Event-related potential arithmetic to analyze offset potentials from conscious mice

Background: This paper presents a method for isolating time-dependent event-related potential (ERP) components which are superimposed on the gross ERP waveform. The experimental data that inspired this approach was recorded from the auditory cortex of conscious laboratory mice in response to presentation of ten different duration pure-tone auditory stimuli. New Method: The grand-average ERP for each individual stimulus displayed a relatively low amplitude deflection following stimulus offset. In order to isolate this component for analysis, a series of simple arithmetic operations were performed, involving averaging of multiple stimuli ERPs and subtracting this from each individual ERP. Results: Offset potentials were isolated and quantified. Peak latency was determined by auditory stimulus duration; peak amplitude did not reach the threshold for statistical significance, over the range of durations tested. Comparison with Existing Method(s): To the best of my knowledge there are no alternative methods for isolating offset potentials from the gross ERP waveform at present. This novel approach may introduce less subjective bias to analyses than manually selecting measurement windows and performing custom baseline corrections. Conclusions: A similar method may be applied to other human or non-human datasets to identify and characterize time-dependent sensory-cognitive processes obscured by gross waveform morphology