Science from April 17, this year, has two feature articles by David Grimm about men and his dog, one perspective article and a report that shows how men-dog but not men-wolf bonding is intensifierd by oxytocin.
One feature article: Dawn of the dog is most instructive about the process in science itself, fighting over data, sparring with opponents, and reconsiliation to a common task with the help of a third party, the other one: How the wolf became a dog is summarizing the different text, the perspective paper by MacLean and Hare shows the implications of the report: How the oxytozin loop between men and dog might shape the bonding and even help in pathological situation like autism and posttraumatic stress. A nice sentence from the feature is “if the dog is staring at you, it might not be after your sandwich!”
The whole bunch of articles is a pleasue to read.
Oxytoxin is the hormone of social interactions, the mechanism of the interaction mostly unknown. Therefore, it is a nice surprise that Nakajima, Görlich, and Heintz from the Rockefeller Univ. in New York report in Cell on a newly identified subset of somatostatin interneurons from the prefrontal cortex of mice which bear the oxytocin receptor.
They silenced then this receptor in some mice. The females in these silenced mice with the oxytocin receptor inactive lacked the social interactions with male mice only during the estrus phase, when copulation would ensure progeny. The interactions with female mice were normal. In the diestrus phase interactions with males were not disturbed.
Similarily they could produce mice where the oxytocin gene was removed in the prefrontal cortex. The female mice showed the same deficit. Even mice treated with an oxytocin antagonist blocking the action of oxytocin had the same effect on the social interactions of the females thus treated.
We do not know whether oxytoxin is acting here in an endocrine way via the blood or as a neurotransmitter via synapses. It is not to far fetched to think oxytocin stimulating these interneurons is required – in mice – for social interactions leading to progeny although it is not in the paper.
A nice bit of information!
In a comment on a paper in the same issue of PNAS Sarina Saturn describes how Abraham et coworkers have analysed the complex relationship of neural activation, hormones and behaviour in first time parents comparing primary care /PC) mothers and secondary care (SC) fathers who are partners of mothers and primary care (PC) fathers who raise a child without a mother.
Abraham et al. have identified characteristic features common to fathers and mothers and, not surprisingly, also features where mothers and fathers differ. An emotional network including the amygdala (AMY),* ventral anterior cingulate cortex (vACC),* insula,* inferior frontal gyrus (IFG), and ventral tegmental area (VTA).* *Subcortical and paralimbic structures not located at the outer cortical surface was found as well as a mentalizing network which includes superior temporal sulcus (STS), frontopolar cortex (FPC), ventromedial prefrontal cortex (vmPFC), and temporal poles (TP). Cites from PNAS:
PC-mothers displayed the greatest activation of the emotional system, and this activation significantly related to parent–infant synchrony and oxytocin levels. SC-fathers, in contrast, exhibited more activation of the cortical system. Fascinatingly, PC-fathers showed amygdala activation similar to PC-mothers and STS activation similar to SC-fathers, with pronounced functional connectivity between the two regions. This suggests that when a baby is raised by PC-fathers, both systems are used for optimal childrearing.
For both PC-fathers and SC-fathers, the STS–amygdala overlap directly related to how much the men were involved in tending to the baby, and STS activation correlated with oxytocin levels and parent–infant synchrony. This provides evidence that exposure to the infants and caretaking activities can groom oxytocin and neural systems to carry out the degree of paternal involvement.
This is a first time that these interactions have been studied. Nicely done!