4000 B.C. to 0 A.D

ca. 4000 B.C. - Euphoriant effect of poppy plant reported in Sumerian records
ca. 4000 B.C. - Clay tablets from Mesopotamia discuss how to use alcohol to dilute medicine
ca. 2700 B.C. - Shen Nung originates acupuncture
ca. 1700 B.C. - Edwin Smith surgical papyrus written. First written record about the nervous system
ca. 1400-1200 B.C. - Ayuvedic system of Hindu medicine develops
ca. 500 B.C. - Alcmaion of Crotona dissects sensory nerves
ca. 500 B.C. - Alcmaion of Crotona describes the optic nerve
ca. 500 B.C. - Empedocles suggests that "visual rays" cause sight
460-379 B.C. - Hippocrates discusses epilepsy as a disturbance of the brain
460-379 B.C. - Hippocrates states that the brain is involved with sensation and is the seat of intelligence
387 B.C. - Plato teaches at Athens. Believes brain is seat of mental process
335 B.C. - Aristotle writes about sleep; believes heart is seat of mental process
335-280 B.C. - Herophilus (the "Father of Anatomy"); believes ventricles are seat of human intelligence
280 B.C. - Erasistratus of Chios notes divisions of the brain
 
Hippocrates

Image courtesy of the Blocker History of Medicine Collections, Moody Medical Library, Univ. Texas Med. Branch, Galveston