Top-down facilitation of visual recognition
Top-down facilitation of visual recognition
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DOI：
10.1073/pnas.0507062103
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发表时间：
2006-01-10
影响因子：
11.1
通讯作者：
Halgren, E
中科院分区：
文献类型：
--
作者：
Bar, M;Kassam, KS;Halgren, E
传统上认为，与视觉物体识别相关的皮质分析会沿着腹侧区域自下而上的层次结构连续传播。最近的提议逐渐促进了自上而下的加工在识别中的作用，但这种促进作用是如何被触发的仍然是一个谜。我们测试了一个特定的模型，提出低空间频率促进视觉物体识别启动自上而下的过程，从眶额投射到视觉皮层。本研究结合脑磁图，它具有上级时间分辨率，功能磁共振成像，和行为的任务，产生成功的识别与刺激重复。物体识别引起的差异活动，在左眶额皮质50毫秒前比它在颞叶皮层的识别相关领域。这种早期的眶额活动直接受到图像中低空间频率的调制。总之，我们揭示的动力学提供了强有力的支持的建议，自上而下的促进对象识别是如何启动的，我们的观察结果被用来获得未来研究的预测。
Cortical analysis related to visual object recognition is traditionally thought to propagate serially along a bottom-up hierarchy of ventral areas. Recent proposals gradually promote the role of top-down processing in recognition, but how such facilitation is triggered remains a puzzle. We tested a specific model, proposing that low spatial frequencies facilitate visual object recognition by initiating top-down processes projected from orbitofrontal to visual cortex. The present study combined magnetoencephalography, which has superior temporal resolution, functional magnetic resonance imaging, and a behavioral task that yields successful recognition with stimulus repetitions. Object recognition elicited differential activity that developed in the left orbitofrontal cortex 50 ms earlier than it did in recognition-related areas in the temporal cortex. This early orbitofrontal activity was directly modulated by the presence of low spatial frequencies in the image. Taken together, the dynamics we revealed provide strong support for the proposal of how top-down facilitation of object recognition is initiated, and our observations are used to derive predictions for future research.