Development of interocular equivalence of place learning in the rat requires convergence sites established prior to...

Interocular equivalence for spatial-navigation learning requires that the neural pathways originating in each eye converge on common memory sites. Rats fail to display interocular equivalence if they are trained and tested on the Morris (1981) place-navigation task when they are 22 days old, but they succeed if they are trained and tested when they are 28 days old (Rudy & Stadler-Morris, 1987). This delay suggests that there is a period in development when the interhemispheric connections necessary for convergence are immature and rats behave temporarily as split-brain organisms. In the present experiment, rats completed training when they were 22 days old but were not tested for interocular equivalence until they were 28 days old. Nevertheless, these subjects failed to demonstrate equivalence. Thus, for interocular equivalence to be observed, the neural pathways from each eye must converge on common neural sites that are functional at the time the memory representation is established.