Characteristics of resting-state EEG after deep brain stimulation in nucleus accumbens and anterior limb of internal capsule: a pilot study

BACKGROUND: The electroencephalogram (EEG) characteristics of treatment-resistant depression (TRD) patients who have undergone deep brain stimulation (DBS) remain unclear. This paper aims to investigate the power spectral density (PSD), coherence, and microstates of resting-state EEG, and provide further insights into neural mechanisms of DBS in TRD. METHODS: Five patients diagnosed with TRD were included in this study (three females/two males, mean age = 26.80 years). Resting-state EEG was recorded before and six months after DBS targeting the bilateral nucleus accumbens (NAc) and the anterior limb of the internal capsule (ALIC). PSD, coherence, and microstate were calculated and analyzed. RESULTS: At six-month follow-up, 60% (3/5) of patients achieved ≥50% reduction in 17-item Hamilton Depression Scale (HAMD-17) scores, while 40% (2/5) showed 25–50% improvement. Significant decreases in PSD were observed in five frontal nodes: F7 (high gamma band), CP2 and CP6 (delta band), FT9 (beta and high gamma band), and Fpz (theta band) (all p < 0.05). Enhanced coherence was observed between CP4 and C6 in both high gamma (0.58→0.70, p = 0.03) and low gamma band (0.62→0.74, p = 0.03), CP6 and C6 (0.38→0.42, p = 0.007) in high gamma band. Microstate analysis revealed increased occurrence of state B (p = 0.002), elevated transition probability for B→D (p = 0.04) and C→B (p = 0.04), and reduced transition probability for D→A (p = 0.04). CONCLUSIONS: These preliminary findings suggest that NAc-ALIC-DBS could attenuate pathological frontal neural oscillations, enhance frontal connectivity, and modulate microstate dynamics in TRD. Large-scale studies are needed to validate these findings.