Hubs are locations in the brain where different networks come together to help us think and complete mental tasks. Now, a new study offers a fresh view of how injury affects the brain. It finds damage to brain hubs disrupts our capacity to think and adapt to everyday challenges more severely than damage to locations distant from hubs.

The researchers, from the University of Iowa in Iowa City, and Washington University in St. Louis (WUSTL), MO, report their study in the Proceedings of the National Academy of Sciences (PNAS).

They hope their findings will improve the prediction of the effects of stroke, trauma and other types of damage to the brain and eventually lead to a better way of weighing up the likely risks of some brain surgeries, as co-senior author Steven Petersen, a professor in cognitive neuroscience and neurology at WUSTL, explains:

This isn’t ready for application in the clinic yet, but as we get a better feel for where these and other hubs are found in the brain, they may factor into surgical decision-making. The risks of surgeries to these sites could include significant impairment of attention, memory, language, speech and many other cognitive functions.”

He goes on to mention how some disorders like schizophrenia also disrupt a similar range of brain functions. He suggests perhaps their findings highlight some of the areas that may contribute to such conditions.

For their study, the researchers used a framework they constructed to locate six hubs – specific points at network boundaries where they come together. Nobody had identified these locations as hubs before.

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Colors illustrate different networks of the brain. Researchers have discovered that injuries to a brain hub (top), where the boundaries of several networks come together, can be much more devastating than similar injuries in other parts of the brain (bottom).
Image credit: Steven E. Petersen

In their background information they explain that previous studies have identified hubs in the human brain, but these used data from patients’ brain scans, and “there is little consensus on the localization of such hubs.”

They proposed that their particular framework – which is based on network measures – would predict and find hubs that play “influential roles in multiple aspects of cognition,” and that other approaches can only find hubs that do not exert such broad influence.

Prof. Petersen says they thought their hubs were points where all the different networks talked to each other, and if that were true, then “damage in these areas could disrupt several networks, impairing multiple mental functions.”

They tested their idea by examining data from the Iowa Neurological Patient Registry – a database of patients who had suffered strokes and other brain injuries. Co-senior author Daniel Tranel, a professor in neuroscience at Iowa, heads the Registry.

The Registry holds data not only on the location of any damage in the brain, but also how the injuries have affected patients’ behavior and thinking skills. For example, it holds results of memory, speech and reasoning tests, and assessments of patients’ ability to work, deal with daily life and relate to family and friends.

Looking through the Registry the team found 19 patients with brain injuries to the six hubs they predicted with their framework. They compared these patients with 11 others who had brain injuries of a similar size but located in places far away from any of the six hubs.

They found the patients with injuries to a hub showed much more impairment to cognitive skills and ability to cope with everyday life.

“For example,” says Prof. Petersen, “18 of the 19 patients with harm to a hub experienced ‘real-world’ problems, while less than half of the group with injuries far from hubs had such difficulties.”

He suggests the findings may explain why some patients experience surprisingly significant impairment following a small brain injury.

He says it would have been very difficult to find the hubs if they had only studied patients. By doing the brain mapping first, they found the hubs fairly quickly, then all they had to do was test the idea using the information in the Iowa Registry.

The team is continuing to investigate other potential brain hubs and to use the Registry to confirm them.

Funds from the National Institutes of Health (NIH), the James S. McDonnell Foundation, and the Simons Foundation helped finance the study.

Medical News Today recently learned about a study that linked decreased brain connectivity to the chronic pain condition fibromyalgia. The researchers found the disorder is associated with abnormal activity in parts of the brain that process pain signals and link them to other regions.