Berger was born in Neuses, Germany, and studied medicine at the University of Jena; having joined the university psychiatric clinic in 1897 as an assistant, he eventually served as its director and professor of psychiatry (1919–38). In his early work, he attempted to correlate physical factors in the brain, such as blood flow and temperature, with brain function. Disappointing results in this area made Berger turn to investigating the electrical activity of the brain. In 1924 he made the first human electroencephalogram by recording, as a trace, the minute changes in electrical potential measured between two electrodes placed on the surface of the head. Berger subsequently characterized the resultant wave patterns, including alpha and beta waves, and published his findings in 1929. The technique of electroencephalography is now used to diagnose such diseases as brain tumors and epilepsy. It is also used in psychiatric research and in diagnosing brain death.