Zack Johnson

A new study of prairie voles, one of the few other mammals that choose just one mate, seems to indicate that the brain's reward system is hard-wired to respond to these bonds.

Scientists have long known that socially monogamous mammals, including humans, actually change their perception of their partners when they bond as adults. What they didn't know was how the brain's neural circuitry is activated by these social interactions. This is the first comprehensive look at that question and it turns out a neural pathway that responds to rewards can be activated to increase a partner's preference for partners over strangers.

How they did it: A certain part of the brain (the corticostriatal circuit) controls the ability of animals to change their behavior in order to receive rewards. In the study, researchers used a pulsating light technique called optogenetics to systematically activate brain cells in this region in female voles that were alone. After their brain cells were bathed with light in this manner in the presence of male voles, the female prairie voles routinely chose those particular male voles over strangers.

Fun fact: The researchers also found that when the circuit's neurons were more strongly connected in females, they bonded faster with male voles they knew from earlier social settings.

What's next: The researchers say they need to test whether the circuit is necessary or just sufficient for bonding behavior and what more is involved.

Go deeper

Trump says G7 summit will be delayed until after the election

President Trump told reporters on Monday that he wants to delay the G7 summit until after November's election and implied that the decision had already been made.

The big picture: Plans for the summit have already been scrapped multiple times, with proposed venues moving from the Trump National Doral resort in Miami to Camp David. In May, Trump postponed the in-person event in Washington, D.C. to September.

Trump whisked out of press briefing after shooting outside White House

President Trump was escorted out of a coronavirus press briefing by a Secret Service agent on Monday after law enforcement reportedly shot an armed suspect outside of the White House.

The state of play: Trump returned to the podium approximately ten minutes later and informed reporters of the news. He said the suspect has been taken to the hospital, but was unable to provide more details and said Secret Service may give a briefing later.

Updated 1 hour ago - Politics & Policy

Coronavirus dashboard

Illustration: Annelise Capossela/Axios

  1. Global: Total confirmed cases as of 5:30 p.m. ET: 19,952,057 — Total deaths: 732,689 — Total recoveries — 12,150,698Map.
  2. U.S.: Total confirmed cases as of 5:30 p.m. ET: 5,074,059 — Total deaths: 163,275 — Total recoveries: 1,656,864 — Total tests: 61,792,571Map.
  3. Politics: House will not hold votes until Sept. 14 unless stimulus deal is reached.
  4. Business: Richer Americans are more comfortable eating out.
  5. Public health: A dual coronavirus and flu threat is set to deliver a winter from hellAt least 48 local public health leaders have quit or been fired during pandemic.
  6. Sports: The cost of kids losing gym class — College football is on the brink.
  7. World: Europe's CDC recommends new restrictions amid "true resurgence in cases."