Republished from Tsinghua IDG/McGovern Institute for Brain Research
External inputs are progressively transformed and processed in the visual system to form perception. The retino-geniculo-striate pathway in the primate visual system is primarily divided into magnocellular and parvocellular pathways, which selectively process different spatiotemporal frequencies and achromatic/chromatic images. After information reaches the primary visual cortex, it further diverges into parallel pathways processing basic visual attributes such as disparity, color, and motion. Although parallel processing has been extensively studied in subcortical structures and higher-tier dorsal and ventral visual cortices, we know very little about parallel processing mechanisms in the low- to mid-level visual cortex.
In recent years, naturalistic texture, as a critical visual attribute in image segmentation and material perception, has attracted widespread attention in computational vision and cognitive neuroscience. The higher-order statistical information contained in naturalistic textures encompasses correlations across different orientations, spatial scales, and local positions. Selective neural responses to naturalistic textures have been found to begin in the secondary visual area V2. However, it remains unclear whether V2 contains specialized functional columns for processing naturalistic texture representations. Relatedly, is naturalistic texture representation primarily generated by local processing in V2, or does it originate from feedback modulation from higher visual areas? This study uses state-of-the-art ultra-high-resolution magnetic resonance imaging methods to provide important findings for understanding functional columns and sublayer processing in the human visual cortex.
On February 2, 2024, Chen Nihong's research group from the Department of Psychology and the Tsinghua-IDG/McGovern Institute for Brain Research at Tsinghua University, in collaboration with Zhang Peng's research group from the Institute of Biophysics, Chinese Academy of Sciences, published a paper titled "Mesoscale functional organization and connectivity of color, disparity, and naturalistic texture in human second visual area" in eLife (preprint). This research utilized ultra-high-resolution 7T fMRI to study the representation of color, disparity, and naturalistic texture in the human secondary visual cortex V2 at the functional column and sublayer scale, revealing the important role of feedback from downstream brain regions in naturalistic texture processing.
The study found that color and disparity information are represented in a stripe-like distribution in area V2, while naturalistic texture representation does not form identifiable functional columns in V2. Cortical sublayer results show that compared to color and disparity, naturalistic texture processing in V2 relies more on feedback mechanisms. Information connectivity analysis further suggests that V2 primarily receives feedback signals from downstream area V4 during naturalistic texture processing.
Associate Professor Chen Nihong from the Department of Psychology and Tsinghua-IDG/McGovern Institute for Brain Research at Tsinghua University, and Researcher Zhang Peng from the Institute of Biophysics, Chinese Academy of Sciences, are the co-corresponding authors of the paper. Doctoral student Ai Hailin from the Department of Psychology at Tsinghua University and doctoral student Lin Weiru from the Institute of Biophysics, Chinese Academy of Sciences, are co-first authors of this paper. This research was supported by relevant funding from the Ministry of Science and Technology and the National Natural Science Foundation of China.
Original article link: https://doi.org/10.7554/eLife.93171.1
