Basso M A, Wurtz R H
Laboratory of Sensorimotor Research, National Eye Institute, Bethesda, Maryland 20892-4435, USA.
Nature. 1997 Sep 4;389(6646):66-9. doi: 10.1038/37975.
Visual scenes are composed of many elements and although we can appreciate a scene as a whole, we can only move our eyes to one element of the scene at a time. As visual scenes become more complex, the number of potential targets in the scene increases, and the uncertainty that any particular one will be selected for an eye movement also increases. How motor systems accommodate this target uncertainty remains unknown. The activities of neurons in both the cerebral cortex and superior colliculus are modulated by this selection process. We reasoned that activity associated with target uncertainty should be evident in the saccadic motor system at the final stages of neural processing, in the superior colliculus. By systematically changing the number of stimuli from which a selection must be made and recording from superior colliculus neurons, we found that as the target uncertainty increased, the neural activity preceding target selection decreased. These results indicate that neurons within the final common pathway for movement generation are active well in advance of the selection of a particular movement. This early activity varies with the probability that a particular movement will be selected.
视觉场景由许多元素组成，尽管我们能够将一个场景作为一个整体来感知，但我们一次只能将眼睛移向场景中的一个元素。随着视觉场景变得更加复杂，场景中潜在目标的数量会增加，而任何特定目标被选中进行眼动的不确定性也会增加。运动系统如何适应这种目标不确定性仍然未知。大脑皮层和上丘中神经元的活动都受到这一选择过程的调节。我们推断，与目标不确定性相关的活动在神经处理的最后阶段，即上丘的扫视运动系统中应该是明显的。通过系统地改变可供选择的刺激数量并记录上丘神经元的活动，我们发现随着目标不确定性的增加，目标选择之前的神经活动会减少。这些结果表明，运动产生的最终共同通路中的神经元在特定运动选择之前就已经活跃起来。这种早期活动会随着特定运动被选中的概率而变化。
