Functional roles of cortico-basal gangila loops in conditional motor learning

为了研究前额叶皮质在任意视觉运动联想中的功能作用，我们记录了一只行为猴在条件视觉运动学习过程中内侧前额叶皮质(9M区)的神经元活动。研究人员向猴子提供了一个提示视觉刺激，并根据提示推、拉或转动机械手所需的一段延迟时间。在控制条件下，三个线索指示猴子在一组试验中做出三种反应。经过几个月的训练，这只动物已经熟悉了这些联系。在学习条件下，三条熟悉的线索中的两条和一条新颖的线索被呈现在一个区块中。猴子需要通过反复试验来学习一种新的线索-反应联系。9M区神经元对线索呈现有反应。无论线索是熟悉的还是新颖的，线索的反应都会发生变化。一组9M区神经元对一种新的线索有反应，但对熟悉的线索没有反应。另一组神经元对熟悉的线索有反应，但对新的线索没有反应。在这些熟悉的线索选择神经元的一个亚群中，学习条件下的线索反应比对照条件下的增强。这些结果表明，线索熟悉性存在于9M区活动中，或该活动可能参与了视觉运动联想学习中的动作选择。

In order to examine functional roles of the prefrontal cortex in arbitrary visuomotor association, we recorded neuronal activity in the medial prefrontal cortex, area 9m, of a behaving monkey during conditional visuomotor learning. The monkey was presented a cueing visual stimulus, and following a delay period required to push, pull, or turn a manipulator according to the cue. Under the control condition three cues instructed the monkey to the three responses in a block of trials. After a few months of training the animal was familiar with these associations. Under the learning condition, two of the three familiar cues and one novel cue were presented in a block. The monkey needed to learn a new cue-response association by trial and error. Area 9m neurons responded to cue presentation. The Cue responses changed whether a cue was familiar or novel. A group of area 9m neurons responded to a novel cue, bur not to familiar ones. Other group of neurons responded to familiar cues, but not to a novel one. In a subgroup of these familiar cue-selective neurons the cue responses were enhanced under the learning condition compared to the control condition. These results suggest that cue familiarity is represented in area 9m activity and/or that the activity may be involved in action selection during the arbitrary visuomotor association learning.