Local hemodynamics dictate long-term dendritic plasticity in peri-infarct cortex

Area of Science:

• Neuroscience
• Cerebrovascular Biology
• Synaptic Plasticity

Background:

• Dendritic spine turnover is crucial for experience-dependent plasticity in the adult neocortex.
• Dendritic spine plasticity may aid functional recovery post-stroke, but is affected by local perfusion changes near the infarct.

Purpose of the Study:

• To investigate the relationship between blood flow and dendritic spine dynamics in the peri-infarct cortex after stroke.
• To understand how altered tissue perfusion impacts synaptic plasticity and neuronal recovery following ischemic events.

Main Methods:

• Simultaneous in vivo two-photon microscopy recording of spine dynamics and capillary blood flow in Thy-1 GFP-M mice.
• Long-term observation of layer 5 pyramidal cell dendrites and surrounding blood flow before and after middle cerebral artery occlusion (MCAO).
• Analysis of spine density changes and blood flow recovery in relation to infarct proximity over a 3-month period.

Main Results:

• Peri-infarct blood flow significantly decreased post-stroke, gradually improving over time but not fully restoring even after 3 months.
• Surviving neurons showed a ~20% decrease in spine density acutely post-stroke, with eventual recovery.
• Recovery dynamics varied with perfusion: cells in ischemic areas retained spines slowly, while those in better-perfused regions added spines rapidly, exceeding baseline by 15%.

Conclusions:

• Tissue perfusion significantly influences the rate and mechanism of dendritic spine recovery after stroke.
• Maintaining adequate blood flow in the peri-infarct zone is critical for enhancing synaptic plasticity.
• Augmenting or preserving local tissue perfusion may accelerate functional recovery following stroke.