Visual representations are dominated by intrinsic fluctuations correlated between areas.
Visual representations are dominated by intrinsic fluctuations correlated between areas.
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DOI：
10.1016/j.neuroimage.2015.04.026
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发表时间：
2015-07-01
期刊：
影响因子：
5.7
通讯作者：
Kriegeskorte N
中科院分区：
文献类型：
--
作者：
Henriksson L;Khaligh-Razavi SM;Kay K;Kriegeskorte N
在动物模型中，固有的皮质动力学被认为是视觉诱发反应的试验到试验的可变性的基础。理解它们在感觉加工和表征方面的功能是当前的一个主要挑战。在这里，我们报告了内在的皮质动力学强烈地影响了大脑区域的表征几何，反映在反应模式的不同上，并夸大了大脑区域之间表征的相似性。我们通过由自然图像刺激的fMRI响应模式构建的表征相异矩阵(RDM)来表征几个人类视觉区域的表征。当基于相同的试验(共享固有的皮质动力学)来估计反应模式时，不同视觉区域的RDM非常相似，而当基于单独的试验来估计模式时(仅共享刺激驱动成分)，不同视觉区域的RDM非常不同。我们表明，表征几何形状的更大相似性可以用视觉皮质内区域平均激活的相干波动来解释，这反映了内在的动力学。使用单独的试验来研究刺激驱动的表征，发现表征几何之间有更明显的区别：Gabor小波金字塔模型解释了视觉区域V1-3的表征几何，而对象反应侧枕皮质的绝对动画-无生命模型解释了表征几何。
Intrinsic cortical dynamics are thought to underlie trial-to-trial variability of visually evoked responses in animal models. Understanding their function in the context of sensory processing and representation is a major current challenge. Here we report that intrinsic cortical dynamics strongly affect the representational geometry of a brain region, as reflected in response-pattern dissimilarities, and exaggerate the similarity of representations between brain regions. We characterized the representations in several human visual areas by representational dissimilarity matrices (RDMs) constructed from fMRI response-patterns for natural image stimuli. The RDMs of different visual areas were highly similar when the response-patterns were estimated on the basis of the same trials (sharing intrinsic cortical dynamics), and quite distinct when patterns were estimated on the basis of separate trials (sharing only the stimulus-driven component). We show that the greater similarity of the representational geometries can be explained by coherent fluctuations of regional-mean activation within visual cortex, reflecting intrinsic dynamics. Using separate trials to study stimulus-driven representations revealed clearer distinctions between the representational geometries: a Gabor wavelet pyramid model explained representational geometry in visual areas V1–3 and a categorical animate–inanimate model in the object-responsive lateral occipital cortex.