Speaker: Howard Kushner, Nat C. Robertson Distinguished Professor of Science & Society, Emory University
In the early 1980s Harvard neurologist Norman Geschwind (1926-1984) proposed a controversial hypothesis that uterine stress produced allergies, immune disorders, and learning disabilities, and initially, left-handedness. Because males were more likely than females to develop these disorders and to be left-handed, Geschwind and his colleagues were persuaded that hormones played a major role in these outcomes. The Geschwind hypothesis built on Geschwind’s earlier work on the role of neuronal lesions in learning disorders. His interest in learning disabilities can be traced to his 1965 landmark study on “disconnection syndromes,” which was in part a reaction to his medical education in the 1940s in which many psychiatry professors taught that behavior was unrelated to neuropathology. The focus of neurology was restricted to the diagnosis and treatment of aphasias and epilepsies while cognitive impairments and developmental disorders were classified as functional (psychological) disorders. Geschwind’s clinical experience contradicted his education. Many of the patients he examined with neurological deficits also presented with behavioral (developmental) disorders. Geschwind’s generation also had been taught that aphasias resulted from global rather than localized or focal neurological lesions. These so-called holists were dismissive of the work of nineteenth-century German aphasiologist Carl Wernicke (1848-1905), suggesting that Wernicke’s localizationism was an updated version of phrenology. Geschwind reread Wernicke in the original German, discovering a complex and multi-layered explanation in which Wernicke distinguished between localized lesions that affected motor movement and multiple lesions located in association pathways, that when extensive, resulted in behavioral disorders. Geschwind also reread the works of the holists, discovering that while their rhetoric rejected Wernicke, their explanations of aphasias actually reinforced Wernicke’s hypothesis. Building on his readings of these historical documents and his clinical experiences, Geschwind urged the resurrection and expansion of Wernicke’s disconnection syndromes that he labeled “Behavioral Neurology.” Geschwind went farther than Wernicke, suggesting that higher function disorders resulted from disconnection. This was articulated in Geschwind’s later belief that learning disabilities, allergies, immune disorders, talent, and left-handedness were, like complex aphasias, association disorders with a common mechanism but with different presentations dependent on the nature and timing of environment insults in utero.
Event is free and open to the public.
This event is part of the Neuroscience and History Lecture Series sponsored by the Center for Science and Society and Presidential Scholars in Society and Neuroscience.