Using extirpations to understand the human motor cortex: Horsley, Foerster, and Bucy.

During the last part of the 19th century and through the middle of the 20th century, surgeons sometimes extirpated parts of the human motor cortex to control abnormal involuntary movements. This procedure can be traced directly to Victor Horsley, who pioneered the first successful surgery of this type in 1886. Although many neurosurgeons followed Horsley's lead in performing this procedure, few used their results, as he did, to formulate concepts on the role of the motor cortex in movement control. Otfrid Foerster and Paul Bucy were the principal exceptions. We reviewed the surgical procedures these 3 notable neurosurgeons performed on the motor cortex and the hypotheses they subsequently developed on the functions of the motor cortex. We also evaluated these writings relative to contemporary views of motor cortex function.