Systems Seminar

EEG/MEG Spatio-Temporal Dipole Source Estimation

Prof. Arye Nehorai
The University of Illinois at Chicago
Department of Electrical Engineering and Computer Science

Abstract

Electro-encephalography (EEG) and magneto-encephalography (MEG) have emerged as powerful non-invasive tools for investigating the functional organization of the human brain and assessing abnormalities associated with neurological and psychiatric disorders. EEG and MEG sensor arrays measure electric potentials on the scalp and magnetic fields around the head, respectively. They are used to detect and locate sources of electric activity in the brain. Typical clinical applications include localization of regions that initiate epileptic seizures and assessment of the extent of cerebral cortex damage resulting from a stroke. In neuro-science, they are used to analyze sensorimotor (visual, auditory, somatosensory, motor), and cognitive (attention, memory, language) functions of the brain.

In this seminar, I will introduce EEG and MEG, compare them with other brain imaging modalities, and discuss related signal processing problems. I will present maximum likelihood methods for estimating evoked responses, using EEG and MEG arrays, that allow for spatially correlated noise between sensors with unknown covariance. The electric sources will be modeled as current dipoles and the head as a spherical conductor. I will estimate the unknown dipoles' locations and moments and present Cramer-Rao lower bounds on the errors of their estimates.

I will also show numerical examples to demonstrate the performance of the proposed methods. Results for realistic head models, obtained from patient-specific magnetic resonance (MR) or computer tomography (CT) images, will illustrate the accuracy to which sources can be localized in different regions in the brain.

Bio

Arye Nehorai received the B.Sc. and M.Sc. degrees in electrical engineering from the Technion---Israel Institute of Technology, and the Ph.D. degree in electrical engineering from Stanford University. From 1985 to 1995 he was a faculty member with the Department of Electrical Engineering at Yale University. In 1995 he joined the Department of Electrical Engineering and Computer Science at The University of Illinois at Chicago (UIC), as a Full Professor. He holds a joint professorship with the Bioengineering Department at UIC. His research interests are in signal and image processing, with applications to radar, sonar, communications, biomedicine, and the environment. Dr. Nehorai serves as Vice-Chair of the IEEE Signal Processing Society's Technical Committee on Sensor Array and Multichannel Processing. He was co-recipient of the 1989 IEEE Signal Processing Society's Senior Award for Best Paper. He has been a Fellow of the IEEE since 1994 and a Fellow of the Royal Statistical Society since 1996.

Time and Place: Wed., Apr. 28, 3:30-4:30 pm in 4610 Engr. Hall.

SYSTEMS SEMINAR WEB PAGE: http://www.cae.wisc.edu/~gubner/seminar/