2014年2月12日水曜日

Cortical Correlates of Human Motion Perception Biases

Brett Vintch and Justin L. Gardner
J. Neurosci. 2014;34 2592-2604
http://www.jneurosci.org/cgi/content/abstract/34/7/2592?etoc

理研時代にものすごくお世話になった Justinの論文.
「動く物体のスピードを知覚する際に存在する偏り」とそれに対応する一次視覚野(V1)の活動。
デコーディング,forward-encoding解析などを使用。

Human sensory perception is not a faithful reproduction of the sensory environment. For example, at low contrast, objects appear to move slower and flicker faster than veridical. Although these biases have been observed robustly, their neural underpinning is unknown, thus suggesting a possible disconnect of the well established link between motion perception and cortical responses. We used functional imaging to examine the encoding of speed in the human cortex at the scale of neuronal populations and asked where and how these biases are encoded. Decoding, voxel population, and forward-encoding analyses revealed biases toward slow speeds and high temporal frequencies at low contrast in the earliest visual cortical regions, matching perception. These findings thus offer a resolution to the disconnect between cortical responses and motion perception in humans. Moreover, biases in speed perception are considered a leading example of Bayesian inference because they can be interpreted as a prior for slow speeds. Therefore, our data suggest that perceptual priors of this sort can be encoded by neural populations in the same early cortical areas that provide sensory evidence.

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