Lateralized Readiness Potentials Recorded with Near-Threshold Auditory Stimuli in Subjects Simulating Hearing loss

Introduction: Preparatory motor cortical responses like the lateralized readiness potential (LRP) may be useful in revealing persistent attempts to feign hearing loss. Previous studies suggest only a marginal effect of stimulus intensity on the amplitude of the LRP. However, this has not been investigated using low-intensity auditory stimuli to cue NoGo trials. We address this in an experiment where subjects were instructed not to give a manual response to low-instensity stimuli, a situation that is akin to simulating hearing loss. Methods: The LRP was recorded from normal hearing listeners (N = 10) with 500 and 4,000-Hz pure tones and trains of 4,000 Hz (2-1-2) tonebursts. Electrophysiologic data underwent processing to (i) analyze the effect of the stimulus type on the LRP, (ii) classify results according to manual response with both logistic regression and linear support vector machine (SVM) models, and (iii) derive auditory brainstem responses (ABRs) from the tonebursts. Results: The amplitude of the LRP did not differ between the 3 stimuli used to elicit the response. Single-trial electrode data from Go and NoGo trials were submitted to supervised binary classification, and the logistic regression model gave a mean accuracy of close to 0.7. The Jewett wave V latencies of the resultant ABRs from some subjects were found to increase between the high (Go) and low (NoGo) intensity tonebursts. Conclusion: This study shows that auditory stimulus type does not affect the amplitude of the LRP and that the response can be recorded with stimuli that are near the auditory threshold. It can also be recorded with transient stimuli, and this allows for the possibility of simultaneously recording other confirmatory measurements, like ABR.