Permanent disorganization of the regenerating optic tract in the frog

The organization of the optic tract as it regenerates following optic nerve transection in adult frogs was studied using microelectrode recordings from optic nerve arborizations in the tectum. In normal frogs, a cut extending from the midline partway across the rostromedial margin of the tectum severs optic axons with receptive fields in the temporosuperior quadrant of the visual field. During regeneration, however, a similar cut spares many axons with temporosuperior fields. This result implies that some fibers which normally enter the tectum via the most medial parts of the optic tract regenerate through other parts of the tract. Despite their anomalous routes, many of these fibers eventually terminate at the appropriate locations in the tectum.