Alexander, Andy •
Christian, Brad • Chung, Moo • Converse, Alex • Dalton, Kim • Davidson, Richard • Nitschke, Jack • Oakes, Terry
The research of the Alexander group is focused on developing imaging and analysis techniques for the study of human brain function with magnetic resonance imaging (MRI) at 3 tesla. The group is actively involved in the following research areas:
- Functional MRI Techniques. They develop and evaluate methods for improving the robust characterization of the BOLD effect in functional brain studies. Developing methods for imaging areas with susceptibility artifacts (e.g., the orbitofrontal cortex, and the temporal lobes) is of particular interest.
- Functional MRI of TMS Brain Stimulation. The group is developing methods to measure the BOLD activity response to transcranial magnetic stimulation.
- Diffusion Tensor MRI. The group is developing acquisition, processing and display algorithms for accurate characterization of brain diffusion properties. These measurements provide unique information about brain tissue microstructure.
- White Matter Organization Mapping. The group is developing methods using diffusion tensor imaging to map out the organization of white matter connections within the brain.
- Structural Characterization of Brain Tissues. The group is using diffusion, magnetization transfer and spectroscopic techniques to evaluate structural properties of brain tissues (e.g., myelination, axon density, brain development, etc.). These techniques may be used to assess structural changes as a function of either brain disfunction or normal brain development.
Brad Christian's research in neuropsychiatric illness involves the application of PET methodologies to investigate neurochemical changes in the brain, including studying novel radioligands to characterize neurotransmitter-protein interactions and how they are influenced by the effects of psychotropic drugs. These imaging methods are being applied to investigate the etiologies and mechanisms in diseases such as schizophrenia, Alzheimer’s disease and Tourette syndrome.
Moo Chung is interested in tensor-based morphometry (TBM) in structural MRIs. This is a new morphometric technique that localizes the structural differences between groups without defining the regions of interest (ROI). He has developed a unified statistical framework for TBM that can be used to quantify the amount of tissue growth and atrophy in the brain. Extending TBM further, he is trying to develop fMRI analysis that facilitates the variations in gray matter density. He is also interested in mathematical/statistical modeling of functional and structural changes over time and subjects.
Alex Converse studies the interaction between modulatory neural pathways, particularly dopamine neurons, and other brain circuitry. The goal is to describe the role of dopaminergic neuromodulation at the systems level in the human brain in such processes as movement, reward, and attention. He is currently working on an NIH funded project to develop a dual tracer PET method to simultaneously image and correlate dopamine release and blood flow alteration. Future work in humans may involve sequential PET and MRI scans and possibly simultaneous PET and MRI imaging. Additionally, he is carrying out a PET study funded by Pfizer to determine the dopamine receptor occupancy of a candidate antipsychotic compound. He is responsible for microPET operations and collaborates with a number of investigators using a variety of PET tracers to study the dopamine and serotonin systems, glucose utilization, microglial activation, and other aspects of brain biology.
Kim Dalton is involved in a program of research, under the direction of Dr. Richard Davidson, on underlying brain structure and function associated with autism and related developmental differences/disabilities such as fragile X, Williams syndrome and ADHD. Her overall career goal is to investigate the central and peripheral physiological profiles associated with a number of developmental disabilities and to eventually relate these physiological/behavioral phenotypes to underlying genetic factors.
Richard Davidson is the Director of the Laboratory for Affective Neuroscience (housed in the Department of Psychology) and of the Waisman Laboratory for Brain Imaging and Behavior. Dr. Davidson's labs are engaged in a broad program of research on the brain mechanisms that subserve affective processing in normal adults and children and in children and adults with psychiatric disorders (primarily autism and fragile X in children and mood and anxiety disorders in adults). His research group also studies the neural bases of affect-cognition interactions. In addition, they conduct research on relations between the central circuitry of emotion and emotion regulation and peripheral biology to explore bi-directional communication between the brain and body that may be consequential for health. Finally, they also examine the impact of interventions designed to treat psychiatric disorders and to improve well-being in non-disordered populations.Current work includes studies on:
- Basic research on the neural substrates of voluntary and automatic emotion regulation and relations between the central circuitry of emotion and emotion regulation and neuroendocrine function.
- The neural and peripheral biological correlates of resilience in aging.
- Basic research on the neural bases of interactions between emotion and cognitive function, particularly working memory and attention.
- Basic research on the central and peripheral biological substrates of temperament in children to determine early signs of vulnerability to psychopathology.
- Neural bases of social and emotional processing differences in children and adults with autism and fragile X.
- Brain mechanisms that subserve mood and anxiety disorders; parsing the heterogeneity of these disorders by using information on brain function.
- Impact of pharmacotherapy and psychotherapy on brain function in patients with mood and anxiety disorders.
- Effects of meditation on brain function in adept practitioners and novices.
- Collaborative research with the Kalin Lab on the neural bases of emotion regulation and affective style in rhesus monkeys.
The methods used include high-density electrophysiology, functional magnetic resonance imaging (fMRI), structural MRI including diffusion tensor imaging (DTI) and positron emission tomography (PET). Researchers also utilize measure of peripheral autonomic and skeletal-muscular measures, along with endocrine and immune measures.
The research focus of the Nitschke laboratory is on the neuroscience of human emotion and affective disorders. One of the lab's primary research goals is to determine the neurobiological substrates of heterogeneity in anxiety and depression. Their studies use clinical and nonclinical samples and employ an array of methodologies including fMRI, EEG, eye-blink startle, neuropsychological tasks, cortisol, and autonomic psychophysiology. They have developed laboratory-based models of anticipatory and reactivity processes elicited by emotional stimuli. Building on this work, they are currently examining the placebo effect as a function of expectancy. Another major interest is the neural circuitry of positive emotion, with fMRI research in this area employing novel paradigms for inducing potent positive emotions.
Terry Oakes' research focuses on quantitative image analysis and display. The aim of a recent grant is a methodical comparison of several leading fMRI analysis packages; the goal is to determine the range of accuracy and utility for each package for each of the various steps of the analytic pathway. As part of this work, a large body of software has been written for efficiently processing fMRI data using a variety of software packages. The large amount of data in imaging studies makes parallel processing important; this is being implemented in the lab via the Condor platform.
Terry's background in Medical Physics is in PET, and his main interest is in tracers of the dopaminergic system. In addition, he helps researchers set up, implement, and analyze PET experiments. Most data analysis involves using dedicated software packages, but Terry has written a large software package, Spamalize, for customized analysis of PET, MRI, and fMRI data. In particular, there are programs for ROI analysis, Patlak/Logan plots, and FDG quantitation. Terry is also responsible for the 6MeV tendem accelerator in the Waisman lab, which is used for making short-lived PET radiotracers.
