Top-down modulation of early sensory cortex
Top-down modulation of early sensory cortex
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DOI：
10.1093/cercor/7.3.193
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发表时间：
1997-04-01
期刊：
影响因子：
3.7
通讯作者：
Petersen, SE
中科院分区：
文献类型：
--
作者：
Shulman, GL;Corbetta, M;Petersen, SE
从九个以前的研究人类的视觉信息处理，使用正电子发射断层扫描的数据进行了重新分析，以对比血流反应在被动观看和主动歧视相同的刺激阵列。该分析检查了主动视觉处理是否（i）增加视觉层次早期内侧视觉区的血流量，以及（ii）减少听觉和躯体感觉皮层的血流量。在9项研究中，有6项观察到内侧视觉区域的显著调制，表明自上而下的过程可以影响早期视觉皮层。调制显示了几个任务的依赖性，这表明在某些情况下，潜在的机制是选择性的（如分析或功能特定），而不是非选择性的。在5项研究中的2项中观察到听觉Brodmann区（BA）左侧41/42处或附近的可复制减少，但位置不同。综合研究数据的分析得出了适度但显著的下降。在初级躯体感觉皮层中没有发现可复制的减少，但在可能是躯体感觉关联区的岛屿区域中观察到。在顶骨盖（可能是SII）和BA 40中也观察到减少。这些结果是不一致的模型中，皮层前区输入任务无关的感觉皮层区被广泛抑制。
Data from nine previous studies of human visual information processing using positron emission tomography were reanalyzed to contrast blood flow responses during passive viewing and active discriminations of the same stimulus array. The analysis examined whether active visual processing (i) increases blood flow in medial visual regions early in the visual hierarchy and (ii) decreases blood flow in auditory and somatosensory cortex. Significant modulation of medial visual regions was observed in six of nine studies, indicating that top down processes can affect early visual cortex. Modulations showed several task dependencies, suggesting that in some cases the underlying mechanism was selective (e.g. analysis-or feature-specific) rather than non-selective. Replicable decreases at or near auditory Brodmann area (BA) left 41/42 were observed in two of five studies, but in different locations. Analyses that combined data across studies yielded modest but significant decreases. Replicable decreases were not found in primary somatosensory cortex but were observed in an insular region that may be a somatosensory association area. Decreases were also noted in the parietal operculum (perhaps SII) and BA 40. These results are inconsistent with a model in which the precortical input to task-irrelevant sensory cortical areas is broadly suppressed.