3D probabilistic maps of the human and macaque posterior default mode network (pDMN) based on cytoarchitectonic, receptor distribution and functional connectivity analyses

• Applicant: Dr. Lucija Rapan, Ph.D.
• Subject Area: Human Cognitive and Systems Neuroscience
• Term: since 2023
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 519392583

The posterior cingulate cortex (PCC), together with the retrosplenial cortex (RSC), constitute a central hub in the default mode network (DMN) (Buckner et al., 2008). In this context, PCC and RSC are commonly referred to as a posterior DMN (pDMN), which plays an important role in the autobiographical memories and an adaptive behavior requiring interaction between the internal and external focus of attention (Leech et al., 2011). Architectonic analyses in the human and non-human primate brain have shown the pDMN to be a heterogeneous region (e.g., Brodmann, 1909; Vogt et al., 1995; Vogt et al., 2005). However, existing maps differ in the number and extent of identified areas, and have not been brought into stereotaxic space. Furthermore, although functional cross-species studies (Xu et al., 2020) point to a low functional similarity between macaques and humans in this brain region, the architectonical underpinnings of this divergency remain unclear. The global aim of the proposed project is to understand the relationship between the structural and functional heterogeneity of the primate pDMN and determine the adequacy of the macaque monkey as an animal model for translational neuroscience of this brain region. To this purpose, we will create 3D probabilistic maps of the human and macaque pDMN based on quantifiable and statistically testable analyses of their cyto- and receptor architecture, and use them as a starting point for the mining of currently available open-source functional and diffusion tensor imaging datasets obtained from both species. The ensuing maps, which will be made publicly available for the neuroscientific community, will not only provide information on interindividual variability regarding the location and extent of cytoarchitectonically identified areas, but also on the distribution patterns of 14 receptor types belonging to distinct neurotransmitter systems. Since receptors are crucial elements in signal transduction, this data will advance our understanding of the structural and functional organization principles within the pDMN. Finally, integrating data on the functional connectivity, cytoarchitecture, and distribution patterns of 14 different neurotransmitter receptors of both primate species in the common space will enable a state-of-the-art approach to comparative neuroscience (Mars et al. 2021). Specifically, a vertical translation will enable to investigate how local architectonic and functional organization relate to regional structure-function differences within each species and across scales, and a horizontal translation will permit comparison of the multimodal analyses across species.

• DFG Programme: Research Grants