Synchronized population oscillation of excitatory synaptic potentials dependent of calcium-induced calcium release in rat neocortex layer II/III neurons.
We examined the roles played by calcium-induced calcium release from ryanodine-sensitive calcium stores in induction of neocortical membrane potential oscillation by using caffeine, an agonist of ryanodine receptors. Intracellular recordings were made from neurons in layer II/III of rat visual cortex slices in a caffeine-containing medium. White matter stimulation initially evoked monophasic synaptic potentials. As low-frequency stimulation continued for over 10 min, an oscillating synaptic potential gradually became evoked, in which a paroxysmal depolarization shift was followed by a 8-10-Hz train of several depolarizing wavelets. This oscillating potential was not induced in a medium containing no caffeine with 2 or 0.5 mM [Mg2+](o). Under blockade of N-methyl-D-aspartate receptors, induction of this oscillating potential failed even with caffeine application. Experiments with the calcium store depletor, thapsigargin, revealed that this oscillating potential is induced in a manner dependent on intracellular calcium release. Dual intracellular recordings revealed that the oscillation was synchronized in pairs of layer II/III neurons. The oscillating potential was detectable by field potential recordings also, suggesting that the present oscillation seems to reflect a network property.
Yoshimura
H
H
Department of Integrative Brain Science, Kyoto University Graduate School of Medicine, Kyoto 606-8501, Japan.
Sugai
T
T
Onoda
N
N
Segami
N
N
Kato
N
N
D000818:Animals; D001683:Biological Clocks / Q000187:drug effects / Q000502:physiology*; D002110:Caffeine / Q000494:pharmacology; D002118:Calcium / Q000378:metabolism* / Q000494:pharmacology; D015220:Calcium Channels / Q000187:drug effects / Q000378:metabolism*; D003344:Cortical Synchronization / Q000187:drug effects*; D004305:Dose-Response Relationship, Drug; D004347:Drug Interactions / Q000502:physiology; D004791:Enzyme Inhibitors / Q000494:pharmacology; D018691:Excitatory Amino Acid Antagonists / Q000494:pharmacology; D019706:Excitatory Postsynaptic Potentials / Q000187:drug effects / Q000502:physiology*; D009474:Neurons / Q000187:drug effects / Q000378:metabolism*; D010726:Phosphodiesterase Inhibitors / Q000494:pharmacology; D051381:Rats; D017208:Rats, Wistar; D016194:Receptors, N-Methyl-D-Aspartate / Q000037:antagonists & inhibitors / Q000378:metabolism; D019284:Thapsigargin / Q000494:pharmacology; D014793:Visual Cortex / Q000187:drug effects / Q000378:metabolism*
D015220:Calcium Channels; D004791:Enzyme Inhibitors; D018691:Excitatory Amino Acid Antagonists; D010726:Phosphodiesterase Inhibitors; D016194:Receptors, N-Methyl-D-Aspartate; D002110:Caffeine; D019284:Thapsigargin; D002118:Calcium