The Legacy of the Kennard Principle

Research into neural plasticity has progressed rapidly over the last few decades, but the origins of this field lie in the early 20th century. In 1936, Margaret Kennard introduced the concept of brain plasticity in an animal model by studying the recovery of motor functions after performing brain lesions in infant and adult monkeys. It took until the 1970s for her work to be widely acknowledged. When her work did eventually make it into the limelight, this led to the synthesis of what scientists dubbed the 'Kennard Principle'. The Kennard Principle states that the younger an organism is, the greater and swifter recovery from brain injury will be. This principle itself is subject to controversy and debate; furthermore, it is based on a simplification of Kennard's original results. This article will explore Kennard's original 1936 paper, published in the American Journal of Physiology, and the context in which the Kennard Principle arose. Kennard's paper demonstrates early pioneering work within the field of behavioral neuroscience which provides a historical foundation for psychology and neuroscience undergraduates. Exploring the context in which the Kennard Principle arose also highlights the importance of tracing the origins of scientific principles and theories for students and researchers alike.