This article envisages the influence of the medico-cultural discourse contemporary to Joyce on his treatment of cognition in Finnegans Wake. Drawing on Samuel Orton and Lee Edward Travis's theory of hemisphere lateralization, which it sees as illustrated in the characters of Shem and Shaun, it argues that stuttering is not only an idiosyncrasy of HCE's, but the gate to a previously undiscovered poetic territory, as Joyce modifies the pathological deferral of meaning produced by stuttering into an epistemological quest for a new order of speech. Shem, in particular, is associated with writing, and his alleged infirmity, which is connected to memory through the amygdala, is read as a challenge to language itself.