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

空间忽视是单侧（主要是右半球）脑损伤后的一种严重而常见的认知障碍。受影响的患者表现出对大脑病变对面的一半空间的意识严重缺乏。神经元是卒中后功能预后不良的最强预测因子之一。一个既定的治疗仍然失踪。忽视的病理生理基础被认为是大脑顶叶中注意力优先图的半球间不平衡，顶叶负责将注意力转移到空间中的外部刺激。在这样的地图中，物体的位置是否主要以自我中心坐标（特别是以眼睛为中心或视网膜为中心）或更确切地说是以非自我中心坐标（物体到物体）表示尚不清楚。大脑病变的确切位置对忽视的发展至关重要，也是一个正在进行的辩论。功能性脑成像的最新进展，评估全球网络中多个大脑区域之间的功能连接，似乎表明忽视可能是由于这些全球注意力网络的干扰，而不仅仅是由于有限的结构性脑损伤。该项目旨在解决这些关于空间注意力的开放性问题，潜在的行为和功能机制以及忽视的潜在治疗方案。我们将研究健康受试者、脑局灶性病变的神经系统患者（空间忽略的中风患者）和经颅磁刺激（TMS）诱导的顶叶短暂性虚拟病变的受试者。方法包括行为神经心理学测试（标准化纸笔测试和新的计算机化任务），眼动记录和凝视视情况显示技术，用于操纵空间感知和引导受试者凝视，最后是大脑的结构和功能磁共振成像，后者在休息和任务相关的情况下，有和没有预先应用经颅磁刺激。

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.