The origins of anatomical projection: not Descartes but Ibn al-Haytham
Gül A. RUSSELL
In mapping the geography of the mind, a key concept has been anatomical projection based on the point to point correspondence. Its origin has been attributed to Descartesís view of the re-projection of the retinal image along the central pathways to the pineal gland.
I will argue that the origin of this concept goes back to Ibn al-Haythamís (Alhazen .d. 1040) theory of image formation. In his experimental researches of light projection in dark rooms, he defined an optical image on the basis of points of light reflected from the surface of the visual object to the eye. The image, preserving its spatially organized punctate order was conveyed, one from each eye, to the chiasma where the point to point matching or superimposition produced a single image. Then the single image was projected with the same punctate organization to the brain. Thus, Ibn al-Haytham introduces not only the essential principle of a point to point correspondence between the object and its representation within the eye, but also the concept of re-projection from the eye to the brain.
It will be shown that in bringing together anatomy and physics. Ibn al-Haytham represents a fundamental shift from the earlier Greek and Arabic qualitiative, holistic concepts and Ďformsí. Subsequently utilized by Kepler and Descartes, Ibn al-Haythamís corresponding point theory made a lasting contribution to the neurosciences.
Session VI. Structures
12th Annual Meeting of the International Society for the
History of the Neurosciences (ISHN)