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Title: 外膝体感受野的时空频率调谐特征可以提高神经元分辨自然图像的能力
Author: 谈仲超
Degree Level: 博士
Issued Date: 2009-11-03
Degree Grantor: 中国科学院上海生命科学研究院
Place of Degree Grantor: 上海生命科学研究院
Supervisor: 姚海珊
Keyword: 外膝体 ; 自然图形 ; 时空感受野 ; 变异系数 ; 分辨度
Alternative Title: The Spatiotemporal Frequency Tuning of LGN Receptive Field Facilitates Neural Discrimination of Natural Stimuli
Major: 神经生物学
Abstract: 高效编码假说认为初级视觉通路被优化来最佳地表征外界自然环境的视觉信息,虽然外膝体被认为作为这个通路中的一个重要的环节可以去除自然电影中冗余的信息,但关于外膝体是不是会选择性地放大其中重要的信息来达到更好的分辨度还不够清楚。我们的工作就着重于外膝体细胞的时空频率选择性在处理自然电影中的功能。首先,通过定量测试外膝体细胞的时间频率和空间频率选择性,我们发现其时空频率具有不可分的性质。 这种不可分性和最优滤波器一样,恰好有助于易化对于自然电影的信息传输。接下来,我们分析了自然电影的时空功率谱,发现了其中某些区段的功率谱变异较大,而且这些变异较大的频率区段恰好吻合于外膝体细胞选择性较大的频率区段。最后,通过对比对于自然刺激和与自然刺激具有相同平均功率谱和不同功率谱变异的人造刺激的细胞反应的分辨度,可以得出这样的结论: 自然电影中变异较大的频率与外膝体细胞选择性较大的频率吻合的特性有助于提高对于自然电影的分辨率。总之,外膝体细胞的时空频率特性不仅能移除冗余信息,还能加强该神经元对于自然电影的分辨。
English Abstract: The efficient coding hypothesis suggests that the early visual system is optimized to represent stimuli in the natural environment. While it is believed that LGN processing removes the redundant information of natural scenes, it is not clear whether the early visual processing can selectively amplify important signals in natural stimuli to facilitate discrimination. In this study, we examined the functional role of LGN spatiotemporal frequency tuning in the processing of natural scenes. First, we characterized the relationship between spatial and temporal frequency tuning for LGN receptive fields. We found that LGN neurons exhibit inseparable spatiotemporal frequency tuning in a manner consistent with the feature of optimal filters that can maximize information transmission of natural scenes. Second, we analyzed the spatiotemporal power spectrum of natural scenes and found that some frequencies exhibit larger variation in power across different scenes. Interestingly, the preferred frequency of ensemble LGN neurons matches the range of frequencies in which natural power spectrum varies most. Comparison of neural discrimination for natural stimuli and for artificial stimuli with similar mean power spectra but different variation structure showed that the match between LGN tuning and natural spectra variation enhances neural discrimination for natural stimuli. Our results indicate that, in addition to removing redundancy, the spatiotemporal frequency characteristics of LGN neurons can facilitate neural discrimination of natural stimuli.
Language: 中文
Content Type: 学位论文
URI: http://ir.sibs.ac.cn/handle/331001/2354
Appears in Collections:神经所(总)_学位论文

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Recommended Citation:
外膝体感受野的时空频率调谐特征可以提高神经元分辨自然图像的能力.谈仲超[d].中国科学院上海生命科学研究院,2009.20-25
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