Ferrera V P, Lisberger S G
University of California at San Francisco, Department of Physiology, W. M. Keck Foundation Center for Integrative Neuroscience 94143, USA.
J Neurosci. 1995 Nov;15(11):7472-84. doi: 10.1523/JNEUROSCI.15-11-07472.1995.
Two rhesus monkeys were trained to track a small moving target in the presence of a moving distractor. The target and distractor were distinguished by their color. Smooth pursuit eye movements were quantified in terms of the latency of the eye movement and the open-loop eye acceleration profile. Smooth pursuit latencies for single targets were on the order of 100 msec. When the target was paired with a distractor moving in the same direction as the target, pursuit latencies decreased to roughly 85 msec. When the target was paired with a distractor moving in the opposite direction, pursuit latencies increased to roughly 150 msec. The motion of the distractor had no significant effect on the eye acceleration profile. Experiments were performed to dissociate visual search for the target from pursuit initiation by providing a spatial cue rather than the color cue. These experiments showed that visual search necessarily preceded pursuit initiation only when the distractor moved in the opposite direction relative to the target. In this case, visual search contributed about 25 msec to the overall latency of pursuit. Control experiments showed that the monkey need not attend to the distractor in order for it to influence the latency of pursuit. A network model was developed in which units that represent the motions of the target and distractor compete against one another. Attention serves to bias the outcome of this competition toward the direction of the selected target. The performance of this network exhibits a striking parallel to the effect of the distractor on smooth pursuit latency.
训练了两只恒河猴在有移动干扰物的情况下追踪一个小的移动目标。目标和干扰物通过颜色来区分。根据眼动潜伏期和开环眼加速度曲线对平稳跟踪眼动进行了量化。单个目标的平稳跟踪潜伏期约为100毫秒。当目标与一个与目标同向移动的干扰物配对时，跟踪潜伏期降至约85毫秒。当目标与一个反向移动的干扰物配对时，跟踪潜伏期增加到约150毫秒。干扰物的运动对眼加速度曲线没有显著影响。通过提供空间线索而非颜色线索进行实验，以将对目标的视觉搜索与跟踪启动区分开来。这些实验表明，只有当干扰物相对于目标反向移动时，视觉搜索才必然先于跟踪启动。在这种情况下，视觉搜索对跟踪的总潜伏期贡献约25毫秒。对照实验表明，猴子无需关注干扰物，干扰物就能影响跟踪潜伏期。开发了一个网络模型，其中代表目标和干扰物运动的单元相互竞争。注意力有助于使这种竞争的结果偏向所选目标的方向。该网络的性能与干扰物对平稳跟踪潜伏期的影响表现出惊人的相似。
