Risk, reward, and decision-making in a rodent model of cognitive aging
Risk, reward, and decision-making in a rodent model of cognitive aging
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DOI：
10.3389/fnins.2011.00144
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发表时间：
2012-01-01
影响因子：
4.3
通讯作者：
Bizon, Jennifer L.
中科院分区：
文献类型：
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作者：
Gilbert, Ryan J.;Mitchell, Marci R.;Bizon, Jennifer L.
老年人决策能力受损会直接影响到对老年人保持生活质量和独立性至关重要的因素(经济安全、医疗保健)。自然主义的啮齿动物模型在其他认知领域模拟了人类的衰老，并以一种相对不受经验因素影响的方式，提供了解析年龄对决策离散方面的影响的机会。年轻的成年(5-7个月)和老年(23-25个月)的雄性F344大鼠接受了概率折扣任务的训练，在这项任务中，它们在小的确定奖励(一个食物粒)和大的但不确定的奖励(两个食物粒的不同交付概率从100%到0%)之间进行离散试验选择。幼鼠在大额奖赏与递送概率高相关时选择大额奖赏，随着大额奖赏概率的降低，幼鼠转向小额但确定的奖赏。作为一个整体，老年大鼠的表现与年轻大鼠相似，但老年大鼠之间的差异明显更大。其中一组老年大鼠表现出强烈的对小而确定的奖赏的偏好。这种偏好在大额奖励发放也是确定的条件下保持，这表明对奖励大小的敏感度降低。相比之下，另一组老年大鼠表现出强烈的偏好，倾向于以较低的分娩概率获得大笔奖励。有趣的是，当奖励幅度相等时，这一亚组也表现出对概率奖励的更高偏好。之前使用相同年龄研究人群的研究结果描述了延迟奖励随着年龄的增加而显著减弱的折现，同时表明老年大鼠的一个子组可能存在与计算奖励成本(即延迟或概率)相关的缺陷。这些成本核算上的缺陷与年龄相关的对奖励大小的敏感性差异无关，这表明年龄影响着多种不同的机制，这些机制可能会影响成本效益决策。
Impaired decision-making in aging can directly impact factors (financial security, health care) that are critical to maintaining quality of life and independence at advanced ages. Naturalistic rodent models mimic human aging in other cognitive domains, and afford the opportunity to parse the effects of age on discrete aspects of decision-making in a manner relatively uncontaminated by experiential factors. Young adult (5-7 months) and aged (23-25 months) male F344 rats were trained on a probability discounting task in which they made discrete-trial choices between a small certain reward (one food pellet) and a large but uncertain reward (two food pellets with varying probabilities of delivery ranging from 100 to 0%). Young rats chose the large reward when it was associated with a high probability of delivery and shifted to the small but certain reward as probability of the large reward decreased. As a group, aged rats performed comparably to young, but there was significantly greater variance among aged rats. One subgroup of aged rats showed strong preference for the small certain reward. This preference was maintained under conditions in which large reward delivery was also certain, suggesting decreased sensitivity to reward magnitude. In contrast, another subgroup of aged rats showed strong preference for the large reward at low probabilities of delivery. Interestingly, this subgroup also showed elevated preference for probabilistic rewards when reward magnitudes were equalized. Previous findings using this same aged study population described strongly attenuated discounting of delayed rewards with age, together suggesting that a subgroup of aged rats may have deficits associated with accounting for reward costs (i.e., delay or probability). These deficits in cost-accounting were dissociable from the age-related differences in sensitivity to reward magnitude, suggesting that aging influences multiple, distinct mechanisms that can impact cost benefit decision-making.