8 - Development

epigenetics

Genetically based traits can be modified by environmental factors and experience

MAOA (monoamine oxidase A)

‘warrior gene’

• short form of the gene has been associated with low levels of MAOA and high levels of aggression

Maternal Nurturing and Anxiety in Rats

• Some rats were extremely anxious and inhibited, others were relaxed

• relaxed rats had hippocampi that contained more glucocorticoid receptors; tolerated stress better

  • because of mothers lavished licks and grooming on them

Darlene Francis using embryo transfer

• If embryo of normal fearless control rat is implanted into fearful strain of rat, pups will grow up to be fearful like adoptive mother

• when the rats became parents themselves, they behaved like their adoptive, rather than their biological, mothers

Meaney studies on brains of suicide victims

The brains of suicide victims with a history of child abuse contained significantly more methylation “off” switches on the gene for the glucocorticoid receptor than controls and suicide victims who had not been abused

Cortisol levels in hair samples

Correlated with

• Exposure to psychosocial stress in childhood

• Risk of future heart attack

Study on identical twins

Twins who led similar lives and spent more of their lifetimes together were more similar epigenetically than identical twins who shared fewer experiences

Attunement

moments when child knows that their emotions are met with empathy; that they are accepted, reciprocated, and validated

Securely attached

• infants explore room and toys confidently when mother is present, become upset and explore less when mother is absent, and show pleasure when mother returns (70%)

• romantic relationships characterized by happiness, trust, and friendship; relationships enduring

Avoidant

• infants avoid mother and seem to act coldly toward her when she returns (20%)

• relationships marked by fear of intimacy, emotional highs and lows, and jealousy

Anxious-ambivalent

• infants continue to cry and fret when mother returns despite her attempts to comfort (10%)

• relationships involving obsession, desire for reciprocation and union, emotional highs and lows, and extreme sexual attraction and jealousy

Disorganized

conflicting infant behaviors and affect; misdirected or jerky movements

• associated w inconsistent parenting or abuse