Improvement of auditory discrimination learning by Ginkgo biloba extract EGb 761

The effect of oral application of Ginkgo biloba extract EGb 761 on auditory discrimination learning in Mongolian gerbils was investigated using discrimination tasks with three different degrees of difficulty and two protocols for administration starting 2 weeks prior to or at the beginning of training. In comparison to placebo-treated controls we observed significant improvement of learning performance in EGb 761 treated gerbils in discrimination tasks of all degrees of difficulty, from the easiest to the most demanding. EGb 761 has been reported to increase the extracellular concentration of dopamine in prefrontal cortex of rats which plays a major role in the type of discrimination learning used in the present study. We, therefore, suppose that EGb 761 improves discrimination learning through its effect on the dopaminergic system.