A concept originating in embryology that referred to a time in development or growth that was most susceptible to the induction of new structures by neurochemical agents and whose effects were considered to be irreversible. Today, the term ‘sensitive period’ is generally used and applied to the development of both structure and function (e.g., learning).
See Embryology, Filial imprinting, Induction (embryology), Ocular dominance columns, Sensitive period