Saccades require a spatiotemporal transformation of activity between the intermediate layers of the superior colliculus (iSC) and downstream brainstem burst generator. The dynamic linear ensemble-coding model (Goossens and Van Opstal 2006) proposes that each iSC spike contributes a fixed mini-vector to saccade displacement. Although biologically-plausible, this model assumes cortical areas like the frontal eye fields (FEF) simply provide the saccadic goal to be executed by the iSC and brainstem burst generator. However, the FEF and iSC operate in unison during saccades, and a pathway from the FEF to the brainstem burst generator that bypasses the iSC exists. Here, we investigate the impact of large yet reversible inactivation of the FEF on iSC activity in the context of the model across four saccade tasks. We exploit the overlap of saccade vectors generated when the FEF is inactivated or not, comparing the number of iSC spikes for metrically-matched saccades. We found that the iSC emits fewer spikes for metrically-matched saccades during FEF inactivation. The decrease in spike count is task-dependent, with a greater decrease accompanying more cognitively-demanding saccades. Our results show that FEF integrity influences the readout of iSC activity in a task-dependent manner. We propose that the dynamic linear ensemble-coding model be modified so that FEF inactivation increases the gain of a readout parameter, effectively increasing the influence of a single iSC spike. We speculate that this modification could be instantiated by FEF and iSC pathways to the cerebellum that could modulate the excitability of the brainstem burst generator.

眼跳需要在上丘 (iSC) 的中间层和下游脑干爆发发生器之间进行活动的时空转换。动态线性集成编码模型（Goossens 和 Van Opstal 2006）提出，每个 iSC 尖峰都会为跳视位移贡献一个固定的小向量。尽管在生物学上是合理的，但该模型假设像额叶眼场 (FEF) 这样的皮层区域只是提供了由 iSC 和脑干脉冲发生器执行的扫视目标。然而，FEF 和 iSC 在扫视期间一致运行，并且存在从 FEF 到绕过 iSC 的脑干爆发发生器的通路。在这里，我们研究了 FEF 的大而可逆的失活在模型的背景下跨越四个扫视任务对 iSC 活动的影响。我们利用 FEF 失活或未激活时生成的扫视向量的重叠，比较度量匹配的扫视的 iSC 尖峰数量。我们发现，在 FEF 失活期间，iSC 为度量匹配的扫视发出更少的尖峰。尖峰计数的减少取决于任务，随着对认知要求更高的扫视，减少幅度更大。我们的结果表明 FEF 完整性以依赖于任务的方式影响 iSC 活动的读数。我们建议修改动态线性集成编码模型，以便 FEF 失活增加读出参数的增益，有效地增加单个 iSC 尖峰的影响。我们推测这种修饰可以通过 FEF 和 iSC 通路到小脑来实例化，这些通路可以调节脑干爆发发生器的兴奋性。