Please use this identifier to cite or link to this item:
Title: The impact of synaptic conductance on action potential waveform: evoking realistic action potentials with a simulated synaptic conductance.
Authors: Johnston, J
Postlethwaite, M
Forsythe, ID
First Published: 15-Oct-2009
Citation: J NEUROSCI METHODS, 2009, 183 (2), pp. 158-164
Abstract: Most current clamp studies trigger action potentials (APs) by step current injection through the recording electrode and assume that the resulting APs are essentially identical to those triggered by orthodromic synaptic inputs. However this assumption is not always valid, particularly when the synaptic conductance is of large magnitude and of close proximity to the axon initial segment. We addressed this question of similarity using the Calyx of Held/MNTB synapse; we compared APs evoked by long duration step current injections, short step current injections and orthodromic synaptic stimuli. Neither injected current protocol evoked APs that matched the evoked orthodromic AP waveform, showing differences in AP height, half-width and after-hyperpolarization. We postulated that this 'error' could arise from changes in the instantaneous conductance during the combined synaptic and AP waveforms, since the driving forces for the respective ionic currents are integrating and continually evolving over this time-course. We demonstrate that a simple Ohm's law manipulation of the EPSC waveform, which accounts for the evolving driving force on the synaptic conductance during the AP, produces waveforms that closely mimic those generated by physiological synaptic stimulation. This stimulation paradigm allows supra-threshold physiological stimulation (single stimuli or trains) without the variability caused by quantal fluctuation in transmitter release, and can be implemented without a specialised dynamic clamp system. Combined with pharmacological tools this method provides a reliable means to assess the physiological roles of postsynaptic ion channels without confounding affects from the presynaptic input.
DOI Link: 10.1016/j.jneumeth.2009.06.025
eISSN: 1872-678X
Type: Journal Article
Appears in Collections:Published Articles, Dept. of Cell Physiology and Pharmacology

Files in This Item:
There are no files associated with this item.

Items in LRA are protected by copyright, with all rights reserved, unless otherwise indicated.