Melatonin: A New Probe in Psychiatric Investigation?

The pineal gland, Descartes' seat of the soul, was variously considered until recently as a somewhat mysterious vestigial organ, or simply a good neuroradiological marker. The former point of view arose partly out of ignorance and the curious mythical associations related to its function as a ‘third eye’ in some lower vertebrates. The latter is due to the calcification which is present in most adult human pineal glands.