Klawohn Julia, Joyner Keanan, Santopetro Nicholas, Brush C J, Hajcak Greg
Department of Psychology, Florida State University, Tallahassee, USA; Department of Medicine, MSB Medical School Berlin, Berlin, Germany.
Department of Psychology, University of California, Berkeley, USA.
J Affect Disord. 2022 Jun 15;307:294-300. doi: 10.1016/j.jad.2022.03.051. Epub 2022 Mar 24.
Depressive disorders have been associated with altered effort-cost decision making (ECDM) in behavioral investigations, such as a decreased willingness to expend effort for reward attainment. However, little is known about neural mechanisms implicated in altered ECDM.
The study investigates neural correlates of reward attainment during a progressive ratio task in participants with a current depressive disorder (n = 65) and never-depressed healthy individuals (n = 44). On each trial, participants completed an increasing number of button presses to attain a fixed monetary reward, indicated by an auditory reward signal. Participants could decide to quit the task anytime (breakpoint). EEG was recorded during the task and P300 amplitudes were examined in response to the auditory signal of reward attainment.
There was no difference in breakpoint, as both groups completed comparable numbers of button presses. In contrast, results from mixed-effects models of trial-level ERP responses indicated depression-related effects on P300 amplitudes over the course of the task. Generally, the reward-locked P300 increased with ascending effort expenditure; however, compared to healthy participants, individuals with current depression were characterized by an attenuated trajectory of the reward-locked P300, pointing towards decreased reactivity to reward attainment with increasing effort.
Sample size and reward magnitude were possibly not large enough to detect differences in breakpoint.
The results of the current study demonstrate that the investigation of reward-related P300 trajectory may represent an informative novel addition to the progressive ratio task, which could help shed light on depression-related alterations in motivation and ECDM.
在行为研究中，抑郁障碍与努力-成本决策（ECDM）改变有关，比如为获得奖励而付出努力的意愿降低。然而，对于ECDM改变所涉及的神经机制知之甚少。
本研究调查了当前患有抑郁障碍的参与者（n = 65）和从未患过抑郁症的健康个体（n = 44）在渐进比率任务中获得奖励的神经关联。在每次试验中，参与者需要完成越来越多的按键操作以获得固定的金钱奖励，奖励通过听觉奖励信号表示。参与者可以随时决定退出任务（断点）。在任务过程中记录脑电图（EEG），并检查对奖励获得的听觉信号做出反应时的P300振幅。
断点没有差异，因为两组完成的按键次数相当。相比之下，试验水平ERP反应的混合效应模型结果表明，在任务过程中，抑郁症对P300振幅有相关影响。一般来说，奖励锁定的P300随着努力支出的增加而增加；然而，与健康参与者相比，当前患有抑郁症的个体的特点是奖励锁定的P300轨迹减弱，这表明随着努力增加，对奖励获得的反应性降低。
样本量和奖励幅度可能不够大，无法检测到断点的差异。
本研究结果表明，对奖励相关P300轨迹的研究可能是渐进比率任务中一个有用的新补充，这有助于揭示与抑郁症相关的动机和ECDM改变。
