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Title: Multiple dipole modeling and localization from spatio-temporal MEG data

An array of biomagnetometers may be used to measure the spatio-temporal neuromagnetic field or magnetoencephalogram (MEG) produced by neural activity in the brain. A popular model for the neural activity produced in response to a given sensory stimulus is a set of current dipoles, where each dipole represents the primary current associated with the combined activation of a large number of neutrons located in a small volume of the brain. An important problem in the interpretation of MEG data from evoked response experiments is the localization of these neural current dipoles. The authors present here a linear algebraic framework for three common spatio-temporal dipole models: (i) unconstrained dipoles, (ii) dipoles with a fixed location, and (iii) dipoles with a fixed orientation and location. In all cases, they assume that the location, orientation, and magnitude of the dipoles are unknown. With a common model, they show how the parameter estimation problem may be decomposed into the estimation of the time invariant parameter using nonlinear least-squares minimization, followed by linear estimation of the associated time varying parameters. A subspace formulation is presented and used to derive a suboptimal least-squares subspace scanning method. The resulting algorithm is a special case of the well-knownmore » MUltiple SIgnal Classification (MUSIC) method, in which the solution (multiple dipole locations) is found by scanning potential locations using a simple one dipole model.« less
Authors:
 [1] ;  [2] ;  [3]
  1. (TRW Systems Engineering and Development Division, Redondo Beach, CA (United States))
  2. (Los Alamos National Laboratory, NM (United States))
  3. (University of Southern California, Los Angeles, CA (United States))
Publication Date:
OSTI Identifier:
6968785
DOE Contract Number:
W-7405-ENG-36
Resource Type:
Journal Article
Resource Relation:
Journal Name: IEEE Transactions on Bio-Medical Engineering (Institute of Electrical and Electronics Engineers); (United States); Journal Volume: 39:6
Country of Publication:
United States
Language:
English
Subject:
59 BASIC BIOLOGICAL SCIENCES; BRAIN; ELECTROPHYSIOLOGY; NERVE CELLS; BIOELECTRICITY; BIOLOGICAL LOCALIZATION; ELECTROMAGNETIC RADIATION; MAGNETOMETERS; MATHEMATICAL MODELS; ANIMAL CELLS; BODY; CENTRAL NERVOUS SYSTEM; ELECTRICITY; MEASURING INSTRUMENTS; NERVOUS SYSTEM; ORGANS; PHYSIOLOGY; RADIATIONS; SOMATIC CELLS 551000* -- Physiological Systems