Breton Yannick-André, Seeland Kelsey D, Redish A David
Department of Neuroscience, University of Minnesota Minneapolis, MN, USA.
Front Aging Neurosci. 2015 Mar 27;7:41. doi: 10.3389/fnagi.2015.00041. eCollection 2015.
Inter-temporal choice depends on multiple, interacting systems, some of which may be compromised with age. Some of these systems may be responsible for ongoing trial-by-trial choice strategies. Some may represent the consequences of action. Some may be necessary for the coupling between anticipated consequences and strategies currently in use, flexibly guiding behavior. When faced with a difficult decision, rats will orient back and forth, a behavior termed "vicarious trial and error" (VTE). Recent experiments have linked the occurrence of VTE to hippocampal search processes and behavioral flexibility. We tested 5 month (n = 6), 9 month (n = 8) and over-27 month-old (n = 10) rats on a Spatial Adjusting Delay Discounting task to examine how aging impacted lap-by-lap strategies and VTE during inter-temporal choice. Rats chose between spatially separated food goals that provided a smaller-sooner or larger-later reward. On each lap, the delay to the larger-later reward was adjusted as a function of the rat's decisions, increasing by 1 s after delayed-side choices and decreasing by 1 s after non-delayed side choices. The strategies that aged rats used differed from those used in young and adult rats. Moreover, aged rats produced reliably more VTE behaviors, for protracted periods of time, uncoupled from behavioral flexibility.
跨期选择取决于多个相互作用的系统，其中一些系统可能会随着年龄增长而受损。这些系统中的一些可能负责逐次试验的选择策略。一些可能代表行动的后果。一些可能是预期后果与当前使用的策略之间耦合所必需的，从而灵活地指导行为。当面对困难的决策时，大鼠会来回定向，这种行为被称为“替代性试错”（VTE）。最近的实验将VTE的发生与海马体搜索过程和行为灵活性联系起来。我们在空间调整延迟折扣任务中测试了5个月大（n = 6）、9个月大（n = 8）和超过27个月大（n = 10）的大鼠，以研究衰老如何影响跨期选择过程中的逐圈策略和VTE。大鼠在空间上分开的食物目标之间进行选择，这些目标提供较小但更快或较大但更晚的奖励。在每一圈中，较大但更晚奖励的延迟会根据大鼠的决策进行调整，在选择延迟一侧后增加1秒，在选择非延迟一侧后减少1秒。老年大鼠使用的策略与年轻和成年大鼠不同。此外，老年大鼠在很长一段时间内可靠地产生了更多的VTE行为，且与行为灵活性无关。
