My research focuses on the brain circuits underlying visual perception. Specifically, I am most interested in the function roles of different cortical layers in visual cortical areas. The cerebral cortex is organized in six distinct layers of neurons that have different physiologies/morphologies, but the functional transformation from one layer to another remains unclear. By simultaneously recording from different layers of macaque monkey primary visual cortex V1, we found that receptive fields mapped with different stimulus ensembles were similar for the input layer-4c neurons but were very different for the output layer-2/3 neurons. Many layer 2/3 cells have receptive fields with multiple elongated subregions when mapped with briefly flashed gratings, but their spatial maps collapse to only a single, less-elongated subregion when mapped with sparse noise. Furthermore, we found that the majority of layer-2/3 neurons were black-preferring (~85%), but the numbers of black- and white-preferring neurons were nearly equal in layer 4c. The predominance of black-preferring neurons in layers 2/3 of V1 may serve as the neural basis for the substantial black-over-white bias in visual perception. My laboratory combines electrophysiological, behavioral, psychophysical, and computational approaches to uncover the functional significances of cortical layers in visual areas.