Department of Psychiatry and Behavioral Sciences, Northwestern University, Chicago, IL, USA.
Departments of Math and Population Health Sciences, University of Wisconsin, Madison, WI, USA.
J Psychiatr Res. 2022 Jan;145:256-262. doi: 10.1016/j.jpsychires.2020.10.046. Epub 2020 Nov 4.
Trauma and trauma-related disorders are characterized by impaired learning processes, including reinforcement learning (RL). Identifying which aspects of learning are altered by trauma is critical endeavor, as this may reveal key mechanisms of impairment and potential intervention targets. There are at least two types of RL that have been delineated using computational modeling: model-free and model-based RL. Although these RL processes differentially predict decision-making behavior, most research has examined the impact of trauma on model-free RL. Currently unclear whether model-based RL, which involves building abstract and nuanced representations of stimulus-outcome relationships, is impaired among individuals with a history of trauma. The present study sought to test the hypothesis of impaired model-based RL among adolescent females exposed to assaultive trauma. Participants (n = 60; 29 without a history of assault and 31 with a history of assault with and without PTSD) completed a three-arm bandit task during fMRI acquisition. Two computational models compared the degree to which participants' task behavior fit the use of a model-free versus model-based RL strategy. Although a history of assaultive trauma did not predict poorer model-based RL, greater sexual abuse severity predicted less use of model-based compared to model-free RL. Additionally, severe sexual abuse predicted less left frontoparietal network encoding of model-based RL updates. Altered model-based RL, which supports goal-directed behavior, may be an important route through which clinical impairment emerges among individuals with a history of severe sexual abuse and should be examined further in future studies.
创伤和与创伤相关的障碍的特征是学习过程受损，包括强化学习（RL）。确定创伤改变了哪些学习方面是至关重要的，因为这可能揭示了损伤的关键机制和潜在的干预靶点。至少有两种使用计算建模来描述的 RL：无模型 RL 和基于模型的 RL。尽管这些 RL 过程对决策行为有不同的预测作用，但大多数研究都考察了创伤对无模型 RL 的影响。目前尚不清楚是否存在创伤史个体的基于模型的 RL 受损，因为基于模型的 RL 涉及到建立刺激-结果关系的抽象和微妙表示。本研究旨在检验遭受攻击创伤的青春期女性存在基于模型 RL 受损的假设。参与者（n=60；29 名无创伤史，31 名有创伤史，其中包括 PTSD）在 fMRI 采集期间完成了三臂赌博任务。两个计算模型比较了参与者的任务行为与无模型 RL 与基于模型 RL 策略的拟合程度。尽管创伤史攻击不预示着基于模型 RL 较差，但性虐待严重程度越高，基于模型 RL 与无模型 RL 相比，使用的模型就越少。此外，严重的性虐待预示着基于模型 RL 更新的左额顶网络编码较少。改变基于模型的 RL，这支持目标导向的行为，可能是一个重要的途径，通过这种途径，有严重性虐待史的个体出现临床损伤，应在未来的研究中进一步研究。
