Disconnection somewhere down the line: Multivariate lesion-symptom mapping of the line bisection error

Abstract

Line Bisection is a simple task frequently used in stroke patients to diagnose disorders of spatial perception characterized by a directional bisection bias to the ipsilesional side. However, previous anatomical and behavioural findings are contradictory, and the diagnostic validity of the line bisection task has been challenged. We hereby aimed to re-analyse the anatomical basis of pathological line bisection by using multivariate lesion-symptom mapping and disconnection-symptom mapping based on support vector regression in a sample of 163 right hemispheric acute stroke patients.In line with some previous studies, we observed that pathological line bisection was related to more than a single focal lesion location. Cortical damage primarily to right parietal areas, particularly the inferior parietal lobe, including the angular gyrus, as well as damage to the right basal ganglia contributed to the pathology. In contrast to some previous studies, an involvement of frontal cortical brain areas in the line bisection task was not observed. Subcortically, damage to the right superior longitudinal fasciculus (I, II and III) and arcuate fasciculus as well as the internal capsule was associated with line bisection errors. Moreover, white matter damage of interhemispheric fibre bundles, such as the anterior commissure and posterior parts of the corpus callosum projecting into the left hemisphere, was predictive of pathological deviation in the line bisection task.

Neural Mechanisms of Prism Adaptation in Healthy Adults and Individuals with Spatial Neglect after Unilateral Stroke: A Review of fMRI Studies

“…Such lesions upset the balance of activity between the two hemispheres, resulting in hyper-activation of the uninjured hemisphere. Consistent with the animal literature, spatial neglect in humans is associated with a partly overlapping set of lesions in parietal, frontal, temporal cortex, fronto-parietal white matter, corpus callosum, superior colliculi, caudate nucleus, and thalamus [44,45]. Although human data do not show the profound interhemispheric rivalry found in animals, there is evidence of hemispheric imbalance.…”

Voxelwise structural disconnection mapping: Methodological validation and recommendations

“…These maps were binarized (in contrast to thresholding, which is the default setting in BCBtoolkit) at an overlap of ≥ 50 % ( Fig. 3 C), which is in analogy with prior studies ( Foulon et al, 2018 , Monai et al, 2020 , Weaver et al, 2021 , Wiesen et al, 2020 ).…”

“…This approach is available within the BCBtoolkit ( https://www.toolkit.bcblab.com ) and has been increasingly used in the recent years (e.g. Alves et al, 2021 , Pacella et al, 2019 , Salvalaggio et al, 2020 , Wiesen et al, 2020 ). It relies on deterministic fiber tracking seeding from individual lesions ( Thiebaut de Schotten et al, 2011 ).…”

“…In some studies, this map is again thresholded at ≥ 50 % (e.g. Alves et al, 2021 , Foulon et al, 2018 , Wiesen et al, 2020 ). The result is one disconnectome map per patient.…”

“…The result is one disconnectome map per patient. Second level statistics in terms of an association with a symptom of interest are performed either using an algorithm called AnaCOM ( Foulon et al, 2018 ), within the framework of the general linear model using permutation tests and threshold-free cluster enhancement ( Alves et al, 2021 , Monai et al, 2020 , Pacella et al, 2019 ) or using multivariate methods ( Salvalaggio et al, 2020 , Weaver et al, 2021 , Wiesen et al, 2020 ). An alternative to the voxelwise approach is to examine disconnection on the level of macroscopic tracts from white matter atlases ( Foulon et al, 2018 ).…”