In 1890, Pavlov became director of the Institute of Experimental Medicine in St. Petersburg. Here he continued his research on digestion and the functions of the liver, pancreas, and other digestive organs. His discoveries of the laws of "conditioned reflection," which became known as Pavlov's conditioned reflexes, were a real scientific revolution that made a significant contribution to the physiology of behavior.
He studied animal behavior and developed the concept of "learning engines," which explains how animals learn through associations and connections between different stimuli. This research gave rise to a new field of science - behavioral psychology.
However, it was not only his scientific achievements that made Pavlov famous around the world. In 1904, during the revolution, Pavlov made a large donation to organize medical care for the wounded. He opened special hospitals for the wounded, where he provided medical care free of charge. Later, in 1917, he was appointed chairman of the commission to combat the cholera epidemic in St. Petersburg.
After the revolution in 1917, Pavlov was elected president of the All-Union Academy of Sciences. He continued to conduct scientific research, in particular, he studied the mechanisms of nervous regulation, as well as the physiology of the cardiovascular system.