Title: A body made of nerves
Description: This dissertation is concerned with the history of sensory-motor, or reflex, physiology in nineteenth- and early twentieth-century German neuroscience. The argument of my dissertation has three main parts: First, I study how the reflex was employed in medical practice, taking as a case study turn-of-the-century Breslau. Psychiatrist Carl Wernicke used sensory-motor physiology to diagnose mental illness; his student Otfrid Foerster drew on reflex physiology to treat ailments of the nervous system including pain and movement disorders. By studying the reflex in these clinical settings, I show that it was not an elementary and rigid principle, but a rich tool to make sense of neurological and mental illness, in both diagnosis and treatment. Second, this study brings to light the subtle theoretical understanding of the reflex that corresponded to its clinical use. I show how the sensory-motor system, and the nervous system more generally, was imagined as a cooperative society of semi-autonomous elements that worked together collaboratively for the common good of the organism. For Theodor Meynert and many of those who followed him, each of these elements was endowed with a soul ( beseelt ); subjectivity was not single and unified, but fragmented and social. Further, following the presentation of the nervous system as a reflex consortium ( Reflexarbeitsgemeinschaft ), subjectivity was spread throughout the nervous system, integrated with the body.

To understand how unified action could arise through the cooperation of individual parts, many neuroscientists turned to state models of the nervous system. In my analyses, I use this theoretical model to reevaluate the history of neuro-rehabilitation and epilepsy, and pay particular attention to early neurological photography and film, which attempted to document and map the living body and nervous system. Finally, I study how American neurosurgeon Wilder Penfield drew on the sensory-motor model in his figure of the "homunculus." Investigating the processes of trans-Atlantic intellectual exchange in the interwar period, I show how the clinical and experimental methods that derived from the embodied reflex paradigm, unexpectedly informed a twentieth-century tradition that privileged the brain over the rest of the nervous system and the body, a tradition that I, following Daniel Dennett, call "Cartesian materialism."