A new perceptual illusion reveals mechanisms of sensory decoding
A new perceptual illusion reveals mechanisms of sensory decoding
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DOI：
10.1038/nature05739
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发表时间：
2007-04-19
期刊：
影响因子：
64.8
通讯作者：
Movshon, J. Anthony
中科院分区：
文献类型：
--
作者：
Jazayeri, Mehrdad;Movshon, J. Anthony
知觉错觉通常被认为是由大脑编码感觉信号的方式产生的，并且实际上经常被用来推断感觉编码的机制(1)。但知觉错觉也可能是大脑解码感官信息的方式造成的(2)，反映了优化特定任务表现的策略。在精细辨别任务中，最准确的信息来自远离辨别边界的神经元 (3,4)，观察者似乎使用来自这些“移位”神经元的信号来优化其性能 (5,6,7)。我们想知道使用来自这些神经元的信号是否也会使感知产生偏差。在使用移动随机点刺激的精细方向辨别任务中，我们发现观察者对运动方向的感知确实偏离了边界。这种错误感知可以通过解码模型来准确描述，该模型优先对来自神经元的信号进行加权，这些神经元的响应最能区分这些方向。在应用不同解码规则的粗略辨别任务中（4），相同的刺激不会被错误感知，这表明错觉是观察者用来做出精细感知判断的解码策略的直接结果。因此，运动的主观体验并不是由感觉神经元的反应直接介导的，而是只有在这些神经元的反应被解码后才产生。
Perceptual illusions are usually thought to arise from the way sensory signals are encoded by the brain, and indeed are often used to infer the mechanisms of sensory encoding(1). But perceptual illusions might also result from the way the brain decodes sensory information(2), reflecting the strategies that optimize performance in particular tasks. In a fine discrimination task, the most accurate information comes from neurons tuned away from the discrimination boundary(3,4), and observers seem to use signals from these 'displaced' neurons to optimize their performance(5,6,7). We wondered whether using signals from these neurons might also bias perception. In a fine direction discrimination task using moving random-dot stimuli, we found that observers' perception of the direction of motion is indeed biased away from the boundary. This misperception can be accurately described by a decoding model that preferentially weights signals from neurons whose responses best discriminate those directions. In a coarse discrimination task, to which a different decoding rule applies(4), the same stimulus is not misperceived, suggesting that the illusion is a direct consequence of the decoding strategy that observers use to make fine perceptual judgments. The subjective experience of motion is therefore not mediated directly by the responses of sensory neurons, but is only developed after the responses of these neurons are decoded.