Data-driven clustering reveals a fundamental subdivision of the human cortex into two global systems

Neuropsychologia. 2008 Jan 31;46(2):540-53. doi: 10.1016/j.neuropsychologia.2007.10.003. Epub 2007 Oct 13.


Global organizational principles are critical for understanding cortical functionality. Recently, we proposed a global sub-division of the posterior cortex into two large-scale systems. One system, labeled extrinsic, comprises the sensory-motor cortex, and is associated with the external environment. The second system, labeled intrinsic, overlaps substantially with the previously described "default-mode" network, and is likely associated with inner-oriented processing. This global partition of the cerebral cortex emerged from hemodynamic imaging data the analysis of which was constrained by pre-determined hypotheses. Here we applied a hypothesis-free, unsupervised two-class clustering algorithm (k-means) to a large set of fMRI data. The two clusters delineated by this unsupervised hypothesis-free procedure showed high anatomical consistency across individuals, and their cortical topography coincided largely with the previously determined extrinsic and intrinsic systems. These new clustering-based results confirm that the intrinsic-extrinsic subdivision constitutes a fundamental cortical divide.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Algorithms
  • Brain Mapping / methods*
  • Cerebral Cortex / anatomy & histology*
  • Cerebral Cortex / physiology
  • Cluster Analysis
  • Cognition / physiology*
  • Humans
  • Models, Neurological*
  • Nerve Net / physiology*
  • Reference Values
  • Somatosensory Cortex / anatomy & histology
  • Somatosensory Cortex / physiology