In Focus: The Marsh Lab

September 4, 2019
Rachel Marsh, PhD

Dr. Rachel Marsh’s Cognitive Development and Neuroimaging Laboratory studies the mechanisms in the brain that underlie an individual’s ability to self-regulate, both in health and in psychiatric disorders. Her team seeks to understand how this capacity for self-regulation develops normally in healthy individuals, and how altered development of neural circuits supporting regulatory processes hinders the ability to control thoughts and behaviors in childhood neuropsychiatric disorders. Dr. Marsh’s lab uses multi-modal Magnetic Resonance Imaging (MRI) techniques to examine the function, structure, and connectivity of these ‘control’ circuits.

Using functional MRI (fMRI) tasks that demand the engagement of control, Dr. Marsh’s lab has revealed alterations in the functioning of fronto-striatal circuits in young girls with bulimia nervosa, a disorder characterized by the inability to control eating behaviors. In her analysis of longitudinal data collected in Dr. Marsh’s lab, Dr. Marilyn Cyr, a postdoctoral research fellow, has detected altered structural and functional development of control circuits in adolescents with bulimia nervosa. This altered development seems to contribute to the persistence of the disorder into adulthood.

Dr. Marsh’s lab has also been conducting studies of adults and children with obsessive-compulsive disorders (OCD), work that has garnered quite a bit of media attention. In collaboration with Dr. Blair Simpson, the lab recently completed collecting MRI data from unmedicated OCD patients before and after exposure and ritual prevention therapy. These data have led to the identification of task-based fMRI predictors of treatment response in OCD patients, work spearheaded by Dr. David Pagliaccio, a staff scientist in Dr. Marsh’s lab. From a similar study of children and adolescents with OCD, Dr. Pagliaccio identified structural predictors of response to Cognitive Behavioral Therapy (CBT) within cingulo-opercular and fronto-parietal control circuits. This research was a collaboration with Dr. Moira Rynn, former Director of the Child Psychiatry Division and current Chair of Psychiatry at Duke. The study’s aim was to understand how control circuits change after remission of OCD symptoms and how those circuits predict response to treatment. Dr. Cyr analyzed resting state functional connectivity data from that study and identified network alterations that predicted response to CBT. These latter findings should be published soon.

Currently, the lab is conducting two new NIMH-funded studies. The first is a collaboration with Dr. Kate Fitzgerald at the University of Michigan. Both sites are recruiting and studying children (ages 7 to 12 years) with a range of obsessive-compulsive symptoms, from symptom-free to subclinical to clinically affected (i.e., OCD). Children with OCD are being treated with CBT before being re-evaluated and re-scanned in the MRI—a wonderful treatment opportunity for children in need at no cost. The goal of the study is to identify alterations in control circuits that improve with the remission of OC symptoms, and also to determine if those alterations are present in children with subclinical symptoms. If so, this study will pave the way for a clinical trial aimed at early targeting of those circuits (with, for example, cognitive control training) for the prevention of this disabling illness in children.

The second new study is a collaboration with Drs. Catherine Monk and Marisa Spann. By combining previously collected prenatal and neonatal data with newly acquired data from mother-child pairs, this study aims to identify circuit-based markers of regulatory deficits that are passed between generations and that persist from infancy to childhood. Dr. Marsh’s lab is now gathering MRI and behavioral measures of control processes from children and their mothers, while Drs. Monk and Spann are working with pregnant mothers and their infants. This is a large and important study that brings the Marsh lab’s focus back to its original goal of uncovering trajectories of regulatory deficits that likely manifest in childhood psychiatric disorders. Identifying such trajectories will inform future research aimed at targeting specific neural circuits for prevention.

Topics

Mental Health, Psychiatry

Tags

cognitive development, neuroimaging