Development and regeneration of the retinotectal map in goldfish: a computational study

Abstract

We present a simple computational model to study the interplay of activity-dependent and intrinsic processes thought to be involved in the formation of topographic neural projections. Our model consists of two input layers which project to one target layer. The connections between layers are described by a set of synaptic weights. These weights develop according to three interacting developmental rules: (i) an intrinsic fibre-target interaction which generates chemospecific adhesion between afferent fibres and target cells; (ii) an intrinsic fibre-fibre interaction which generates mutual selective adhesion between the afferent fibres; and (iii) an activity-dependent fibre-fibre interaction which implements Hebbian learning. Additionally, constraints are imposed to keep synaptic weights finite. The model is applied to a set of eleven experiments on the regeneration of the retinotectal projection in goldfish. We find that the model is able to reproduce the outcome of an unprecedented range of experiments with the same set of model parameters, including details of the size of receptive and projective fields. We expect this mathematical framework to be a useful tool for the analysis of developmental processes in general.