Unità Cerebrolesioni Acquisite, Auxilium Vitae Volterra, Spa, Borgo San Lazzero 5, Volterra, Pisa, Italy.
Exp Brain Res. 2010 Oct;206(2):209-17. doi: 10.1007/s00221-010-2230-6. Epub 2010 Apr 6.
Left unilateral neglect is frequently reported after right hemispheric lesions of the middle cerebral artery (MCA) damaging the parietal-frontal cortical-subcortical network subserving space representation and awareness. However, accumulating evidence shows that neglect can also follow lesions of the posterior cerebral artery (PCA) that do not directly affect this parietal-frontal network. Surgical studies in the monkeys have demonstrated that complete callosal resection combined with lesion of the right optic tract entirely deprives the right hemisphere of visual inputs from the left hemispace provoking severe left unilateral neglect. Here, through the detailed study of two patients we show, for the first time, that PCA lesions selectively affecting the splenium of the corpus callosum and the adjacent right primary visual cortex provoke severe neglect selectively restricted to the visual domain. No trace of personal, motor or representational-imagery neglect was found. Also at variance with previous case studies in which neglect followed lesion of the trunk or the genu of the corpus callosum, no restriction of neglect to tasks performed with the right hand, no left hemispatial limb akinesia, no tactile extinction for the left hand and no tactile anomia for stimuli explored with the left hand were observed. These findings demonstrate that brain lesions depriving intact parietal and frontal attentional areas from specific sensory inputs can yield spatial neglect limited to specific sensory modalities or sectors of space.
左侧忽略症通常发生在大脑中动脉（MCA）右侧病变后，损伤了空间表示和意识的顶叶-额叶皮质下网络。然而，越来越多的证据表明，即使在后循环的大脑后动脉（PCA）病变后，也可能发生忽略症，而这些病变不会直接影响这个顶叶-额叶网络。猴子的外科研究表明，完全切断胼胝体并损伤右侧视束会使右半球完全失去来自左侧半空间的视觉输入，从而引起严重的左侧单侧忽略症。在这里，我们通过对两名患者的详细研究首次表明，选择性地影响胼胝体压部和相邻右侧初级视觉皮层的 PCA 病变会选择性地引起严重的仅局限于视觉领域的忽略症。没有发现个人、运动或表象意象忽略的痕迹。与之前的病例研究也不同，之前的病例研究中忽略症是由于胼胝体干或膝部的病变引起的，没有观察到忽略症仅限于用右手进行的任务、左手半空间肢体运动不能、左手触觉失认或左手触觉命名障碍。这些发现表明，大脑病变使完整的顶叶和额叶注意区域失去特定的感觉输入，可能导致特定感觉模式或空间区域的空间忽略症。
