J Neurosci, 2009, 29(48):15341-15350

Outwardly rectifying tonically active GABAA receptors in pyramidal cells modulate neuronal offset, not gain

Hippocampal pyramidal cell excitability is regulated both by fast synaptic inhibition and by tonically active high-affinity extrasynaptic GABAA receptors. The impact of tonic inhibition on neuronal gain and offset, and thus on information processing, is unclear. Offset is altered by shunting inhibition, and the gain of a neuronal response to an excitatory input can be modified by changing the level of "background" synaptic noise. Therefore, tonic activation of GABAA receptors would be expected to modulate offset and, in addition, to alter gain through a shunting effect on synaptic noise. Here we show that tonically active GABAA receptors in CA1 pyramidal cells show marked outward rectification, while the peaks of IPSCs exhibit a linear current-voltage relationship. As a result, tonic GABAA receptormediated currents have a minimal effect upon subthreshold membrane potential variation due to synaptic noise, but predominantly affect neurons at spiking threshold. Consistent with this, tonic GABAA receptor-mediated currents in pyramidal cells exclusively affect offset and not gain. Modulation of tonically active GABAA receptors by fluctuations in extracellular GABA concentrations or neuromodulators acting on high-affinity receptors potentially provides a powerful mechanism to alter neuronal offset independently of neuronal gain. Copyright © 2009 Society for Neuroscience.

Pavlov I, Savtchenko LP, Kullmann DM, Semyanov A, Walker MC

IBCH: 6923
Ссылка на статью в журнале: http://www.jneurosci.org/cgi/doi/10.1523/JNEUROSCI.2747-09.2009
Кол-во цитирований на 01.2024: 98
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