2.10.3 Neurobiology of attachment

The caregiver as regulator

Attachment develops between infant and caregiver. Infant signals draw care, and the caregiver regulates the infant's arousal and stress until self-regulation matures.

• Social buffering is the reduced stress response in an attachment figure's presence, and it can be stronger with secure relationships.

• In young rodents, maternal presence suppresses amygdala and corticosterone responses.

• Sensitive care can reduce human infants' cortisol responses.

Maternal sensitivity and the brain

• Maternal sensitivity is the accurate reading of infant signals and a prompt, appropriate response to them.

• Maternal sensitivity is associated with greater functional connectivity between the hippocampus and the amygdala.

• The amygdala contributes to threat responses, and the developing hippocampus provides context for threat learning.

Oxytocin

Oxytocin is made in the hypothalamic paraventricular and supraoptic nuclei. It acts centrally and is released through the posterior pituitary.

Tap to enlarge

• Breastfeeding and contact release oxytocin, and peripheral levels correlate modestly with maternal sensitivity.

• Early maternal care alters methylation of the oxytocin receptor gene (OXTR).

• These methylation differences relate to social sensitivity, prosocial behaviour, stress responsiveness and infant temperament.

Epigenetic transmission through care

• Meaney's rodent studies linked maternal licking and grooming to epigenetic glucocorticoid receptor regulation and later stress responses.

• Cross-fostering reversed these effects, supporting transmission through care.

Limits

• Secure, avoidant, resistant and disorganised classifications describe observed behaviour, not neural types.

• Early care influences mental health without determining it.