Fine-tuning neural excitation/inhibition for tailored ketamine use in treatment-resistant depression
arXiv Preprint Archive February 4, 2021 Erik D. Fagerholm, Robert Leech, Steven Williams et al.
Ketamine rapidly reduces depressive symptoms in treatment-resistant major depressive disorder. Using brain imaging and dynamic causal modeling, researchers analyzed neural excitation/inhibition interactions in the primary somatosensory cortex of 18 unmedicated patients and 18 healthy controls during a somatosensory task. Patients were scanned at baseline, 6-9 hours after ketamine infusion, and 6-9 hours after placebo. A shift in neural dynamics toward a stable region of the Poincaré diagram—requiring increased excitatory and inhibitory coupling—predicted symptom improvement specifically after ketamine, not placebo. This drug-specific neural shift may serve as a biomarker for treatment response.