Boch R, Fischer B
Exp Brain Res. 1983;50(2-3):201-10. doi: 10.1007/BF00239184.
Rhesus monkeys were trained to fixate a small spot and saccade to a second stimulus in the near periphery if the fixation spot went off. In different tests the target stimulus could occur at various delay times before or after the offset of the fixation spot. During periods of single unit recording from the prelunate cortex neural events were measured together with saccadic reaction times (SRT): If the stimulus was visible for a period of time (1 or 0.5 s) before the fixation spot disappeared (positive "delayed saccade" task) the SRT reached values of more than 300 ms. The SRTs were shorter when the target stimulus occurred simultaneously with the offset of the fixation spot ("saccade" task). SRT were shortest (approximately 150 ms) if the target stimulus appeared 100-250 ms after the offset of the fixation spot (negative "delayed saccade" task). Moreover, they decreased with the time of daily training. The different behavioural conditions resulted in different types of cortical activity with different latencies: In "saccade" and negative "delayed saccade" tasks the neurons on-responses could be enhanced in comparison to the passive visual on-responses during stationary fixation. The latencies of the on-response and the enhanced on-response were equal with approximately 80 ms. In striking contrast the latencies of the presaccadic activation (PSA) in the positive "delayed saccade" tasks were more than twice as long with about 200 ms. Daily training influences both the SRTs and the PSA: The SRTs become shorter by more than 150 ms in positive "delayed saccade" tasks (delay: 300-500 ms) and the percentage of PSA-neurons decrease from more than 70% to less than approximately 20% after 3 weeks of daily training and recording. The temporal aspects of events preceding visually guided eye movements are important to understand the serial and parallel processing in cortical and subcortical structures that are involved in the learning, initiation, and execution of goal directed movements.
恒河猴经过训练，学会注视一个小点，若注视点消失，就向近周边视野中的第二个刺激目标进行扫视。在不同测试中，目标刺激可在注视点消失之前或之后的不同延迟时间出现。在从前额叶皮层进行单神经元记录的期间，将神经活动与扫视反应时间（SRT）一起测量：如果在注视点消失之前刺激可见一段时间（1秒或0.5秒）（正向“延迟扫视”任务），SRT达到300毫秒以上的值。当目标刺激与注视点消失同时出现时（“扫视”任务），SRT较短。如果目标刺激在注视点消失后100 - 250毫秒出现（负向“延迟扫视”任务），SRT最短（约150毫秒）。此外，它们随着每日训练时间而减少。不同的行为条件导致具有不同潜伏期的不同类型的皮层活动：在“扫视”和负向“延迟扫视”任务中，与静止注视期间的被动视觉开启反应相比，神经元的开启反应可得到增强。开启反应和增强的开启反应的潜伏期相等，约为80毫秒。形成鲜明对比的是，在正向“延迟扫视”任务中，扫视前激活（PSA）的潜伏期要长得多，约为200毫秒。每日训练会影响SRT和PSA：在正向“延迟扫视”任务（延迟：300 - 500毫秒）中，SRT缩短超过150毫秒，经过3周的每日训练和记录后，PSA神经元的百分比从超过70%降至约20%以下。视觉引导眼球运动之前事件的时间方面对于理解参与目标导向运动的学习、启动和执行的皮层和皮层下结构中的串行和平行处理很重要。
