The functions and roles of parallel motion processes

人类视觉系统有两种不同的视觉运动机制，它们的最敏感速度不同。然而，慢动作的机制以及它与快动作的相互作用尚不清楚。通过心理物理方法和功能磁共振成像方法中的方向选择自适应技术和心理物理学中的掩蔽技术来解决这些问题。心理物理结果表明，存在两种不同的运动系统，具有不同的时空调节。功能磁共振成像结果表明，这两种运动系统存在于不同的视觉区域：第一运动系统在MT中，慢动作系统在V4中。结果表明，与静止时相比，运动时的刺激有向高时间频率扩展的趋势。这些结果可能表明，这两个不同的运动系统存在于不同的皮质部位，发挥不同的功能。

Human visual system is suggested to have two kinds of visual motion mechanisms that differ in their most sensitive velocity. However, the mechanisms of very slow motion, and its interaction with the fast motion are unclear. We addressed these issues with a direction selective adaptation technique in both psychophysical and fMRI methods, and with a masking technique in psychophysics.Psychophysical results showed that there are two different motion systems with different spatiotemporal tunings.fMRI results showed that the two motion systems exist in different visual areas: first motion system in MT+ and slow motion system in V4.We also investigated the spatiotemporal stimulation on retina in everyday life. The results showed tendency that the stimulation extends to high temporal frequencies when people are moving comparing with when people are immobile. These results may indicate that the two different motion systems exist at different cortical sites and works for different functions.