Organization of the visual projection upon the optic tectum of some freshwater fish

In four species of freshwater fish, bass, carp, bluegill and goldfish, the topographical relations of the visual field with the contralateral optic tectum were investigated, using a small light as stimulus in the visual field and recording the electrical response of the tectum with a metal microelectrode. The results show a precisely organized visual projection onto the contralateral tectum in which the anterior visual field lies anteriorly on the tectum, the temporal field posteriorly, the dorsal field medio‐dorsally, and the ventral field in the latero‐ventral part of the tectum. The projection was found to be essentially linear and uniform with no indication of a specialized area in the visual field in those species investigated. Some receptive fields extended into the anterior binocular visual field.