Cassanello Carlos R, Nihalani Abhay T, Ferrera Vincent P
Department of Neuroscience, Columbia University, and Keck-Mahoney Center for Mind and Brain, New York, New York, USA.
J Neurophysiol. 2008 Sep;100(3):1544-56. doi: 10.1152/jn.01401.2007. Epub 2008 Jul 16.
Due to delays in visuomotor processing, eye movements directed toward moving targets must integrate both target position and velocity to be accurate. It is unknown where and how target velocity information is incorporated into the planning of rapid (saccadic) eye movements. We recorded the activity of neurons in frontal eye fields (FEFs) while monkeys made saccades to stationary and moving targets. A substantial fraction of FEF neurons was found to encode not only the initial position of a moving target, but the metrics (amplitude and direction) of the saccade needed to intercept the target. Many neurons also encoded target velocity in a nearly linear manner. The quasi-linear dependence of firing rate on target velocity means that the neuronal response can be directly read out to compute the future position of a target moving with constant velocity. This is demonstrated using a quantitative model in which saccade amplitude is encoded in the population response of neurons tuned to retinal target position and modulated by target velocity.
由于视觉运动处理过程中的延迟，指向移动目标的眼球运动必须整合目标位置和速度才能准确。目前尚不清楚目标速度信息在何处以及如何被纳入快速（扫视）眼球运动的规划中。我们记录了猴子向静止和移动目标进行扫视时额叶眼区（FEF）神经元的活动。结果发现，相当一部分FEF神经元不仅编码移动目标的初始位置，还编码拦截目标所需扫视的指标（幅度和方向）。许多神经元还以近乎线性的方式编码目标速度。放电率对目标速度的准线性依赖意味着，可以直接读出神经元反应以计算匀速移动目标的未来位置。这通过一个定量模型得到了证明，在该模型中，扫视幅度在调谐到视网膜目标位置并受目标速度调制的神经元群体反应中进行编码。
