Has Dr. Rita Levi Montalcini unlocked the secret of eternal life? The oldest living and the longest-lived Nobel laureate in history, Montalcini celebrates today her 103th birthday.

"I can say my mental capacity is greater today than when I was 20, since it has been enriched by so many experiences," she says.

Her longevity might be the result of an unusual potion she takes every day in the form of eye drops -- a dose of nerve growth factor, which she discovered (jointly with American co-worker Stanley Cohen), in June 1951 in the labs of Washington University in St. Louis.

A protein essential for the growth, maintenance, and survival of sensory and sympathetic neurons (nerve cells) in the peripheral nervous system, NGF was not widely recognized until 1986, when it won Levi Montalcini and Cohen the Nobel Prize in physiology or medicine.

Levi Montalcini still follows the developments of her findings at the European Brain Research Institute, which she founded in Rome.

Indeed, her work has had a significant influence on research exploring several diseases, including cancer, Parkinson's disease and Alzheimer's disease.