Maharishi Vedic Astrology (also known as Maharishi Jyotish) premises that planets influence individual health. Jotyish is a vedanga within the field of vedic literature. Maharishi Jyotish is premised on the ability to precisely calculate mathematically the unfolding pattern of life, and to locate the trends and tendencies of an individual life within that pattern, making it possible to determine in advance whether a difficult period was coming, and to take action in the present to amend a future difficulty. Maharishi Jyotish asserts that the solar system has an influence on the human brain, cells and DNA. According to the Maharishi and his successor, Tony Nader, there is a correspondence between the nine Grahas of Vedic Astrology and the structure of DNA, the brain and the structure of cells. Each graha is associated with a gemstone: Maharishi Vedic Astrology associates the planets with the basal ganglia, thalmus and hypothalmus; the 12 Bhavas (astrological houses) with cortical areas; the 12 Rashis (zodiac signs) with the cranial nerves; and the 27 Nakshatras (lunar mansions) with groups of the brainstem.