6533b7d9fe1ef96bd126b99a

RESEARCH PRODUCT

Instrument transfer as knowledge transfer in neurophysiology: François Magendie's (1783-1855) early attempts to measure cerebrospinal fluid pressure.

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Francois Magendie's (1783-1855) experimental model for measuring blood pressure in animals, which he developed in 1838, had a major impact on French physiology in the nineteenth century, especially upon Etienne-Jules Marey (1830-1904) in Paris. In due course it was also adopted by other European investigators, such as the Leipzig physiologist Carl Ludwig (1816-1895), and by clinicians who developed it into a major measuring tool. Historians of science, however, have paid hardly any attention to Magendie's further laboratory investigations conducted with the assistance of Jean-Louis Marie Poiseuille's (1799-1869) sphygmometre (blood pressure meter). After having used the apparatus to conduct his experiments on a variety of blood vessels, Magendie also applied the sphygmometre in 1840 to the ventricular system of the brain in order to measure cerebrospinal fluid (CSF) pressure. But the scope of this new procedure had yet to be defined: the new measuring device invited many speculative interpretations about the meaning of CSF flow for the physiology of the ventricular system in healthy and diseased brain function. As such, Magendie's experiments produced phenomena in very heterogeneous knowledge areas, and CSF measurement was situated at the interface of quite disparate investigative spaces regarding the structure and function of the brain. In his textbook Lecons sur les Fonctions et les Maladies du Systeme Nerveux (Lectures on the Functions and Diseases of the Nervous System), Magendie described extending application of the measuring "apparatus of Poiseuille" from blood vessels to parts of the brain. The instrument thus became something of a liquidodynamometre (liquor dynamometer), that paved the way for later applications, including (after 1896) diagnostic intracranial pressure (ICP) measurement by Theodor Kocher (1841-1917) and Harvey Cushing (1869-1939). The current paper focuses on the experimental contingencies that prompted the instrument transfer in Magendie's laboratory and opened up new epistemological perspectives for research in neurophysiology.