Reformation of retinotectal projections after various tectal ablations in adult goldfish

Abstract

The retinotectal connections, formed during optic nerve regeneration in adult goldfish, were mapped several months after various tectal ablations. In the first case, when the rostral tectum alone was removed, the displaced projection from the missing half tectum was partially restored over the caudal tectum. In the second case, with tectal lesion and optic nerve crush, there was compression of the entire visual field onto the remaining half tectum. In the third case, the central one-third dorsal tectum was removed with and without optic nerve crush. In cases where the optic nerve was crushed, the entire visual field redistributed itself onto the remaining rostral and caudal tectum. However, a few positions in the rostral one-third tectum alone reduplicated in animals without optic nerve crush resulting into a compressed visual field. It is concluded that pattern recognition mechanisms, rather than a strict form of place specificity, control the reformation of optic nerve connections in adult goldfish.