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Yes, Brains — Like Computers — Have a Low-Power Mode

Evolution News
Photo credit: Marcus Ganahl via Unsplash.

Neuroscientists have often wondered if the high-metabolism human brain had a power conservation mode and a recent open-access paper in Neuron finds that brains use an energy-saving strategy to cope with shortages. Cognitive neuroscientist Allison Whitten explains:

Now, in a paper published in Neuron in January, neuroscientists in Nathalie Rochefort’s lab at the University of Edinburgh have revealed an energy-saving strategy in the visual systems of mice. They found that when mice were deprived of sufficient food for weeks at a time — long enough for them to lose 15%-20% of their typical healthy weight — neurons in the visual cortex reduced the amount of ATP used at their synapses by a sizable 29%.

But the new mode of processing came with a cost to perception: It impaired how the mice saw details of the world. Because the neurons in low-power mode processed visual signals less precisely, the food-restricted mice performed worse on a challenging visual task.

“What you’re getting in this low-power mode is more of a low-resolution image of the world,” said Zahid Padamsey, the first author of the new study. 

ALLISON WHITTEN, “THE BRAIN HAS A ‘LOW-POWER MODE’ THAT BLUNTS OUR SENSES” AT QUANTA (JUNE 14, 2022)

The test mice weren’t actually “starving”; they were on low enough rations that natural defenses against food shortages to the brain would kick in. It was those defenses that the researchers wanted to identify and study in a mammal.

A Lower Visual Resolution

How did the researchers know that the food-deprived mice had a lower visual resolution of their world? They constructed a test where the object was to get out of a chamber onto a platform by spotting the correct visual image:

The food-deprived mice easily found the platform when the difference between the right and wrong images was large. But when the difference between the pictured angles was less than 10 degrees, suddenly the food-deprived mice could no longer distinguish between them as accurately as well-fed mice. The consequence of saving energy was a slightly lower-resolution view of the world.

ALLISON WHITTEN, “THE BRAIN HAS A ‘LOW-POWER MODE’ THAT BLUNTS OUR SENSES” AT QUANTA (JUNE 14, 2022)

Other researchers have found that roughly the same thing happens with flies.

Read the rest at Mind Matters News, published by Discovery Institute’s Bradley Center for Natural and Artificial Intelligence.