Analysis of monkey brains
Approximately 32 areas of the monkey cerebral cortex contain neurons that respond selectively to visual input; moreover, about half of these areas are topographically organized—they preserve (roughly) the geometric structure of the retina.
Felleman & Van Essen, 1991; Tootell, Silverman, Switkes, & De Valois, 1982.
Discussed in: Kosslyn and Thompson (2003).