Modeling the Shape of Synaptic Spines by Their Actin Dynamics
Bonilla-Quintana, Mayte ; Wörgötter, Florentin ; Tetzlaff, Christian ; Fauth, Michael
Citable Link (URL):http://resolver.sub.uni-goettingen.de/purl?gs-1/17387
Journal Article (Published version)
First published (peer reviewed)
Frontiers in Synaptic Neuroscience 2020; 12 p.1-19: Art. 9
Abstract
Dendritic spines are the morphological basis of excitatory synapses in the cortex
and their size and shape correlates with functional synaptic properties. Recent
experiments show that spines exhibit large shape fluctuations that are not related to
activity-dependent plasticity but nonetheless might influence memory storage at their
synapses. To investigate the determinants of such spontaneous fluctuations, we propose
a mathematical model for the dynamics of the spine shape and analyze it in 2D—related
to experimental microscopic imagery—and in 3D. We show that the spine shape is
governed by a local imbalance between membrane tension and the expansive force
from actin bundles that originates from discrete actin polymerization foci. Experiments
have shown that only few such polymerization foci co-exist at any time in a spine, each
having limited life time. The model shows that the momentarily existing set of such foci
pushes the membrane along certain directions until foci are replaced and other directions
may now be affected. We explore these relations in depth and use our model to predict
shape and temporal characteristics of spines from the different biophysical parameters
involved in actin polymerization. Approximating the model by a single recursive equation
we finally demonstrate that the temporal evolution of the number of active foci is sufficient
to predict the size of the model-spines. Thus, our model provides the first platform to
study the relation between molecular and morphological properties of the spine with a
high degree of biophysical detail.
Sponsor:
Open-Access-Publikationsfonds 2020
These documents are avalilable under the license: