Experimental and clinical studies of localisation before Flourens

Experimental studies in the localisation of brain function did not begin with Flourens, nor did clinical studies with the phrenologists or physicians like Auburtin, Bouillaud, or Dax, shortly afterward. Although the pre-1820 literature is moderate, some of it is worth examining because of the problems associated with interpreting it. There are three separate but related problems: philosophical, methodological, and conceptual. Philosophically, whether one saw the brain as the main organ of sensibility, as did the Hippocratic writers and Galen, or the heart, as did Aristotle, determined the attention given to the brain. The methodological problems arose from the gross structure of the brain not being immediately obvious and the dominant technique of dissecting the brain in transverse sections revealing the ventricles and their immediately associated structures more readily than other structures. Conceptually, the ventricles were seen as the sites through which sensations were transferred to the muscles. Observations relevant to localisation were thus related to the ventricles or to structures lying outside the cerebrum. What are now considered major structural landmarks were not discovered until late: the Sylvian fissure in about 1640 and the fissure of Rolando in 1829, the former being dependent on new methods of dissection. In general, it was not until the first half of the nineteenth century that the cerebral structures were properly differentiated. Consequently, calls for comparative clinical studies of the effects of lesions in different parts of the brain inevitably fell on ears tuned to a framework which could not incorporate them. So, did the results of the earlier experimental studies.