Synaptic pruning through glial synapse engulfment upon motor learning

Area of Science:

• Neuroscience
• Cell Biology
• Neuroimmunology

Background:

• Synaptic pruning is crucial for learning and memory.
• Glia are known to sculpt neural circuits via synapse engulfment.
• The specific role of glial synaptic pruning in memory formation is not fully understood.

Purpose of the Study:

• To investigate the role of cerebellar Bergmann glia (BG) in synaptic pruning during motor learning.
• To determine if glial engulfment of synapses contributes to memory formation.

Main Methods:

• Utilized novel phagocytosis reporter mice for visualizing synapse engulfment.
• Employed three-dimensional ultrastructural characterization for detailed analysis.
• Administered Annexin V to pharmacologically block glial engulfment.

Main Results:

• Synaptic engulfment by BG increased during cerebellum-dependent motor learning in mice.
• BG exhibited increased pre- and postsynaptic nibbling, with reduced spine volume post-learning.
• Blocking engulfment with Annexin V prevented spine volume reduction and hindered overnight motor adaptation improvement.

Conclusions:

• Cerebellar Bergmann glia actively participate in refining mature cerebellar cortical circuits.
• Glial synaptic engulfment is a key mechanism underlying motor learning and memory consolidation.