Unresolved issues in unilateral neglect: An update

15/07/2017 to 14/03/2020

Hemispatial neglect is one of the most common syndromes showing behavioral abnormalities after unilateral brain injury, especially the right hemisphere. Patients with this syndrome often face the ipsilesional side and are not able to orient or respond to contralateral stimuli. Neglect can be distinguished along different modalities, e.g. the lines of input/output dimensions, sectors of space, sensory modality, processing domain, or the reference frame. According to the reference frames, hemispatial (usually left) neglect can be divided into two groups: egocentric (eye-, head- and trunk-centered) neglect and allocentric (stimulus-centered) neglect. As recent investigations could associate egocentric to allocentric neglect we will investigate if egocentric variation is also influencing results in another modality recently related to hemispatial neglect, namely spatial working memory (SWM). The independence of hemispatial neglect and SWM still remains unclear. We would like to suggest egocentric neglect and SWM are strongly associated and not only share similar brain regions, but also SWM performance varies with egocentric position. Several studies have emphasized that egocentric neglect and SWM are part of a common core concept of the disorder. We would like to present an adapted SWM task to neglect patients to reveal whether the performance of SWM would vary with egocentric position. Illuminating the basis of this association, we will be able to direct patients to more effective management and treatment schedules, essential for recovery, while spatial neglect generally has been regarded as a negative prognosis factor. Moreover, we will use and extend new multivariate techniques, using Machine Learning Algorithms (e.g. Multivariate Lesion Symptom Mapping), trying to delineate specific anatomical underpinnings of neglect behavior and related deficits, allowing to cancel out the drawbacks of mass univariate inference testing in classical Voxel-Based Lesion Symptom Mapping methods.