By Submitted in Partial Satisfaction of the Requirements for Degree of in in the GRADUATE DIVISION of the UNIVERSITY of CALIFORN
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The Brain Electric: A History of Neuroscientific Ideas About How We Change by Cristina Nigro DISSERTATION Submitted in partial satisfaction of the requirements for degree of DOCTOR OF PHILOSOPHY in History of Health Sciences in the GRADUATE DIVISION of the UNIVERSITY OF CALIFORNIA, SAN FRANCISCO Approved: ______________________________________________________________________________Dorothy Porter Chair ______________________________________________________________________________Brian Dolan ______________________________________________________________________________Aimee Medeiros ______________________________________________________________________________Elizabeth Watkins ______________________________________________________________________________ Committee Members Copyright 2020 by Cristina Nigro ii Acknowledgements I have to start by thanking my dissertation advisor, Dorothy Porter, for her unwavering support and enthusiasm when I needed it most. Her guidance expanded my knowledge and understanding in so many ways and for that I will always be grateful. Dorothy’s influence runs throughout this dissertation and I simply cannot thank her enough. I also must thank my dissertation committee members Brian Dolan, Aimee Medeiros, and Liz Watkins for their sage advice and feedback on the many drafts of this dissertation as well as their expert tutelage throughout my graduate career. I have learned so much from all of them. I owe many thanks to my friend and colleague, Paxon Frady, who chatted with me about neuroscience and society over many happy hours, who pointed me in the right direction multiple times, and who provided constructive comments on nearly every aspect of this dissertation. I would also like to thank Andrea Tanner for welcoming me into her home during my research trip in London, and for introducing me to valuable resources and colleagues. And I extend my deepest gratitude to Greg Minah for his copy editing and emotional support in the final stretch. Thank you to all of my friends and family who have been there for me at various stages throughout this process, especially my Mom and Dad, without whom none of this would be possible—thank you, I love you. Finally, I must acknowledge the sources of financial and institutional support that helped me complete my research and writing, including the Department of Humanities and Social Sciences at the University of California, San Francisco, the Consortium for History of Science, Technology and Medicine, the McGill University Osler Library, and the Montreal Neurological Institute and Library. iii The Brain Electric: A History of Neuroscientific Ideas About How We Change Cristina Nigro Abstract This dissertation examines the historical context of nineteenth- and twentieth-century neurophysiological ideas and experiments. It uses archival records and correspondence, primary scientific literature, and secondary materials to explain and interpret the origins of contemporary neuroscience and, concurrently, explains and interprets modern ideas of the self. It analyzes nineteenth-century investigations into the nature of the nervous impulse via the examination of the laws of electrical activity as part of new formulations of natural law and the natural order. It demonstrates how nineteenth-century neurophysiological findings and interpretations were shaped by discoveries in electromagnetism and thermodynamics and must be understood through philosophical and evolutionary discourse. Twentieth-century neurophysiologists made the electroconductive model of nervous system functionality axiomatic through the methods and tools of reductive experimentation and analysis which depended on instrumentation developed for industrial and military purposes. Psychologists, cyberneticists, and modelers of neural computation engaged with neurophysiological research and concepts to create new theories and frameworks of functionality which took for granted the notion of the nervous system as continuously active, temporally dynamic, finely regulated, and incessantly adapting. A neuropsychological theory from the mid-twentieth century conceived of human behavior and cognition as the integration of neural activity which preserved permanency yet allowed for iv generalization through neurophysiological processes of learning and remembering. Neural modelers mechanized the notion of human cognition as distributed across networks of neurons that are continuously changing into themselves. By investigating neurophysiological research and concepts from the mid-nineteenth to the late twentieth centuries, this dissertation reveals the fundamental ideas, experimental approaches, and physical tools that continue to shape how we make sense of ourselves. v Table of Contents Introduction .............................................................................................................................. 1 Outline of the dissertation ......................................................................................................... 7 An historical epistemology of Du Bois-Reymond’s neurophysiology .................................... 13 Experimenting with galvanism and electrodynamics............................................................. 15 The philosophical foundation from Descartes to Kant .......................................................... 25 Materialism and studies of the action current ........................................................................ 32 Conclusion ............................................................................................................................... 48 Helmholtz on energy and the biological natural order .......................................................... 52 Vital forces reframed in physical terms ................................................................................. 53 Physiological interrogation of the conservation of energy ..................................................... 56 Thermodynamics and progressive decay................................................................................ 59 Geological change and Darwinian biological change ............................................................. 62 Conclusion ............................................................................................................................... 64 Sherrington and company refine the electroconductive model ............................................. 66 The reflex and the synapse ...................................................................................................... 68 Temporal relations and biophysical properties ...................................................................... 79 The membrane and the action potential ................................................................................. 94 vi Conclusion ............................................................................................................................. 105 Hebb’s union of psychology and neurophysiology ............................................................... 111 Considering how to understand the mind leading up to behaviorism ................................. 114 Shifting from behaviorism and the stable route assumption ............................................... 130 Attempting to reconcile the nature vs. nurture debate ........................................................ 148 Conclusion ............................................................................................................................. 155 From Wiener’s cybernetics to a parallel distributed processing approach ........................ 161 Modeling intelligent behavior probabilistically.................................................................... 165 Incorporating neurophysiological evidence into neural models .......................................... 177 Nervous information processing as microstructural change ............................................... 187 Conclusion ............................................................................................................................. 193 Epilogue ................................................................................................................................. 197 References ............................................................................................................................. 208 vii List of Figures Figure 1.1: Du Bois-Reymond’s diagram of the peripolar distribution of molecules in muscle . 41 Figure 4.1: Example stimuli presented to rats to illustrate perceptual generalization ............... 151 viii Introduction Having trained in psychology during the interwar years, the Canadian neuropsychologist Donald Hebb (1904-1985) began to pen his crowning achievement as the mid-twentieth century approached. His written work, The Organization of Behavior, contributed to a larger and longstanding conversation about the role of nature versus nurture in the configuration of the self and resulted in an original formulation of the dynamic relationship between brain and mind. It contained Hebb’s theory of the cell assembly, a notion understood by twenty-first-century neuroscientists as the forerunner to modern conceptions of synaptic plasticity—the idea that activity-generated physical alterations in the connections between brain cells, or neurons, leads to lasting neurobiological and mental change. According to Hebb, a cell assembly forms when a particular stimulus drives a diffuse network of neurons to act together