(A) Retinotopic map sample from a representative participant illustrates the dorsal and ventral halves of early retinotopic visual cortices (V1d, V1v, V2d, V2v, V3d, V3v). To map the visual areas, neuronal responses (measured by fMRI) to stimulation in different visual fields (see color-wheel legend) were projected onto an inflated cortical surface, and the boundaries of the visual areas were delineated manually by the mirror reversals in the retinotopic map. (B-D). Results of common factor analysis on gray matter volume (B), surface area (C), and cortical thickness (D) of early retinotopic visual cortices (V1d, V1v, V2d, V2v, V3d, V3v) were visualized using the bi-plot figure (left panel) and the statistic table (right panel), indicating that the inter-individual variability in six visual cortices can be characterized with two common factors (N=30). The values of the factor loadings (the correlation coefficients between the visual cortices and the underlying factor) and the communality (the percentage of variance explained by the two common factors) are listed in the table and can be inspected from the direction and length of the vectors in the bi-plot figure.