Study provides a "bird's eye view" of the brain and its functions

A new study provides the best evidence to date that the connection patterns between various parts of the human brain can tell scientists the specialized functions of each region.

Previous research has shown the relationship between connectivity and brain function for just one or a few functions, such as perception or social interactions.

But this study goes further by providing a "bird's eye view" of the whole brain and its many functions, said Kelly Hiersche, lead author of the study and doctoral student in psychology at The Ohio State University.

We found evidence suggesting that connectivity is a fundamental organizational principle governing brain function, which has implications for understanding what happens when things go wrong in the brain."

Kelly Hiersche, doctoral student in psychology, The Ohio State University

The findings give scientists a better picture of the "connectivity fingerprint" of specific regions of the human brain.

"Just like how everyone's fingerprint is unique, we find that different brain regions have uniquely identifying connectivity fingerprints based on what mental function they perform," said co-author Zeynep Saygin, associate professor of psychology at Ohio State.

Therefore, scientists can use specific connectivity fingerprints to infer the function of that region, said senior author David Osher, assistant professor of psychology at Ohio State.

"Our findings help us understand the connectivity pattern that makes a language area unique, for example, and what makes it different from adjacent areas in the brain," Osher said.

The findings were published recently in the journal Network Neuroscience. 

The researchers used data from the Human Connectome Project, which included 1,018 individuals whose brains were scanned in an MRI to examine connectivity patterns in their brains.

They then used NeuroQuery, an online meta-analysis tool that provides a brain map for any cognitive process, which reflects how a person's brain would activate across 33 cognitive processes, including speech, decision making, listening to music, and face perception. Next, Hiersche and colleagues built computational models that link the connectivity data with the meta-analytic results from NeuroQuery.

The results showed a consistent and robust correlation between connectivity and function across the whole brain and across cognitive domains. In other words, the researchers saw that particular patterns of connectivity could predict whether or not a part of the brain would be active – and inactive - across many tasks, whether that be looking at a face, or talking, or making a decision.

"It supports a broadly held hypothesis among neuroscientists, that brain connectivity determines brain function, but this has not been explicitly shown until now, and not across such a large breadth of cognitive domains," Osher said.

While all cognitive domains and brain regions showed a tight relationship between connectivity and activation, the researchers did find something interesting. The very tightest connections were in the higher-level skills, such as executive function and memory, in contrast to sensory or social skills, Hiersche said.

"These higher-level skills take many years to develop in people, much longer than sensory or social skills," she said.

"It may be that as you continually use these regions of the brain for them to develop, it results in this very tight link between connectivity and function for these higher-order skills."

A major contribution of this study is that, because of the bird's eye view of the brain, is that it can give scientists a baseline of how normal brains work in young adults, Hiersche said.

This will allow researchers to study people with various diseases or conditions and see how their brain functions and connectivity differ from what was found in this work, she said.

"Knowing that connectivity is a general organizational principle of brain function across the entire brain provides a foundation for future work in this area."