Ginseng improves strategic learning by normal and brain-damaged rats.

Adult rats were prepared with either sham or medial prefrontal cortex lesions and administered, beginning on the third post-operative day, either, 0, 40, or 80 mg kg-1 crude ginseng extract suspended in saline daily for the next 30 days. Later, kinetic functions were evaluated on an elevated rotating rod. No long-term influences of the treatments were observed on this task. Significant positive influences of ginseng were observed in the position reversal task. The learning deficits observed in the saline control brain-damaged rats were significantly attenuated in the ginseng-treated animals. An analysis of trial 2 response accuracy across reversals revealed enhanced cognitive abilities (i.e. acquisition of a win-stay, lose-shift strategy) in both the brain damaged and sham control rats administered ginseng. Generally, administration of the higher dose resulted in better performance in the learning paradigm. The exact mechanism responsible for these promising results remains to be discovered. Several possible mechanisms are discussed.