Abstract
The pulvinar is highly interconnected with both low- and high-level visual cortex. While extensive work in non-human primates has demonstrated the presence of retinotopic maps and sensitivity to low-level visual features such as local contrast in the pulvinar, connectivity with high-level visual cortex suggests that the pulvinar may also play a role in high-level vision. To explore this possibility, we investigated subcortical activity in the 7T fMRI Natural Scenes Dataset consisting of 1.8-mm responses to 9,000–10,000 unique natural scenes in each of 8 participants. We fit population receptive field models to individual voxels, systematically evaluating different stimulus features (contrast, saliency, faces, bodies, foreground, background, words) that might be encoded in voxel responses. This analysis confirmed that, consistent with prior work, the LGN and inferior-lateral pulvinar respond selectively to local contrast and are retinotopically organized. However, the analysis also revealed an area of the pulvinar, located medial and posterior to the contrast-selective region, that responds selectively to bodies and faces in the contralateral visual hemifield. To further explore these findings, we performed a thalamocortical correlation analysis in which stimulus-evoked responses in the thalamus were correlated with stimulus-evoked responses in cortex. This analysis revealed that pulvino-cortical correlations are largely restricted to the visual cortex and have rich structure consistent with prior anatomical data. The contrast-selective portion of pulvinar correlates most with early visual cortex while the body- and face-selective portion of pulvinar correlates most with face- and body-selective cortical regions. More generally, there is a gradient of pulvino-cortical correlations such that progression from anterior-lateral to posterior-medial in the pulvinar recapitulates the posterior-to-anterior organization of visual cortex. Our results indicate that the pulvinar also likely plays an important role in high-level vision and illustrate that principles of cortical organization may hold for the thalamus as well.