Neuronal substrates of Corsi Block span: Lesion symptom mapping analyses in relation to attentional competition and spatial bias (original) (raw)
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Spatial working memory capacity in unilateral neglect
2005
Lesion anatomy indicated that neglect patients with a SWM deficit were most likely to have damage to parietal white matter, plus, in the second experiment, to the insula also. These findings demonstrate that an impairment in SWM capacity can contribute to the neglect syndrome in patients with stroke involving regions within the right parietal lobe and insula.
Neural basis and recovery of spatial attention deficits in spatial neglect
Nature Neuroscience, 2005
The syndrome of spatial neglect is typically associated with focal injury to the temporoparietal or ventral frontal cortex. This syndrome shows spontaneous partial recovery, but the neural basis of both spatial neglect and its recovery is largely unknown. We show that spatial attention deficits in neglect (rightward bias and reorienting) after right frontal damage correlate with abnormal activation of structurally intact dorsal and ventral parietal regions that mediate related attentional operations in the normal brain. Furthermore, recovery of these attention deficits correlates with the restoration and rebalancing of activity within these regions. These results support a model of recovery based on the re-weighting of activity within a distributed neuronal architecture, and they show that behavioral deficits depend not only on structural changes at the locus of injury, but also on physiological changes in distant but functionally related brain areas.
A Parietofrontal Network for Spatial Awareness in the Right Hemisphere of the Human Brain
Archives of Neurology, 2006
Patients with lesions of the right hemisphere often show signs of left-sided unilateral neglect. Left-sided neglect may impair the ability of patients to live independently and entails a poor functional outcome. When exploring a visual scene, patients with left-sided neglect fail to pay attention to left-sided objects. They do not eat from the left part of their dish, they bump their wheelchair into obstacles situated on their left, and they have a tendency to look to right-sided details as soon as a visual scene unfolds, as if their attention were "magnetically" attracted by these details.
Behavioural Neurology, 2013
Spatial neglect is generally defined by various deficits in processing information from one (e.g. left) side of space contralateral to focal (e.g. right) hemisphere damage. The talk will review evidence that the clinical syndrome of neglectis likely to reflect a combination of disorders that may co-occur due to concomitant damage affecting juxtaposed brain areas and their connections, and that such lesions may induce functional disturbances in structurally intact areas through losses of top-down control from fronto-parietal cortical areas. Improved knowledge in these functional anomalies at the network levelalso points to new approaches for rehabilitation strategies. In particular, I will illustrate how theattentional deficits associated with neglect can at least partly be alleviated by manipulations influencing perceptual processing throughpathways outside the damagedfronto-parietal network, including emotional conditioning or reward learning, or by using methods that may help restore top-downattention signalssuchprism adaptation or neurofeedback.
The critical lesion site responsible for the syndrome of unilateral spatial neglect has been debated for more than a decade. Here we performed an activation likelihood estimation (ALE) to provide for the first time an objective quantitative index of the consistency of lesion sites across anatomical group studies of spatial neglect. The analysis revealed several distinct regions in which damage has consistently been associated with spatial neglect symptoms. Lesioned clusters were located in several cortical and subcortical regions of the right hemisphere, including the middle and superior temporal gyrus, inferior parietal lobule, intraparietal sulcus, precuneus, middle occipital gyrus, caudate nucleus, and posterior insula, as well as in the white matter pathway corresponding to the posterior part of the superior longitudinal fasciculus. Further analyses suggested that separate lesion sites are associated with impairments in different behavioral tests, such as line bisection and target cancellation. Similarly, specific subcomponents of the heterogeneous neglect syndrome, such as extinction and allocentric and personal neglect, are associated with distinct lesion sites. Future progress in delineating the neuropathological correlates of spatial neglect will depend upon the development of more refined measures of perceptual and cognitive functions than those currently available in the clinical setting.
Cortex; a journal devoted to the study of the nervous system and behavior, 2016
Spatial neglect is a neuropsychological syndrome in which patients fail to perceive and orient to stimuli located in the space contralateral to the lesioned hemisphere. It is characterized by a wide heterogeneity in clinical symptoms which can be grouped into distinct behavioral components correlating with different lesion sites. Moreover, damage to white-matter (WM) fiber tracts has been suggested to disconnect brain networks that mediate different functions associated with spatial cognition and attention. However, it remains unclear what WM pathways are associated with functionally dissociable neglect components. In this study we examined nine patients with a focal right hemisphere stroke using a series of neuropsychological tests and diffusion tensor imaging (DTI) in order to disentangle the role of specific WM pathways in neglect symptoms. First, following previous work, the behavioral test scores of patients were factorized into three independent components reflecting perceptua...
Cortex, 2014
Unawareness/anosognosia for left neglect and hemiplegia Right-brain damage Evaluation of cognitive performance a b s t r a c t Right-brain-damaged patients with unilateral spatial neglect are usually unaware (anosognosic) about their spatial deficits. However, in the scientific literature there is a lack of systematic and quantitative evaluation of this kind of unawareness, despite the negative impact of anosognosia on rehabilitation programs. This study investigated anosognosia for neglect-related impairments at different clinical tasks, by means of a quantitative assessment. Patients were tested in two different conditions (before and after execution of each task), in order to evaluate changes in the level of awareness of neglect-related behaviours triggered by task execution.
European Journal of Neuroscience, 2014
The human dorsolateral prefrontal cortex (dlPFC) is crucial for monitoring and manipulating information in working memory, but whether such contributions are domain-specific remains unsettled. Neuroimaging studies have shown bilateral dlPFC activity associated with working memory independent of stimulus domain, but the causality of this relationship cannot be inferred. Repetitive transcranial magnetic stimulation (rTMS) has the potential to test whether the left and right dlPFC contribute equally to verbal and spatial domains, however this is the first study to investigate the interaction of task domain and hemisphere using offline rTMS to temporarily modulate dlPFC activity. In separate sessions, twenty healthy right-handed adults received 1Hz-rTMS to left dlPFC, right dlPFC, plus the vertex as a control site. Working memory performance was assessed pre-and post-rTMS using both verbal-'letter' and spatial-'location' versions of the 3-back task. Response times were faster post-rTMS, independent of task domain or stimulation condition, indicating the influence of practice or other nonspecific effects. For accuracy, rTMS of the right dlPFC, but not the left dlPFC or vertex, led to a transient dissociation: reducing spatial, but increasing verbal accuracy. A post-hoc correlation analysis found no relationship between these changes indicating the substrates underlying verbal and spatial domains are functionally independent. Collapsing across time, there was a trend towards a double dissociation, suggesting a potential laterality in functional organization of verbal and spatial working memory. At a