Resting-State Theta/Beta Ratio Reveals Distinct Neural Signatures in High Sign-Tracking Individuals

Background: Individual differences in reward learning and motivational processes are reflected in sign-tracking behavior. This phenotype, characterized by heightened attraction to reward-associated cues, is linked to increased impulsivity, addiction vulnerability, and externalizing psychiatric disorders. Methods: To identify underlying neural differences, we tested whether high sign-tracking individuals exhibit an elevated mid-frontal theta/beta ratio, a resting EEG biomarker indicating reduced cortical control over subcortical motivational circuits. Sixty volunteers completed a 5-minute resting-state EEG session followed by a Pavlovian learning task. Participants were classified into high or low sign-tracking groups based on objective eye-gaze metrics. Results: High sign-tracking participants demonstrated a significantly higher mid-frontal theta/beta ratio compared to the low sign-tracking group. Conclusions: These findings identify the mid-frontal theta/beta ratio as a neural marker capable of distinguishing individual differences in reward cue reactivity. This suggests a pathway for targeted interventions aimed at the underlying cortical-subcortical dysregulation associated with sign-tracking and related vulnerabilities.