Seeing and believing: three episodes in the history of neurophysiology

Christopher U.M. Smith

Research output: Unpublished contribution to conferenceOtherpeer-review


In this contribution I look at three episodes in the history of neurophysiology that bring out the complex relationship between seeing and believing. I start with Vesalius in the mid-sixteenth century who writes that he can in no way see any cavity in nerves, even in the optic nerves. He thus questions the age-old theory (dating back to the Alexandrians in the third century BC) but, because of the overarching psychophysiology of his time, does not press his case. This conflict between observation and theory persisted for a quarter of a millennium until finally resolved at the beginning of the nineteenth century by the discoveries of Galvani and Volta. The second case is provided by the early history of retinal synaptology. Schultze in 1866 had represented rod spherules and bipolar dendrites in the outer plexiform layer as being separated by a (synaptic) gap, yet in his written account, because of his theoretical commitments, held them to be continuous. Cajal later, 1892, criticized Schultze for this pusillanimity, but his own figure in La Cellule is by no means clear. It was only with the advent of the electron microscopy in the mid-twentieth century that the true complexity of the junction was revealed and it was shown that both investigators were partially right. My final example comes from the Hodgkin-Huxley biophysics of the 1950s. Their theory of the action potential depended on the existence of unseen ion pores with quite complex biophysical characteristics. These were not seen until the Nobel-Prize-winning X-ray diffraction analyses of the early twenty-first century. Seeing, even at several removes, then confirmed Hodgkin and Huxley’s belief. The relation between seeing and believing is by no means straightforward.
Original languageEnglish
Publication statusUnpublished - 2009
EventThirteenth Annual Meeting of the International Society for the History of the Neurosciences - Berlin (DE)
Duration: 1 Jun 2008 → …


OtherThirteenth Annual Meeting of the International Society for the History of the Neurosciences
CityBerlin (DE)
Period1/06/08 → …

Bibliographical note

Abstract published in Journal of the History of the Neurosciences, 18(1):128, 2009, 0964-704X. Copyright © Taylor & Francis Group, LLC


  • history
  • neurophysiology
  • Vesalius
  • optic nerves
  • psychophysiology
  • Galvani
  • Volta
  • retinal synaptology
  • Schultze
  • Cajal
  • electron microscopy
  • Hodgkin-Huxley
  • ion pores
  • X-ray diffraction analyses
  • seeing
  • believing


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