IMI Interdisciplinary Mathematics InstituteCollege of Arts and Sciences

Modeling Functional Networks of the Primate Cortex

  • April 22, 2010
  • 2 p.m.
  • Sumwalt 102


Surprisingly little is known about the network properties of the cortex due to lack of data on direct connectivity and its properties. Using brain-wide, extensive (70 man-years work) retrograde tracing experiments in macaque, our anatomist collaborators from Lyon's Stem Cell and Brain Research Group generated a consistent database of interareal connections comprising projection densities (link weights) and physical lengths. This dense network (66% density) is neither a sparse small-world graph nor scale-free. Local connectivity accounts for 79% of labeled neurons. Link weights are highly characteristic across brains, decay exponentially with distance, and follow a heavy-tailed lognormal distribution over 6 orders of magnitude. Weighted network analysis reveals a trade-off between local and global communication efficiencies. A distance rule predicts the binary features, the global and local communication efficiencies as well as the functionally clustered topography of the graph. These findings underline the importance of weight-based hierarchical layering in cortical architecture and processing.

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