Reward-Based Decision-Making Engages Distinct Modes of Cross-Frequency Coupling

Prefrontal cortex exerts control over sensory and motor systems via cross-frequency coupling. However, it is unknown whether these signals play a role in reward-based decision-making and whether such dynamic network configuration is altered in a major depressive episode. We recruited men and women with and without depression to perform a streamlined version of the Expenditure of Effort for Reward Task during recording of electroencephalography. Goal-directed behavior was quantified as willingness to exert physical effort to obtain reward, and reward-evaluation was the degree to which the decision to exert effort was modulated by incentive level. We found that the amplitude of frontal-midline theta oscillations was greatest in participants with the greatest reward-evaluation. Furthermore, coupling between frontal theta phase and parieto-occipital gamma amplitude was positively correlated with reward-evaluation. In addition, goal-directed behavior was positively correlated with coupling between frontal delta phase to motor beta amplitude. Finally, we performed a factor analysis to derive 2 symptom dimensions and found that mood symptoms positively tracked with reward-evaluation and motivation symptoms negatively tracked with goal-directed behavior. Altogether, these results provide evidence that 2 aspects of reward-based decision-making are instantiated by different modes of prefrontal top-down control and are modulated in different symptom dimensions of depression.

Automated summary

The prefrontal cortex controls sensory and motor systems through cross-frequency coupling. This study investigates whether these signals are involved in reward-based decision-making and whether this dynamic network configuration is changed in major depressive episodes. The results show that the amplitude of frontal-midline theta oscillations is highest in participants with the highest reward-evaluation. Additionally, the coupling between frontal theta phase and parieto-occipital gamma amplitude is positively correlated with reward-evaluation. Moreover, goal-directed behavior is positively correlated with coupling between frontal delta phase and motor beta amplitude. Finally, mood symptoms positively correlate with reward-evaluation, while motivation symptoms negatively correlate with goal-directed behavior. These findings indicate that different modes of prefrontal top-down control are involved in different aspects of reward-based decision-making and are modulated in different symptom dimensions of depression.