Radial arm maze performance in rats following neonatal dopamine depletion

Neonatal dopamine (DA) depletion produces learning impairments both during development and throughout adulthood in the rat. The present experiment further investigated the memory capabilities of the dopamine-depleted rat by assessing performance in the radial arm maze. Results showed that, following neonatal injection of 6-hydroxydopamine and desmethylimipramine, lesioned rats per-performed more accurately than controls. In this paradigm, DA-depleted rats tended to enter each arm to obtain a food pellet and not enter unbaited, incorrect arms. The difference in performance of control and treated rats could not be accounted for by differences in locomotor activity, body weights, or motivational factors. A computer analysis of the data revealed that DA-depleted animals adopted a strategy of choosing adjacent arms consecutively, which probably accounted for their superior performance. Results are discussed in terms using algorithms versus extra-maze cues to complete the maze following early brain injury.