Neurologic heuristics and artistic whimsy: the cerebral cartography of Wilder Penfield.

Neurosurgeon Wilder Penfield played a singularly important role in expanding our knowledge of functional neuroanatomy and neurophysiology in the twentieth century. Trained under Charles Sherrington, William Osler, and Otfrid Foerster, Penfield was an early leader in efforts to map the cerebral cortex via direct electrical stimulation of the brain. In 1937, Penfield introduced an entirely new concept for illustrating the relative sizes and locations of discrete functional regions within the sensorimotor cortex--the homunculus-to exemplify the "order and comparative extent" of specific functional regions. Over the subsequent two decades, Penfield and colleagues introduced several more "little men" to portray the functional maps of other important brain structures (i.e., supplementary motor area, insular cortex, thalamus). These later homunculi were more crudely drawn, and Penfield referred to them as essentially heuristic devices. The actual intent in producing these homunculi remains uncertain, and despite the extraordinary impact of these artistic renderings on the field, the question is raised as to whether the allure of the artwork seemed to wrest control from-and then to guide-the dissemination of science, rather than the other way around.