Fig. 4: LTP-induced changes in actin dynamics and spine volume persist longer with stable pool.

A Example spine shapes at different time-points as indicated on top. At t = 1800s an increased size is still visible, whereas it has decayed at 12000s. B Time-course of normalized rates determining actin dynamics (upper scale bar applies for unbinding and nucleation). C Total number of barbed ends in the spine (summed over all polymerization foci). Blue curves show simulations using the the novel stable pool, and red curves the model without the stable pool equivalent to q = 0, compare Fig. 1). Curves depict mean (solid) and standard deviation (shaded) over 20 simulations of the stochastic actin dynamics. D Time-course of the stable pool. E Time-course of the fraction of actin allocated to stable pool. F Time-course of the spine volume. With the stable pool, a slowly decaying component of the spine volume is clearly observable. (Inset) Time until 90% of the volume increase have decayed for models with and without stable pool. The time-course of further model quantities is depicted in Supp. Figs. 1 and 6.