Figure 1.

Classical and modern views of avian cerebral organization. Shown are sagittal views of a songbird (zebra finch) brain with subdivisions colored-coded according to the meaning of the names given to those brain regions in different nomenclature schemas over time. A: Classic view of avian brain relationships according to popular terminology given to those regions (Edinger, 1885, 1908; Ariëns Kappers et al., 1936), although past authors had different opinions about which brain regions are pallium versus subpallium. B: Modern 2004–2005 consensus view of avian brain relationships according to the conclusions of the Avian Brain Nomenclature Forum (Reiner et al., 2004b; Jarvis et al., 2005). C: Revised modern view according to this study. D: Higher contrast color-coded scheme for the modern 2004–2005 view to highlight contrast of pallial regions with each other. E: Higher contrast color-coded scheme for the view presented in this study to highlight the alternative new numbered terminology based on shared gene expression profiles and connectivity. F: Color-coded scheme of the rodent brain according to the nuclear-to-layered hypothesis of homology with the avian brain (D). G: Color-coded scheme of the rodent brain according to the claustrum-amygdala hypothesis of homology with the avian brain (D). H: Color-coded scheme of the rodent brain according to the field hypothesis of homology with the avian brain proposed in this study (E). For all images, solid white lines are lamina (relatively cell sparse zones) that separates subdivisions; dashed lines divide regions within a subdivision, whether a lamina is present or not. Comparison of spelled out names with abbreviations for each of the views is shown in Table 2 and Fig. 3B.