Integration of Contour and Terminator Signals in Visual Area MT of Alert Macaque
Integration of Contour and Terminator Signals in Visual Area MT of Alert Macaque
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DOI：
10.1523/jneurosci.4387-03.2004
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发表时间：
2004-03
期刊：
影响因子：
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通讯作者：
Christopher C. Pack;Andrew J. Gartland;R. Born
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文献类型：
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作者：
Christopher C. Pack;Andrew J. Gartland;R. Born
视觉信息的整合是灵长类大脑纹外皮层神经元的一项重要任务。对于运动信号，视觉世界的几何形状使积分变得复杂，这使得一些速度测量结果模糊不清，而另一些则不正确。模糊性的出现是因为在视觉处理的早期阶段，神经元的感受野很小，只能恢复垂直于轮廓方向的运动分量（孔径问题）。无障碍运动信号位于端点和拐角处，这些端点和拐角被称为终止点。然而，当物体在遮挡表面后面移动时，在由物体和遮挡物的相交形成的终止点处进行的运动测量通常与物体运动的方向不一致。为了研究皮层神经元如何整合这些不同的运动线索，我们使用了经典的“理发杆”刺激的变化，并测量了警觉猕猴纹外皮层中颞区（MT或V5）神经元的反应。我们的研究结果表明，MT神经元更强烈的影响，由终结符产生的明确的运动信号比轮廓产生的模糊信号。此外，这些神经元对运动物体固有的终止符的反应要比对遮挡事故的反应好。V1神经元对局部线索（轮廓和终止符）表现出类似的反应模式，但对于大的刺激，它们不反映MT神经元计算的全局运动方向。这些观察结果与心理物理学的发现是一致的，这些发现表明我们对移动物体的感知通常取决于终结者的运动。
The integration of visual information is a critical task that is performed by neurons in the extrastriate cortex of the primate brain. For motion signals, integration is complicated by the geometry of the visual world, which renders some velocity measurements ambiguous and others incorrect. The ambiguity arises because neurons in the early stages of visual processing have small receptive fields, which can only recover the component of motion perpendicular to the orientation of a contour (the aperture problem). Unambiguous motion signals are located at end points and corners, which are referred to as terminators. However, when an object moves behind an occluding surface, motion measurements made at the terminators formed by the intersection of the object and the occluder are generally not consistent with the direction of object motion. To study how cortical neurons integrate these different motion cues, we used variations on the classic “barber pole” stimulus and measured the responses of neurons in the middle temporal area (MT or V5) of extrastriate cortex of alert macaque monkeys. Our results show that MT neurons are more strongly influenced by the unambiguous motion signals generated by terminators than to the ambiguous signals generated by contours. Furthermore, these neurons respond better to terminators that are intrinsic to a moving object than to those that are accidents of occlusion. V1 neurons show similar response patterns to local cues (contours and terminators), but for large stimuli, they do not reflect the global motion direction computed by MT neurons. These observations are consistent with psychophysical findings that show that our perception of moving objects often depends on the motion of terminators.