Gender & the Nervous System

Question 1

Incidence of aphasia in women vs. men

Answer 1

• female language representation (~Broca’s area) >> male language representation (Broca’s area)
  
  • • language is represented somewhat more bilaterally in women
• smaller stroke ==> aphasia in men
• small stroke in women most likely spares some portion of Broca

Question 2

Effects of prenatal & perinatal exposure to sex steriods

Answer 2

• Prenatal: Sex steroids have organizational effects
  
  • determine the fate of cells in an irreversible way when developing.
• Perinatal: changes short term physiological functions
  
  • “activational”

Question 3

Sex steroids impact on brain activity/structure in adults

Answer 3

• Classic steroid receptors - change transcription over days to months.
• Unknown GPCR on neurons and glia
• Direct interaction with GABAA receptors

Question 4

Cerebral cortex targets of androgens

Answer 4

• areas involved in sexual fxns
  
  • hypothalamus
  • preoptic area
  • amygdala
• cerebral cortex
  
  • steroids can be used as anxiolytics or anesthetics
  • interaction (estradiol) w/GABA receptors ==> lower seizure threshold (e.g. during menses)

Question 5

Steroid impact on development

Answer 5

• sex-associated brain differences = secondary sexual traits
  
  • depend on teststerone and Mullerian duct inhibitory hormone
  • exposure must occur during critical period for permanent effects
• female brain state = default; male brain development depends on testosterone

Question 6

Organizational effects vs. Activating effects of sex hormones

Answer 6

• organization = permanent alterations that occur during developmental critical period
• activational = temporary, reverrsible changes (e.g. anxiolysis or cognitive abilities)

Question 7

Testosterone role in early development

Answer 7

• Creates subtle differences in male brain
• Androgen insensitivity disorder
  
  • lack of fxn androgen receptors
  • XY genotypes have “female-type psychosexual orientation” (whatever that means) w/normal testes and testosterone levels

Question 8

Sexual dimorphism in human brains

Answer 8

• Preoptic area & anterior hypothalamus
  
  • in females: neurons @ preoptic area release LHRH ==> LH and FSH release
    
    • LHRH neurons are linked by gap jxns (but not in males) ==> synchronized discharge
• sex steroid receptors (esp. estrogen) located throughout brain
• corpus callosum, lateral fissurem amygdala

Question 9

Steriod effects on adult nervous system

Answer 9

• main source of steroids at brain = brain itself (not gonads)
• have fast MOAs @ brain:
  
  • Membrane-associated and cytoplasmic classical steroid receptors that use second messengers (instead of DNA-binding)
  • cell surface steroid receptors acting via second messengers
  • direct allosteric interaction between steroids and GABA_A receptors
    
    • ==> use as anxiolytic or anesthetics