Elucidating the Neurocircuitry of Irritability With High-Field Neuroimaging to Identify Novel Therapeutic Targets

The proposed study aims to 1 (Aim 1) identify dysfunctions in neurocircuitry that engender irritability, and (Aim 2) determine how changes in neurocircuit function related to change in irritability. We will accomplish Aim 1 with resting-state and frustrative nonreward (FNR) task-based fMRI data from n=30 HCs and n=60 subjects with MDD ((Fig 3). For Aim 2, we will randomize the MDD cohort (n=60; same as Aim 1) to 2 weeks of twice-weekly 40-minutes long intravenous infusion of either ketamine (0.5 mg/kg) or midazolam (0.02 mg/kg) in a double-blind parallel-arm fashion, and by repeating clinical assessments and fMRI scans after the last infusion. The central hypothesis of the proposed study is that striatum is a key hub in the neurocircuitry of irritability, and that treatment-related improvement in irritability is associated with normalization of these neurocircuit functioning.