Spatially global effects of feature-based attention in functional subdivisions of human subcortical nuclei

Attention can prioritize the processing of non-spatial features throughout the visual field. While human subcortical nuclei are known to play important roles in spatial attention, the subcortical mechanisms of feature-based attention remain elusive. Using high-resolution 7T fMRI, we investigated the spatially global effects of color-based attention in functional subdivisions of human subcortical nuclei. Paying attention to a color matching the unattended stimulus across the visual field selectively modulated BOLD signals in the parvocellular (P) layers of the lateral geniculate nucleus (LGN) of the thalamus, enhancing the response to the unattended stimulus while reducing the response to the attended stimulus. The spatially global effects of color-based attention were also found in the deeper layers of the superior colliculus (SC), early visual cortices, and the intraparietal sulcus (IPS) of the parietal lobe. Effective connectivity analyses further revealed enhanced feedforward and feedback connectivity between LGN and V1, along with top-down modulation from IPS through the SC and ventral pulvinar. Finally, attended color can be decoded from multi-voxel response patterns in frontoparietal regions. These findings demonstrate that color-based attention selectively modulates color processing in P subdivisions of the LGN of the thalamus throughout the visual field, controlled by top-down signals from the parietal cortex through the SC and pulvinar.