Department of Psychiatry and Behavioral Sciences, University of California, Davis, CA.
Center for Neuroscience, University of California, Davis, CA.
Schizophr Bull. 2023 May 3;49(3):717-725. doi: 10.1093/schbul/sbac204.
The neuronal mechanisms that underlie deficits in effort cost computation in schizophrenia (SZ) are poorly understood. Given the role of frontostriatal circuits in valence-oriented motivation, we hypothesized that these circuits are either dysfunctional in SZ or do not appropriately predict behavior in SZ when task conditions are difficult and good performance is rewarded.
A total of 52 people with recent onset SZ-spectrum disorders and 48 healthy controls (HCs) performed a 3T fMRI task with 2 valence conditions (rewarded vs neutral) and 2 difficulty conditions. Frontostriatal connectivity was extracted during the cue (anticipatory) phase. Individual behavior was fit using a drift-diffusion model, allowing the performance parameter, drift rate (DR), to vary between task conditions. Three models were examined: A group × condition model of DR, a group × condition model of connectivity, and a regression model of connectivity predicting DR depending on group and condition.
DRs showed the expected positive correlation with accuracy and a negative association with reaction time. The SZ group showed a deficit in DR but did not differ in overall connectivity or show a valence-specific deficit in connectivity. Significant group × valence × difficulty interactions, however, were observed on the relationship between right dorsolateral prefrontal (DLPFC)-striatal connectivity and DR (DLPFC-Caudate: F = 10.92, PFDR = .004; DLPFC-Putamen: F = 5.14, PFDR = .048) driven by more positive relationships between DR and connectivity during cues for the difficult-rewarded condition in HCs compared to SZ.
These findings suggest that frontostriatal connectivity is less predictive of performance in SZ when task difficulty is increased and a reward incentive is applied.
精神分裂症（SZ）患者在努力成本计算方面存在缺陷，其神经机制尚不清楚。鉴于额-纹状体回路在价值导向动机中的作用，我们假设这些回路在 SZ 中要么功能失调，要么在任务条件困难且良好表现得到奖励时，无法适当地预测 SZ 中的行为。
共有 52 名近期发病的 SZ 谱系障碍患者和 48 名健康对照者（HCs）在 3T fMRI 任务中完成 2 种效价条件（奖励 vs 中性）和 2 种难度条件。在提示（预期）阶段提取额-纹状体连接。使用漂移扩散模型拟合个体行为，允许性能参数漂移率（DR）在任务条件之间变化。检查了三种模型：DR 的组×条件模型、连接的组×条件模型和连接预测 DR 的回归模型，具体取决于组和条件。
DR 与准确性呈正相关，与反应时间呈负相关。SZ 组的 DR 降低，但总体连接没有差异，也没有表现出连接的效价特异性缺陷。然而，在右背外侧前额叶（DLPFC）-纹状体连接与 DR 之间的关系上观察到显著的组×效价×难度交互作用（DLPFC-Caudate：F=10.92，PFDR=0.004；DLPFC-Putamen：F=5.14，PFDR=0.048），这是由 HCs 中困难奖励条件下提示期间 DR 和连接之间的关系更积极驱动的，而 SZ 则不然。
这些发现表明，当任务难度增加且应用奖励激励时，额-纹状体连接对 SZ 中的表现预测性降低。
