Head trauma causes widespread changes in neuronal connections

Head trauma severe enough to affect brain function, such as that caused by a car accident or sudden fall, leads to changes in the brain beyond the site of impact, report scientists at the University’s School of Medicine. Tufts University in the journal. Cerebral cortex. In an animal model of head trauma, researchers found that the two hemispheres work together to forge new neural pathways in an effort to reproduce lost ones.

“Even areas distant from the injury behaved differently immediately afterward,” says first author Samantha Bottom-Tanzer, MD/Ph.D. student in neuroscience at the Faculty of Medicine. “Research on head trauma tends to focus on the affected region, but this study clearly demonstrates that the entire brain can be affected, and imaging in distal regions can provide valuable information.”

Bottom-Tanzer and his colleagues are the first to use an imaging technique combining fluorescent sensors of neuronal activity and electrodes to record how many parts of the brain communicate with each other after brain injury. The team tracked neuronal activity in mice for up to three weeks after injury, during periods of exercise and rest.

While overall neuron-to-neuron connectivity decreased after brain injury, all mice were able to use an exercise wheel normally. However, the activity of injured brains during periods of running and rest was remarkably different from that of healthy brains. Surprisingly, they didn’t show distinct brain wave patterns when they were moving or when they were still, which is what the researchers would have expected.

“Whether it’s paying attention or walking, the brain changes state depending on the task you’re doing,” says lead author Chris Dulla, professor and interim chair of neuroscience in the Faculty of Medicine. medicine. “After head trauma, this ability is no longer as robust, indicating that such events alter how the brain changes states in ways we don’t yet understand.”

“What we can see from the data is that the brain has new solutions to accomplish all of these complex tasks,” he adds.

This plasticity has clinical implications. Head injuries often lead to long-term health problems and kill tens of thousands of Americans each year, the Centers for Disease Control and Prevention reports. Researchers predict that imaging a patient’s brain while they perform various activities could better determine how a person might be injured or what functions are affected, thereby improving an individual’s treatment.

“This study highlights the complexity of how injuries affect a dynamic and ever-changing brain,” says Bottom-Tanzer. “Most people think of the brain in a single state, but our data indicates that there are fluctuations and could provide opportunities to explore different interventions in physical therapy, speech therapy, etc..”

In the future, Bottom-Tanzer, Dulla and colleagues plan to look for changes in neuronal activity following head trauma for an even longer post-recovery period. They will also explore how their imaging technology can be used to identify changes in brain activity that may translate into specific types of dysfunction or correlate with the long-term consequences of a disease.