Category Archives: Circuits

Prediction of the prey’s path by dragonflies

Hunting a moving target involves reaction to the prey’s movement, so you would think. It involves, however, in vertebrates also a model how the prey may move, to be able to predict the possible flight routes. This model was thought to be lacking in invertebrates.

In a paper in Nature Mischiati and colleagues describe that dragonflies have this internal model, too. They show that vision is to react to the prey’s escape but underlying the dragonfly’s steering is brain model how the prey might fly. You have to keep in mind that dragonflies hunt in 3D and not in 2D as tetrapods do. We are proud that comet lander does find and land on the target some 100000 miles away, and use immense computer power for this task. Dragonflies have it all in their tiny heads.

The paper uses fly models in the lab as prey. It will be some time before it will be possible to test the facts on free flying dragonfly. But it is a nice piece of information already.


Oxytocin for pairing — in mice

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!

Brain structures and hormones in parents when children are raised

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!