Abstract: BACKGROUND: This study combined fiber photometry calcium signal recording with C-fos immunohistochemistry to systematically investigate the neural modulation mechanisms of deep brain stimulation (DBS) in the anterior cingulate cortex (ACC). It also compared the effects of DBS and electro-ablation on depressive-like behaviors, providing experimental evidence for optimizing neuromodulation treatment strategies. 
METHODS: Grouping and Modeling: Mice were randomly divided into control, CRS_Sham (sham stimulation), and CRS_DBS (intervention) groups. The latter two groups underwent 3.5 weeks of chronic restraint stress (CRS) modeling and had DBS electrodes implanted in the ACC. Intervention Protocol: The DBS group received daily high-frequency electrical stimulation (130 Hz, 200 μA, 50 μs, 2 hours/day for 1 week), while the Sham group underwent electrode implantation without current stimulation. Behavioral Assessment: Depressive-like behaviors were quantified using the forced swim test (FST) and tail suspension test (TST). Anxiety-like behaviors were assessed via the open field test (OFT) in 10 mice (5 in each of the DBS and Sham groups). Circuit Mechanism Analysis: Real-time neural activity was monitored by fiber photometry to assess the activation effect of ACC-DBS on the ACC-BLA circuit. Whole-brain activation patterns were analyzed using C-fos immunohistochemistry to quantify downstream neuronal activity. Electro-ablation Validation: An additional experiment was conducted with an electro-ablation group and a sham stimulation group to verify their effects on depressive-like behaviors. 
RESULTS: Behavioral Analysis: FST showed that immobility times in the CRS_DBS and CRS_Sham groups were significantly higher than in the control group (P < 0.05), but no significant difference was observed between the two groups. No significant differences were found in TST among the groups. OFT results indicated that central zone duration and total distance traveled were significantly lower in the DBS group than in the Sham group (P < 0.05), suggesting that DBS may exacerbate anxiety-like behaviors. In contrast, the immobility time in the electro-ablation group was significantly lower than in the sham stimulation group (P < 0.01). Neural Mechanisms: Fiber photometry confirmed that ACC-DBS specifically activated the ACC-BLA circuit. C-fos staining revealed that DBS significantly enhanced neuronal activity in downstream brain regions of the ACC.
CONCLUSION: Traditional high-frequency ACC-DBS effectively activates target neural circuits but fails to improve depressive-like behaviors and may exacerbate anxiety states by enhancing limbic system activity. In contrast, ACC functional inhibition via electro-ablation demonstrates significant antidepressant effects, offering new directions for optimizing neuromodulation strategies.

Key words: Deep brain stimulation, Depression, Anterior Cingulate Cortex, Electroablation, Fiber photometry