""The wrinkles that give the human brain its familiar walnut-like appearance have a large effect on brain activity, in much the same way that the shape of a bell determines the quality of its sound, a study suggests1. The findings run counter to a commonly held theory about which aspect of brain anatomy drives function.

The study’s authors compared the influence of two components of the brain’s physical structure: the outer folds of the cerebral cortex — the area where most higher-level brain activity occurs — and the connectome, the web of nerves that links distinct regions of the cerebral cortex. The team found that the shape of the outer surface was a better predictor of brainwave data than was the connectome, contrary to the paradigm that the connectome has the dominant role in driving brain activity.. “
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The researchers calculated the modes of brainwave propagation for the cortical surface and for the connectome. As a model of the connectome, they used information gathered from diffusion magnetic resonance imaging (MRI), which images brain anatomy. They then looked at data from more than 10,000 records of functional MRI, which images brain activity based on blood flow.

The analysis showed that brainwave modes in the resting brain as well as during a variety of activities — such as during the processing of visual stimuli — were better explained by the surface geometry model than by the connectome one, the researchers found.

David Van Essen, a neuroscientist at Washington University in St. Louis, Missouri, who leads a connectome project, says that the diffusion MRI data the team used has well-documented drawbacks that make the comparison “not fair”. The team should have also looked at brain activity from simple stimuli that activate only local regions of the cortex, according to Van Essen. “It is extremely unlikely that the travelling wave model favoured by the authors could replicate such patterns,” he says.

Pang says that it would be interesting to test their models with such stimuli, and that the analyses he and his co-authors have done so far were a “proof of principle”."

https://www.nature.com/articles/d41586-023-01774-8