American Statistical Association
New York City
Metropolitan Area Chapter

The Child Study Center
At NYU Langone Medical Center
Division of Biostatistics
Seminars on Analysis of Neuroimaging Data



Tingting Zhang, Ph.D.
Department of Statistics
University of Virginia

A DYNAMIC DIRECTIONAL MODEL FOR EFFECTIVE
BRAIN CONNECTIVITY USING
ELECTROCORTICOGRAPHIC (ECoG) TIME SERIES

We introduce a dynamic directional model (DDM) for studying brain effective connectivity based on intracranial electrocorticographic (ECoG) time series. The DDM consists of two parts: a set of differential equations describing neuronal activity of brain components (state equations), and observation equations linking the underlying neuronal states to observed data. When applied to functional MRI or EEG data, DDMs usually have complex formulations and thus can accommodate only a few regions, due to limitations in spatial and/or temporal resolution of these imaging modalities. In contrast, we formulate our model in the context of ECoG data. The combined high temporal and spatial resolution of ECoG data result in a much simpler DDM, allowing investigation of complex connections between many regions. To identify functionally-segregated sub-networks, a form of biologically economical brain networks, we propose the Potts model for the DDM parameters. The neuronal states of brain components are represented by cubic spline bases and the parameters are estimated by minimizing a log-likelihood criterion that combines the state and observation equations. The Potts model is converted to the Potts penalty in the penalized regression approach to achieve sparsity in parameter estimation, for which a fast iterative algorithm is developed. An L1 penalty is also considered for comparison. The methods are applied to an auditory ECoG data set.


Date: Tuesday, March 11, 2014
Time: 4:00 P.M.
Location: “Central Park” meeting area at the Child Study Center
One Park Avenue (between 32nd and 33rd Streets)
7th Floor
New York, New York

The Series is open to all; RSVPs are requested.
Due to new security procedures at One Park Ave., those wishing to attend
who do not have an NYU ID are required to RSVP.
To do so, please contact Cielo Diaz at cielo.diaz@nyumc.org or 646-754-5195.


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