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Science 28 March 2008:
Vol. 319. no. 5871, pp. 1845 - 1849
DOI: 10.1126/science.1154330
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Reports

Electric Fields Due to Synaptic Currents Sharpen Excitatory Transmission

Sergiy Sylantyev,1* Leonid P. Savtchenko,1,2* Yin-Ping Niu,3* Anton I. Ivanov,4* Thomas P. Jensen,1* Dimitri M. Kullmann,1 Min-Yi Xiao,3 Dmitri A. Rusakov1{dagger}

The synaptic response waveform, which determines signal integration properties in the brain, depends on the spatiotemporal profile of neurotransmitter in the synaptic cleft. Here, we show that electrophoretic interactions between AMPA receptor–mediated excitatory currents and negatively charged glutamate molecules accelerate the clearance of glutamate from the synaptic cleft, speeding up synaptic responses. This phenomenon is reversed upon depolarization and diminished when intracleft electric fields are weakened through a decrease in the AMPA receptor density. In contrast, the kinetics of receptor-mediated currents evoked by direct application of glutamate are voltage-independent, as are synaptic currents mediated by the electrically neutral neurotransmitter GABA. Voltage-dependent temporal tuning of excitatory synaptic responses may thus contribute to signal integration in neural circuits.

1 Institute of Neurology, University College London, Queen Square, London, WC1N 3BG, UK.
2 Laboratory of Biophysics and Bioelectronics, Dnepropetrovsk National University, Dnepropetrovsk, Ukraine.
3 Institute of Neuroscience and Physiology, Gothenburg University, Gothenburg, Sweden.
4 INMED-INSERM U29, Marseille, France.

* These authors contributed equally to this work.

{dagger} To whom correspondence should be addressed. E-mail: d.rusakov{at}ion.ucl.ac.uk

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THIS ARTICLE HAS BEEN CITED BY OTHER ARTICLES:
A role of electrical inhibition in sensorimotor integration.
S. A. Weiss, T. Preuss, and D. S. Faber (2008)
PNAS 105, 18047-18052
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