Neural Mechanisms of Head Pursuit and Predictive Orienting

猫被训练站在一个小盒子里，盯着面板中心投射的光点，并被要求定位或追逐从凝视点移动到目标的光点。当一个光点以斜面保持的方式从凝视点移动到目标物时，由于前庭-眼反射，猫咪会缓慢地向目标物移动头部，伴随着争议性的眼球运动，导致平坦的凝视轨迹，然后做出快速的头部运动和向目标物的扫视来注视目标物。从移动到静止的视觉刺激使定向潜伏期显著延长，头部和凝视速度的降低对扫视速度几乎没有影响，这表明定向有两种类型，即速度引导定向和位置引导定向，它们分别利用视觉刺激的速度和位置信号。速度导向定向又分为两种亚型。在预测定向中，头部和眼睛在刺激过程中开始移动，在光点到达目标后，凝视略有到达目标，这表明他们根据移动的视觉刺激的速度准确地预测了目标光的目标。规则定向的特点是头部和眼跳的潜伏期比预测性定向更长，预测性定向是在光点到达目标后利用刺激的位置和速度信息进行定向。猫咪顺畅地追逐光点，并通过多次纠正眼跳进行慢点运动(头部追逐)，这可能是由一条速度引导定向路径诱导的。

Cats were trained to stand in a small box and to fixate at a light spot projected on a center of the panel and were required to orient or pursuit the light spot which moved from the fixation point to a target. When a light spot moved from a fixation point to the target with ramp-hold manner, cats moved their heads slowly toward the target with the concomitant controversive eye movements due to the vestibulo-ocular reflex, resulting in a flat gaze traces and then made rapid head movements and saccades toward the target to fixate it. Switching from moving to step (stationary) visual stimuli produced pronounced prolongation of latencies of orienting and reduction of head and gaze velocities with little effects on saccade velocities, suggesting that there are two types of orienting, i.e., volocity guided and position guided orienting, which utilize velocity and position signals of visual stimuli, respectively. Velocity guided orienting were further subdivided into two subtypes. In predictive orienting, head and eyes started to move during stimulation and the gaze reached the target slightly after the light spot reached its destination, indicating that they made an accurate prediction of the destination of the target light from the velocity of the moving visual stimulus. Regular orienting was characterized by longer latencies of both head and eye saccades than the predictive orienting, in which orienting was made after the light spot reached at the target using both positional and velocity information of stimuli. Cats pursued the light spot smoothly with multiple correction saccades for slow spot movements (head pursuit), which were suggested to be induced by a pathway of velocity guided orienting.