The Mechanism of Extracellular Stimulation of Nerve Cells on an Electrolyte-Oxide-Semiconductor Capacitor

Extracellular excitation of neurons is applied in studies of cultured networks and brain tissue, as well as in neuroprosthetics. We elucidate its mechanism in an electrophysiological approach by comparing voltage-clamp and current-clamp recordings of individual neurons on an insulated planar electro...

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Bibliographic Details
Published in:Biophysical journal 2007-02, Vol.92 (3), p.1096-1111
Main Authors: Schoen, Ingmar, Fromherz, Peter
Format: Article
Language:English
Subjects:
Action Potentials - physiology
Animals
Biophysics
Brain research
Cells, Cultured
Electric Capacitance
Electric Stimulation - instrumentation
Electric Stimulation - methods
Electrolytes
Electrophysiology
Equipment Design
Equipment Failure Analysis
Extracellular Fluid - physiology
Lymnaea
Lymnaea stagnalis
Microelectrodes
Models, Neurological
Neurons
Neurons - physiology
Semiconductors
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Summary:Extracellular excitation of neurons is applied in studies of cultured networks and brain tissue, as well as in neuroprosthetics. We elucidate its mechanism in an electrophysiological approach by comparing voltage-clamp and current-clamp recordings of individual neurons on an insulated planar electrode. Noninvasive stimulation of neurons from pedal ganglia of Lymnaea stagnalis is achieved by defined voltage ramps applied to an electrolyte/HfO 2/silicon capacitor. Effects on the smaller attached cell membrane and the larger free membrane are distinguished in a two-domain-stimulation model. Under current-clamp, we study the polarization that is induced for closed ion channels. Under voltage-clamp, we determine the capacitive gating of ion channels in the attached membrane by falling voltage ramps and for comparison also the gating of all channels by conventional variation of the intracellular voltage. Neuronal excitation is elicited under current-clamp by two mechanisms: Rising voltage ramps depolarize the free membrane such that an action potential is triggered. Falling voltage ramps depolarize the attached membrane such that local ion currents are activated that depolarize the free membrane and trigger an action potential. The electrophysiological analysis of extracellular stimulation in the simple model system is a basis for its systematic optimization in neuronal networks and brain tissue.
ISSN:0006-3495
1542-0086
DOI:10.1529/biophysj.106.094763