Abstract
Previous studies in nonhuman primates and cats have shown that the pulvinar receives input from various cortical and subcortical areas involved in vision. Although the contribution of the pulvinar to human vision remains to be established, anatomical tracer and electrophysiological animal studies on cortico-pulvinar circuits suggest an important role of this structure in visual spatial attention, visual integration, and higher-order visual processing. Because methodological constraints limit investigations of the human pulvinar's function, its role could, up to now, only be inferred from animal studies. In the present study, we used an innovative imaging technique, Diffusion Tensor Imaging (DTI) tractography, to determine cortical and subcortical connections of the human pulvinar. We were able to reconstruct pulvinar fiber tracts and compare variability across subjects in vivo. Here we demonstrate that the human pulvinar is interconnected with subcortical structures (superior colliculus, thalamus, and caudate nucleus) as well as with cortical regions (primary visual areas (area 17), secondary visual areas (area 18, 19), visual inferotemporal areas (area 20), posterior parietal association areas (area 7), frontal eye fields and prefrontal areas). These results are consistent with the connectivity reported in animal anatomical studies.
Highlights
Previous studies in nonhuman primates and cats have shown that the pulvinar is interconnected with various subcortical and cortical areas
The study was approved by the Montreal Neurological Institute & Hospital (MNI) Research Ethics Committee
Diffusionweighted images were acquired by using echo-planar imaging (EPI) with a standard head coil
Summary
Previous studies in nonhuman primates and cats have shown that the pulvinar is interconnected with various subcortical and cortical areas. The connections of the pulvinar are less well known because the number of anatomical studies is limited by methodological constraints and access only to postmortem samples. The major retinal-cortical pathway is known to connect directly via the Lateral Geniculate Nucleus (LGN) to visual cortical areas; extensive cortico-pulvinar connections exist (e.g., [2,3,4]) and suggest an important role of the pulvinar in vision, its precise function remains unknown. With regard to the human pulvinar, its function and anatomical connections remain speculative and are based mainly on nonhuman primate research [7, 13]
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