Theta-Band Temporal Interference Stimulation Modulates Food Reward Prediction Error Encoding in Individuals with Elevated Food Addiction Symptoms.

Prediction error (PE) signals support feedback evaluation and adaptive updating, and are closely linked to medial frontal theta dynamics, particularly within dorsal anterior cingulate cortex (dACC)-centered networks. However, evidence linking these oscillatory mechanisms to the modulation of PE encoding remains limited. Here, we tested whether theta-band modulation of a dACC-centered medial frontal network altered trial-level PE encoding during food-reward processing. In a single-blind, sham-controlled pre-post design, individuals with elevated food addiction symptoms performed a food incentive-delay task while undergoing electroencephalographic recordings combined with theta-band temporal interference stimulation. Single-trial analyses revealed that feedback-related negativity (FRN) amplitudes varied as a function of both behavioral and model-derived prediction errors. Critically, theta-band modulation altered FRN-PE coupling, with the effect most pronounced for unfavorable outcomes, whereas anticipatory activity remained unchanged. These findings support the hypothesis that theta-band modulation can alter feedback-related PE encoding within this population and task context.