The brain shows a capacity to recover from traumatic injury, which somewhat contradicts the widely accepted idea that neurons do not regenerate. So how is recovery possible? In a new JNeurosci paper, Athanasios Alexandris and colleagues, from Johns Hopkins University, used mice to explore how the visual brain system recovers following traumatic injury.
The researchers monitored connections from cells in the eye to the brain after injury. They discovered that surviving cells compensated for cell death by sprouting extra branches to make connections with more neurons in the brain. This sprouting occurred to such an extent that connections between the eye and brain matched preinjury levels. Activity measures showed that these connections were functional. Notably, there were sex differences: Female mice had delayed or incomplete repair.
According to the authors, this work points to a compensatory mechanism following brain injury that differs between sexes. Says Alexandris, "We didn't expect to see sex differences, but this aligns with clinical observations in humans. Women experience more lingering symptoms from concussion or brain injury than men. Understanding the mechanism behind the branch sprouting we observed—and what delays or prevents this mechanism in females—could eventually point toward strategies to promote recovery from traumatic or other forms of neural injury." The researchers plan to continue exploring underlying mechanisms and why they may be different in females and males.
