Texture segregation in the human visual cortex: A functional MRI study

Texture segregation in the human visual cortex: a functional MRI study. J. Neurophysiol. 83: 2453-2457, 2000. The segregation of visual scenes based o n contour information is a fundamental process of early vision. Contours ca n be defined by simple cues, such as luminance, as well as by more complex cues, such as texture. Single-cell recording studies in monkeys suggest tha t the neural processing of complex contours starts as early as primary visu al cortex. Additionally, lesion studies in monkeys indicate an important co ntribution of higher order areas to these processes. Using functional MRI, we have investigated the level at which neural correlates of texture segreg ation can be found in the human visual cortex. Activity evoked by line text ures, with and without texture-defined boundaries, was compared in five hea lthy subjects. Areas V1, V2/VP, V4, TEO, and V3A were activated by both kin ds of line textures as compared with blank presentations. Textures with bou ndaries forming a checkerboard pattern, relative to uniform textures, evoke d significantly more activity in areas V4, TEO, less reliably in V3A, but n ot in V1 or V2/VP. These results provide evidence that higher order areas w ith large receptive fields play an important role in the segregation of vis ual scenes based on texture-defined boundaries.