Oxytocin is a peptide hormone found in the brain, which is known to play a role in sexual reproduction, childbirth and reciprocal social bonding. Over the past decade, there has been a rise in the number of research publications exploring the possible pro-social effects of administering synthetic oxytocin.
In particular, much of this research has focused on the potential applications of oxytocin as a theapeutic treatment in conditions known to affect trust and social interaction, such as generalised anxiety disorder and autism spectrum conditions (ASC).
A new study, led by PhD student Richard Bethlehem, looked at the effects of oxytocin on brain connectivity within a sample of typically developing women. The groups findings, published last month in Translational Psychiatry, shed light on how intranasal administration of oxytocin affects the way in which different regions of the brain communicate with each other.
A unique aspect of this study is that it was conducted in a female sample. There is a tendency within neuroscience for research to focus predominantly on males. Having a strong understanding of the effects of oxytocin in both males and females is particularly important due to the interest in it as a potential therapeutic for ASC, a condition where there are known to be complex modulatory effects of sex.
The study used an exploratory, ‘data driven’ approach to try to identify the key networks the brain affected by oxytocin. The results suggested that oxytocin administration led to an increase in connectivity between corticostriatal circuitry in the brain. This result fits with previous behavioural results that linked oxytocin to increases in prosocial behaviour, as these brain regions are typically involved in reward, emotion and social communication.
While the study was conducted in females without a diagnosis of autism, the participants completed a questionnaire measure of autistic traits designed to assess the degree to which individuals show certain behaviours commonly associated with autism. The authors found that the effects on brain connectivity exerted by oxytocin administration were greatest in individuals with higher levels of autistic traits. Again, this effect is in line with previous behavioural research, which has found oxytocin to have the most pronounced pro-social effects in individuals who are most affected by the condition.
The study also made use of data collected by the Allen Institute for Brain Science that links gene expression with cortical regions in the brain. The authors used this to map expression levels of the OXTR gene, which encodes oxytocin receptors. These results suggested that OXTR expression was highest in regions in the ventral striatum, substantia nigra, and the hypothalamus.
We spoke to the first author, Richard Bethlehem, about the implications of these results:
“Oxytocin has long been speculated as a potential therapeutic drug for a variety of psychiatric disorders, yet we know very little about how administering it affects basic neurobiology in general and for women in particular. Our study shows how at a basic neurobiological level oxytocin increases the communication between brain regions associated with socio-emotional behaviour. Additionally, it seems that this increase is positively correlated with autistic symptoms. Much more research is still needed to assess its efficacy as a therapeutic, but these initial results are hopeful.”
We also spoke to the principal investigator on the project, Professor Simon Baron-Cohen, who outlined the what the study added to the existing literature:
“In our previous study we found that oxytocin leads individuals with autism to engage in more eye-contact during a structured interview. This new study reveals differences in brain activity that are mediated by how many autistic traits a person has, during oxytocin administration. The study is also novel in being conducted in typical women. A test of these effects in people with autism is underway. This program of research is teaching us about how oxytocin changes brain function and behaviour in people with autism and in typical individuals.”
Written by Owen Parsons.