Cerebellar Neuromodulation and Affective Empathy: An Investigation of Subjective and Facial Emotional Responses

Empathy is a multidimensional construct involving distinguishable cognitive and affective processes. Cognitive empathy concerns understanding or inferring another person's internal state, while affective empathy involves the observer's emotional response to another person's experience. Growing evidence implicates the cerebellum in emotional and social processing, however, its causal contribution to affective responding during dynamic interpersonal experiences remains insufficiently understood. The present study investigated whether transient modulation of the medial posterior cerebellum influences participants' affective responses while observing others describe emotionally significant experiences. Thirty Italian-speaking students from the University of Pavia participated in two experimental sessions using a within-subject design. Participants received 15 minutes of offline 1-Hz repetitive transcranial magnetic stimulation (rTMS; 900 pulses) over either the medial cerebellum or the vertex control site. After stimulation, participants viewed eight videos in which individuals recounted negative autobiographical experiences and continuously rated their own emotional valence. The temporal correspondence between participants' ratings and the targets' continuous emotional ratings was quantified using the Empathic Accuracy Index, while observable facial responses were assessed using FaceReader-derived measures of facial valence and arousal. Medial cerebellar stimulation did not significantly affect the Empathic Accuracy Index. In contrast, participants reported significantly more negative subjective valence following medial cerebellar stimulation than following vertex stimulation. No significant stimulation effects were observed for FaceReader-derived facial valence or facial arousal. These findings suggest that medial cerebellar modulation selectively influenced participants' subjective affective responses to emotionally salient interpersonal information without producing detectable changes in 1 target–perceiver affective correspondence or observable facial responding. The results support a functionally differentiated account of cerebellar involvement in social-emotional processing and highlight the importance of distinguishing affective responding from cognitive empathic inference when investigating the neural mechanisms of empathy. Keywords: Affective empathy, cerebellum, cerebellar neuromodulation, repetitive transcranial magnetic stimulation, emotional processing, social cognition