IBM Research may have cracked the brain’s energy puzzle
“The Grand Loop” theory suggests the brain is constantly retracing its neural pathways, even when at rest
The brain, in terms of energy consumption, punches massively above its weight. In your average human, the brain takes up around 2% of the mass, but 20% of the oxygen. On one level, that’s wholly unsurprising: it’s obviously massively important. But that doesn’t explain why it uses similar energy levels when at rest as when it's doing something massively complicated. The vast majority of the brain’s energy use remains unaccounted for.
Now a possible answer has come courtesy of neuroscientist James Kozloski at IBM Research. His theory is that the brain, when on standby, is constantly looping signals through its neural pathways. He’s coined it “The Grand Loop”.
“You don’t spend that much energy on noise unless there’s a really good reason,” Kozloski told Popular Science, arguing that the brain is tracing and retracing neural pathways in a similar way to how you would wander streets in an unfamiliar city.
How do you even begin to go about testing something like this? Well, fortunately, IBM is well-equipped in this department, and he was able to run his model through the company’s neural tissue simulator, which emulates the way neurons communicate in the brain.
There are two particularly interesting things about this. The first is that Kozloski reckons it could explain why humans use past experiences to predict what will happen in the future, but the second is a little less philosophical and a lot more practical: it could help with understanding puzzling neurological disorders.
“We’re really stuck when it comes to mental health and neurodegenerative disease,” explained Kozloski. “Huntington’s is caused by a single gene, but there’s been no progress in understanding how that gene causes neurodegeneration.”
It’s possible, with the new theory in mind, that a single gene could cause havoc along an entire neural pathway. In other words, if that gene is responsible for one protein that happens to change how neurons send signals, it could set off a chain reaction that disrupts all of the other neurons.
Whether his theory is right or wrong, the unaccounted-for energy has to be doing something, and this is as convincing as anything else to date. As Kozloski himself says, from an evolutionary perspective: “If it wasn’t doing something important, it would have been weeded out long ago.”
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Image: Ton Haex, used under Creative Commons