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Updated: Aug 10, 2026
10:45
In Situ Visualization of Axon Growth and Growth Cone Dynamics in Acute Ex Vivo Embryonic Brain Slice Cultures
Published on: October 14, 2021
Axons and synaptic boutons are highly dynamic in adult visual cortex
Dan D Stettler1, Homare Yamahachi, Wu Li
1The Rockefeller University, New York, New York, USA.
Neuron
|March 18, 2006
Summary
Axons in the adult brain remain dynamic, with weekly turnover of small branches and boutons. This suggests continuous synapse formation and elimination occur in the primary visual cortex.
Area of Science:
- Neuroscience
- Cell Biology
Background:
- Recent research on synaptic stability in the adult cerebral cortex has primarily focused on dendrites.
- The dynamics of axons in the adult brain remain largely unexplored.
Purpose of the Study:
- To investigate axon branching and bouton dynamics in the primary visual cortex (V1) of adult Macaque monkeys.
- To determine the extent of axonal changes in the adult brain using advanced imaging techniques.
Main Methods:
- Utilized advances in viral axon labeling with a nonreplicative adeno-associated virus (AAV.EGFP) for persistent labeling.
- Employed in vivo two-photon microscopy for repeated imaging of the intact brain over several weeks.
Main Results:
- Observed stable large-scale axon branching patterns.
- Found that a subset of small branches and boutons (both terminal and en passant) appeared and disappeared weekly.
- Quantified bouton loss and gain at approximately 7% of the total population per week, with no net change in overall density.
Conclusions:
- Suggests ongoing processes of synaptogenesis and elimination in the adult primary visual cortex.
- Highlights the dynamic nature of axons in the adult brain, challenging the notion of axonal stability.
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