Kane Gary A, Vazey Elena M, Wilson Robert C, Shenhav Amitai, Daw Nathaniel D, Aston-Jones Gary, Cohen Jonathan D
Department of Psychology and Neuroscience Institute, Princeton University, Princeton, NJ, 08540, USA.
Department of Biology, University of Massachusetts, Amherst, MA, 01003, USA.
Cogn Affect Behav Neurosci. 2017 Dec;17(6):1073-1083. doi: 10.3758/s13415-017-0531-y.
High levels of locus coeruleus (LC) tonic activity are associated with distraction and poor performance within a task. Adaptive gain theory (AGT; Aston-Jones & Cohen, 2005) suggests that this may reflect an adaptive function of the LC, encouraging search for more remunerative opportunities in times of low utility. Here, we examine whether stimulating LC tonic activity using designer receptors (DREADDs) promotes searching for better opportunities in a patch-foraging task as the value of a patch diminishes. The task required rats to decide repeatedly whether to exploit an immediate but depleting reward within a patch or to incur the cost of a time delay to travel to a new, fuller patch. Similar to behavior associated with high LC tonic activity in other tasks, we found that stimulating LC tonic activity impaired task performance, resulting in reduced task participation and increased response times and omission rates. However, this was accompanied by a more specific, predicted effect: a significant tendency to leave patches earlier, which was best explained by an increase in decision noise rather than a systematic bias to leave earlier (i.e., at higher values). This effect is consistent with the hypothesis that high LC tonic activity favors disengagement from current behavior, and the pursuit of alternatives, by augmenting processing noise. These results provide direct causal evidence for the relationship between LC tonic activity and flexible task switching proposed by AGT.
蓝斑（LC）紧张性活动水平较高与任务中的注意力分散和表现不佳有关。适应性增益理论（AGT；Aston-Jones和Cohen，2005年）表明，这可能反映了LC的一种适应性功能，即在效用较低时鼓励寻找更有回报的机会。在这里，我们研究了使用设计受体（DREADDs）刺激LC紧张性活动是否会在斑块觅食任务中随着斑块价值的降低而促进寻找更好的机会。该任务要求大鼠反复决定是利用斑块内即时但会耗尽的奖励，还是承担时间延迟的成本前往一个新的、更丰富的斑块。与其他任务中与高LC紧张性活动相关的行为类似，我们发现刺激LC紧张性活动会损害任务表现，导致任务参与度降低、反应时间增加和遗漏率上升。然而，这伴随着一个更具体、预测的效应：显著更早离开斑块的倾向，这最好用决策噪声增加来解释，而不是系统地更早离开（即，在更高价值时）的偏差。这种效应与高LC紧张性活动通过增加处理噪声有利于脱离当前行为并追求替代行为的假设一致。这些结果为AGT提出的LC紧张性活动与灵活任务切换之间的关系提供了直接的因果证据。
