It is worth noting that in the first study of RF properties of area 19 neurons of anesthetized cat (Hubel and Wiesel, 1965), no simple cells were reported (see also Guillemot et al., 1993). On the other hand, the proportions of simple or simple-like (see S cells, Sh cells and A cells of Henry, 1977) cells defined on the basis of existence of spatially distinct on (light bar) and/or off (dark bar) discharge regions are quite similar (25%—Dreher, 1986; Pettigrew and Dreher, 1987; to 31%—Duysens et al., 1982b) to that reported here. However, the reported proportions of simple-like cells defined on the basis of modulation ratio of the responses to moving luminance-modulated sinusoidal achromatic gratings (Skottun et al., 1991) with one exception (27%—Tanaka et al., 1987) were much lower (~10%—Tardif et al., 1997; Bergeron et al., 1998; Mimeault et al., 2002).