Foreword

Céline Cherici's book explores the place of electricity in the history of medical science over a period ranging from the 18th to the 21st Centuries, from its discovery to the recent use of deep brain stimulation. Some contextual data helps us to grasp the full importance and scope of this undertaking.

The current importance of chemical and molecular representations, which have become consubstantial with biology, means it is easy that we forget that, from a historical point of view, it is physics that has constantly provided neurophysiology with explanatory models.

Galvani's use of artificial electricity as a stimulant led him, by analogy, to conceive of muscle fibers as small Leyden jars. Thus, the mysterious nature of nervous fluid, which was therefore electric, a model which was vary different from the humoral model described by the Encyclopedists, was unraveled. The fruitfulness of the polemic between the proponents of metallic and animal electrics is well known in the history of physics, since the voltaic pile battery triggered the development of electrophysics, electromagnetism and electrochemistry, the development of which, in turn, went hand in hand with the invention of two instruments of considerable heuristic value in 19th Century Life Sciences: the galvanometer and the impolarizable electrode. These instruments led to the development of the great German electrophysiology, that is to say, the classical works of du Bois-Reymond, Helmholtz, Hermann, Bernstein, etc., which made it possible to propose various hypotheses on the nature of the action and rest currents. These currents were often considered to be the result of purely physical phenomena occurring in living tissue. In accordance with the dominant physical and technical models, nerve fiber was likened to a metal wire, a circuit, a magnet and, finally, a battery - a living battery the functioning of which physicists sought to understand by taking inspiration from the model of the electric battery. The origin of the battery's electromotive force, how the nerve impulse was conducted and the changes produced in the fibers by this impulse were also investigated, leading to imported notions such as "polarized structures" or "local circuits". In France, it was this tradition, that of the physical explanation of the functioning of living organisms, that was taken up by Louis Lapicque when he likened nerve fiber to a radio transmitter.

This electrical power was also supported by electrodiagnosis and electrotherapy. Studying the effect of electricity on the living was done in many ways, depending on the intention. The problem of elucidating the nature of nerve impulses, excitability and underlying processes seemed to be distinct from the problem of investigating the possible use of electricity in medicine. For a physician, knowledge of the laws of excitability, or even that of simple correlations or modifications of excitability according to the pathology making electrodiagnosis possible, as well as the revelation of the therapeutic effects of electricity, could be quite sufficient. In this sense, the electrophysiological studies carried out in the laboratory on animals seemed to have little relevance to medicine. Under the influence of positivism, empiricism and pragmatism, a myth of 19th Century medical thought was forged, that of the independence of the experimental and the clinical.

In fact, the history of electrodiagnosis attests to the close and constant links between the laboratory and the clinic from the very beginning. One of its founders, the clinician Duchenne de Boulogne, who gave his name to various myopathies, conceived it as a true experiment in the examination of patients. In the 19th Century, electrophysiological instrumentation was common to both the laboratory and the hospital. The characters who have marked the history of electrodiagnosis were often both laboratory technicians and clinicians. Duchenne used the induction coil (faradic current), with which it was possible to excite nerves and muscles through the skin at certain points. He established the topography of these motor points, skin regions where the electrodes had to be placed to obtain the muscle jolt with the least possible intensity (bipolar excitation). He thus inaugurated electrical semiology: either the muscles no longer responded to induction excitations (faradic hypoexcitability; Duchenne reaction), or the excitability was normal. As for anatomopathology, it was the electrodiagnosis inaugurated by Duchenne that contributed to the creation of a nosological group, that of degenerative diseases, and, more generally, of an electrical semiology of muscular and neuromuscular diseases.

In France, chairs of medical physics were developed and journals were created for the new specialty, such as the Archives d'électricité médicale (1893) or the Annales d'électrobiologie (1898). Following Duchenne, prestigious names, often both doctors and physicists, devoted themselves to medical electricity and wrote treatises in which electrology held a central place, such as Jean Bergognié, founder of French radiobiology and creator of the first anti-cancer centers, Emmanuel Doumer, who studied the use of electricity in surgery, or Jacques d'Arsonval, a student of Claude Bernard, a Brown-Sequard collaborator who worked with diathermic currents, electrocoagulation (electric scalpel) and electrotherapy with high-frequency currents (darsonvalization, 1913). Forms of electrodiagnosis were developed that were not based on neuromuscular excitability (electrical resistance of the human body, voltaic vertigo), preceding an electrodiagnosis no longer based on stimulation, but simply on detection (EEG, electromyography). It should be noted that while English-speaking countries were engaged in electromyography (Adrian and Bronk), the Netherlands in electrocardiography (Einthoven, Nobel Prize 1924), Germany in electroencephalography (Berger), France's focus in the thirties remained on chronaximetry with Louis Lapicque, and thus demonstrated a considerable delay between the two wars.

Electrotherapy was another cornerstone of electricity in the medical sciences. In the 18th Century, ignorance of the exact nature of nervous fluid did not prevent the empirical use of electricity for therapeutic purposes by great names such as Nollet, Jalabert, Aldini, or Marat. During the 19th Century, electrotherapy instrumentation developed considerably in the field of galvanization, faradization, galvanofaradization, franklinization and hertzian and other darsonvalization, up to the point of the electroshock of patients.

It is necessary to underline how poor and disappointing neurochemistry remained for a long time, in comparison with this wealth of medical electricity. Moreover, some physiologists still had the diffuse idea, inherited from the 19th Century, that it was not necessary to precisely identify the charge carriers, that is, to penetrate to the deepest level of the phenomena, in order to explain cerebral or nervous functioning. Electricity was still "the essence of life". The dominant paradigm and culture of electricity explained, for example, the skepticism with which the first real experimental argument in favor of chemical neurotransmission at the ends of the autonomic nervous system was greeted, the experiment of Otto Loewi (1921), and then, from the 1930s onwards, the results of Henry Dale's school concerning chemical transmission at the lymph node and neuro-muscular scales. In 1936, when Loewi and Dale were awarded the Nobel Prize, the accumulation of divergent data led to major difficulties in chemical theory, giving way to the development of elaborate electrical designs following Lapicque's ancient chronaxial theory, such as that of John Eccles. While, at the beginning of the 1950s, a consensus had been established among pharmacologists in view of the considerable therapeutic perspectives offered by chemical theory, it remained limited to the peripheral nervous system, especially since explanations of the characteristics of the most elementary central activity, reflex activity, had been proposed, avoiding any departure from a strictly electrical determinism using neuronal circuits. For these reasons, and for reasons of anatomical complexity, the penetration of chemical theory at the central level was slow. It was finally made possible by techniques (microiontophoresis), by the renewal of the neurochemical context (neuroendocrinology), and, above all, by the appearance of psychotropic drugs, despite the subsequent discovery of electrical synapses. Chemical theory offered a considerable range of interpretations of the mode of action of psychotropic drugs, from which one sought to extrapolate the pathogenesis of neurological (Parkinson's, epilepsy) or even psychiatric (depression, psychoses) diseases.

It is the importance of this culture of electricity that Céline Cherici develops in her book. The judicious choices of the long period and the resonance of different disciplinary fields (physics, physiology, medicine, in particular, neurology and psychiatry) around this theme of electricity have allowed her to propose research at the crossroads of the history of techniques and the history of biology and medicine. Céline Cherici demonstrates the imprint left by electricity in culture and life sciences, focusing her analyses on the links between electricity and the nervous system ("from the clouds to the brain") and the medical appropriation of electricity. The aim is to describe the establishment of this culture, and to analyze, beyond the origin of ideas and facts, the beginnings (Canguilhem),...