Spatial neglect and attention networks in the human brain: disturbances of functional connectivity and interhemispheric imbalance of an attentional priority map for retinotopic space

点击翻译按钮获取中文摘要

Spatial neglect represents a severe and common cognitive disorder following unilateral (mostly right hemisphere) brain damage. Affected patients show a profound lack of awareness for the one half of space opposite to their brain lesion. Neglect counts among the strongest predictors for poor functional outcome after stroke. An established therapy is still missing. The pathophysiological base of neglect has been proposed to be an interhemispheric imbalance of an attentional priority map in the parietal lobe that is responsible for shifting attention to external stimuli in space. Whether the location of objects in such a map are mainly represented in egocentric coordinates (especially eye-centric or retinotopic) or rather allocentric coordinates (object-to-object) is unclear. The exact location of the brain lesion, that is crucial for the developement of neglect, is also a matter of ongoing debate. Recent advances in functional brain imaging, assessing the functional connectivity between multiple brain areas in global networks, seem to indicate that neglect may rather be due to a disturbance of these global attention networks and not (only) to the circumscribed structural brain damage. This project aims to tackle these open questions regarding spatial attention, the underlying behavioural and functional mechanisms as well as a potential treatment option for neglect. We will investigate healthy subjects, neurological patients with focal brain lesions (stroke patients with spatial neglect) and subjects with a transient virtual lesion in the parietal lobe, induced by transcranial magnetic stimulation (TMS). Methods include behavioural neuropsychological testing (standardized paper-pencil tests and novel computerized tasks), eye movement recordings and a gaze-contingent display technology for manipulating spatial perception and guiding the subjects gaze, and finally structural and functional magnetic resonance imaging of the brain, the latter at rest and task-related, with and without prior application of transcranial magnetic stimulation.