The concept of plasticity infused regenerative approaches to brain science in Switzerland in the mid-twentieth century, shaping a holistic tradition prominent among Zurich’s psychiatrists and neurologists. From 1910 to about 1950, they sought to objectify the dynamic unconscious using a psychobiological approach to mental pathology pioneered by the neuroanatomists August Forel and Constantin von Monakow. Little scholarship, however, has explored this tradition. Both Forel and Monakow influenced Rudolf Brun, a Zurich neurologist and ant expert, who championed parallels between biological conflicts measured in social insects and Sigmund Freud’s drive energetics. Brun’s concept of drive conflict integrated Richard Semon’s theory of plastic heredity as “species memory” with a revision of Monakow to explain mental pathology in the brain. Through them, he proposed the neuropathology underlying Freud’s “genuine” psychoneuroses: those caused by unconscious memories of traumatic experience. This paper uses primary historical sources from the Swiss scientific literature to demonstrate that (1) Brun combined Semon’s plastic heredity, Cannon’s physiology and Pavlov’s conditional reflex to objectify Freud’s dynamic unconscious; and (2) though he rejected Monakow’s teleology, Brun’s holistic mind-body approach owed much to Monakow’s theory of emotions and pathology manifest in the brain. Brun elaborated Monakow’s view that psychopathology occurs as unconscious drive conflicts produce neurotoxicity, enabling excess hormones to disrupt the brain’s protective filtering system. Brun’s ant experiments confirmed evolutionary “laws” governing drive conflict and framed the neuro-energetics underlying the resolution of repressed emotional trauma. Tests pitted conflicts between social drives and those serving self-interest. Through them, Brun extended moral conflict beyond the Oedipal domain of psychoanalysis to encompass conflicts in a biological hierarchy of drives. This drive-based account of conscience explored neural pathways reaching back from the cortex to the body, so enabling traumatic memories to generate psychoneuroses. Plasticity could then justify the use of psychotherapy to reverse these pathogenic connections. Brun’s example demonstrates both the significance of Semon’s theory of heredity for objective accounts of the unconscious mind in Central Europe and the hidden legacy of Monakow’s neuroendocrine holism. Brun combined that legacy with objective evidence and Zurich’s emphasis on plasticity to endorse—somewhat paradoxically—the reversal of psychoneuroses in the brain.
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