Toward a Common Terminology for the Thalamus

Abstract

The wealth of competing parcellations with limited cross-correspondence between atlases of the human thalamus raises problems in a time when the usefulness of neuroanatomical methods is increasingly appreciated for modern computational analyses of the brain. An unequivocal nomenclature is, however, compulsory for the understanding of the organization of the thalamus. This situation cannot be improved by renewed discussion but with implementation of neuroinformatics tools. We adopted a new volumetric approach to characterize the significant subdivisions and determined the relationships between the parcellation schemes of nine most influential atlases of the human thalamus. The volumes of each atlas were 3d-reconstructed and spatially registered to the standard MNI/ICBM2009b reference volume of the Human Brain Atlas in the MNI (Montreal Neurological Institute) space (Mai and Majtanik, 2017). This normalization of the individual thalamus shapes allowed for the comparison of the nuclear regions delineated by the different authors. Quantitative cross-comparisons revealed the extent of predictability of territorial borders for 11 area clusters. In case of discordant parcellations we re-analyzed the underlying histological features and the original descriptions. The final scheme of the spatial organization provided the frame for the selected terms for the subdivisions of the human thalamus using on the (modified) terminology of the Federative International Programme for Anatomical Terminology (FIPAT). Waiving of exact individual definition of regional boundaries in favor of the statistical representation within the open MNI platform provides the common and objective (standardized) ground to achieve concordance between results from different sources (microscopy, imaging etc.).

The effects of Thalamic Deep Brain Stimulation on speech dynamics in patients with Essential Tremor: An articulographic study

“…Electrode locations were then standardized into stereotactic brain space [ 18 ]. Stereotactic coordinates of the active electrode contacts are listed in S1 Appendix , and a visualization of the active contacts with surrounding atlas anatomy [ 19 ] can be seen in Fig 1 . The mean location of the most ventral contacts was 10.7 mm lateral, 6.3 mm posterior and 1.3 mm ventral to the mid-commissural point while the mean location of active electrodes was 11.6 mm lateral, 4.2 mm posterior and 0.6 mm dorsal to the mid-commissural point.…”

Structure-function relationship of the posterior subthalamic area with directional deep brain stimulation for essential tremor

“…These fiber tracts were historically considered as the prelemniscal radiations due to their anatomical position anterior to the sensory lemniscal pathway. An older view by Hassler describes the prelemniscal radiations as proprioceptive fibers from the medial lemniscus entering the VIM ( Mai and Majtanik, 2019 ). More recently, anatomical and imaging analysis based on diffusion-weighted imaging identified the DRTT (or cerebello-thalamic tract) and pallidothalamic fibers as the two principal components of the prelemniscal radiations ( Gallay et al, 2008 , Coenen et al, 2011 , Fiechter et al, 2017 , Petersen et al, 2019 ).…”

Improved Vim targeting for focused ultrasound ablation treatment of essential tremor: A probabilistic and patient‐specific approach

“…All segmentations were performed while blinded to the post‐treatment MRI scan. The Vim nucleus of the Schaltenbrand and Wahren atlas (Schaltenbrand, Spuler, Wahren, & Rümler, 1971) corresponds to the ventral portion of the VLp nucleus of the Morel atlas, abutting the inferior border of VLp (Mai & Majtanik, 2019). While the overall VLp body can be delineated using WMnMPRAGE imaging (Tourdias et al, 2014), there is a dorsal‐ventral cytoarchitectonic gradient, rather than a sharp internal boundary, between the Vim and the dorsal portion of VLp (Morel et al, 1997).…”

“…Previously, we found that the mammillothalamic tract and 11 thalamic nuclei, including the ventral lateral posterior (VLp) nucleus of which Vim is the ventral portion (Mai & Majtanik, 2019), could be visually identified and manually segmented from WMnMPRAGE images in healthy subjects and multiple sclerosis patients (Tourdias et al, 2014). Subsequently, based on 20 manually segmented subjects, we trained a multi‐atlas automated segmentation method named THalamus Optimized Multi Atlas Segmentation (THOMAS) to accurately identify and segment these 12 thalamic structures in WMnMPRAGE images (Su et al, 2019).…”