Ionic currents through postsynaptic receptors can produce an electric field inside the synaptic cleft, which raises the possibility that they can affect the dwell time of electrically charged neurotransmitters. Sylantyev et al. analyzed excitatory postsynaptic currents in acute rat brain slice cultures and in cultured neurons. Electric fields present in the extracellular space of the synaptic cleft generated by open ion channels during synaptic transmission accelerated diffusion of charged glutamate molecules out of the cleft via electrodiffusion, which altered signal integration in hippocampal pyramidal cells.
S. Sylantyev, L. P. Savtchenko, Y.-P. Niu, A. I. Ivanov, T. P. Jensen, D. M. Kullmann, M.-Y. Xiao, D. A. Rusakov, Electric fields due to synaptic currents sharpen excitatory transmission. Science 319, 1845-1849 (2008). [Abstract] [Full Text]