Prior Expectations Bias Sensory Representations in Visual Cortex
Prior Expectations Bias Sensory Representations in Visual Cortex
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DOI：
10.1523/jneurosci.0742-13.2013
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发表时间：
2013-10-09
影响因子：
5.3
通讯作者：
de lange, Floris P.
中科院分区：
文献类型：
--
作者：
Kok, Peter;Brouwer, Gijs Joost;de lange, Floris P.
感知受到期望的强烈影响。因此，感知有时被视为一种推理过程，感官输入与先验知识相结合。然而，尽管有大量的行为文献支持感知作为概率推理的解释，但这一过程背后的神经机制在很大程度上仍然未知。一个重要的问题是，自上而下的期望是否会使早期感觉皮层的刺激表征产生偏差，即，先验知识和自下而上的输入的整合是否已经在感觉处理的最早层次上被观察到。或者，早期的感觉处理可能不受自上而下的期望，和整合的先验知识和自下而上的输入可能发生在下游的关联领域，被建议参与知觉决策。在此，我们隐式地操纵了人类被试对视觉运动刺激的先验期望，并探讨了视觉运动刺激对视觉皮层知觉和感觉表征的影响。为此，我们使用功能磁共振成像非侵入性地测量神经活动，并应用前向建模方法从视觉皮层中的信号重建感知刺激的运动方向。我们的研究结果表明，自上而下的期望偏见表示在视觉皮层，表明先前的信息和感官输入的整合反映在感官处理的最早阶段。
Perception is strongly influenced by expectations. Accordingly, perception has sometimes been cast as a process of inference, whereby sensory inputs are combined with prior knowledge. However, despite a wealth of behavioral literature supporting an account of perception as probabilistic inference, the neural mechanisms underlying this process remain largely unknown. One important question is whether top-down expectation biases stimulus representations in early sensory cortex, i.e., whether the integration of prior knowledge and bottom-up inputs is already observable at the earliest levels of sensory processing. Alternatively, early sensory processing may be unaffected by top-down expectations, and integration of prior knowledge and bottom-up input may take place in downstream association areas that are proposed to be involved in perceptual decision-making. Here, we implicitly manipulated human subjects' prior expectations about visual motion stimuli, and probed the effects on both perception and sensory representations in visual cortex. To this end, we measured neural activity noninvasively using functional magnetic resonance imaging, and applied a forward modeling approach to reconstruct the motion direction of the perceived stimuli from the signal in visual cortex. Our results show that top-down expectations bias representations in visual cortex, demonstrating that the integration of prior information and sensory input is reflected at the earliest stages of sensory processing.