Love hormone involved in brain development

Oxytocin has gained a lot of attention over the last few years. The reason for this is the changed perspective: from a hormone in the periphery to a potent modulator of the central nervous system. In adulthood, oxytocin, also known as the ‘cuddle hormone’ or ‘love hormone’, plays a major role in prosocial behavior. However, oxytocin and its receptors are already expressed at birth, which raises the question of the function of oxytocin during development. Researchers of the Netherlands Institute for Neuroscience (NIN) aim to answer this question. They found that oxytocin modulates the activity patterns of the brain by activating a specific neuron subtype. The results were published in Current Biology.

Human oxytocin is already expressed in the 14th embryonic week. During early stages of brain development, when neuronal connections are shaped by spontaneous activity, neuromodulators play an important role. “In the developing brain, neuronal connections form with remarkable precision. Already before the senses become active, spontaneous activity prepares the brain for interacting with the outside world” explains Christian Lohmann, group leader at the NIN.

Using an animal model, the scientists found that oxytocin affects this spontaneous activity, by specifically activating somatostatin interneurons, a neuron subtype that inhibits other neurons. Oxytocin specifically modulated the activity of the primary visual cortex by decreasing its activity. Interestingly, this inhibition was sufficient to decorrelate the network promoting the development of local subnetworks. These findings clarify the cellular mechanism of how oxytocin modulates sensory activity and affects the development of sensory circuits and their refinement.

Nurturing

Oxytocin levels in parents and infants have been positively correlated with parental engagement. In contrast, poor parental bonding has been associated with an increased risk for psychological disorders. The bonding of a mother and a child is thus very important for modulating the levels of oxytocin and, in that way, for promoting brain development. “Interactions with the mother constitute the whole world for an infant. It represents a frame that not only ensures survival, but also provides the nurture necessary for successful brain development”, says Paloma Maldonado, the first author of the paper.