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Nonie Finlayson, Julie Golomb; Human visual cortex gradually transitions from 2D to 3D spatial representations. Journal of Vision 2015;15(12):1289. doi: 10.1167/15.12.1289.
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© 2017 Association for Research in Vision and Ophthalmology.
We live in a 3D world, and yet the majority of vision research is restricted to 2D phenomena. Previous research has shown that neural representations of 2D visual space are present throughout visual cortex. Many of these visual areas are also known to be sensitive to depth information (including V3, V3A, V3B/KO, V7, LO, and MT) – how does this depth information interact with 2D spatial information? Using fMRI and multi-voxel pattern analysis, we investigated the relationship between horizontal (x), vertical (y), and depth (z) representations in the brain. Participants viewed random dot stereograms with red/green anaglyph glasses. Eight different locations were stimulated in a blocked design: each location was defined by x, y, and z location (left or right, above or below, and in front or behind the fixation cross). The patterns of activation for each of the x, y, and z location conditions were compared across the brain with a searchlight analysis and within functionally localized ROIs. As expected, both x and y location information was present all along the visual pathways, with x information outperforming y information in higher visual areas. Importantly, while only 2D location information could be decoded in early visual cortex, all three types of location information could be decoded in several higher visual cortex regions. Moreover, this pattern seemed to emerge gradually: we found opposite trends for y and z location information, with y information decreasing and z information increasing along the visual hierarchy (both dorsal and ventral streams). In addition, we found that representations of depth are dependent on x location, but tolerant of changes in y location. We conclude that what begins as purely 2D spatial information in early visual areas gradually transitions to 3D spatial representations higher along the visual hierarchy.
Meeting abstract presented at VSS 2015
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