First Description of Wernicke's Area (1874) - German physician Carl Wernicke described a brain region crucial for language comprehension, distinguishing it from Broca's area and establishing the first language network model.
Discovery of Rapid Eye Movement (REM) Sleep (1953) - Eugene Aserinsky and Nathaniel Kleitman identified REM sleep and its connection to dreaming, fundamentally changing sleep research and understanding memory consolidation.