Cross-species embryonic septal transplants: restoration of conditioned learning behavior.

Embryonic septal and hippocampal tissue from mice was transplanted between species into the brains of adult rat hosts as cell suspensions. Deficits in the ability to learn a conditioned, hippocampally mediated, forced alternation behavior, which were caused by a bilateral transection of the fornix-fimbria pathway, were ameliorated in the septal transplant recipients. The successful performance of the task was correlated to the density index of acetylcholinesterase in the hippocampal section.