Interference between field excitatory postsynaptic potentials and simultaneously recorded chronoamperometric l-glutamate currents in mouse hippocampal slices

Here we report on an unexpected interaction between field excitatory postsynaptic potentials (fEPSPs) and simultaneously recorded chronoamperometric l-glutamate currents based on time-resolved (200 Hz) amperometry in mouse hippocampal slices. It was found that electric stimuli and evoked fEPSPs induced an artifact on amperometric currents due to an unintentionally formed junction between the circuits of the amperometric and fEPSP measurements. The origin of the artifact was investigated using circuit simulation. To extract a faradaic signal from the observed currents, we sampled currents when the artifact decayed, i.e., 450 ms after the stimulation. The reliability of the extracted signal was examined through the manipulation of l-glutamate release probability.