Arai Kuniharu, Keller Edward L
The Smith-Kettlewell Eye Research Institute, 2318 Fillmore Street, San Francisco, CA, 94115, USA.
Biol Cybern. 2005 Jan;92(1):21-37. doi: 10.1007/s00422-004-0526-y. Epub 2004 Dec 10.
Variable saccade trajectories are produced in visual search paradigms in which multiple potential target stimuli are present. These variable trajectories provide a rich source of information that may lead to a deeper understanding of the basic control mechanisms of the saccadic system. We have used published behavioral observations and neural recordings in the superior colliculus (SC), gathered in monkeys performing visual search paradigms, to guide the construction of a new distributed model of the saccadic system. The new model can account for many of the variations in saccade trajectory produced by the appearance of multiple visual stimuli in a search paradigm. The model uses distributed feedback about current eye motion from the brainstem to the SC to reduce activity there at physiologically realistic rates during saccades. The long-range lateral inhibitory connections between SC cells used in previous models have been eliminated to match recent physiological evidence. The model features interactions between visually activated multiple populations of cells in the SC and distributed and topologically organized inhibitory input to the SC from the SNr to produce some of the types of variable saccadic trajectories, including slightly curved and averaging saccades, observed in visual search tasks. The distributed perisaccadic disinhibition of SC from the substantia nigra (SNr) is assumed to have broad spatial tuning. In order to produce the strongly curved saccades occasionally recorded in visual search, the existence of a parallel input to the saccadic burst generators in addition to that provided by the distributed input from the SC is required. The spatiotemporal form of this additional parallel input is computed based on the assumption that the input from the model SC is realistic. In accordance with other recent models, it is assumed that the parallel input comes from the cerebellum, but our model predicts that the parallel input is delayed during highly curved saccadic trajectories.
在存在多个潜在目标刺激的视觉搜索范式中会产生可变的扫视轨迹。这些可变轨迹提供了丰富的信息来源,可能会加深我们对扫视系统基本控制机制的理解。我们利用在执行视觉搜索范式的猴子中收集到的上丘(SC)已发表的行为观察结果和神经记录,来指导构建一个新的扫视系统分布式模型。新模型可以解释在搜索范式中多个视觉刺激出现时产生的许多扫视轨迹变化。该模型利用从脑干到SC的关于当前眼球运动的分布式反馈,以生理现实的速率在扫视期间降低那里的活动。以前模型中使用的SC细胞之间的长程侧向抑制连接已被消除,以匹配最近的生理学证据。该模型的特点是SC中多个视觉激活细胞群之间的相互作用,以及从黑质网状部(SNr)到SC的分布式和拓扑组织的抑制性输入,以产生在视觉搜索任务中观察到的一些可变扫视轨迹类型,包括轻微弯曲和平均扫视。假设来自黑质(SNr)的SC扫视周围分布式去抑制具有广泛的空间调谐。为了产生在视觉搜索中偶尔记录到的强烈弯曲的扫视,除了由SC的分布式输入提供的输入之外,还需要存在一个到扫视爆发发生器的并行输入。基于模型SC的输入是现实的这一假设,计算这种额外并行输入的时空形式。与其他最近的模型一致,假设并行输入来自小脑,但我们的模型预测,在高度弯曲的扫视轨迹期间,并行输入会延迟。