After decades following thousands of mother-infant dyads, hundreds from birth to young adulthood, my lab has mapped the ‘neurobiology of affiliation’ – the emerging scientific field that describes the neural, endocrine and behavioural systems sustaining our capacity to love. The foci of our research – the oxytocin system (based on the neurohormone of bonding); the affiliative, or social, brain; and biological synchrony between mother and child – are all marked by great plasticity, and sculpted throughout animal evolution to reach their exquisite complexity in humans. And they all lean on automatic and ancient machinery that runs the risk of turning love on its head into fear.
Oxytocin, the first element in the neurobiology of bonding, is an important driver of both care and prejudice. A large molecule produced mainly by neurons in a small region of the brain called the hypothalamus, oxytocin is known for coordinating bonding, sociality, and group living. From the hypothalamus, oxytocin targets receptors in the body and the brain, primarily the amygdala, a centre for fear and vigilance; the hippocampus, where memory resides; and the striatum, a locus of motivation and reward. Through these pathways, the bonding hormone, oxytocin, functions with the precision of a neurotransmitter and the longevity of a hormone, reaching faraway locations and broadly influencing behaviour. Importantly, oxytocin is released not only through the central part of the neuron, but also its extensions, called dendrites. The dendrites are primed to increase oxytocin release whenever attachment memories are invoked. This way, early attachments prime us for a lifetime, and we keep seeking echoes of early experiences in later relationships, whether being carried on mother’s back throughout the day or exploring nature with father.
Memory of these early attachments helps us re-enact the unique state that Sue Carter, a neurobiologist at the University of Indiana, calls ‘immobility without fear’. These same memories enable what the English psychoanalyst Donald Winnicott in 1958 described as ‘the capacity to be alone’ in the presence of someone in a state of peace, serenity and transcendence, where aloneness is not loneliness. In our studies, we found that, throughout life, during periods of bond-formation – for instance, when we fall in love or form a close friendship – oxytocin production increases to cement the new bond, as it does at birth. During birth, a surge of oxytocin triggers uterine contractions, and oxytocin release initiates milk letdown. Maternal oxytocin is then transferred to the infant through the mother’s milk, touch and caregiving behaviour. It bonds mother and child forever but it also reorganises the infant’s brain to what it means to be in love and what it takes to feel safe. This is how cultures ‘stamp’ the infant’s brain with the distinct social patterns that reflect their philosophies on human relationships, particularly those across the generational divide – for instance, are adults and children allowed to be in direct eye contact and dialogue as equals? [Continue reading…]