In the primate visual system, form (shape, location) and color information are processed in separate but interacting pathways. Recent access to high-resolution neuroimaging has facilitated the exploration of the structure of these pathways at the mesoscopic level in the human visual cortex. We used 7T fMRI to observe selective activation of the primary visual cortex to chromatic versus achromatic stimuli in five participants across two scanning sessions. Achromatic checkerboards with low spatial frequency and high temporal frequency targeted the color-insensitive magnocellular pathway. Chromatic checkerboards with higher spatial frequency and low temporal frequency targeted the color-selective parvocellular pathway. This work resulted in three main findings. First, responses driven by chromatic stimuli had a laminar profile biased towards superficial layers of V1, as compared to responses driven by achromatic stimuli. Second, we found stronger preference for chromatic stimuli in parafoveal V1 compared with peripheral V1. Finally, we found alternating, stimulus-selective bands stemming from the V1 border into V2 and V3. Similar alternating patterns have been previously found in both NHP and human extrastriate cortex. Together, our findings confirm the utility of fMRI for revealing details of mesoscopic neural architecture in human cortex.
Bibliographical noteFunding Information:
We would like to thank Katherine Tregillus for assistance designing the experiment. We would like to acknowledge funding from the following sources: [NIH R21 EY025371] and [R01 MH111447] to C. O.; National Science Foundation [ NRT-1734815 ] to K. N.; [NIH S10 RR026783], [P30 NS076408]; WM KECK Foundation; [NIBIB P41 EB027061].
Copyright 2020 Elsevier B.V., All rights reserved.
- Cortical layers
- Cortical mapping
- Depth-dependent fMRI
- High-resolution imaging
- Magnocellular and parvocellular pathway
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