Song Joo-Hyun, Jiang Yuhong
Department of Psychology, Harvard University, 33 Kirkland Street, WJH 820, Cambridge, MA 02138, USA.
Neuroimage. 2006 Apr 15;30(3):963-72. doi: 10.1016/j.neuroimage.2005.10.006. Epub 2005 Nov 21.
Visual working memory (VWM) allows us to hold visual information briefly in our minds after its disappearance. It is important for bridging the present to the immediate past. Previous neuroscience studies on VWM have shown that several parietal, frontal, and occipitotemporal brain regions subserve this function. Those studies, however, have often focused on VWM for a single property, such as color. Yet, in behavior, the capacity of VWM is sensitive to the complexity of to-be-remembered visual features. How do different brain areas represent VWM for visual features of different complexity and for combination of features? To address this question, we used functional MRI to study the response profile of several brain regions in three VWM tasks. In all tasks, subjects saw 1 to 7 colored polygons and had to remember their color (a simple feature), shape (a complex feature), or both color and shape. Behavioral performance showed that VWM reached capacity limit at about 3 colors, 2 shapes, and 2 compound objects. In the fMRI data, we found different functional profiles for frontal, parietal, and occipitotemporal regions. Specifically, the posterior parietal cortex was sensitive to both featural and VWM load manipulations. The prefrontal regions were sensitive to VWM load manipulation but relatively insensitive to featural differences. The occipitotemporal regions were sensitive to featural differences, but not to VWM load manipulation. We propose that the response properties of these regions can jointly account for several findings in human VWM behavior.
视觉工作记忆（VWM）使我们能够在视觉信息消失后，在脑海中短暂保留这些信息。它对于连接当下与刚过去的时刻很重要。先前关于VWM的神经科学研究表明，几个顶叶、额叶和枕颞叶脑区参与了这一功能。然而，这些研究通常聚焦于单一属性的VWM，比如颜色。然而，在行为中，VWM的容量对要记忆的视觉特征的复杂性很敏感。不同脑区如何表征不同复杂性视觉特征以及特征组合的VWM呢？为了解决这个问题，我们使用功能磁共振成像来研究三个VWM任务中几个脑区的反应情况。在所有任务中，受试者看到1至7个彩色多边形，并且必须记住它们的颜色（一个简单特征）、形状（一个复杂特征）或者颜色和形状两者。行为表现表明，VWM在大约3种颜色、2种形状和2个复合物体时达到容量极限。在功能磁共振成像数据中，我们发现额叶、顶叶和枕颞叶区域有不同的功能特征。具体来说，顶叶后皮质对特征和VWM负荷操作都敏感。前额叶区域对VWM负荷操作敏感，但对特征差异相对不敏感。枕颞叶区域对特征差异敏感，但对VWM负荷操作不敏感。我们认为，这些区域的反应特性可以共同解释人类VWM行为中的几个发现。
