Differential dependency on motion coherence in subregions of the human MT plus complex
Differential dependency on motion coherence in subregions of the human MT plus complex
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DOI：
10.1111/j.1460-9568.2008.06457.x
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发表时间：
2008-10-01
影响因子：
3.4
通讯作者：
Haarmeier, Thomas
中科院分区：
文献类型：
--
作者：
Becker, Hubertus G. T.;Erb, Michael;Haarmeier, Thomas
嵌入噪声的相干运动检测作为全局视觉运动处理的一种手段得到了广泛的应用。动物研究表明，这种表现与猕猴中颞叶(MT)和内侧上颞叶(MST)区域的方向敏感神经元的反应密切相关。尽管人类和非人灵长类动物的视皮层有很大的相似之处，但位于颞下沟后部的人类中颞叶复合体(MT+区)可能由MT区和MST区组成，但并不一致地发现它们具有MT和MST神经元的功能特征，即它们倾向于连贯的视觉运动。为了在人脑MT+区寻找这种偏好，本文研究了右半视野随机点运动图对血氧水平的依赖反应，作为刺激大小和点密度的函数。刺激范围是不同的，覆盖的区域等于、超过或低于猕猴MT区的平均感受野大小。与人脑MT+区的后部不同，前部及其右半球同源脑区对连贯运动的反应明显强于对非连贯运动的反应。这些差异只存在于较大的刺激，推测超过了MT区神经元的感受野大小。我们的结果表明，功能磁共振成像可以显示出人类MST区对连贯视觉运动的更强反应，前提是刺激允许在感受野内进行足够的求和。相比之下，功能性磁共振成像可能无法揭示人类MT区的同样依赖关系。
The detection of coherent motion embedded in noise has been widely used as a measure of global visual motion processing. Animal studies have demonstrated that this performance is closely linked to the responses of direction-sensitive neurons in the macaque middle temporal (MT) and medial superior temporal (MST) areas. Despite the strong similarities between the visual cortex of human and that of non-human primates, the human middle temporal complex (area MT+), located in the posterior part of the inferior temporal sulcus and presumably comprising both area MT and area MST, has not consistently been found to share the functional hallmark of MT and MST neurons, i.e. their preference for coherent rather than incoherent visual motion. In order to search for such preferences in human area MT+, blood oxygen level-dependent responses to random dot kinematograms presented in the right visual hemifield were studied here as a function of stimulus size and dot density. The stimulus extensions were varied in such a way as to cover an area either equaling, exceeding or falling below the mean receptive field size of macaque area MT. Unlike the posterior part of human area MT+, the anterior part and its right-hemisphere homolog showed significantly stronger responses to coherent than to incoherent motion. These differences were only present for large stimuli that presumably exceeded the receptive field size of neurons in area MT. Our results suggest that functional magnetic resonance imaging may reveal stronger responses to coherent visual motion in human area MST, provided that the stimulus allows for sufficient summation within the receptive fields. In contrast, functional magnetic resonance imaging may fail to reveal the same dependency for human area MT.