Ultrastructural membrane dynamics of mouse and human cortical synapses

Area of Science:

• Neuroscience
• Cell Biology
• Biophysics

Background:

• Understanding synaptic transmission is crucial for brain physiology and pathophysiology.
• Previous studies lacked visualization of dynamic synaptic vesicle trafficking in live human brain tissue.
• Key parameters like synaptic vesicle dynamics remained unobserved.

Purpose of the Study:

• To visualize synaptic vesicle dynamics in live human brain tissue.
• To investigate the mechanism of ultrafast endocytosis in human and mouse brain slices.
• To assess the conservation of synaptic endocytosis mechanisms between species.

Main Methods:

• Zap-and-freeze time-resolved electron microscopy was employed.
• The technique was validated using acute mouse brain slices.
• Calcium signaling and ultrafast endocytosis were induced and captured in both mouse and human brain slices.

Main Results:

• The study successfully visualized calcium signaling in stimulated axons of mouse brain slices.
• Ultrafast endocytosis was observed and captured in both mouse and human brain slices.
• Dynamin 1xA (Dyn1xA), essential for ultrafast endocytosis, localized to the putative endocytic zone in both species.

Conclusions:

• Zap-and-freeze time-resolved electron microscopy is a viable method for studying synaptic vesicle dynamics in intact human brain slices.
• Ultrafast endocytosis is conserved between mouse and human brains, with Dynamin 1xA playing a key role.
• This approach offers potential for high-resolution insights into synaptic membrane trafficking in humans.