Reversed visuomotor behavior mediated by induced ipsilateral retinal projections in goldfish

Abstract

1. When one optic lobe of a goldfish is removed and the optic nerve from the contralateral eye is deflected ipsilaterally, the nerve innervates the intact, previously foreign side. When the control eye is left intact, the animal shows normal swimming and coordination of head and eyes. In some cases, however, optokinetic nystagmus evoked through the experimental eye is reversed, indicating a functional ipsilateral projection which was apparently outweighed by the normal projection during swimming. 2. When the same surgical procedure is accompanied by partial or complete destruction of the control eye, the animals show overt reversal of visuomotor behavior soon after the ipsilateral projection is established. They make a spontaneous nystagmus and circle continuously. The nystagmus and the circling persist in total darkness for days before they are extinguished. They resume as soon as the animal returns to light. 3. The vestibuloocular reflex is biased differently from normal, but the sign of the gain is normal. 4. We conclude that the neurological reversal of vision triggered the nystagmus and the circling, and that the many months with reversed vision resulted in some longer lasting change in the nervous system such that the behaviors persisted even in the absence of moment-to-moment visual stimulation.