Department of Psychiatry, Depression and Anxiety Center for Discovery and Treatment, Icahn School of Medicine at Mount Sinai, New York, New York, United States of America.
Department of Psychiatry, Icahn School of Medicine at Mount Sinai, New York, New York, United States of America.
PLoS One. 2020 May 19;15(5):e0232949. doi: 10.1371/journal.pone.0232949. eCollection 2020.
Insight into motivational processes may be gained by examining measures of willingness to exert effort for rewards, which have been linked to neuropsychiatric symptoms of anhedonia and apathy. However, while much work has focused on the development of models of motivation based on classic tasks of externally-generated levels of effort for reward, there has been less focus on the question of self-generated motivation or volition. We developed a task that aims to capture separate measures of self-generated and externally-generated motivation, with two task variants for physical and cognitive effort, and sought to test and validate this measure in two populations of healthy volunteers (N = 27 and N = 28). Similar to previous reports, a sigmoid function represented a better overall fit to the effort-reward data than a linear or Weibull model. Individual sigmoid function shapes were governed by two free parameters: bias (the amount of reward needed for effort initiation) and reward insensitivity (the amount of increase in reward needed to accelerate effort expenditure). For both physical and cognitive effort, bias was higher in the self-generated condition, indicating reduced self-generated volitional effort initiation, compared to externally-generated effort initiation, across effort domains. Bias against initial effort initiation in the self-generated condition was related to a specific dimensional measure of anticipatory anhedonia. For physical effort only, reward insensitivity was also higher in the self-generated condition compared to the externally-generated motivation condition, indicating lower self-generated effort acceleration. This work provides a novel objective measure of self-generated motivation that may provide insights into mechanisms of anhedonia and related symptoms.
通过考察为获得奖励而付出努力的意愿程度的测量指标，可以深入了解动机过程，因为这些指标与快感缺失和冷漠等神经精神症状有关。然而，虽然大量工作集中在基于经典外部产生的努力水平的奖励的动机模型的开发上，但对自我产生的动机或意志的问题关注较少。我们开发了一项任务，旨在分别测量自我产生和外部产生的动机，有两种用于体力和认知努力的任务变体，并试图在两个健康志愿者群体（N=27 和 N=28）中测试和验证该测量方法。与之前的报告类似，与线性或威布尔模型相比，S 形函数更能代表努力-奖励数据的整体拟合度。个体 S 形函数的形状由两个自由参数决定：偏差（努力启动所需的奖励量）和奖励不敏感性（需要增加多少奖励来加速努力支出）。对于体力和认知努力，自我产生条件下的偏差较高，表明与外部产生的努力启动相比，自我产生的意志努力启动减少，跨越努力领域。自我产生条件下初始努力启动的偏差与预期快感缺失的特定维度测量指标有关。仅对于体力劳动，自我产生条件下的奖励不敏感性也高于外部产生动机条件下的奖励不敏感性，表明自我产生的努力加速较低。这项工作提供了一种新的自我产生动机的客观测量方法，可能为快感缺失和相关症状的机制提供深入了解。
