Jerzy Konorski (1 December 1903 in Łódź, Congress Poland – 14 November 1973 in Warsaw, Poland) was a Polish neurophysiologist who further developed the work of Ivan Pavlov by discovering secondary conditioned reflexes and operant conditioning. He also proposed the idea of gnostic neurons, a concept similar to the grandmother cell. He coined the term neural plasticity, and he developed theoretical ideas regarding it that are similar to those proposed soon after by Donald Hebb.