1) stimulations: (i) the area for each body part as a 2D surface displayed on the lateral aspect of the central fronto-parietal cortex ( Fig. 2) and the somatosensory ( Supplementary Fig. The maps that displayed the positive responses for the toes, legs, trunk, arm, digits, hand, face, eyes, mouth and tongue were used to extract three separate measures for the motor ( Fig. The neurological homunculus was generated from 170 summary maps of the number and location of stimulation points for each body part, each patiently sketched by Boldrey from PenfieldвЂ™s operation notes, photographs and drawings. Their approach was systematic and laborious. In modern times, Penfield and Boldrey brewed their own version of the homunculus using more controlled, though no less controversial, ingredients. In the Middle Ages, a homunculus was an artificial humanoid created through alembics and mysterious alchemy. Surprisingly, the picture that emerged from their work was a clear degree of functional overlap between stimulation fields rather than an orderly sequence of segregated areas as their homunculus suggests.ДЇor the 80th anniversary of this seminal paper, the authorsвЂ™ original findings are re-examined with the intent to clarify the substrate that generated the homunculus, arguably the most reproduced yet unreplicated figure in neuroscience. Many stimulations eliciting motor responses were indeed located in the somatosensory cortex of the postcentral gyrus and an even greater proportion of tactile responses in the motor cortex of the precentral gyrus. Second, contrary to what others recorded in animals, the central sulcus of the human brain was not a clear boundary between motor and somatosensory areas. First, while acknowledging the lack of histological analysis as a limitation of their study, they were confident they demonstrated the impossibility of confining вЂfunctional representation within strict cytoarchitectural boundariesвЂ™. The homunculus was certainly their most striking proposition, but overshadowed other important conclusions made by the authors.

Clinically, it helped to establish direct cortical stimulation as an important method for functional mapping in neurosurgery scientifically, it reinforced cortical localization as a valid paradigm to understand motor cognition, somatosensory perception and higher cognitive functions more generally. The paper had a long-lasting impact on both neurosurgical practice and scientific research. Wilder Penfield ( left) and Edwin Boldrey ( centre), creators of the homunculus ( right). 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. All patient recordings were collated to obtain the first comprehensive map of motor and somatosensory localization in the human brain.

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. 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 19. 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 homunculus made his first appearance in the field of neurology on 1 December 1937, when Wilder Penfield and Edwin Boldrey ( Fig.

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