The role of long-range connections on the specificity of the macaque interareal cortical network

Nikola T. Markov, Maria Ercsey-Ravasz, Camille Lamy, Ana Rita Ribeiro Gomes, Loïc Magrou, Pierre Misery, Pascale Giroud, Pascal Barone, Colette Dehay, Zoltán Toroczkai, Kenneth Knoblauch, David C. Van Essen, Henry Kennedy

Research output: Contribution to journalArticlepeer-review

115 Scopus citations


We investigated the influence of interareal distance on connectivity patterns in a database obtained from the injection of retrograde tracers in 29 areas distributed over six regions (occipital, temporal, parietal, frontal, prefrontal, and limbic). One-third of the 1,615 pathways projecting to the 29 target areas were reported only recently and deemed new-found projections (NFPs). NFPs are predominantly long-range, low-weight connections. A minimum dominating set analysis (a graph theoretic measure) shows that NFPs play a major role in globalizing input to small groups of areas. Randomization tests show that (i) NFPs make important contributions to the specificity of the connectivity profile of individual cortical areas, and (ii) NFPs share key properties with known connections at the same distance. We developed a similarity index, which shows that intraregion similarity is high, whereas the interregion similarity declines with distance. For area pairs, there is a steep decline with distance in the similarity and probability of being connected. Nevertheless, the present findings reveal an unexpected binary specificity despite the high density (66%) of the cortical graph. This specificity is made possible because connections are largely concentrated over short distances. These findings emphasize the importance of long-distance connections in the connectivity profile of an area. We demonstrate that long-distance connections are particularly prevalent for prefrontal areas, where they may play a prominent role in large-scale communication and information integration.

Original languageEnglish
Pages (from-to)5187-5192
Number of pages6
JournalProceedings of the National Academy of Sciences of the United States of America
Issue number13
StatePublished - Mar 26 2013


  • Anatomy
  • Monkey
  • Neocortex


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