Abstract #0124

Ketamine Decreases Resting State Functional Connectivity between Networks Via the Dorsal Nexus: Implications for Major Depression

Milan Scheidegger¹,², Martin Walter³, Mick Lehmann², Coraline Metzger³, Simone Grimm²,⁴, Heinz Boeker², Peter Boesiger¹, Erich Seifritz², Anke Henning¹

¹Institute for Biomedical Engineering, University and ETH Zurich, Zurich, Switzerland; ²Clinic of Affective Disorders and General Psychiatry, University Hospital of Psychiatry Zurich, Zurich, Switzerland; ³Department of Psychiatry, Otto-von-Guericke University, Magdeburg, Germany; ⁴Cluster Languages of Emotion, Freie Universitt Berlin, Berlin, Germany

Using resting state fMRI (rsfMRI), the dorsal nexus (DN) was recently identified as a dorsomedial prefrontal cortex region showing increased depression-associated fMRI connectivity with portions of the cognitive control (CCN), the default mode (DMN), and the affective (AN) network. In this double-blind, randomized, placebo-controlled, crossover study we report decreased connectivity of the sgACC (AN) and PCC (DMN) via the DN 24 hours following the administration of an antidepressant dose of ketamine. We conclude that reducing the hyperconnectivity via the DN may play a critical role in reducing depressive symptomatology and thus represent a systems level mechanism of antidepressant treatment response.