Lappe M, Bremmer F, Pekel M, Thiele A, Hoffmann K P
Department of Zoology and Neurobiology, Ruhr University Bochum, Germany.
J Neurosci. 1996 Oct 1;16(19):6265-85. doi: 10.1523/JNEUROSCI.16-19-06265.1996.
How does the brain process visual information about self-motion? In monkey cortex, the analysis of visual motion is performed by successive areas specialized in different aspects of motion processing. Whereas neurons in the middle temporal (MT) area are direction-selective for local motion, neurons in the medial superior temporal (MST) area respond to motion patterns. A neural network model attempts to link these properties to the psychophysics of human heading detection from optic flow. It proposes that populations of neurons represent specific directions of heading. We quantitatively compared single-unit recordings in area MST with single-neuron simulations in this model. Predictions were derived from simulations and subsequently tested in recorded neurons. Neuronal activities depended on the position of the singular point in the optic flow. Best responses to opposing motions occurred for opposite locations of the singular point in the visual field. Excitation by one type of motion is paired with inhibition by the opposite motion. Activity maxima often occur for peripheral singular points. The averaged recorded shape of the response modulations is sigmoidal, which is in agreement with model predictions. We also tested whether the activity of the neuronal population in MST can represent the directions of heading in our stimuli. A simple least-mean-square minimization could retrieve the direction of heading from the neuronal activities with a precision of 4.3 degrees. Our results show good agreement between the proposed model and the neuronal responses in area MST and further support the hypothesis that area MST is involved in visual navigation.
大脑如何处理关于自身运动的视觉信息？在猴脑皮层中，视觉运动分析是由专门负责运动处理不同方面的连续区域完成的。颞中区（MT）的神经元对局部运动具有方向选择性，而颞上内侧区（MST）的神经元则对运动模式做出反应。一个神经网络模型试图将这些特性与基于光流的人类航向检测心理物理学联系起来。该模型提出，神经元群体代表特定的航向方向。我们对MST区的单单元记录与该模型中的单神经元模拟进行了定量比较。预测来自模拟，并随后在记录的神经元中进行测试。神经元活动取决于光流中奇点的位置。对于视野中奇点的相反位置，会出现对相反运动的最佳反应。一种运动的兴奋与相反运动的抑制相配对。活动最大值通常出现在周边奇点处。记录的反应调制的平均形状呈S形，这与模型预测一致。我们还测试了MST区神经元群体的活动是否能够代表我们刺激中的航向方向。一个简单的最小均方最小化方法能够以4.3度的精度从神经元活动中检索出航向方向。我们的结果表明，所提出的模型与MST区的神经元反应之间具有良好的一致性，并进一步支持了MST区参与视觉导航的假设。
