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Evaluation of the somatotopic organization of corticospinal tracts in the internal capsule and cerebral peduncle: results of diffusion-tensor MR tractography.

Park JK, Kim BS, Choi G, Kim SH, Choi JC, Khang H - Korean J Radiol (2008 May-Jun)

Bottom Line: In all subjects, the CSTs were organized along the long axis of the PLIC, and the hand fibers were located anterior to the foot fibers.The CSTs showed transverse orientation in the CP, and the hand fibers were located usually medial to the foot fibers.Corticospinal tracts are organized along the long axis of the PLIC and the horizontal direction of the CP.

View Article: PubMed Central - PubMed

Affiliation: Department of Radiology, Cheju National University College of Medicine, Jeju, Korea. jkcontrast@naver.com

ABSTRACT

Objective: We have used diffusion tensor tractography (DTT) for the evaluation of the somatotopic organization of corticospinal tracts (CSTs) in the posterior limb of the internal capsule (PLIC) and cerebral peduncle (CP).

Materials and methods: We imaged the brains of nine healthy right-handed subjects. We used a spin-echo echo-planar imaging (EPI) sequence with 12 diffusion-sensitized directions. DTT was calculated with an angular threshold of 35 degrees and a fractional anistropy (FA) threshold of 0.25. We determined the location of the CSTs by using two regions of interest (ROI) at expected areas of the pons and expected areas of the lateral half of the PLIC, in the left hemisphere of the brain. Fiber tracts crossing these two ROIs and the precentral gyrus (PCG) were defined as CSTs. Four new ROIs were then defined for the PCG, from the medial to lateral direction, as ROI 1 (medial) to ROI 4 (lateral). Finally, we defined each fiber tract of the CSTs between the pons and each ROI in the PCG by using two ROIs methods.

Results: In all subjects, the CSTs were organized along the long axis of the PLIC, and the hand fibers were located anterior to the foot fibers. The CSTs showed transverse orientation in the CP, and the hand fibers were located usually medial to the foot fibers.

Conclusion: Corticospinal tracts are organized along the long axis of the PLIC and the horizontal direction of the CP.

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Intermixing of fibers from lateral regions of interest.A. ROI 3 fibers divided anterior and posterior division at precentral gyrus (B0 image).B, C. ROI 4 fibers were located between anterior and posterior divisions at posterior limb of internal capsule and cerebral peduncle.
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Figure 5: Intermixing of fibers from lateral regions of interest.A. ROI 3 fibers divided anterior and posterior division at precentral gyrus (B0 image).B, C. ROI 4 fibers were located between anterior and posterior divisions at posterior limb of internal capsule and cerebral peduncle.

Mentions: In all cases, the two medial ROIs (ROI 1 and ROI 2) were located slightly posterior to the two lateral ROIs (ROI 3 and ROI 4) at the PCG. In the all subjects, the CSTs traversed the mid to posterior portion of the lateral half of the PLIC, and showed somatotopic organization along the long axis (anterior-posterior) of the PLIC. The CSTs from ROI 1 and ROI 2 (foot fibers) were located posterior and medial to the CSTs from ROI 3 and ROI 4 (hand fibers) in the PLIC (Fig. 3). In all subjects, the CSTs traversed the mid to lateral portion of the CP, and they showed a transverse orientation (right to left) of the somatotopic organization in the CP. In the left hemisphere, the CSTs looked like they were rotating in a clockwise direction descending from the PCG to the CP and the foot fibers were located lateral to the hand fibers in the CP (Fig. 4). In four cases, intermixing of the fibers was present within the hand fibers. The CSTs from ROI 3 were divided as anterior and posterior bundles, and the CSTs from ROI 4 were located between the anterior and posterior bundles of ROI 3 at the PLIC and the CP (Fig. 5).


Evaluation of the somatotopic organization of corticospinal tracts in the internal capsule and cerebral peduncle: results of diffusion-tensor MR tractography.

Park JK, Kim BS, Choi G, Kim SH, Choi JC, Khang H - Korean J Radiol (2008 May-Jun)

Intermixing of fibers from lateral regions of interest.A. ROI 3 fibers divided anterior and posterior division at precentral gyrus (B0 image).B, C. ROI 4 fibers were located between anterior and posterior divisions at posterior limb of internal capsule and cerebral peduncle.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC2627255&req=5

Figure 5: Intermixing of fibers from lateral regions of interest.A. ROI 3 fibers divided anterior and posterior division at precentral gyrus (B0 image).B, C. ROI 4 fibers were located between anterior and posterior divisions at posterior limb of internal capsule and cerebral peduncle.
Mentions: In all cases, the two medial ROIs (ROI 1 and ROI 2) were located slightly posterior to the two lateral ROIs (ROI 3 and ROI 4) at the PCG. In the all subjects, the CSTs traversed the mid to posterior portion of the lateral half of the PLIC, and showed somatotopic organization along the long axis (anterior-posterior) of the PLIC. The CSTs from ROI 1 and ROI 2 (foot fibers) were located posterior and medial to the CSTs from ROI 3 and ROI 4 (hand fibers) in the PLIC (Fig. 3). In all subjects, the CSTs traversed the mid to lateral portion of the CP, and they showed a transverse orientation (right to left) of the somatotopic organization in the CP. In the left hemisphere, the CSTs looked like they were rotating in a clockwise direction descending from the PCG to the CP and the foot fibers were located lateral to the hand fibers in the CP (Fig. 4). In four cases, intermixing of the fibers was present within the hand fibers. The CSTs from ROI 3 were divided as anterior and posterior bundles, and the CSTs from ROI 4 were located between the anterior and posterior bundles of ROI 3 at the PLIC and the CP (Fig. 5).

Bottom Line: In all subjects, the CSTs were organized along the long axis of the PLIC, and the hand fibers were located anterior to the foot fibers.The CSTs showed transverse orientation in the CP, and the hand fibers were located usually medial to the foot fibers.Corticospinal tracts are organized along the long axis of the PLIC and the horizontal direction of the CP.

View Article: PubMed Central - PubMed

Affiliation: Department of Radiology, Cheju National University College of Medicine, Jeju, Korea. jkcontrast@naver.com

ABSTRACT

Objective: We have used diffusion tensor tractography (DTT) for the evaluation of the somatotopic organization of corticospinal tracts (CSTs) in the posterior limb of the internal capsule (PLIC) and cerebral peduncle (CP).

Materials and methods: We imaged the brains of nine healthy right-handed subjects. We used a spin-echo echo-planar imaging (EPI) sequence with 12 diffusion-sensitized directions. DTT was calculated with an angular threshold of 35 degrees and a fractional anistropy (FA) threshold of 0.25. We determined the location of the CSTs by using two regions of interest (ROI) at expected areas of the pons and expected areas of the lateral half of the PLIC, in the left hemisphere of the brain. Fiber tracts crossing these two ROIs and the precentral gyrus (PCG) were defined as CSTs. Four new ROIs were then defined for the PCG, from the medial to lateral direction, as ROI 1 (medial) to ROI 4 (lateral). Finally, we defined each fiber tract of the CSTs between the pons and each ROI in the PCG by using two ROIs methods.

Results: In all subjects, the CSTs were organized along the long axis of the PLIC, and the hand fibers were located anterior to the foot fibers. The CSTs showed transverse orientation in the CP, and the hand fibers were located usually medial to the foot fibers.

Conclusion: Corticospinal tracts are organized along the long axis of the PLIC and the horizontal direction of the CP.

Show MeSH