School of Psychology, Shenzhen University, Shenzhen 518060, China.
Psychiatry Research Center, Beijing Huilongguan Hospital, Beijing 100096, China.
J Affect Disord. 2024 Jul 1;356:414-423. doi: 10.1016/j.jad.2024.04.064. Epub 2024 Apr 18.
Amotivation is a typical feature in major depressive disorder (MDD), which produces reduced willingness to exert effort. The dorsolateral prefrontal cortex (DLPFC) is a crucial structure in goal-directed actions and therefore is a potential target in modulating effortful motivation. However, it remains unclear whether the intervention is effective for patients with MDD.
We employed transcranial magnetic stimulation (TMS), computational modelling and event-related potentials (ERPs) to reveal the causal relationship between the left DLPFC and motivation for effortful rewards in MDD. Fifty patients underwent both active and sham TMS sessions, each followed by performing an Effort-Expenditure for Rewards Task, during which participants chose and implemented between low-effort/low-reward and high-effort/high-reward options.
The patients showed increased willingness to exert effort for rewards during the DLPFC facilitated session, compared with the sham session. They also had a trend in larger P3 amplitude for motivated attention toward chosen options, larger CNV during preparing for effort exertion, and larger SPN during anticipating a high reward. Besides, while behavior indexes for effortful choices were negatively related to depression severity in the sham session, this correlation was weakened in the active stimulation session.
These findings provide behavioral, computational, and neural evidence for the left DLPFC on effortful motivation for rewards. Facilitated DLPFC improves motor preparation and value anticipation after making decisions especially for highly effortful rewards in MDD. Facilitated DLPFC also has a potential function in enhancing motivated attention during cost-benefit trade-off. This neuromodulation effect provides a potential treatment for improving motivation in clinics.
动机缺乏是重性抑郁障碍（MDD）的一个典型特征，它导致人们减少努力意愿。背外侧前额叶皮层（DLPFC）是目标导向行为的关键结构，因此是调节努力动机的潜在靶点。然而，对于 MDD 患者，干预是否有效仍不清楚。
我们采用经颅磁刺激（TMS）、计算建模和事件相关电位（ERPs）来揭示 MDD 中左 DLPFC 与努力获取奖赏动机之间的因果关系。50 名患者接受了真刺激和假刺激 TMS 治疗，之后分别进行了努力付出获取奖赏任务，在任务中参与者需要在低努力/低回报和高努力/高回报选项之间进行选择和实施。
与假刺激治疗相比，DLPFC 促进治疗组患者表现出更强的努力意愿来获取奖赏。他们对所选选项的动机注意的 P3 波幅也有增大趋势，在努力付出前准备阶段的 CNV 波幅增大，在预期高回报时的 SPN 波幅增大。此外，在假刺激治疗中，努力选择的行为指标与抑郁严重程度呈负相关，而在真刺激治疗中，这种相关性减弱。
这些发现为 DLPFC 对奖赏努力动机的作用提供了行为、计算和神经学证据。DLPFC 促进治疗可改善 MDD 患者做出决策后的运动准备和价值预期，尤其是对高努力要求的奖赏。DLPFC 促进治疗还有可能增强成本效益权衡期间的动机注意。这种神经调节作用为改善临床动机提供了一种潜在治疗方法。
