For the first of Sunday's poster blogging we're going to look at some dutiful dads. Some dutiful monkey dads.
Meet the titi monkey.
Hinde et al. "Separation from pairmate disrupts activity throughout social reward neurocircuitry in monogamous titi monkeys" 186.17, SS16
When we talk about good mates in the animal kingdom, we often talk about voles, or penguins. But what about the titi monkey? Titis (ok, I have to admit I'm giggling every time I get to write "titis"...heeeeee "titis") form life long monogamous bonds between partners, and thus make a good model to study pair bonding in something a little closer to us than the iconic prairie vole.
And not only are titi monkeys monogamous mates, they are also very involved dads. The babies often return to their mothers only to nurse, all the carrying and cuddling and retrieval is done by the dads. The authors of this study thus wanted to look at the brains of these doting monkey daddies, to observe how they reacted when separated from their mates and then reunited, and whether it was the MATE that mattered.
So they look a bunch of monkeys that had been pair bonded for four months with their chosen lady. They then took the male away from his mate and his baby for 2 days. They placed some of the males back with their chosen significant other for 30 minutes, and others with a strange new lady. They then took the monkeys and gave them PET imaging for measures of glucose uptake in the brain, which they mapped on to structural MRI images of the monkey's brains, to get an idea as to which parts of the brain were changing their glucose utilization.
What they found was that glucose utilization in the brain as a whole DECREASED as the length of time spent away from their mate increased. This came up again when the male was presented with his favorite girl. But this wasn't a significant difference...
...unless the males were FATHERS. The titi monkeys who were dads not only had higher glucose utilization in general, they also had higher glucose utilization measures after they were reunited with their loved one...but NOT when presented with a stranger. Not just any girl will do. But non-fathers were not so picky, and had increases in glucose utilization when they were given their previous mate or presented with a new girlfriend.
When they broke it down by brain area, the authors found that differences were largest in areas like the supraoptic nucleus, the paraventriular nulceus, the medial and central amygdala, and the periaqueductal grey, all areas which previous studies have shown to mediate pair bonding. The authors hypothesize that becoming a father changes the brain's response to the titi's mate, and the changes in glucose utilization may signal to the father that they've picked a lady winner, one who has good reproductive quality. Fatherhood really changes these doting monkey dads.