List a few gender dimorphisms in the brain

1. Sexual behaviour
2. Sets mediated analgesia
3. Cognitive function
4. Maternal behaviour


Describe how sexual behaviour is dimorphic in the brain

There is a region in the brain called the Sexually dimorphic nucleus of the Preoptic area

During mating, different neurons fire in this nucleus and at different times depending on the gender of the rat


Describe how stress mediated analgesia is gender dimorphic

The analgesic response to stress is different in males and females

In warm water:
Analgesia depends on endogenous opioids
In males, there is greater sensitivity to the antagonist

In cold water:
Males : analgesia depends on NMDA receptors
Females: this isn't present


What are the organisational effects of the sex hormones on the brain?

During development, the sex hormones cause differential arrangement and organisation of the brain.

Absence of testosterone will produce a "female" arrangement


What are the activational effects of the sex hormones on the brain?

Give some examples

After development, the circulating levels of the sex hormones brings about different behaviours or activational responses

Premenstrual behaviour
Stress mediated analgesia
Regulation of steroid production


What is responsible for the dimorphisms of monogamy and polygamy in different species of voles?

Oxytocin and long vasopressin expression activating the reward centres


Describe how female prairie voles form pair bonds

During copulation, oxytocin is released

These voles have very dense oxytocin receptors

Thus, mating stimulates the reward centres and pair bonds are formed


Describe how male prairie voles form pair bonds

During copulation, long vasopressin is released
This activates the reward centres, and pair bonds are formed


What happens if there is a block in oxytocin in female prairie voles?

The females will not form pair bonds


What happens if long vasopressin is given to a male prairie vole?

He will form a pair bond with a female without copulation taking place


Why don't Montaine voles form pair bonds?

They don't have the oxytocin receptors and long vasopressin

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