Attention and biased competition in multi-voxel object representations
Attention and biased competition in multi-voxel object representations
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DOI：
10.1073/pnas.0907330106
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发表时间：
2009-12-15
影响因子：
11.1
通讯作者：
VanRullen, Rufin
中科院分区：
文献类型：
--
作者：
Reddy, Leila;Kanwisher, Nancy G.;VanRullen, Rufin
偏置竞争理论在单神经元水平上解释了注意力效应：它预测神经元对错误呈现的刺激的反应是对孤立刺激的反应的加权平均，注意力使权重偏向于关注的刺激。然而，感知并不依赖于单个神经元，而是依赖于更大的神经元群体。这些人群的反应部分反映在大规模的多体素功能磁共振成像激活模式。由于神经元反应汇集成血氧水平依赖的信号是非线性的，注意力的功能磁共振成像效应不需要反映在神经元水平上观察到的结果。因此，为了弥合神经元反应和人类感知之间的差距，理解注意力对错误呈现对象的大规模多元表征的影响是至关重要的。在这里，我们问如何反应同时刺激相结合的多体素功能磁共振成像模式，以及注意力如何影响配对的反应。来自四个类别的对象被单独呈现，或成对呈现，使得每个类别被关注，无人关注，或注意力在两者之间分配。在多维体素空间中，对错误呈现的类别的响应被很好地描述为加权平均。权重偏向于类别选择区域中的首选类别。与单单位报告一致，注意力转移的权重约30%，有利于出席刺激。这些发现将偏置竞争框架扩展到大规模多体素大脑激活的领域。
The biased-competition theory accounts for attentional effects at the single-neuron level: It predicts that the neuronal response to simultaneously-presented stimuli is a weighted average of the response to isolated stimuli, and that attention biases the weights in favor of the attended stimulus. Perception, however, relies not on single neurons but on larger neuronal populations. The responses of such populations are in part reflected in large-scale multivoxel fMRI activation patterns. Because the pooling of neuronal responses into blood-oxygen-level-dependent signals is non-linear, fMRI effects of attention need not mirror those observed at the neuronal level. Thus, to bridge the gap between neuronal responses and human perception, it is fundamental to understand attentional influences in large-scale multivariate representations of simultaneously-presented objects. Here, we ask how responses to simultaneous stimuli are combined in multivoxel fMRI patterns, and how attention affects the paired response. Objects from four categories were presented singly, or in pairs such that each category was attended, unattended, or attention was divided between the two. In a multidimensional voxel space, the response to simultaneously-presented categories was well described as a weighted average. The weights were biased toward the preferred category in category-selective regions. Consistent with single-unit reports, attention shifted the weights by approximate to 30% in favor of the attended stimulus. These findings extend the biased-competition framework to the realm of large-scale multivoxel brain activations.