Accurate localization of electrical sources in the brain using EEC's or MEG's measured on the surface of the head has many important clinical and research applications. Localization is most simply and easily done by calculating an inverse solution for a source in a spherical model of the head which produces EEC's or MEG's that most closely match the measured values. The location of the solution is taken to indicate the location of the actual source. However, modeling errors caused by the differences between the geometry of actual heads and a spherical model produce localization errors. The first specific aim of this research project is to determine the effects of such model in errors on localization accuracy and to determine the optimal conditions for using a spherical head model, i.e., the conditions that produce the best localization accuracy. Investigations will be performed to determine the optimal model parameters, measurement grid size and location, measurement point density, etc. Recently, methods have been developed as part of this research project which make it practical to calculate inverse solutions in realistic head models. This presents the opportunity for significant improvements in localization accuracy. The second specific aim of this project is to determine the improvement in localization accuracy that can be achieved by using realistic models and, as for the spherical model studies above, determine optimal conditions for using realistic models. The realistic models will be generated from X-rays, MRI's, CT's, etc. of actual subjects. The third specific aim of this project is to develop guidelines for the selection of the appropriate head model to be used for various localization tasks. These guidelines will indicate when a simple spherical head model is adequate or when a realistic model must be used. In addition, these guidelines will indicate the conditions that must be met in order to achieve improved accuracy using a realistic model. These conditions would include such fairs as adequate number of EEC or MEG measurements, adequate signal-to-noise ratio of the measurements, etc.

Agency
National Institute of Health (NIH)
Institute
National Institute of Neurological Disorders and Stroke (NINDS)
Type
Research Project (R01)
Project #
2R01NS022703-08
Application #
2264606
Study Section
Neurology A Study Section (NEUA)
Project Start
1986-12-01
Project End
1998-06-30
Budget Start
1995-07-05
Budget End
1996-06-30
Support Year
8
Fiscal Year
1995
Total Cost
Indirect Cost
Name
Massachusetts Institute of Technology
Department
Type
Organized Research Units
DUNS #
City
Cambridge
State
MA
Country
United States
Zip Code
02139
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Cuffin, B N (1996) EEG localization accuracy improvements using realistically shaped head models. IEEE Trans Biomed Eng 43:299-303
Cuffin, B N (1995) A method for localizing EEG sources in realistic head models. IEEE Trans Biomed Eng 42:68-71
Cuffin, B N (1993) Effects of local variations in skull and scalp thickness on EEG's and MEG's. IEEE Trans Biomed Eng 40:42-8
Cuffin, B N; Cohen, D; Yunokuchi, K et al. (1991) Tests of EEG localization accuracy using implanted sources in the human brain. Ann Neurol 29:132-8
Cuffin, B N (1991) Eccentric spheres models of the head. IEEE Trans Biomed Eng 38:871-8
Cohen, D; Cuffin, B N (1991) EEG versus MEG localization accuracy: theory and experiment. Brain Topogr 4:95-103
Cuffin, B N (1991) Moving dipole inverse solutions using MEGs measured on a plane over the head. Electroencephalogr Clin Neurophysiol 78:341-7
Cuffin, B N (1990) Effects of head shape on EEG's and MEG's. IEEE Trans Biomed Eng 37:44-52