Atypical Gender Development Flashcards
1
Q
Gender Dysphoria
A
- Chronic Distress due to perception of sex & gender mismatch
- Excludes intersex conditions, which are biologically verifiable
2
Q
Gender Dysphoria development over time
A
- First appeared in DSM-III (1980) as Gender Identity Disorder
- Culture Bias identified - eg. Samoan culture has 3 genders (extra feminine male), none at increased risk of psychological disorder
- Social construction of gender in the West changes over time
- DSM-V (2013) replaced GID with Gender Dysphoria (spectrum)
3
Q
Genes: Hare et al (2009)
A
- Possible transgender gene identified
- Studied 112 mtf transexuals’ (undergoing sex change) DNA
- Androgen receptor gene significantly longer - reduces ability of testosterone to cause changes in development
- Transexual brain may be much less masculine than average if threshold level for masculine developmnent is never reached
4
Q
Brain Structure
A
- Many sex & gender differences in brain structure and functioning - possible that transexuals’ brains don’t match genetic sex
- BSTc (Bed Nucleus of Stria Terminalis) is twice the size in straight men than women - integrates info from across limbic system, which is used to monitor stress readiness levels
- BSTc size correlates with preferred sex, not biological
5
Q
BSTc Size in Transexuals: Research
A
- Zhou et al (1995): MtF’s BSTc similar size to female average
- Kraijver et al (2000): FtM’s BSTc usually within male range
6
Q
Issues with Brain Structure Research
A
- Zhou et al (1995) used post-mortem examination of hormone-trated brains - changes may have been result, not cause
- Savic & Arver (2011): without hormone treatment, transgender brain structures & functions are as expected for their sex
- Some differences found in grey matter thickness, but not reliably replicated
- Mueller et al (2017): reliable differences between male & female brains, but not between trans & cis brains - supports psychological, not physiological cause
7
Q
Current Beliefs
A
- Combination of 2 competing models - Atypical Neurodevelopmental Pattern & Structural Deficits or Atypical Functioning of Brain Areas
- Both trying to explain connectivity issues between brain areas involved in self-representation, personality, executive function - including communication across hemispheres
- Uribe et al (2020): Current consensus is that both are well supported and combination is best way forward
8
Q
Atypical Neurodevelopmental Pattern
A
- Guillamon et al (2016): caused by levels of sex hormones and/or receptors for those hormones in the brain
- This could prevent normal connections and communication between forming brain regions
9
Q
Structural Deficits or Atypical Functioning of Brain Areas
A
Feusner et al (2017): responsible for personality and representation of one’s own body
10
Q
Biological Differences
A
- Very few stable behavioural differences between men & women
- Brains not 100% masculine or feminine
- Male brains larger than female brains by ~12%
- Females have proportionally thicker cortex and more grey matter/less white matter
- Females better at deep processing (slower), Males better at shallow processing (faster)
- Men have larger ventricles (glymphatic structures) - better at cleaning toxins associated with stress
11
Q
Stress & the Brain
A
- Stress can change sex cell characteristics of brain regions in >15 mins
- Typical female neurons have more dendritic spines than male - important for firing, processing speed, plasticity
- After 15 mins of stress, there was a reversal in this pattern in rats’ hippocampus
- Physical brain cell structure can’t determine sex - need to know if there was high or low stress - interactionism
11
Q
Diathesis-Stress & Gender
A
- Environmental factors have been shown to change default cell sex pattern of developing brain regions - eg. life stages, size of social group, level of environmental stimulation
- Can happen at all times, for many reasons, but some areas are not vulnerable
- During pregnancy, every time the mother is stressed, some areas of the baby’s developing brain will change sex characteristics
12
Q
Mosaic of Brain Gender Regions
A
- We are all born with this
- It will change throughout our lives
- All brains androgynous too in some respects
- Overall, average gender differences remain
13
Q
Phantom Limb & Cross-Wiring
A
- Ramachandran (2008): Phantom limb due to plasticity & cross-wiring after injury - Homolougous recruitment (1995)
- Ramachandran & McGeoch (2007) - sex organs have specific brain locations that are hard-wired
- Wiring is disrupted/develops atypically (eg. due to low foetal testosterone activity) = genitals can be represented opposite to sex
- Can lead to phantom penis (claimed by 2/3 FtM), phantom erections, and loss of feeling in female genitals
14
Q
Pesticides
A
- DDT (insecticide) banned in UK & USA from 1972 - still used in developing countreis (eg. India = biggest user/producer)
- DDT causes sodium channels to open - death in insects
- Not deadly to most animals
- Contains oestrogen - can reach bloodstream in exposed humans
- Vreugdenhil et al (2002): Boys born to DDT-exposed mothers showed feminine characteristics - increased exposure to oestrogen in womb
