Diffusion Tensor Imaging Investigation of Uncinate Fasciculus Anatomy in Healthy Controls: Description of a Subgenual Stem

Neuropsychobiology. 2017;75(3):132-140. doi: 10.1159/000485111. Epub 2018 Jan 12.


The uncinate fasciculus is the largest white matter association tract connecting the prefrontal cortex and the anteromedial temporal lobe. The traditional anatomical description outlines a temporal stem that hooks around the posterior insula, a subinsular body, and 2 prefrontal stems extending to the lateral orbital gyri and the frontopolar cortex. Recent imaging studies of the white matter tracts deep to the subgenual cingulate gyrus (Brodmann area 25: BA25) suggest the presence of white matter fibers extending from BA25 to the amygdala, via a route that would run in close proximity to the uncinate fasciculus, that are of functional importance in mood disorders. We hypothesized that these fibers represent a third, medial prefrontal stem of the uncinate fasciculus. Using diffusion tensor imaging in 74 healthy volunteer humans, we seeded the uncinate fasciculus using 2 regions of interest centered over the temporal stem and the caudal body of the uncinate fasciculus in the coronal plane at the level of the anterior commissure. A medial prefrontal stem extending to the subgenual cingulate gyrus was demonstrated in 65/74 left and 70/74 right cerebral hemispheres, and had a mean fractional anisotropy value of 0.43 (95% CI 0.40-0.47). The medial subgenual stem fibers were inseparable from the caudal body and temporal stem of the main uncinate fasciculus and followed the same hook-shaped morphology. A probable medial subgenual prefrontal stem of the uncinate fasciculus was demonstrated in a cohort of healthy volunteers and is of potential significance in our understanding of neuropsychiatry and mood disorders.

Keywords: Brodmann area 25; Diffusion tensor imaging; Neuroanatomy; Subgenual stem; Uncinate fasciculus.

MeSH terms

  • Adolescent
  • Adult
  • Aged
  • Aged, 80 and over
  • Diffusion Tensor Imaging
  • Female
  • Humans
  • Magnetic Resonance Imaging
  • Male
  • Middle Aged
  • Prefrontal Cortex / anatomy & histology*
  • Prefrontal Cortex / diagnostic imaging
  • Temporal Lobe / anatomy & histology*
  • Temporal Lobe / diagnostic imaging
  • White Matter / anatomy & histology*
  • White Matter / diagnostic imaging
  • Young Adult