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在记忆引导的扫视和空间工作记忆任务中揭示的人类额叶皮质地形图。

Topographic maps in human frontal cortex revealed in memory-guided saccade and spatial working-memory tasks.

作者信息

Kastner Sabine, DeSimone Kevin, Konen Christina S, Szczepanski Sara M, Weiner Kevin S, Schneider Keith A

机构信息

Dept. of Psychology, Center for the Study of Brain, Mind, and Behavior, Princeton University, Green Hall, Princeton, NJ 08544, USA.

出版信息

J Neurophysiol. 2007 May;97(5):3494-507. doi: 10.1152/jn.00010.2007. Epub 2007 Mar 14.

Abstract

We used fMRI at 3 Tesla and improved spatial resolution (2 x 2 x 2 mm(3)) to investigate topographic organization in human frontal cortex using memory-guided response tasks performed at 8 or 12 peripheral locations arranged clockwise around a central fixation point. The tasks required the location of a peripheral target to be remembered for several seconds after which the subjects either made a saccade to the remembered location (memory-guided saccade task) or judged whether a test stimulus appeared in the same or a slightly different location by button press (spatial working-memory task). With these tasks, we found two topographic maps in each hemisphere, one in the superior branch of precentral cortex and caudalmost part of the superior frontal sulcus, in the region of the human frontal eye field, and a second in the inferior branch of precentral cortex and caudalmost part of the inferior frontal sulcus, both of which greatly overlapped with activations evoked by visually guided saccades. In each map, activated voxels coded for saccade directions and memorized locations predominantly in the contralateral hemifield with neighboring saccade directions and memorized locations represented in adjacent locations of the map. Particular saccade directions or memorized locations were often represented in multiple locations of the map. The topographic activation patterns showed individual variability from subject to subject but were reproducible within subjects. Notably, only saccade-related activation, but no topographic organization, was found in the region of the human supplementary eye field in dorsomedial prefrontal cortex. Together these results show that topographic organization can be revealed outside sensory cortical areas using more complex behavioral tasks.

摘要

我们使用3特斯拉的功能磁共振成像(fMRI)并提高空间分辨率(2×2×2立方毫米),通过在围绕中央固定点按顺时针方向排列的8个或12个外周位置执行记忆引导反应任务,来研究人类额叶皮质的地形组织。这些任务要求记住外周目标的位置几秒钟,之后受试者要么向记住的位置进行扫视(记忆引导扫视任务),要么通过按键判断测试刺激是否出现在相同或稍有不同的位置(空间工作记忆任务)。通过这些任务,我们在每个半球发现了两个地形图,一个位于中央前回上支和额上沟最尾端部分,即人类额叶眼区所在区域,另一个位于中央前回下支和额下沟最尾端部分,这两个区域都与视觉引导扫视诱发的激活有很大重叠。在每个图中,激活的体素主要编码对侧半视野中的扫视方向和记忆位置,相邻的扫视方向和记忆位置在图的相邻位置表示。特定的扫视方向或记忆位置常常在图的多个位置被表示。地形激活模式在不同受试者之间显示出个体差异,但在同一受试者内是可重复的。值得注意的是,在背内侧前额叶皮质的人类辅助眼区区域仅发现与扫视相关的激活,而没有地形组织。这些结果共同表明,使用更复杂的行为任务可以在感觉皮质区域之外揭示地形组织。

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