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, yet the neural mechanisms of feature-based attention in subcortical regions remain poorly understood. Using high-resolution functional magnetic resonance imaging (fMRI) at 7 T, we investigated the global effects of color-based attention in functional subdivisions of human subcortical nuclei. Color-based attention selectively enhanced activity in the parvocellular layers of the lateral geniculate nucleus of the thalamus for unattended stimuli across the visual field, while reducing responses to attended stimuli. Both feedforward and feedback connectivity with the primary visual cortex were enhanced. In addition, our results suggest that the deeper layers of the superior colliculus contribute to attentional control of this spatially global effect, while the ventral pulvinar coordinates connectivity between visual areas. Together, these findings uncover a global attention mechanism in the visual thalamus and reveal the distinct roles of subcortical nuclei in feature-based attention.