Radboud University Nijmegen, Donders Institute for Brain, Cognition and Behaviour, Kapittelweg 29, 6525 EN Nijmegen, The Netherlands.
Princeton University, Princeton Neuroscience Institute, 301 Peretsman-Scully Hall, Princeton, NJ 08544, US.
Sci Rep. 2016 Nov 22;6:37706. doi: 10.1038/srep37706.
During natural perception, we often form expectations about upcoming input. These expectations are usually multifaceted - we expect a particular object at a particular location. However, expectations about spatial location and stimulus features have mostly been studied in isolation, and it is unclear whether feature-based expectation can be spatially specific. Interestingly, feature-based attention automatically spreads to unattended locations. It is still an open question whether the neural mechanisms underlying feature-based expectation differ from those underlying feature-based attention. Therefore, establishing whether the effects of feature-based expectation are spatially specific may inform this debate. Here, we investigated this by inducing expectations of a specific stimulus feature at a specific location, and probing the effects on sensory processing across the visual field using fMRI. We found an enhanced sensory response for unexpected stimuli, which was elicited only when there was a violation of expectation at the specific location where participants formed a stimulus expectation. The neural consequences of this expectation violation, however, spread to cortical locations processing the stimulus in the opposite hemifield. This suggests that an expectation violation at one location in the visual world can lead to a spatially non-specific gain increase across the visual field.
在自然感知过程中，我们经常会对即将到来的输入形成预期。这些预期通常是多方面的——我们期望在特定位置出现特定的物体。然而，关于空间位置和刺激特征的预期大多是孤立地进行研究的，目前尚不清楚基于特征的预期是否可以具有空间特异性。有趣的是，基于特征的注意力会自动扩展到未被注意的位置。基于特征的预期的神经机制是否与基于特征的注意力的神经机制不同，这仍然是一个悬而未决的问题。因此，确定基于特征的预期的效果是否具有空间特异性可能有助于解决这一争论。在这里，我们通过在特定位置诱导特定刺激特征的预期，并使用 fMRI 探测整个视野中对感觉处理的影响来研究这个问题。我们发现，对于意外刺激，会产生增强的感觉反应，只有当在参与者形成刺激预期的特定位置发生预期违反时，才会产生这种反应。然而，这种预期违反的神经后果会扩展到处理对侧视野中刺激的皮质位置。这表明，在视觉世界中的一个位置的预期违反会导致整个视野中空间非特异性的增益增加。
