Fig. 6. A convection-diffusion model for filopodial effects on synchronous versus asynchronous release.

(A) Schematic: Filopodial extension generates in-plane membrane flow that clears vesicular components stranded at the AZ during repeated SV fusion, directing them toward the periactive zone. (B) Stochastic SV-fusion model: After an AP, the RRP undergoes probabilistic fusion and replenishment; release events occurring after 10 ms are classified as asynchronous. (C and D) Predicted spatiotemporal profiles of vesicular components (C) and corresponding release probabilities (D) at 400 ms in boutons with or without filopodia. (E) The model predicts that asynchronous release proportion decreases with increasing in-plane membrane flow rate. Assuming that convective speed without filopodia is 0 μm s⁻¹, the model predicts that a speed of ∼1 μm s⁻¹ is necessary to quantitatively capture the twofold decrease in asynchronous release upon filopodial extension (red dashed line).