A matched-filter algorithm to detect amperometric spikes resulting from quantal secretion

Publication date: 1 January 2018
Source:Journal of Neuroscience Methods, Volume 293
Author(s): Supriya Balaji Ramachandran, Kevin D. Gillis
BackgroundElectrochemical microelectrodes located immediately adjacent to the cell surface can detect spikes of amperometric current during exocytosis as the transmitter released from a single vesicle is oxidized on the electrode surface. Automated techniques to detect spikes are needed in order to quantify the spike rate as a measure of the rate of exocytosis.New methodWe have developed a Matched Filter (MF) detection algorithm that scans the data set with a library of prototype spike templates while performing a least-squares fit to determine the amplitude and standard error. The ratio of the fit amplitude to the standard error constitutes a criterion score that is assigned for each time point and for each template. A spike is detected when the criterion score exceeds a threshold and the highest-scoring template and the time of peak score is identified. The search for the next spike commences only after the score falls below a second, lower threshold to reduce false positives. The approach was extended to detect spikes with double-exponential decays with the sum of two templates.ResultsReceiver Operating Characteristic plots (ROCs) demonstrate that the algorithm detects >95% of manually identified spikes with a false-positive rate of ∼2%.Comparison with existing methodsROCs demonstrate that the MF algorithm performs better than algorithms that detect spikes based on a derivative-threshold approach.ConclusionsThe MF approach performs well and leads into approaches to identify spike parameters.



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