Palanca Ben J A, DeAngelis Gregory C
Department of Anatomy and Neurobiology, Washington University School of Medicine, St. Louis, Missouri 63110, USA.
J Neurosci. 2003 Aug 20;23(20):7647-58. doi: 10.1523/JNEUROSCI.23-20-07647.2003.
The middle temporal (MT) visual area is widely accepted to play important roles in motion processing. It is unclear, however, whether MT contributes to visual perception during the viewing of static scenes, when there is little retinal image motion during the interval between saccades. Some previous studies suggest that MT neurons give little or no response to stationary stimuli that are flashed onto the receptive field, but no previous study has directly examined the fidelity with which MT neurons code visual information in moving versus stationary stimuli. In this study, we compare the ability of MT neurons to signal binocular disparity in moving versus stationary random-dot stereograms. Although responses to moving stimuli are typically stronger, many MT neurons give robust responses to stationary stereograms, and some MT neurons actually prefer stationary patterns to those moving at any tested speed. These responses to stationary stimuli are not caused by monitor refresh or microsaccades. Disparity tuning curves for moving and stationary stimuli are nearly identical in shape for most neurons. Although the disparity discriminability of MT neurons is generally higher for moving stereograms when responses are averaged over the entire 1.5 sec trial epoch, discriminability is comparable for moving and stationary stimuli during the first 200-300 msec of the response. Thus, in a normal time interval between saccades, MT neurons signal the binocular disparity of stationary stimuli with high fidelity. These findings show that MT can be a reliable source of visual information during the viewing of static scenes.
颞中区（MT）视觉区域在运动处理中发挥重要作用，这一点已得到广泛认可。然而，目前尚不清楚在扫视间隔期间视网膜图像运动很少的情况下，MT在静态场景观察过程中是否对视觉感知有贡献。此前一些研究表明，MT神经元对投射到感受野上的静止刺激几乎没有反应或完全不反应，但之前没有研究直接考察MT神经元在移动刺激与静止刺激中编码视觉信息的保真度。在本研究中，我们比较了MT神经元在移动随机点立体图和静止随机点立体图中传递双眼视差的能力。虽然对移动刺激的反应通常更强，但许多MT神经元对静止立体图有强烈反应，而且一些MT神经元实际上更喜欢静止图案，而不是任何测试速度下移动的图案。这些对静止刺激的反应不是由显示器刷新或微扫视引起的。对于大多数神经元来说，移动刺激和静止刺激的视差调谐曲线形状几乎相同。虽然在整个1.5秒试验期内对反应进行平均时，MT神经元对移动立体图的视差辨别能力通常更高，但在反应的前200 - 300毫秒内，移动刺激和静止刺激的辨别能力相当。因此，在扫视之间的正常时间间隔内，MT神经元能高保真地传递静止刺激的双眼视差。这些发现表明，在观察静态场景时，MT可以是视觉信息的可靠来源。
