Visual Cortical Lateralization in Activations and Functional Connectivity to the Sight of Faces, Scenes, Body Parts, and Tools

The lateralization of cortical activations and functional connectivities was analyzed when 833 Human Connectome Project (HCP) right-handed participants were viewing faces, spatial scenes, body parts, and tools, using the HCP-Multimodal Parcellation atlas. Spatial scenes produce stronger activations (Bonferroni corrected) in the right hemisphere, especially in the ventromedial visual cortical stream from early visual cortical regions via ventromedial visual cortical regions (VMV1-3) and medial parahippocampal regions (PHA1-3) to the hippocampus, and in inferior parietal visual cortical regions (PGi, PGs, and PFm), and in posterior cingulate division regions. Faces, tools, and body parts produce stronger activations in the left hemisphere in some of the ventrolateral temporal lobe and superior temporal sulcus (STS) visual cortical regions. Some activations were independent of the stimulus type, such as language, and anterior temporal lobe STS semantic regions consistently have higher activations and/or functional connectivities on the left, consistent with the importance of the left hemisphere in language in right-handed people. Also, early visual cortical regions, V2-V4 and POS1, have higher activations in the right hemisphere independently of stimulus type. The lateralizations of the functional connectivities were largely consistent with the activations, but additionally showed that groups of functional connectivities lateralize together (e.g., inferior parietal PGi, PGs, and PFm on the right for scenes but not for any other stimuli), providing further evidence on computational units of the cerebral cortex.