American Statistical Association
New York City
Metropolitan Area Chapter

New York State Psychiatric Institute
at Columbia University Medical Center
Biostatistics Seminar



SINGLE AND MULTI-LEVEL MEDIATION IN fMRI:
A STRATEGY FOR LOCALIZING FUNCTIONAL PATHWAYS

by

Tor D. Wager, Ph.D.
Assistant Professor of Psychology
Columbia University
Cognitive and Affective Control Laboratory


Abstract

Background: Functional magnetic resonance imaging (fMRI) provides the capability to collect approximately 100,000 measures related to neural activity across the functioning human brain every 2 seconds. There is increased interest in using this data to understand how brain regions interact with one another across time during different kinds of mental activity, and how these interactions support diverse aspects of human psychology, including task performance and emotional experience. Strategies have ranged from exploratory functional connectivity analyses to confirmatory structural equation models and state-space models. However, the use of confirmatory models has been hampered by the simple fact that in most applications, investigators do not know precisely which brain areas to enter into the model.

Approach: In this talk, I will describe a hybrid technique that combines a simple structural model that defines a brain pathway with an exploratory, whole-brain mapping approach. Its main function is to provide whole-brain statistical maps of mediation effects - a powerful concept designed to permit inference about intervening variables. This technique can be used to localize functional pathways and locate additional brain regions that should be included in a confirmatory structural model. I will describe the approach and demonstrate it with examples of pathway-mapping in the areas of pain, stress, and negative emotion.

Biographical Note

Dr. Tor Wager is an Assistant Professor of Psychology at Columbia University. He received his Ph.D. from the University of Michigan in cognitive psychology, with a focus in cognitive neuroscience. He has authored over 40 peer-reviewed publications and chapters in books and has received 9 grants, totaling more than 4 million dollars in support of his research. His primary research interest is in the neural and psychological bases of cognitive and affective control. His research quantifies behavioral performance and brain activity -- measured primarily using functional magnetic resonance imaging (fMRI) -- to investigate the neural mechanisms by which humans have flexible control over their behavior. He is also interested in developing image analysis and statistical modeling methods that will improve our ability to use fMRI as a research tool in cognitive and affective neuroscience. Current projects along these lines include: optimization of experimental design for fMRI experiments, including computer aided design using genetic algorithms; meta-analysis of functional imaging data; nonlinear alternatives to hemodynamic response fitting; robust regression techniques in massively univariate linear models; and application of multivariate techniques.


Date: Tuesday, September 23, 2008
Time: 3:30 - 4:30 P.M.
Location: New York State Psychiatric Institute
1051 Riverside Drive
6th Floor Multi-Purpose Room (6602)
New York, New York
(Directions)

RESERVATIONS ARE NOT REQUIRED

Refreshments will be served from 3:00 to 3:30 P.M.,
with a reception from 4:30 to 5:00 P.M.


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