Cerebral localization in the eighteenth century--an overview.

At the beginning of the eighteenth century, attempts to localize cerebral functions generated a wide range of different ideas. Ancient theories and their revisions stood next to new doctrines; anatomical, pathological, and surgical observations stood beside philosophical conjectures or conclusions from physiological experiments. Echoing Descartes and Willis, many scholars placed the sensorium commune in structures such as corpus callosum, cerebellum, or meninges. Since the explanatory power of these ideas was limited, a strictly holistic approach gained momentum around 1750. The key neurophysiological concept of the second half of the eighteenth century was Haller's doctrine of the equipotentiality of all cerebral structures including the cortex. However, shortly before 1800, one final effort to reconcile philosophy and science was made. The anatomist Samuel Thomas Soemmerring contended that ventricular fluid was the immediate organ of the soul. The refutation of this hypothesis and the rise of Gall's doctrine mark the end of the premodern era of cerebral localization. This paper reconstructs the era's principle arguments and contemporary experiments. It demonstrates that some current controversies regarding the mind-body problem are repetitions of eighteenth-century neuro-philosophical debates.