It was business as usual at the University of Pittsburgh School of Medicine — monkey business, that is.

Sitting in chairs with their arms gently restrained, monkeys used their minds to manipulate the movements of a robotic arm to feed themselves marshmallows, Reuters reported.

The feat offers hope to the injured or disabled who one day possibly could use brain-powered prosthetic limbs.

"They are using a motorized prosthetic arm to reach out, grab and bring the food back to their face," said Andrew Schwartz, who led a team of researchers whose study will appear in the journal Nature.

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In it, the monkeys took about three days to learn to use the arm and improved in following sessions.

The robotic arm works like this: Microelectrodes implanted in the monkeys’ brains send signals to a computer, which then directs the arm to move, Reuters reported.

The monkeys seem to enjoy the challenge.

"They sure like eating their marshmallows," as well as pieces of apple, orange and zucchini, Schwartz said in the story. "Just about anything we can that doesn't make too big of a mess."

• Click here to read more on this story from Reuters.