Fig. 1.

Recording sites, connectivity, and color stimuli. a To identify the correct color of an object, e.g., an apple (left), local hue information (right) needs to be integrated with global shape information. b Schemes for co-representing color and object shape information in visual system. Initially, before the visual system has explicitly segmented objects, color information and object shape information are largely entangled, with individual cells participating in the coding of multiple hues and object shapes. Two main strategies could be used to represent colored-objects in an organized way: (1) segregation of color and object information into parallel channels, resulting in object shape-invariant color-selective units and color-invariant shape selective units (top); (2) formation of units sharply tuned to both color and object shape (bottom). c Coronal and sagittal slices showing location of fMRI-identified face (blue) and color patches (yellow) in one monkey (M2) targeted for recording; dark-black line indicates electrode. The most anterior color patch was not observed with fMRI using the color localizer in this animal, and was located by electrical microstimulation in ALC (bottom panel, changes in BOLD signal of the identified voxels during microstimulation shown below). d Comparison between color patches identified by color localizer (top) and by microstimulation (bottom). The contrasts are overlaid on high-resolution coronal slices. Asterisk (*) indicates the stimulation site (ALC). The anterior–posterior position of each slice in mm relative to the interaural line is given in the top right corner. e 82 images of 10 categories were used (see Supplementary Fig. 2a for all the stimuli). Each image underwent a series of transformation in hues. For each pixel of the image, luminance was kept constant, while chromatic coordinates (CIE 1960) fell on a circle with the same distance to “white” (filled circle) as the original pixel. Eight hues with different angles were used (open circles, starting from 0°, going clockwise at 45° step). A grayscale image with the same luminance and the natural color image were also presented