Scientists have long believed people's thoughts, feelings, and behavior resulted from different interconnected neurons in the brain. But a new study published in Nature suggests that the shape of the brain, including its size, curves, and grooves, may actually have a greater impact on how we think, feel, and behave, Aria Bendix reports for NBC News.

Study details

For the study, researchers from Australia took MRI scans of 255 people's brains while the participants performed different tasks like tapping their fingers or recalling a sequence of images. Then, the researchers looked at 10,000 different maps of people's brain activity gathered from more than 1,000 experiments across the world in order to better assess the potential role of brain shape.

The researchers then created a computer model that simulated the way a brain's size and shape affected brain waves and compared that model to another pre-existing computer model of brain activity that closely aligns with the idea that neuron connectivity is the driver of brain function.

Ultimately, the researchers found that the new computer model provided a more accurate reconstruction of brain activity shown in the MRI scans and brain activity maps than the pre-existing model.

Discussion

James Pang, lead author on the study and a research fellow at Monash University in Australia, said the significance of brain shape is like a pebble making ripples in a pond — the size and shape of the pond affects the nature of the ripples.

"The geometry is pretty important because it guides how the wave would look, which in turn relates to the activity patterns that you see when people perform different tasks," he said.

Pang added that his research doesn't discount the significance of neuron communication, but instead suggests the geometry of the brain plays a more important role in brain function.

"What the work is showing is that the shape has a stronger influence, but it's not saying that connectivity is not important," Pang said.

According to Pang, the potential role of brain shape in the development of psychiatric and neurological diseases is worth exploring. Since brain shape is easier to measure than brain wiring, paying closer attention to brain shape could open new areas of research.

Pang said it's possible the speed at which waves spread to different regions of the brain could affect how people process information, which could then contribute to brain activity patterns associated with diseases like schizophrenia or depression.

The findings aren't definitive, Pang cautioned, but added that he believes the new study "strengthens the theory" that brain shape has a greater influence on brain activity than neuron connectivity does.

David Van Essen, a neuroscience professor at Washington University in St. Louis, said the brain shape theory has existed for more than a decade, but most researchers still believe that neuron connectivity holds a greater influence on brain activity.

"The fundamental starting hypothesis is that the wiring of the brain is central to understanding how the brain functions," he said.

Van Essen said he remains skeptical of the brain shape theory. "It would be an understatement to say this is a controversial theory, and it really needs to be put through its paces to evaluate critically whether it stands the test of time," he said.

Van Essen raised a number of concerns about the study, noting the researchers' models are based on the average of the shapes of peoples' brains — an approach that glosses over the significant difference in patterns of surface folds between brains.

He added that MRIs are imperfect tools and might not capture the nature of a person's brain wiring reliably.

"As exciting and informative as it [MRI technology] is, it's still inaccurate in fundamental ways and incomplete, and leaves a lot left to be sorted out by future studies," Van Essen said. (Bendix, NBC News, 5/31)