The arrow model: retinotectal specificity and map formation in the goldfish visual system

Retinal ganglion cells in the vertebrate eye connect with tectal cells in a continuously ordered fashion. Experiments performed on goldfish and amphibians, in particular experiments involving the rotation of tectal grafts, have been interpreted by some authors as indicating that the tectum is ‘specified’. We present in this paper the computer simulation of a model – the simple-arrow model – which does not require the tectum to be specified but does account for most of the previously published data. We also present preliminary results of an experiment performed on adult goldfish, involving the reciprocal translocation of two tectal grafts, which indicate that the simple-arrow model is unable to account for regeneration of retinotectal connections in this animal.