Humans can quickly identify target information based on simple features, such as color or shape. While previous studies have confirmed the spatial effects of feature-based attention at the cortical level, the subcortical neural mechanisms remain unclear.

To address this gap, a research team led by Prof. ZHANG Peng from the Institute of Biophysics of the Chinese Academy of Sciences has revealed the critical role of human subcortical nuclei in spatially global feature-based attention by using high-resolution 7-Tesla functional magnetic resonance imaging (7T fMRI).

The study was published in Communications Biology on October 15.

The researchers designed a red-green (L-M) contrast visual paradigm based on the color-encoding properties of neurons in the parvocellular layers of the lateral geniculate nucleus (LGN). They found that, when a stimulus outside the spatial focus of attention (the unattended side) shared the same color as the attended target, the color response in the LGN parvocellular layers and the feedforward and feedback connectivity between the LGN and the primary visual cortex (V1) were significantly enhanced.

These findings indicate that the LGN acts as an early gating site for cross-field, global feature-based attention.

Further analyses revealed that the deeper layers of the superior colliculus (SC) participated in the control of global feature-based attention, and the ventrolateral subdivision of the pulvinar nucleus coordinates the transmission of attentional information between cortical regions.

Interestingly and unexpectedly, the enhanced activity in the visual thalamus for the unattended stimulus was accompanied by reduced responses to the attended stimulus, an effect not observed in cortical areas. These results support the existence of a thalamus-mediated, spatially global attentional sampling mechanism.

For the first time, this study uncovers the key roles of subcortical nuclei in global feature-based attention, providing important evidence toward an integrated theoretical framework of attention that encompasses both cortical and subcortical mechanisms.

Layer-specific modulation and functional connectivity of global feature-based attention in the thalamic lateral geniculate nucleus (Image by ZHANG Peng's group)