Topographic organization for delayed saccades in human posterior parietal cortex
Topographic organization for delayed saccades in human posterior parietal cortex
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DOI：
10.1152/jn.01290.2004
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发表时间：
2005-08-01
影响因子：
2.5
通讯作者：
Heeger, DJ
中科院分区：
文献类型：
--
作者：
Schluppeck, D;Glimcher, P;Heeger, DJ
后顶叶皮层（PPC）被认为在决策、感觉注意、运动意图和/或工作记忆中起着关键作用。对非人灵长类PPC的研究主要集中在顶内沟（IPS）中的外侧顶内区（LIP）。LIP中的神经元在视觉目标出现之后、在对这些目标扫视之前以及在其间的延迟期间做出反应。为了研究人类后顶叶皮层的功能，有一个常规的和可靠的方法来定位特定的顶叶区域在个体受试者将是至关重要的。在这里，我们表明，人类PPC包含至少两个地形组织的地区，这是候选人的人类同源LIP。我们映射的地形组织人类PPC延迟（记忆引导）扫视使用功能磁共振成像。指示受试者集中注视，同时简要介绍外周目标。在进一步的3秒延迟后，受试者进行扫视到记忆中的目标位置，然后扫视回到固定和1秒的试验间隔。目标“昼夜不停地”出现在连续的地点（同样的偏心率，大约30度角步），在地形上有组织的地区产生活动的行波。PPC表现出地形组织延迟眼跳。我们在每个半球定义了两个区域，其中包含对侧视野的地形图。这两个区域如标准视网膜定位图所定义的那样紧邻V7的嘴侧。这两个区域彼此分离，并通过视野方向的反转与V7分离。然而，我们保留开放的可能性，这两个领域将在未来的研究中进一步细分。我们的研究结果表明，地形图瓷砖皮质连续从V1以及到PPC。
Posterior parietal cortex (PPC) is thought to play a critical role in decision making, sensory attention, motor intention, and/or working memory. Research on the PPC in non-human primates has focused on the lateral intraparietal area ( LIP) in the intraparietal sulcus (IPS). Neurons in LIP respond after the onset of visual targets, just before saccades to those targets, and during the delay period in between. To study the function of posterior parietal cortex in humans, it will be crucial to have a routine and reliable method for localizing specific parietal areas in individual subjects. Here, we show that human PPC contains at least two topographically organized regions, which are candidates for the human homologue of LIP. We mapped the topographic organization of human PPC for delayed ( memory guided) saccades using fMRI. Subjects were instructed to fixate centrally while a peripheral target was briefly presented. After a further 3-s delay, subjects made a saccade to the remembered target location followed by a saccade back to fixation and a 1-s inter-trial interval. Targets appeared at successive locations "around the clock" ( same eccentricity, approximate to 30 degrees angular steps), to produce a traveling wave of activity in areas that are topographically organized. PPC exhibited topographic organization for delayed saccades. We defined two areas in each hemisphere that contained topographic maps of the contra-lateral visual field. These two areas were immediately rostral to V7 as defined by standard retinotopic mapping. The two areas were separated from each other and from V7 by reversals in visual field orientation. However, we leave open the possibility that these two areas will be further subdivided in future studies. Our results demonstrate that topographic maps tile the cortex continuously from V1 well into PPC.