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MINIREVIEW
Inhibitory Transmission,
Activity-Dependent Ionic Changes and Neuronal Network
Oscillations
P. JEDLIČKA1, 2, K. H. BACKUS1
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
Summary
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
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