Motion mechanisms in macaque MT
Motion mechanisms in macaque MT
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DOI：
10.1152/jn.00473.2004
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发表时间：
2005-05-01
影响因子：
2.5
通讯作者：
Albright, TD
中科院分区：
文献类型：
--
作者：
Krekelberg, B;Albright, TD
猕猴中颞区（MT）对视觉运动非常敏感，大量证据表明MT的神经活动与运动感知密切相关。然而，MT神经元实现其方向选择性的机制却受到了相当少的关注。我们研究了运动能量模型作为猕猴MT运动机制的描述.我们首先证实了运动-能量模型的一个预测;猕猴-就像人类一样-当刺激与每个位移（reverse-phi）的对比度反转时，会感知到相反的运动方向。这种感知方向的逆转与MT细胞的神经反应有明显的相关性，MT细胞可以预测猴子的行为决定。其次，我们研究了多个运动能量分量是如何组合的。心理物理学的数据已经被用来证明，代表相反方向的运动能量分量是相互减去的。然而，我们的数据表明，动能分量之间的相互作用更为复杂.特别是，我们发现，一个给定的组件对由多个组件组成的刺激的反应的影响取决于其他因素，而不是单独的组件的反应。这表明在多个运动能量分量之间存在亚阈值非线性相互作用;这些可能发生在MT内或运动网络的早期阶段，如V1。我们提出了一个模型，捕捉这些组件之间的相互作用的竞争手段的复杂性。这提供了比运动能量模型中设想的相减运动相干性更好的MT响应的描述，即使当后者与增益控制机制组合时。这种竞争性的相互作用扩大了细胞的动态范围，使它们能够提供有关运动模式更微妙变化的信息，包括不纯粹是方向性的变化。
The macaque middle temporal area (MT) is exquisitely sensitive to visual motion and there is a large amount of evidence that neural activity in MT is tightly correlated with the perception of motion. The mechanisms by which MT neurons achieve their directional selectivity, however, have received considerably less attention. We investigated the motion - energy model as a description of motion mechanisms in macaque MT. We first confirmed one of the predictions of the motion - energy model; macaques - just like humans - perceive a reversed direction of motion when a stimulus reverses contrast with every displacement (reverse-phi). This reversal of perceived direction had a clear correlate in the neural responses of MT cells, which were predictive of the monkey's behavioral decisions. Second, we investigated how multiple motion - energy components are combined. Psychophysical data have been used to argue that motion - energy components representing opposite directions are subtracted from each other. Our data show, however, that the interactions among motion - energy components are more complex. In particular, we found that the influence of a given component on the response to a stimulus consisting of multiple components depends on factors other than the response to that component alone. This suggests that there are subthreshold nonlinear interactions among multiple motion - energy components; these could take place within MT or in earlier stages of the motion network such as V1. We propose a model that captures the complexity of these component interactions by means of a competitive interaction among the components. This provides a better description of the MT responses than the subtractive motion opponency envisaged in the motion - energy model, even when the latter is combined with a gain-control mechanism. The competitive interaction extends the dynamic range of the cells and allows them to provide information on more subtle changes in motion patterns, including changes that are not purely directional.