Functional Organization of the Lateral Prefrontal Cortex in Time-Emotion Integration

This study investigates how the human brain integrates dynamic emotional signals over time to guide context-dependent action. While humans often exhibit biases in evaluating emotional episodes—such as the peak-end effect—the neural mechanisms behind this integration remain unclear. The researchers developed a novel Emotional Sequences Task, where participants viewed 12-second sequences of positive and negative images with varying durations. Participants had to judge the predominant emotional valence and then execute a button press based on a contextual rule. The study combined fMRI with information-guided, inhibitory transcranial magnetic stimulation (cTBS) to test the causal roles of specific LPFC subregions.

The researchers identified a rostro-caudal functional gradient in the LPFC. The frontopolar cortex (FP) showed robust ramping activity during sequence processing and specifically represented temporally extended emotional information. This neural representation in the FP was behaviorally relevant, as it predicted participants' subsequent valence judgments. In contrast, the mid-LPFC maintained separable, approximately orthogonal representations of contextual rules and emotional information, facilitating flexible action control. Finally, the caudal premotor cortex (PMd) held robust action-goal representations that generalized across emotional contexts. TMS results confirmed that the FP is causally involved in this process, as inhibitory stimulation to the right FP significantly impaired task accuracy compared to control sites.

These findings extend the hierarchical model of cognitive control to the domain of dynamic emotional processing. By demonstrating that the FP acts as a hub for integrating past emotional information to inform future-oriented action, the study provides a mechanistic basis for understanding how emotional biases arise and how they might be regulated. This research offers a framework for how the brain transforms abstract emotional experiences into concrete, context-appropriate behaviors, which is critical for understanding both healthy emotional regulation and the neural underpinnings of affective disorders.