Physiol. Res. 55: 139-149, 2006


Inhibitory Transmission, Activity-Dependent Ionic Changes and Neuronal Network Oscillations


1Institute of Physiology II, Cellular Neurophysiology, J.W. Goethe University, Frankfurt am Main, Germany and 2Institute of Pathological Physiology, Comenius University, Bratislava, Slovak Republic

Received February 3, 2005
Accepted April 26, 2005
On-line available May 24, 2005

Oscillatory network activity arises from interactions between synaptic and intrinsic membrane properties of neurons. In this review, we summarize general mechanisms of synchronous neuronal oscillations. In addition, we focus on recent experimental and computational studies which suggest that activity-dependent changes of ionic environment can affect both the synaptic and intrinsic neuronal properties and influence the network behavior. GABAA receptor (GABAAR)-mediated signaling, that is based on Cl– and HCO3– permeability, is thought to be important for the oscillogenesis and synchronization in cortical networks. A remarkable feature of GABAergic synapses is that prolonged GABAAR activation may lead to switching from a hyperpolarizing to a depolarizing response. This is partly due to a positive shift of the GABAAR reversal potential (EGABA) that is generated by GABA-induced Cl– accumulation in neurons. Recent studies suggest that activity-dependent EGABA changes may have important implications for the mechanisms of gamma oscillations and seizure-like discharges. Thus, a better understanding of the impact of intracellular Cl– dynamics on network behavior may provide insights into the mechanisms of physiological and pathological brain rhythms. Combination of experiments and simulations is a promising approach for elucidating which properties of the time-varying ionic environment can shape the dynamics of a given circuit.

Key words
Neuronal oscillations • Synchrony • GABAergic transmission • Computational model • HCO3– permeability •
Cl- accumulation • Intrinsic currents

© 2006 by the Institute of Physiology, Czech Academy of Sciences