The extreme capsule in humans and rethinking of the language circuitry

Brain Struct Funct. 2009 Feb;213(3):343-58. doi: 10.1007/s00429-008-0199-8. Epub 2008 Dec 23.

Abstract

Experimental and imaging studies in monkeys have outlined various long association fiber pathways within the fronto-temporo-parietal region. In the present study, the trajectory of the extreme capsule (EmC) fibers has been delineated in five human subjects using DT-MRI tractography. The EmC seems to be a long association fiber pathway, which courses between the inferior frontal region and the superior temporal gyrus extending into the inferior parietal lobule. Comparison of EmC fibers with the adjacent association fiber pathway, the middle longitudinal fascicle (MdLF), in the same subjects reveals that EmC is located in a medial and rostral position relative to MdLF flanking in part the medial wall of the insula. The EmC can also be differentiated from other neighboring fiber pathways such as the external capsule, uncinate fascicle, arcuate fascicle, superior longitudinal fascicles II and III, and the inferior longitudinal fascicle. Given the location of EmC within the language zone, specifically Broca's area in the frontal lobe, and Wernicke's area in the temporal lobe and inferior parietal lobule, it is suggested that the extreme capsule could have a role in language function.

Publication types

  • Research Support, N.I.H., Extramural

MeSH terms

  • Anisotropy
  • Basal Ganglia / anatomy & histology*
  • Brain / anatomy & histology
  • Brain Mapping
  • Diffusion Magnetic Resonance Imaging
  • Female
  • Humans
  • Imaging, Three-Dimensional
  • Male
  • Neural Pathways / anatomy & histology
  • Parietal Lobe / anatomy & histology*
  • Software
  • Temporal Lobe / anatomy & histology*
  • Young Adult