The homunculus made his first appearance in the field of neurology on 1 December 1937, when Wilder Penfield and Edwin Boldrey (Fig. 1) published in Brain a 55-page article entitled Somatic motor and sensory representation in the cerebral cortex of man as studied by electrical stimulation (Penfield and Boldrey, 1937). The article is filled with painstakingly crafted summaries of data sourced from the cortical stimulation of 126 patients, who were operated under local anaesthesia by Penfield between 1928 and 1936. Compared to previous publications in animals, the authors had the advantage of operating on awake patients and relying on their verbal report of elicited movements and tactile sensation. All patient recordings were collated to obtain the first comprehensive map of motor and somatosensory localization in the human brain. This map was visualized as a distorted human-like figure—the homunculus—whose form indicates the amount of cortical area dedicated to motor or somatosensory functions of each body part.
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