Krauzlis Richard J, Liston Dorion, Carello Christopher D
Systems Neurobiology Laboratory, Salk Institute for Biological Studies, 10010 North Torrey Pines Road, La Jolla, CA 92037, USA.
Vision Res. 2004 Jun;44(12):1445-51. doi: 10.1016/j.visres.2004.01.005.
The intermediate and deep layers of the superior colliculus (SC) compose a retinotopically organized motor map and are known to be important for the control of saccadic eye movements. However, recent studies have shown that the functions of the SC are not restricted to the motor control of saccades. The pattern of activity observed during multi-saccade movements, combined eye-head movements, and pursuit eye movements argue that activity in the SC indicates the location of the goal, but does not specify the particular movements that will be used to acquire the goal. Prior to the onset of a movement, the SC is involved in representing possible targets, as has been shown by the effects of manipulating target probability and the changes in pre-motor activity found during visual search tasks. A major unresolved issue is how target-related activity in the SC is transformed into the signal that triggers the movement. One possibility is that the levels of activity across the SC motor map correspond to the likelihood of the possible targets, and that the movement decision is based on the neural equivalent of hypothesis testing. In one version of this mechanism, the decision to select a new goal would occur each time the null hypothesis, represented by neurons in the rostral SC, was rejected in favor of an alternative represented elsewhere in the SC.
上丘（SC）的中层和深层构成了一个视网膜拓扑组织的运动图谱，并且已知其对于扫视眼动的控制非常重要。然而，最近的研究表明，上丘的功能并不局限于扫视的运动控制。在多扫视运动、联合眼头运动和跟踪眼动过程中观察到的活动模式表明，上丘中的活动指示了目标的位置，但并未指定用于获取目标的特定运动。在运动开始之前，上丘参与表征可能的目标，这已通过操纵目标概率的影响以及在视觉搜索任务中发现的运动前活动变化得到证明。一个主要未解决的问题是上丘中与目标相关的活动如何转化为触发运动的信号。一种可能性是，上丘运动图谱上的活动水平对应于可能目标的可能性，并且运动决策基于神经等效的假设检验。在这种机制的一个版本中，每次由 Rostral SC 中的神经元代表的原假设被拒绝而支持上丘其他地方代表的备择假设时，就会做出选择新目标的决定。
