Division of Biology, California Institute of Technology, Pasadena, CA 91125, USA.
Proc Natl Acad Sci U S A. 2012 May 22;109(21):8274-9. doi: 10.1073/pnas.1204789109. Epub 2012 May 4.
Impairments of spatial awareness and decision making occur frequently as a consequence of parietal lesions. Here we used event-related functional MRI (fMRI) in monkeys to investigate rapid reorganization of spatial networks during reversible pharmacological inactivation of the lateral intraparietal area (LIP), which plays a role in the selection of eye movement targets. We measured fMRI activity in control and inactivation sessions while monkeys performed memory saccades to either instructed or autonomously chosen spatial locations. Inactivation caused a reduction of contralesional choices. Inactivation effects on fMRI activity were anatomically and functionally specific and mainly consisted of: (i) activity reduction in the upper bank of the superior temporal sulcus (temporal parietal occipital area) for single contralesional targets, especially in the inactivated hemisphere; and (ii) activity increase accompanying contralesional choices between bilateral targets in several frontal and parieto-temporal areas in both hemispheres. There was no overactivation for ipsilesional targets or choices in the intact hemisphere. Task-specific effects of LIP inactivation on blood oxygen level-dependent activity in the temporal parietal occipital area underline the importance of the superior temporal sulcus for spatial processing. Furthermore, our results agree only partially with the influential interhemispheric competition model of spatial neglect and suggest an additional component of interhemispheric cooperation in the compensation of neglect deficits.
空间意识和决策能力的损伤经常是顶叶损伤的结果。在这里，我们使用猴子的事件相关功能磁共振成像（fMRI）来研究外侧顶内区（LIP）可逆药理学失活期间空间网络的快速重组，该区域在眼球运动目标的选择中起作用。当猴子执行记忆扫视以到达指令或自主选择的空间位置时，我们在对照和失活期间测量 fMRI 活动。失活导致对侧选择减少。失活对 fMRI 活动的影响在解剖学和功能上是特异性的，主要包括：（i）单侧目标时，上颞叶回（颞顶枕区）的活动减少，尤其是在失活的半球中；（ii）双侧目标之间的对侧选择时，几个额和顶颞区的活动增加，在两个半球中都是如此。同侧目标或完整半球中的对侧选择没有过度激活。LIP 失活对颞顶枕区血氧水平依赖活动的特定任务影响强调了颞上回对空间处理的重要性。此外，我们的结果与空间忽视的有影响力的半球间竞争模型仅部分一致，并表明在忽视缺陷的补偿中存在额外的半球间合作成分。
