title: Somatotopic organization of motor pathways in the internal capsule: a probabilistic diffusion tractography study.
abstract: OBJECTIVE
  The location of the motor pathways in the PLIC remains controversial. In the current study, we trace the fibers from the tongue, face, hand, and foot motor cortices by using probabilistic diffusion tractography and define their somatotopic organization in the PLIC.
  
  
  METHODS
  Twenty subjects were retrospectively studied. Fiber tracts were separately calculated between ROIs in the cerebral peduncle and in the 4 different motor regions in the precentral gyrus. Probabilistic connectivity maps were generated, and the voxel with the highest probability was designated as the position of the motor pathway. The PI and LI were defined as the relative anteroposterior and mediolateral locations of the motor pathways.
  
  
  RESULTS
  Tongue pathways were located anteromedial to face in 16 hemispheres (40%), with P < .05 for the PI and LI. Face pathways were located anteromedial to hand in 25 hemispheres (62.5%) with P < .05 for PI and LI. Hand pathways were anteromedial to foot in 14 hemispheres (35%) and anterior in 11 hemispheres (27.5%), with P < .05 for PI but P > .13 for LI. Group analysis showed that the somatotopic arrangement of the bilateral hemispheres was symmetric.
  
  
  CONCLUSIONS
  Probabilistic tractography demonstrated the anteroposterior alignment of the motor pathways along the long axis in the PLIC. Probabilistic tractography successfully tracked the motor pathways of the tongue, face, hand, and foot from the precentral gyrus through their intersection with the larger superior longitudinal fasciculus to the PLIC in all cases, overcoming limitations of standard (nonprobabilistic) tractography methods.
authors.affiliation: Department of Radiology, Memorial Sloan-Kettering Cancer Center, 1275 York Ave, New York, NY 10065, USA.
authors.forename: C
authors.initials: C
authors.lastname: Pan
authors.forename: K K
authors.initials: KK
authors.lastname: Peck
authors.forename: R J
authors.initials: RJ
authors.lastname: Young
authors.forename: A I
authors.initials: AI
authors.lastname: Holodny
mesh_terms: D000328:Adult; D003198:Computer Simulation; D003627:Data Interpretation, Statistical; D056324:Diffusion Tensor Imaging / Q000379:methods*; D005260:Female; D006801:Humans; D020772:Internal Capsule / Q000033:anatomy & histology*; D008297:Male; D008875:Middle Aged; D008953:Models, Anatomic; D008959:Models, Neurological; D015233:Models, Statistical; D009044:Motor Cortex / Q000033:anatomy & histology*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D055815:Young Adult