Title :
Effect of surface boundary on neuronal magnetic stimulation
Author :
Durand, Dominique ; Ferguson, A. Stewart ; Dalbasti, Tayfun
Author_Institution :
Dept. of Biomed. Eng., Case Western Reserve Univ., Cleveland, OH, USA
Abstract :
The effect of the surface boundary between free space and a conducting medium on the excitation properties of neurons by magnetic fields is analyzed. The electric field and the spatial derivative of the induced field generated by a coil mounted both parallel and perpendicular to the surface of a semi-infinite conducting medium were calculated using the method of images. An imaginary axon is located in the same relative position from the coil in both configurations and the excitation properties are compared. The calculations are expressed in terms of the activating function for the electrical stimulation of axons. The calculations indicate that the activating function of magnetic stimulation is biphasic as opposed to triphasic for electrical stimulation. The large spatial extent of the magnetically induced electric field compared to the electric field generated by a point source electrode suggests a different mode of excitation for neuronal structures in the CNS. The field distribution has been verified experimentally.
Keywords :
biomagnetism; neurophysiology; CNS; axon; biphasic function; coil; conducting medium; electrical stimulation; field distribution; free space; method of images; neuron excitation properties; neuronal magnetic stimulation; point source electrode; semi-infinite conducting medium; surface boundary effect; Central nervous system; Coils; Electrical stimulation; Electrodes; Magnetic analysis; Magnetic properties; Magnetic stimulation; Nerve fibers; Nervous system; Neurons; Axons; Computer Simulation; Evaluation Studies as Topic; Humans; Magnetics; Models, Neurological; Surface Properties;
Journal_Title :
Biomedical Engineering, IEEE Transactions on
