Electrical phosphenes: on the influence of conductivity inhomogeneities and small-scale structures of the orbita on the current density threshold of excitation |
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Authors: | Lindenblatt G Silny J |
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Institution: | (1) Research Center for Bioelectromagnetic Interaction, Aachen University of Technology, Aachen, Germany |
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Abstract: | Electrical and magnetic phosphenes, perceptions of light as a result of non-adequate stimulation of the eye by electrical
current or magnetic induction, respectively, are one of the cornerstones to justify limit values for extreme low-frequency
fields specified by statutory regulations. However, the mechanism and place of action, as well as the excitation threshold,
remain unknown until now. We suggest that the origin of phosphene excitation is the synaptic layer of the eye. The current
density threshold value for electrical phosphene excitation was numerically quantified for this area on the basis of a detailed
geometrical model in original submillimetre resolution and specifically measured conductivities in the LF range. The threshold
values found were 1.8 Am−2 at 60 Hz and 0.3 Am−2 at 25 Hz. These values are comparable with values of other excitable tissues. It has been shown that the current density
threshold for phosphene generation depends on small-scale structures not taken into account by previous models. |
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Keywords: | Electrical stimulation Electrophysiology Eye physiology Models Biological Phosphenes |
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