Long-term dendritic spine stability in the adult cortex

Area of Science:

• Neuroscience
• Cell Biology
• Developmental Biology

Background:

• Synaptic structural dynamics are critical for nervous system development and plasticity.
• Excitatory axo-dendritic synapses in the mammalian brain primarily occur on dendritic spines.
• Long-term changes in dendritic spines in vivo remain poorly understood.

Purpose of the Study:

• To investigate the long-term structural dynamics of dendritic spines in the developing and adult mammalian brain.
• To understand the stability and turnover rates of dendritic spines over time in vivo.

Main Methods:

• Developed a transcranial two-photon imaging technique for in vivo observation.
• Tracked identified dendritic spines of layer-5 pyramidal neurons in the primary visual cortex of living transgenic mice.
• Quantified spine stability and elimination rates over a one-month interval in young and adult mice.

Main Results:

• Filopodia-like dendritic protrusions were abundant in young mice but absent in adults.
• In young mice during the critical period, approximately 73% of spines remained stable over one month, with most changes involving spine elimination.
• In adult mice, approximately 96% of spines were stable over one month, with a half-life exceeding 13 months.

Conclusions:

• Dendritic spines exhibit high plasticity during early development.
• Spines become remarkably stable in the adult brain.
• This transition from plasticity to stability in dendritic spines may underpin long-term information storage in the adult nervous system.