Figure A1. The clearest and most compelling demonstration of the nonlinear mapping from retinal to cortical coordinates. Equation A2 is a complex logarithmic mapping from retinal polar coordinates to cortical Cartesiancoordinates, which formed the basis for Ermentrout and Cowan's (1979) hypothesis. The polar web pattern onthe top (A) was used to stimulate the visual system of a macaque treated with radioactively labeled glucose. Aftersufficient time to accumulate the tracer in the most active cells (for details, see the Appendix), the radiograph(B) of the animal's cortex was made. The radial and concentric features of the polar web stimulation on retinaare transformed to the nearly rectilinear grid shown on V1. Almost two decades later, it became possible for Tootell et al. (1998) to recreate this demonstration noninvasively in living humans using functional magneticresonance imaging (see Figure 5), but the clarity of this early demonstration has not yet been equaled. From“Deoxyglucose Analysis of Retinotopic Organization in Primate Striate Cortex,” by R. B. H. Tootell, M. S. Silverman, E. Switkes, & R. L. De Valois, 1982, Science, 218, p. 902. Copyright 1982 by the American Association for the Advancement of Science. Reprinted with permission from AAAS. (Appendix continues )773 HALLUCINATIONS AND CORTICAL PATTERN FORMATION