Connections of the Dorsomedial Visual Area: Pathways for Early Integration of Dorsal and Ventral Streams in Extrastriate Cortex
Connections of the Dorsomedial Visual Area: Pathways for Early Integration of Dorsal and Ventral Streams in Extrastriate Cortex
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DOI：
10.1523/jneurosci.0529-09.2009
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发表时间：
2009-04-08
影响因子：
5.3
通讯作者：
Galletti, Claudio
中科院分区：
文献类型：
--
作者：
Rosa, Marcello G. P.;Palmer, Susan M.;Galletti, Claudio
背内侧区（DM）是灵长类动物纹状皮层（V1）投射的主要目标，是纹状皮层（V1）的一个分支，其特征是有大量髓鞘形成，相对强调周边视觉。在这里，我们将逆行示踪剂注射到狨猴的整个区域，并对其传入连接的数值强度和层流模式进行了定量分析。我们发现，来自V1和第二视觉区域（V2）的前馈投影占DM输入的一半以上，其余绝大多数连接来自其他地形组织的视觉皮层。丘脑外投射到下丘脑的比例大致相等，它们分别来自相邻的内侧枕顶区、以颞中区（MT）为中心的颞上运动敏感复合体和腹侧流相关区域。来自后顶叶皮质和其他关联区域的反馈占连接的< 10%。这些结果不支持DM与背流内侧亚回路特异性相关的假设，背流内侧亚回路对视觉运动整合很重要。相反，他们认为一个早期的视觉处理节点能够跨皮质流发挥作用，就像V1和V2一样。因此，虽然右脑在为引导的身体运动（通常依赖于周边视觉中包含的信息）提供视觉输入方面可能很重要，但该区域也可能参与其他需要整合广泛视觉空间的功能，如自我运动感知和轮廓完成。
The dorsomedial area (DM), a subdivision of extrastriate cortex characterized by heavy myelination and relative emphasis on peripheral vision, remains the least understood of the main targets of striate cortex (V1) projections in primates. Here we placed retrograde tracer injections encompassing the full extent of this area in marmoset monkeys, and performed quantitative analyses of the numerical strengths and laminar patterns of its afferent connections. We found that feedforward projections from V1 and from the second visual area (V2) account for over half of the inputs to DM, and that the vast majority of the remaining connections come from other topographically organized visual cortices. Extrastriate projections to DM originate in approximately equal proportions from adjacent medial occipitoparietal areas, from the superior temporal motion-sensitive complex centered on the middle temporal area (MT), and from ventral stream-associated areas. Feedback from the posterior parietal cortex and other association areas accounts for < 10% of the connections. These results do not support the hypothesis that DM is specifically associated with a medial subcircuit of the dorsal stream, important for visuomotor integration. Instead, they suggest an early-stage visual-processing node capable of contributing across cortical streams, much as V1 and V2 do. Thus, although DM may be important for providing visual inputs for guided body movements ( which often depend on information contained in peripheral vision), this area is also likely to participate in other functions that require integration across wide expanses of visual space, such as perception of self-motion and contour completion.