Researchers at Johns Hopkins University have discovered that surviving neurons in the visual system can sprout new branches to rebuild connections with the brain after traumatic injury, restoring function without regenerating lost cells. The process, observed in mice, proved effective but slower in females, highlighting sex-based differences in recovery. This finding challenges long-held beliefs about neural regeneration and offers insights into human brain injury treatment.
For decades, scientists believed that damaged or destroyed neurons do not regenerate, complicating recovery from brain injuries. However, a new study published in The Journal of Neuroscience challenges this view by examining the visual system in mice subjected to traumatic brain injury.
Athanasios Alexandris and colleagues at Johns Hopkins University tracked connections between retinal cells in the eye and brain neurons post-injury. Rather than new cell growth, surviving retinal cells adapted by sprouting extra branches, forming additional links to compensate for lost ones. Over time, the total number of eye-to-brain connections returned to pre-injury levels. Brain activity measurements confirmed these new pathways transmitted visual signals effectively, enabling restored function.
The research revealed notable sex differences: male mice exhibited robust recovery through this sprouting mechanism, while females showed slower or incomplete repair, with connections not fully recovering. As Alexandris noted, "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 study, detailed in a 2025 paper (DOI: 10.1523/JNEUROSCI.0792-25.2025), involved co-authors including Jaeyoon Yi, Chang Liu, and others. The team plans further investigation into these biological factors to aid healing from concussions and similar traumas, potentially benefiting human patients.