Neuronal plasticity affects correlation between the size of dendritic spine and its postsynaptic density

Area of Science:

• Neuroscience
• Cell Biology
• Synaptic Plasticity

Background:

• Dendritic spine structural plasticity is fundamental to memory formation.
• Spine size is typically correlated with postsynaptic density (PSD) size, glutamate receptors, and synaptic strength.

Purpose of the Study:

• To investigate the correlation between dendritic spine volume and PSD size across various volumes.
• To determine if this correlation remains stable during synaptic plasticity.
• To elucidate the role of smooth endoplasmic reticulum (SER) in regulating these parameters.

Main Methods:

• 3D electron microscopy was used to reconstruct dendritic spines and PSD cores.
• Analysis was performed on organotypic hippocampal slices from the CA1 stratum radiatum.
• Measurements included spine volume, PSD surface area, and PSD-core volume.

Main Results:

• Approximately one-third of medium-sized dendritic spines showed no significant correlation between spine volume and PSD size.
• During NMDA receptor-dependent chemical long-term potentiation (NMDAR-cLTP), both spines and PSDs grew, increasing the PSD area to spine volume ratio.
• Spines containing SER exhibited enhanced correlation between volumetric parameters during cLTP, unlike those without SER.

Conclusions:

• The correlation between PSD surface area and spine volume is not uniform across all spine sizes.
• Synaptic plasticity modifies and strengthens this correlation, with SER playing a regulatory role.
• SER-containing spines demonstrate a more robust and plasticity-dependent correlation between volumetric parameters.