The Cerebellum’s Role in Empathy: Neural Mechanisms and Behavioral Implications

The cerebellum has long been viewed as a motor structure however, there is a plethora of research currently that implies its role in social cognition, more particularly, empathy. Emerging evidence shows links between the posterior cerebellar regions (e.g., Crus I/II) and the vermis to emotional processing and mentalising yet, causal evidence for its role in empathic accuracy remains limited. This study in the cerebellum’s contribution to empathy using transcranial alternating current stimulation (tACS) over the cerebellar vermis, combined with heart rate variability (HRV) measures. Thirteen female participants were recruited (mean age ≈ 23 years) to complete an Empathic accuracy task during three tACS conditions: gamma (50 Hz), theta (6 Hz), and sham (control condition). Participants continuously rated the emotional valence of autobiographical videos (5 positive, 5 negative) while empathic accuracy (Pearson correlation between perceiver and target ratings) and RMSSD (vagal tone index of HRV) were assessed. Results showed a significant interaction between tACS condition and video valence on empathic accuracy (p < .001). Positive videos elicited higher accuracy overall, but gamma stimulation selectively enhanced accuracy for negative videos while reducing it for positive ones compared to sham and theta. Gamma tACS also robustly increased RMSSD relative to sham and theta (p < .001), independent of valence, suggesting enhanced vagal activity. These findings provide preliminary evidence that cerebellar oscillations, particularly the gamma band, modulate valence-specific empathic processing and autonomic responses during empathy. Gamma stimulation may facilitate negative-valence empathy (possibly via improved inhibition or salience detection), while HRV changes highlight cerebellum- autonomic links. Despite limitations (small all-female sample, vermis-focused stimulation), this is the first study combining cerebellar tACS with HRV in empathic accuracy, underscoring the cerebellum’s role beyond motor functions, and suggesting avenues for future neuromodulation research in socio-affective disorders. Keywords: Cerebellum, emotions, empathy, transcranial alternating current stimulation (tACS)