We have developed a method for estimating the three-dimensional distribution of equivalent current sources inside the brain from scalp potentials. Laplacian weighted minimum norm algorithm has been used in the present study to estimate the inverse solutions. A three-concentric-sphere inhomogeneous head model was used to represent the head volume conductor. A closed-form solution of the electrical potential over the scalp and inside the brain due to a point current source was developed for the three-concentric-sphere inhomogeneous head model. Computer simulation studies were conducted to validate the proposed equivalent current source imaging. Assuming source configurations as either multiple dipoles or point current sources/sinks, in computer simulations we used our method to reconstruct these sources, and compared with the equivalent dipole source imaging. Human experimental studies were also conducted and the equivalent current source imaging was performed on the visual evoked potential data. These results highlight the advantages of the equivalent current source imaging and suggest that it may become an alternative approach to imaging spatially distributed current sources-sinks in the brain and other organ systems.
Bibliographical noteFunding Information:
Manuscript received May 21, 2001; revised October 31, 2001. This work was supported in part by the National Science Foundation (NSF) under CAREER Award BES-9875344, in part by a grant from the Whitaker Foundation, and in part by a grant from the Campus Research Board of the University of Illinois at Chicago. Asterisk indicates corresponding author. *B. He is with the Department of Bioengineering and the Department of Electrical and Computer Engineering, The University of Illinois at Chicago, M/C-063, 851 S. Morgan Street, Chicago, IL 60607 USA. (e-mail: email@example.com).
- Brain electric source imaging
- Equivalent current source
- Equivalent dipole source
- Forward problem
- High-resolution EEG
- Inverse problem