Abstract
Neuronal networks in the mammalian brain can generate various frequencies of synchronized membrane potential oscillations. It has been reported that synchronized oscillation of excitatory synaptic potentials at 5-10Hz can be evoked in neocortex slices under three different conditions: 1) with low concentrations of Mg2+ in ACSF, 2) with blockade of GABAa receptors, or 3) under bath-applications of caffeine. Synchronized activities evoked under all these conditions exhibited similar waveforms and, once induced, were able to survive replacement of the medium by normal ACSF. The latter result suggests involvement of long-term changes in neural or network properties. Antagonists of NMDA receptor inhibited both induction and expression of synchronized activities. On the other hand, IP3R antagonists inhibit expression of these synchronized activities, but not the induction. Furthermore, these synchronized activities were not inhibited by blockade of any of the followings: ryanodine receptors, sarcoplasmic endplasmic reticulum Ca2+-ATPase(SERCA), PLC, group I mGluRs, muscarinic acetylcholin receptors and store operated calcium (SOC) channels. These findings suggest that expression of the present synchronized activities requires IP3Rs, which may play different roles than calcium release channels. [Jpn J Physiol 55 Suppl:S155 (2005)]
