The magnetoencephalogram (MEG) is a recently developed method of noninvasively localizing and studying the summed intracellular currents of epileptic paroxysms in animal and man by mapping the extranial magnetic fields that they produce. The long-term goal of this project is to use a penicillin model of epilepsy in rat cortex to establish an empirical basis for the neurogenesis of epileptiform magnetic fields in man, and to combine MEG with detailed electrical arecording to obtain information about the intra and extracellular currents produced by excitability changes in the in vivo epileptic neocortex. The present proposal consist of an integrated series of 5 experiments that combine MEG with laminar microelectrod recording of field potentials to study the eletrophysicolgical differences between norman and epileptic cortex in response to direct erlectrical stimulation(direct cortical response or DCR). The first experiment introduces a quantitative computer model to relate the MEG to current source-density. The second experiment is a comprehensive study of the slow wave components of the DCR complex designed to evaluate their possibile thalamocortical basis and their relation to excitability cycles. The third experiment extends the analysis of the DCR to steady electrical and magnetic field shifts produced by extended stimulation bursts. In the forth experiment, these responses in norman cortex are re-analized in the penicillin focus as epileptic excitability is periodically increased and decreased during the """"""""cyclical spike driving"""""""" phenomena. Finally in the fifth experiment, possible steady magnetic field shifts accompanying the slow excitability changes of cyclical spike driving in the pencillin focus are studied to determine if these are associated wiwth organized intracellular currents. The results of this work will not only provide insights into membrane excitability changes that result in epileptic seizures, but will also be directly relevant to the intrpretation of extracranial magnetic fields measured from normal and epiletic human neocortex.

Agency
National Institute of Health (NIH)
Institute
National Institute of Neurological Disorders and Stroke (NINDS)
Type
Research Project (R01)
Project #
2R01NS022575-04
Application #
3405136
Study Section
Neurology A Study Section (NEUA)
Project Start
1985-07-01
Project End
1991-06-30
Budget Start
1988-07-01
Budget End
1989-06-30
Support Year
4
Fiscal Year
1988
Total Cost
Indirect Cost
Name
University of California Los Angeles
Department
Type
Schools of Arts and Sciences
DUNS #
119132785
City
Los Angeles
State
CA
Country
United States
Zip Code
90095
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