Repetitive concussions promote microglia-mediated engulfment of presynaptic excitatory input associated with...

Area of Science:

• Neuroscience
• Traumatic Brain Injury Research
• Cellular Biology

Background:

• Concussions are a significant health issue, with repetitive head impacts common in sports.
• While single concussions often have transient symptoms, repeated injuries can lead to persistent deficits.

Purpose of the Study:

• To investigate the long-term effects of repetitive concussions on learning and memory.
• To examine the role of microglial cells in the brain's response to single versus repetitive concussions.

Main Methods:

• A mouse model of bilateral midline-centered concussions was utilized.
• Microglial structure and function were assessed in the cortex and hippocampus after single and repetitive impacts.
• Synapse engulfment by microglia was quantified.

Main Results:

• Repetitive concussions selectively impaired learning ability compared to single-impact injuries.
• Only repetitive concussions induced long-lasting microglial activation.
• Microglia-mediated engulfment of excitatory synapses increased significantly after repetitive concussions.

Conclusions:

• Repetitive concussions lead to persistent behavioral deficits, specifically in learning.
• Long-term microglial activation and altered synapse dynamics are key features of repetitive concussion injury.
• While the brain may compensate anatomically for synapse turnover, behavioral recovery is not achieved.