May, 2019 Publications
Threat of Punishment and Model-Based Learning in Late-Life Depression and Suicidal Behavior
Introduction: Previous research shows that acute stress impairs model-based learning, but studies of depression are few and no studies have examined suicidal behavior. We examined the effects of a threat of punishment on model-based learning (MBL) and in depression with and without history of suicidal behavior. Methods: Eighty participants (21 suicide ideators, 25 suicide attempters, 12 non-suicidal depressed patients, 22 healthy controls) performed a two-step decision task with probabilistic transitioning (rare/common) during fMRI scanning. A threat of punishment existed on half of the trials. Mixed-effects regression models assessed threat by group interactions on choice and decision times (DT)...
May, 2020 Publications
Neural Correlates of Antidepressant Expectancies Positively Moderate Antidepressant Treatment Response to Placebo but Not Escitalopram in Major Depression
August, 2020 Publications
Naltrexone modulates contextual processing in depression
Context, the information surrounding an experience, can significantly alter the meaning and the affective responses to events. Yet the biological mechanisms through which context modulate experiences are not entirely understood. Here, we hypothesized that the µ-opioid system—extensively implicated in placebo effects, a clinical phenomenon thought to rely on contextual processing—modulates the effects of contextual information on emotional attributions in patients with depression. To test this hypothesis, 20 unmedicated patients with depression completed a randomized, double-blind, placebo-controlled, crossover study of one dose of 50 mg of naltrexone, or placebo immediately before completing two sessions of the Contextual Framing fMRI task...
January, 2020 Publications
Improving the Reliability of Computational Analyses: Model-Based Planning and Its Relationship With Compulsivity
Background Computational models show great promise in mapping latent decision-making processes onto dissociable neural substrates and clinical phenotypes. One prominent example in reinforcement learning (RL) is model-based planning, which specifically relates to transdiagnostic compulsivity. However, the reliability of computational model-derived measures like model-based planning is unclear. Establishing reliability is necessary to ensure such models measure stable, trait-like processes, as assumed in computational psychiatry. Although analysis approaches affect validity of RL models and reliability of other task-based measures, their effect on reliability of RL models of empirical data has not been systematically studied...
May, 2019 Publications
Neural Correlates of Naltrexone-induced blockade of Contextual Effects on Emotion Perception
Introduction: Prior research shows that contextual cues modulate emotional perception, but the molecular bases of this interaction are unknown. Here, we hypothesized that opioid neurotransmission in regions relevant to emotional processing will modulate the effect of contextual cues on evaluation of face valence. Methods: Twenty-five volunteers...