Methods and systems are described for providing deep brain stimulation (DBS) of the subcallosal cingulate region (SCC) to provide symptom relief in patients with treatment-resistant depression (TRD). The DBS devices may enable chronic electrophysiology recording to deliver SCC DBS therapy. One or more machine-learning models may identify SCC LFP changes that indicate the patient's current clinical state. The clinical state is distinct from acute transient stimulation effects, is sensitive to DBS stimulation adjustments, and accurately captures individual differences in recovery trajectory.