Department of Psychology, University of California Berkeley, Berkeley, CA 94720, USA.
Neuron. 2013 May 8;78(3):554-62. doi: 10.1016/j.neuron.2013.03.010.
How is visual space represented in cortical area MT+? At a relatively coarse scale, the organization of MT+ is debated; retinotopic, spatiotopic, or mixed representations have all been proposed. However, none of these representations entirely explain the perceptual localization of objects at a fine spatial scale--a scale relevant for tasks like navigating or manipulating objects. For example, perceived positions of objects are strongly modulated by visual motion; stationary flashes appear shifted in the direction of nearby motion. Does spatial coding in MT+ reflect these shifts in perceived position? We performed an fMRI experiment employing this "flash-drag" effect and found that flashes presented near motion produced patterns of activity similar to physically shifted flashes in the absence of motion. This reveals a motion-dependent change in the neural representation of object position in human MT+, a process that could help compensate for perceptual and motor delays in localizing objects in dynamic scenes.
大脑中 MT+ 区域如何表示视觉空间？在相对粗糙的尺度上，MT+ 的组织尚存在争议；有人提出了视网膜映射、空间映射或混合表示。然而，这些表示都不能完全解释在精细空间尺度上对物体的感知定位，这种尺度与导航或操纵物体等任务相关。例如，物体的感知位置会受到视觉运动的强烈调制；静止的闪光在附近运动的方向上会出现位移。MT+ 中的空间编码是否反映了这些感知位置的变化？我们进行了一项 fMRI 实验，采用了这种“闪光拖拽”效应，发现运动附近呈现的闪光会产生与没有运动时物理上移位的闪光相似的活动模式。这揭示了人类 MT+ 中物体位置的神经表示依赖于运动的变化，这个过程可以帮助补偿在动态场景中定位物体时的感知和运动延迟。
