Resting-State Functional Networks of Different Topographic Representations in the Somatosensory Cortex of Macaque Monkeys and Humans

Thomas, John; Sharma, Dixit; Mohanta, Sounak; Jain, Neeraj

Information processing in the brain is mediated through a complex functional network architecture whose comprising nodes integrate and segregate themselves on different timescales. To gain an understanding of the network function it is imperative to identify and understand the network structure with respect to the underlying anatomical connectivity and the topographic organization. Here we show that the previously described resting-state network for the somatosensory area 3b comprises of distinct networks that are characteristic for different topographic representations. Seed-based resting-state functional connectivity analysis in macaque monkeys and humans using BOLD-fMRI signals from the face, the hand and rest of the medial somatosensory representations of area 3b revealed different correlation patterns. Both monkeys and humans have many similarities in the connectivity networks, although the networks are more complex in humans with many more nodes. In both the species face area network has the highest ipsilateral and contralateral connectivity, which included areas 3b and 4, and ventral premotor area. The area 3b hand network included ipsilateral hand representation in area 4. The emergent functional network structures largely reflect the known anatomical connectivity. Our results show that different body part representations in area 3b have independent functional networks perhaps reflecting differences in the behavioral use of different body parts. The results also show that large cortical areas if considered together, do not give a complete and accurate picture of the network architecture. Highlights Somatosensory resting-state functional network is not uniform across the entire area 3b. Different body part representations have different connectivity networks. These functional connectivity networks have many similarities in the two primate species, i.e. macaque monkeys and humans, although the human network is more complex. In both the species network of the face representation is most extensive, which includes ipsilateral face motor cortex and PMv in both hemispheres. The hand representation in area 3b has connectivity with ipsilateral hand motor cortex. Bilateral connectivity with homologous and nonhomologous area 3b representations was observed only in humans. The functional connectivity networks largely reflect the underlying anatomical connectivity.