A model for growth cone guidance by attractive or repulsive cues

During development and regeneration the neuronal growth cone is responsible for guiding the axon to its final target. Much of our insight into this process has been obtained from experimental studies, both in vitro and in vivo. Additional understanding is possible through quantitative models that divide complex migration behavior into components that can be manipulated through simulation experiments. This work focuses on the development of a model for growth cone guidance based on previous models of filopodial dynamics and growth cone migration. Two parameters have been incorporated to represent guidance behavior; a permissivity index, PI, accounts for the repulsive or attractive nature of a guidance cue, and a constraint parameter, δ, quantifies a bias in growth cone migration either toward or away from a guidance cue. Simulated guidance cues range from strongly attractive to strongly repulsive and appear to the growth cone as either discrete or continuous. From these simulations we can infer how the arrangement and permissivity of guidance cues might affect growth cone pathfinding.