Changes in the Injured Brain are revealed in the Connection Map

Changes in the Injured Brain are revealed in the Connection Map ...

Scientists at the University of California and Irvine have discovered that a brain injury to one part has altered the relationship between nerve cells across the entire body. This week, inNature Communications, the study was published.

Every year, around two million people live with a traumatic brain injury (TBI) in the United States. Survivors can have a lifelong physical, cognitive, and emotional habileness. There are no treatments available.

One of the most important challenges facing neuroscientists has been to fully understand how a TBI alters the cross-talk between different cells and brain regions.

Researchers developed a software called iDISCO, which uses solvents to make biological samples transparent. The process leaves behind a fully stable brain that can be illuminated with lasers and imaged in 3D with special microscopes.

The researchers studied the prefrontal cortex, a brain region that works together with the hippocampus. In both cases, the imaging showed that inhibitory neurons gain many additional connections from the adjacent nerve cells after TBI, but they become disconnected from the rest of the brain.

According toRobert Hunt, the doctor, who is an associate professor ofanatomy and neurobiology and who is currently working on the study. However, we haven''t seen what happens in the whole brain until now.

Hunt and his team devised a technique for reversing the clearing procedure and investigating the brain with traditional anatomical approaches.

The findings were surprising that the long projections of distant nerve cells were still present in the damaged brain, but they no longer formed connections with inhibitory neurons.

Although the whole brain is being carefully rewired to accommodate the damage, it appears, regardless of whether the region had a direct injury or not, according to Alexa Tierno, a graduate student and co-first author of the study. However, many parts of the brain are unlikely to work together quite as well as they did before the injury.

Researchers used brain imaging to see if inhibitory neurons might be connected with distant neural regions. Using teamearlier research, Hunt and his team determined how interneuron transplantation works to improve memory and prevent seizures in mice.

Despite this, the new neurons received appropriate connections from all over the brain. While this might be possible to enable the injured brain to repair these lost connections on its own, Hunt said, learning how transplanted interneurons integrate into damaged brain circuits is necessary for any future attempt to utilize these cells for brain repair.

According to Hunt, our study is a valuable addition to our understanding of how inhibitory progenitors can one day be used therapeutically for treatment of TBI, epilepsy, or other brain diseases. Several people have suggested that a interneuron transplant might rejuvenate the brain by releasing unknown substances to improve its intrinsic regenerative capacity, but it was found that the new neurons are really being hard wired into the brain.

Hunt hopes to continue to pursue cell therapy for people with TBI and epilepsy. The UCI team is now repeating the experiments using inhibitive neurons created from human stem cells.

This work takes us one step closer to a future cell-based therapy for people, according to Hunt. Understanding the kinds of plasticity that occurs after an injury will help us recover the injured brain with a very high degree of precision. However, it is very important that we proceed step wise toward this goal, and that takes time.

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