F-dynamics: automated quantification of dendrite filopodia dynamics in living neurons

Dendritic filopodia are highly motile and flexible protrusions that explore the surroundings in search for an appropriate presynaptic partner. Dendritic filopodia morphologically and functionally transform into postsynaptic dendritic spines, once the appropriate partner has been chosen. Therefore, proper formation of synapses depends on the dynamics of dendritic filopodia and spines. Thus, a rigorous assessment of dendrite filopodia behavior could be informative in providing a link between filopodia dynamics and synaptic development.

In this paper, a tool for automated tracking of filopodia dynamics, the Filopodia-dynamics program (F-dynamics), will be described, tested and applied. The aim of this study is to validate the accuracy and reliability of F-dynamics and to test the program in live neurons.

We demonstrate that filopodia dynamics can be reliably and accurately quantified using the F-dynamics program. In the present study, this program was used to successfully show that lithium treatment increases filopodia motility.

F-dynamics is the first analysis program that is able to determine dendritic filopodia dynamics automatically across both the longitudinal and lateral dimensions.

Our data suggests that this analysis method can be used to differentiate between different experimental conditions and illustrates the potential of the program to measure pharmaceutical or genetic effects on filopodia dynamics.