Accurate electrophysiological neuroimaging using high density EEG and MEG increasingly requires knowledge of both head geometry and electrical conductivity. Head and brain geometry can be obtained from structural tomographic techniques such as CT and MRI, but the conductivity of different head tissues cannot currently be measured. We propose to demonstrate the feasibility of a technique for measuring human scalp, skull, and brain conductivities noninvasively using low-level scalp current injection. The process will first be modeled with computer simulations including the effect of noise and measurement errors. Prototype hardware will be constructed to provide the necessary switching and current injection circuitry, then tested with physical models having known geometry and conductivities. Finally, the entire system will be applied to human subjects to demonstrate its overall practicality. With accurate conductivities, realistic head-brain models can be constructed for individual subjects or patients, making EEG/MEG inverse procedures for spatiotemporal localization of neurological activity more accurate as well. In addition, since the conductivity estimation procedure will only take a few minutes, changes in conductivity can be tracked over time scales appropriate for following abnormal physiological changes associated with stroke, epilepsy, and head injury.

Proposed Commercial Applications

The head conductivity scanner will be a useful and necessary addition to any research or clinical EEG/MEG lab that utilizes quantitative inverse methods, alone or in conjunction with other functional imaging modalities such as PET,SPECT, or fMRI.

Agency
National Institute of Health (NIH)
Institute
National Institute of Neurological Disorders and Stroke (NINDS)
Type
Small Business Innovation Research Grants (SBIR) - Phase I (R43)
Project #
1R43NS038788-01
Application #
2867678
Study Section
Special Emphasis Panel (ZRG1-BDCN-1 (06))
Program Officer
Heetderks, William J
Project Start
1999-06-15
Project End
2000-04-10
Budget Start
1999-06-15
Budget End
2000-04-10
Support Year
1
Fiscal Year
1999
Total Cost
Indirect Cost
Name
Electrical Geodesics, Inc.
Department
Type
DUNS #
809845365
City
Eugene
State
OR
Country
United States
Zip Code
97403
Ferree, Thomas C (2006) Spherical splines and average referencing in scalp electroencephalography. Brain Topogr 19:43-52
Clay, M T; Ferree, T C (2002) Weighted regularization in electrical impedance tomography with applications to acute cerebral stroke. IEEE Trans Med Imaging 21:629-37
Ferree, T C; Eriksen, K J; Tucker, D M (2000) Regional head tissue conductivity estimation for improved EEG analysis. IEEE Trans Biomed Eng 47:1584-92