Flourens, Pierre Jean Marie (1794–1867)

French physiologist who experimented widely on the effects of the removal of various parts of the central nervous system. He determined the function of different parts of the mammalian brain and the role of the semi-circular canals of the inner ear in balance.

Flourens experimented widely on the central nervous system. He removed the cerebral hemispheres in the brain of a pigeon and observed that this made the bird blind. When one cerebral hemisphere was removed, the bird lost the sight from its opposite eye. Flourens therefore demonstrated that vision depends on the integrity of the cerebral cortex. He next removed only the cerebellum and determined that while the bird could see and hear well, it stood, walked, and flew in an indecisive manner. The bird's equilibrium was almost entirely abolished. Flourens later demonstrated the same results on a dog. Injury to the cerebellum therefore causes loss of coordination. Flourens introduced the idea of nervous coordination to physiology.

Flourens also did important work on the role of the semicircular canals of the inner ear on balance and demonstrated that the respiratory centre is situated in the brain stem, the medulla oblongata, the area in the brain that is responsible for the involuntary contraction of the respiratory muscles.