Article Figures & Data
Figures
- FIG 1.
Axial 7T image (A) and axial 3T FGATIR image (B) illustrating the internal architecture of the ventral thalamus with key ventral nuclei outlined, including the ventral caudal (VC), VIM, and VO nuclei lying anterior to the pulvinar (Pul). Sagittal oblique (C) and coronal (D) images showing the relationship of the decussating (red) and nondecussating (green) tracts of the left DRTT and their relationship to the VIM nucleus and ZI (blue). The decussating fibers can be seen along the anterior border of the VIM in the location of the posterior VO. The DRTT extends from the dentate nucleus through the superior cerebellar peduncle, with part of the tract decussating in the midbrain and part continuing ipsilateral to the level of the red nucleus (RN), through the posterior subthalamic region and ZI, thalamus, and terminating in the primary motor cortex.
- FIG 2.
Coronal (A) and axial 7T MR imaging (B) showing the relationship of structures of the basal ganglia and subthalamic area. The ZI is bordered inferiorly by the FL and superiorly by the TF as it inserts into the thalamus. The Edinger comb system can be seen as dark lines traversing the internal capsule perpendicularly (arrowheads) composed of the pallidofugal tracts, fasciculus subthalamicus, and FL. Axial susceptibility-weighted MR imaging (C) shows similar anatomy including the Edinger comb (arrowheads) and the ansa subthalamica (arrow). RN indicates red nucleus.
- FIG 3.
Sagittal view of the tripartite division of the STN (A) and corresponding hyperdirect fibers (orange = posterolateral sensorimotor STN; cyan = middle associative STN; yellow = anteromedial limbic STN). Axial (B) and oblique coronal views (C) show the course of the AS (blue fibers) extending from the anteroventral pole of the globus pallidus internus (green region) and curving into the anterior pole of the limbic division of the STN (yellow region), while the FS (pink fibers) traverses the Edinger comb system extending from the globus pallidus externus (light blue region) to the middle associative STN (cyan).
- FIG 4.
Axial 7T MR imaging (A) showing the anatomy of the pallidum and adjacent structures. Posterior oblique (B) and anterior oblique views (C) highlight the relationship of the AL (yellow fibers) that originates from the anteroventral pole of the globus pallidus internus near the origin of the AS (purple fibers) but courses more dorsal to the AS. The FS is shown as red fibers. Sagittal view (D) shows the components of the thalamic fasciculus: dentatorubrothalamic tract (green), AL (yellow), and FL (red) associated with the VIM, ventralis oralis posterior (VOp), and ventralis oralis anterior (VOa) nuclei, respectively.
- FIG 5.
Sagittal (A) and posterior oblique views (B) showing the relationship of tracts associated with deep brain stimulation of the ALIC for treatment of OCD. The ATR (Red) extend anteriorly from the thalamus (yellow). The MFB (cyan) connects the ventral tegmental area with the nucleus accumbens and olfactory cortex. The MFB does not traverse the ALIC, but, rather, lies ventral and medial to ALIC. The tracts described as a superolateral branch of the MFB (green) mirror the position of the frontal connections of the anteromedial subthalamic nucleus (purple fibers) within the ALIC—both lying lateral to the ATR. These fibers of the subthalamic nucleus may account for the tractography findings previously reported as the superolateral branch of the MFB (more recently referred to as the projection pathway from the ventral tegmental [vtaPP] area). The subthalamic nucleus is shown in orange.
- FIG 6.
Sagittal 3T FGATIR MR imaging (A) compared with MPRAGE (B) in the same patient. The FGATIR more clearly highlights the course of the mammillothalamic tract (arrow) seen as a dark band extending from the mammillary body, through the thalamus, and terminating at the base of the anterior ANT (outlined by arrowheads). Sagittal view of the main connections of the ANT (purple region) (C). The mammillothalamic tract (green) connects the mamillary body to the ANT. Tracts (blue) then connect the ANT (through the stria terminalis) with the anterior cingulate and cingulate bundle (orange).
Tables
Summary of key anatomic tracts and structures
Structure Figure Regions Connected Relevant Disorders Hypothesized Effects of Stimulation AL Fig 4B, -D (yellow) GPi, VOa PD and dystonia Improve dystonia and dyskinesia AS Fig 4B, -C (purple); Fig 3B, -C (blue) STN, GPi PD and dystonia Direct stimulation effect unknown ATR Fig 5A, -B (red) Thalamus, prefrontal cortex OCD Improve OCD DRTT Fig 1C, -D (red and green); Fig 4D (green) DN, RN, VIM/VOp, M1 ET and tremor-predominant PD Improve tremor, worsen ataxia FL Fig 2A; Fig 4D (red) GPi, VOa PD and dystonia Improve dystonia and parkinsonism FS Fig 3B, -C (Pink); Fig 4B, -C (red) STN, GPe PD and dystonia Direct stimulation effect unknown Hyperdirect pathway (limbic/associative) Fig 3A (cyan, yellow) STN, broad limbic and associative regions OCD Improve OCD Hyperdirect pathway (motor) Fig 3A (orange) STN, motor cortex PD Improve parkinsonism MMT Fig 6C (green) Mammillary body, ANT Epilepsy Decrease seizures MFB Fig 5A, -B (cyan) VTA, nucleus accumbens and olfactory cortex Depression (off-label use) Possibly worsens OCD TF Fig 2A Combination of FL, AL, and DRTT, thalamus PD, dystonia, ET Improve tremor vtaPP (formerly slMFB)a Fig 5A, -B (green) DN, VTA, SFG, MFG, and lateral OFC OCD Possibly improve OCD ANT Fig 6A–C Epilepsy Decrease seizures VIM Fig 1A–C; Fig 4D ET and tremor-predominant PD Improve tremor, worsen ataxia, dysarthria VOa/VOp Fig 1A, -B; Fig 4D ET and tremor-predominant PD Improve tremor, dystonia, worsen ataxia ZI Fig 1C; Fig 2A ET and tremor-predominant PD Improve tremor, worsen ataxia Note:—DN indicates dentate nucleus; M1, primary motor cortex; MFG, middle frontal gyrus; OFC, orbitofrontal cortex; RN, red nucleus; SFG, superior frontal gyrus; VOa, ventralis oralis anterior; VOp, ventralis oralis posterior; VTA, ventral tegmental area; vtaPP, projection pathway from the ventral tegmental area.
↵a vtaPP (slMFB) likely represents misidentification of the limbic/associative hyperdirect pathway.
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