Functional specialization and dynamical interaction in human amygdala subregions support fearful-expression processing

Fearful-expression processing supports adaptive responses to potential threats, requiring both rapid threat evaluation and face-related information processing. However, how human amygdala subregions contribute to these complementary processes remains unclear. Here we record intracranial electroencephalography from twelve patients with epilepsy during an emotional face-matching task, sampling 58 amygdala contacts with balanced hemispheric distributions. Condition-specific analyses reveal separable theta/alpha dynamics between the lateral and medial amygdala within fearful-face and neutral-face matching conditions, but not shape matching. Between-condition contrasts further reveal earlier lateral amygdala engagement and stronger lateral-to-medial directional interactions for fearful-face versus neutral-face matching, whereas later medial engagement and stronger medial-to-lateral interactions emerge for neutral-face versus shape matching. Control analyses preserve the main neural effects. In a separate cohort of seven patients, intracranial stimulation produces dissociable behavioral effects, with lateral stimulation impairing fear matching and medial stimulation facilitating neutral-face matching. Together, these findings reveal a condition-dependent functional differentiation within the human amygdala during fearful-expression processing.