Neuroanatomical Dissections of Unilateral Visual Neglect Symptoms: ALE Meta-Analysis of Lesion-Symptom Mapping

Abstract

Unilateral visual neglect is commonly defined as impaired ability to attend to stimuli presented on the side of visual space contralateral to the brain lesion. However, behavioral analyses indicate that different neglect symptoms can dissociate. The neuroanatomy of the syndrome has been hotly debated. Some groups have argued that the syndrome is linked to posterior parietal cortex lesions, while others report damage within regions including the superior temporal gyrus, insula, and basal ganglia. Several recent neuroimaging studies provide evidence that heterogeneity in the behavioral symptoms of neglect can be matched by variations in the brain lesions, and that some of the discrepancies across earlier findings might have resulted from the use of different neuropsychological tests and/or varied measures within the same task for diagnosing neglect. In this paper, we review the evidence for dissociations between both the symptoms and the neural substrates of unilateral visual neglect, drawing on ALE (anatomic likelihood estimation) meta-analyses of lesion-symptom mapping studies. Specifically, we examine dissociations between neglect symptoms associated with impaired control of attention across space (in an egocentric frame of reference) and within objects (in an allocentric frame of reference). Results of ALE meta-analyses indicated that, while egocentric symptoms are associated with damage within perisylvian network (pre- and postcentral, supramarginal, and superior temporal gyri) and damage within sub-cortical structures, more posterior lesions including the angular, middle temporal, and middle occipital gyri are associated with allocentric symptoms. Furthermore, there was high concurrence in deficits associated with white matter lesions within long association (superior longitudinal, inferior fronto-occipital, and inferior longitudinal fasciculi) and projection (corona radiata and thalamic radiation) pathways, supporting a disconnection account of the syndrome. Using this evidence we argue that different forms of neglect link to both distinct and common patterns of gray and white matter lesions. The findings are discussed in terms of functional accounts of neglect and theoretical models based on computational studies of both normal and impaired attention functions.

Dissociating the neural mechanisms of distance and spatial reference frames

“…This result with regards to distance is in keeping with earlier TMS 18 studies (Lane et al, 2013;Mahayana et al, 2014), and although rFEF has been specifically associated with egocentric processing by some (Grimsen et al, 2008), other studies have demonstrated overlapping activation in such frontal regions between egocentric and allocentric tasks (Chechlacz et al, 2012;Committeri et al,. 2004;Galati et al, 2000;Zaehle et al, 2007).…”

“…There may also be a particular role for associated 5 frontal areas, including the rFEF, for egocentric space (Grimsen et al, 2008;Neggers et al, 2006;Vallar et al, 1999). However, there is also evidence for considerable overlap in the areas associated with egocentric and allocentric processing, particularly within the right frontoparietal network (Chechlacz, Rothstein, & Humpreys, 2012;Committeri et al, 2004;Galati et al, 2000;Zaehle et al, 2007).…”

The angular gyrus and visuospatial attention in decision-making under risk

“…Göbel et al, 2001;Taylor et al, 2011) and cued attention orientation paradigms (Chen et al, 2012;Heinen et al, 2011), potentially by altering goal-directed salience representations (Zenon et al, 2010). A recent meta-analysis of neuropsychological studies on neglect by Chechlacz et al (2012) furthermore revealed that damage of the AG is associated with impaired control of attention within objects. The current results suggest that the AG is also responsible for the guidance of visuospatial attention in a decision-making context.…”

“…The AG is also thought to be a key area for visuospatial attention. Lesions to the AG are associated with neglect (Chechlacz et al, 2012), and temporary disruption of AG activity by means of transcranial magnetic stimulation (TMS) affects performance on tasks requiring allocation and reorientation of visuospatial attention (reviewed in Rushworth and Taylor, 2006). Attentional processes interact with decision-making in multiple ways.…”

Spatial and Non-Spatial Aspects of Neglect

“…Molenberghs et al (2012; see commentary by Bartolomeo, 2012) found specific anatomical clusters for distinct neglect subtypes (e.g., personal vs. extrapersonal neglect). Chechlacz et al (2012) focuses on the dissociation between egocentric and allocentric signs of neglect. Both studies suggest that different forms of neglect are linked to both distinct and common lesion patterns involving gray and white matter.…”