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Illustration: Eniola Odetunde/Axios

A new study uses a brain-computer interface (BCI) to observe the neural activity in monkeys during the process of learning.

Why it matters: The internal state of the brain is often a mystery — including to ourselves — but new neural interfaces are making it easier for scientists to observe the mind in action.

How it works: In a paper published recently in Nature Neuroscience, a large team of researchers hooked up a group of monkeys to BCIs while the study subjects were trained to play a basic computer game.

Details: The researchers found that neural fluctuations took place when the monkeys were surprised by something happening during the game.

  • Those monkeys that showed greater engagement performed better during following rounds of the test, indicating that arousal and engagement — internal states that can be difficult to track without a BCI — can affect the act of learning something new.

What they're saying: "Our understanding of what happens in the brain as one learns is super limited right now," says Byron Yu, a professor at Carnegie Mellon University and a co-author of the paper. But BCI "gives us an amazing window into how this happens."

Context: BCI technology has emerged as a major area of scientific research and increasingly consumer technology as the interfaces have slowly improved.

  • On Friday, Elon Musk's BCI company Neuralink released a video of a monkey with chips embedded on each side of its brain as it played a basic video game using only its thoughts.

Yes, but: BCI technology would have to progress significantly — and the applications would need to go beyond video games — before many people would be willing to have an interface drilled into their skull.

Go deeper: Elon Musk's Neuralink wants to read your brain

Go deeper

Biden says he'll make Supreme Court pick by end of February

President Biden speaks on the retirement of Supreme Court Justice Stephen Breyer in the Roosevelt Room of the White House. Photo: Yuri Gripas/Abaca/Bloomberg via Getty Images

President Biden on Thursday said he will announce the nominee for Supreme Court Justice Stephen Breyer's replacement by the end of February.

Driving the news: Biden also affirmed that he will nominate a Black woman to replace Breyer, saying "it's long overdue."

Stephen Breyer formally announces retirement from Supreme Court

Photo: Andrew Harnik/AP

Justice Stephen Breyer on Thursday sent a letter to President Biden formally announcing his retirement from the Supreme Court.

State of play: Breyer said his retirement will take effect when the court "rises for the summer recess (typically late June or early July) assuming that by then my successor has been nominated and confirmed."

COVID created an epic U.S. trade gap

Chart: Axios Visuals. Data: Census Bureau/Bureau of Economic Analysis

The details of the blockbuster fourth quarter GDP report released Thursday morning tell a vivid story of how the underpinnings of the world economy have been reshaped by the pandemic.

One example: In the arithmetic around U.S. economic output, trade acted as a more severe drag last year than it has in a generation.