Measurement of Projections Between Dentate Nucleus and Contralateral Frontal Cortex in Human Brain Via Diffusion Tensor Tractography

Dentate nucleus deep brain stimulation: Technical note of a novel methodology assisted by tractography

“…The DN is the largest of the deep cerebellar nuclei and plays a critical role in movement, cognition, autonomic functions, and behavior. [ 3 , 14 , 15 , 17 , 19 ] It is situated adjacent to the fourth ventricle buried by white matter and measures approximately 9–20 mm in width, 13–23 mm in length, and 7–20 mm in height. It has unique shape and is oriented in craniocaudal direction and from lateral to medial.…”

“…Its largest efferent is the dentatorubrothalamic tract (DRT) fiber bundle that plays a role not only in motor functions but also in cognition and behavior. [ 15 , 17 , 19 , 37 ]…”

Evidence for Reciprocal Structural Network Interactions Between Bilateral Crus Lobes and Broca’s Complex

“…Two studies reported evidence for the decussate streamlines originating from Broca's area and projecting into the cerebellum as part of their reconstructed pathway (Palesi et al, 2017;Pieterman et al, 2017). Recently, Ji et al (2019) used seed ROI in the DN and target ROI in the contralateral frontal cortex to reconstruct the decussate cerebello-thalamocortical pathway, which included those projecting into BA 44 and BA 45. In the present study focused on structural connections between the left IFG and the cerebellum, the tractography results showed reciprocal structural network interactions between bilateral Crus lobes and Broca's complex which, in the above-mentioned context, were not unreasonable but needed to be verified.…”

“…Hence, recent studies have often used the RN (Palesi et al, 2015;Jakab et al, 2016;Fenoy et al, 2017;Schlaier et al, 2017;Petersen et al, 2018;Jang and Kwon, 2019) and/or the thalamus (Kwon et al, 2011;Surova et al, 2015;Bernard et al, 2016;Jakab et al, 2016;Meola et al, 2016;Mollink et al, 2016;Fenoy et al, 2017;Oh et al, 2017;Pieterman et al, 2017;Petersen et al, 2018;Jang and Kwon, 2019) as a 'waypoint region' to reconstruct the streamlines originating from the cerebellum and projecting in the cerebrum via tractography, but none of them reported the streamlines originating from the cerebellum and projecting in the left IFG. As mentioned previously, Ji et al (2019) reconstructed the decussate cerebellothalamocortical pathway, including those projecting into BA 44 and BA 45, without using the RN or the thalamus as a "waypoint mask." They declare that 85 to 98% and 100% of the whole reconstructed pathway passed through the contralateral RN and contralateral thalamus, respectively.…”

“…They declare that 85 to 98% and 100% of the whole reconstructed pathway passed through the contralateral RN and contralateral thalamus, respectively. Unfortunately, the authors never refer to the method used for obtaining this result and no image material was used to display the exact spatial relationships between the whole pathway and the RN or the thalamus, let along between the cerebellar streamlines projecting into the BA 44 and BA 45 and the RN or the thalamus (Ji et al, 2019). If our findings about the trajectory of the Crus-Broca tracts were true, then the ROI approach with the thalamus or the RN as a "waypoint mask" used for reconstruction of all cerebello-cerebellar tracts for tract-based analysis would result in at least the Crus-Broca tracts excluded.…”