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Letter: How useful is the brain chaos hypothesis?

Published 15 October 2025

From Lawrence Ryan, Wilsonville, Oregon, US

The idea that our brains are always on the verge of disorder seems to me to have quite limited explanatory value. Criticality in the brain may describe seizure states well mathematically, but it doesn’t explain them. If it also describes Alzheimer’s disease, in which there is widespread and progressive loss of neuronal function, akin to an oil painting flaking paint until the image is no longer discernible, it doesn’t explain the condition. And if it describes creativity, consciousness, perception, etc., it explains none of them(6 September, p 30).

Criticality is a limited measurement. You could liken it to a thermometer: you can use it to measure the temperature of a bowl of soup, but it wouldn’t tell you the kind of soup in the bowl, nor the ingredients the chef used.

Issue no. 3565 published 18 October 2025

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