Two Phases of V1 Activity for Visual Recognition of Natural Images
Two Phases of V1 Activity for Visual Recognition of Natural Images
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DOI：
10.1162/jocn.2009.21253
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发表时间：
2010-06-01
影响因子：
3.2
通讯作者：
Pascual-Leone, Alvaro
中科院分区：
文献类型：
--
作者：
Camprodon, Joan A.;Zohary, Ehud;Pascual-Leone, Alvaro
目前的视觉识别理论强调在给定的网络中跨神经元群体的交互处理的作用，但这些交互作用的性质仍然没有得到解决。特别是，描述有意识视觉的前馈算法的充分性的数据，以及揭示反馈连接与纹状皮质的功能相关性的研究，似乎对视觉信息处理提供了相互矛盾的描述。TMS是一个很好的实验解决这个问题的方法，因为它具有极好的时间分辨率和建立大脑功能和行为之间的因果关系的能力。我们研究了20名健康志愿者的视觉识别任务。研究人员向受试者简要展示了自然场景中动物(鸟类或哺乳动物)的图像，并要求他们指出动物的类别。采用MRI引导的单次TMS立体定位脉冲，在成像开始后不同时间对纹状体皮质功能进行一过性干扰。当TMS在100毫秒和220毫秒的SOAS作用于枕极时，视觉识别能力显著受损。第一个间期在先前的TMS研究中得到了一致的描述，并被解释为前馈抽射活动的中断。考虑到第二个峰的延迟和离散性质，我们假设它代表了对V1的反馈投影的中断，可能来自视觉网络中的其他区域。这些结果为在自然复杂图像的视觉识别中通过前馈和反馈连接进行反复交互处理的必要性提供了因果证据。
Present theories of visual recognition emphasize the role of interactive processing across populations of neurons within a given network, but the nature of these interactions remains unresolved. In particular, data describing the sufficiency of feedforward algorithms for conscious vision and studies revealing the functional relevance of feedback connections to the striate cortex seem to offer contradictory accounts of visual information processing. TMS is a good method to experimentally address this issue, given its excellent temporal resolution and its capacity to establish causal relations between brain function and behavior. We studied 20 healthy volunteers in a visual recognition task. Subjects were briefly presented with images of animals (birds or mammals) in natural scenes and were asked to indicate the animal category. MRI-guided stereotaxic single TMS pulses were used to transiently disrupt striate cortex function at different times after image onset (SOA). Visual recognition was significantly impaired when TMS was applied over the occipital pole at SOAs of 100 and 220 msec. The first interval has consistently been described in previous TMS studies and is explained as the interruption of the feedforward volley of activity. Given the late latency and discrete nature of the second peak, we hypothesize that it represents the disruption of a feedback projection to V1, probably from other areas in the visual network. These results provide causal evidence for the necessity of recurrent interactive processing, through feedforward and feedback connections, in visual recognition of natural complex images.