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Suppression of epileptiform activity by high frequency sinusoidal fields in rat hippocampal slices
Author(s) -
Bikson Marom,
Lian Jun,
Hahn Philip J.,
Stacey William C.,
Sciortino Christopher,
Durand Dominique M.
Publication year - 2001
Publication title -
the journal of physiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.802
H-Index - 240
eISSN - 1469-7793
pISSN - 0022-3751
DOI - 10.1111/j.1469-7793.2001.0181j.x
Subject(s) - picrotoxin , depolarization , stimulation , chemistry , stimulus (psychology) , extracellular , hippocampal formation , neuroscience , electrophysiology , potassium , biophysics , tonic (physiology) , biology , gabaa receptor , psychology , biochemistry , receptor , organic chemistry , psychotherapist
1 Sinusoidal high frequency (20‐50 Hz) electric fields induced across rat hippocampal slices were found to suppress zero‐Ca 2+ , low‐Ca 2+ , picrotoxin, and high‐K + epileptiform activity for the duration of the stimulus and for up to several minutes following the stimulus. 2 Suppression of spontaneous activity by high frequency stimulation was found to be frequency (< 500 Hz) but not orientation or waveform dependent. 3 Potassium‐sensitive microelectrodes showed that block of epileptiform activity was always coincident with a stimulus‐induced rise in extracellular potassium concentration during stimulation. Post‐stimulus inhibition was always associated with a decrease in extracellular potassium activity below baseline levels. 4 Intracellular recordings and optical imaging with voltage‐sensitive dyes showed that during suppression neurons were depolarized yet did not fire action potentials. 5 Direct injection of sinusoidal current into individual pyramidal cells did not result in a tonic depolarization. Injection of large direct current (DC) depolarized neurons and suppressed action potential generation. 6 These findings suggest that high frequency stimulation suppresses epileptiform activity by inducing potassium efflux and depolarization block.