Yajeya J, Quintana J, Fuster J M
Department of Psychiatry, School of Medicine, University of California, Los Angeles 90024.
Brain Res. 1988 Dec 6;474(2):222-30. doi: 10.1016/0006-8993(88)90437-4.
Rhesus monkeys were trained to perform two visual discrimination tasks with delayed response. In both tasks, the response depended on the color of the cue, a lighted circle in the center of a panel. Red and green guided one task, yellow and blue the other. In the course of performance, a fifth color (violet), non-relevant and inconsequential, was presented at random in the same location as the cues. All 5 stimuli were of equal brightness. Many cells in the dorsolateral prefrontal cortex (sulcus principalis and superior convexity) treated the relevant cues differently than the irrelevant stimulus. In general, cellular reactions to that stimulus were of lesser magnitude than the reactions to the cues. Cell reaction differences as a function of stimulus significance outnumbered and overshadowed differences as a function of cue-color or any other task variable. The results indicate that, during visual delay tasks, units in the dorsolateral prefrontal cortex differentiate stimuli by their behavioral significance, as well as by other stimulus attributes, including color. Because the motivational evaluation of sensory stimuli is an integral part of the cognitive processes in delay tasks (together with short-term memory and motor set), these results support the notion that the prefrontal cortex integrates motivational inputs into the structure of behavioral action.
恒河猴经过训练，能够执行两项带有延迟反应的视觉辨别任务。在这两项任务中，反应都取决于提示信号的颜色，提示信号是面板中央一个点亮的圆圈。红色和绿色引导一项任务，黄色和蓝色引导另一项任务。在执行过程中，第五种颜色（紫色）作为无关紧要的颜色，随机出现在与提示信号相同的位置。所有这5种刺激的亮度均相同。背外侧前额叶皮层（主沟和上凸面）中的许多细胞对相关提示信号和无关刺激的反应不同。一般来说，细胞对该刺激的反应强度小于对提示信号的反应。细胞反应因刺激显著性而产生的差异，在数量上超过并掩盖了因提示信号颜色或任何其他任务变量而产生的差异。结果表明，在视觉延迟任务中，背外侧前额叶皮层中的神经元通过刺激的行为显著性以及包括颜色在内的其他刺激属性来区分刺激。由于感觉刺激的动机评估是延迟任务中认知过程的一个组成部分（与短期记忆和运动准备一起），这些结果支持了前额叶皮层将动机输入整合到行为动作结构中的观点。
