A. Visual stimuli for the fMRI experiments. Left: chromatic and achromatic gratings for the color experiment; Middle: disparity-defined grating and zero-disparity disc from random dots for the disparity experiment; Right: naturalistic texture and spectrally matched noise for the texture experiment. B. Parallel information processing pathways in the early visual areas. C. Layer-specific neural circuitry of feedforward, feedback, and horizontal connections in the early visual areas. S: Superficial layers, M: Middle layers, D: Deep layers.

A. Activation maps in a representative subject (S09). The scale bar denotes percent signal change of BOLD response. From left to right: Chr - Ach (color), 3D - 2D (disparity), color - disparity, T – N (texture). The bottom panels show enlarged activations in the black square. The highlighted region in the bottom panels represents area V2.Color-selective and disparity-selective stripe-shaped activations arranged perpendicular to the V1-V2 border. Red arrowheads denote the location of color-selective (thin) stripes and blue arrowheads denote the location of disparity-selective (thick) stripes. The ROIs for pale stripes were defined as vertices in-between adjacent thin and thick stripes (see methods for details). B. Selectivity indices for color, disparity and naturalistic texture in different types of columns. Error bar indicates 1 SEM across subjects. **: p < 0.01, ***: p < 0.001.n.s.: none significance. C. Inter-session correlations for the color- and disparity-selective functional maps in S09. Each blue dot represents one vertex on V2 surface.

Layer-specific response selectivity for color (A), disparity (B) and naturalistic texture (C). Error bars indicate 1 SEM across subjects. *: p < 0.05, **: p < 0.01.

Layer-specific feedforward and feedback informational connectivity of color, disparity, and naturalistic texture. Numbers denote the mean values of connection (Pearson’s r) across all subjects. *: p < 0.05, **: p < 0.01, ***: p < 0.001

The functional maps in V2 for all ten subjects. The scale bar denotes percent signal change of BOLD response. Color-selective thin and disparity-selective thick stripes were denoted by red and blue arrows, respectively. LH: left hemisphere; RH: right hemisphere.

The manually defined ROIs for disparity-selective thick, color-selective thin stripes, and the pale stripes in-between in a representative subject (S09). The scale bar denotes percent signal change of BOLD response. The stripes are framed with dashed lines. Black: thin and thick stripes (Figure 2A); purple: pale stripes.

The bootstrapped distributions of stimulus-selectivity indices in different types of column ROIs. Dashed lines indicate zero selectivity. Color- and disparity-selective indices both show significant difference across three stripes. Texture-selective index shows non-significant difference across different stripes.

Inter-session correlations for the color- and disparity-selective activation maps in four subjects who scanned both color and disparity experiments in two days. The results for S09 were shown in figure 2.

Results of isoluminance adjustment.

The measured luminance values of gray (A) and red (B) that match the luminance of maximum blue values across three eccentricities.

Illustrations of depth map (A) and pial vein removal (B). Red pixels in Figure B represents vertices with extremely large signal changes (top 5%) that were excluded.

Null distributions of pattern correlation coefficients from Monto-Carlo simulation.