Alessandro Presacco1, Hamish Innes-Brown, Matthew J Goupell, Samira Anderson. 1. 1Department of Hearing and Speech Sciences, 2Neuroscience and Cognitive Science Program at the University of Maryland, College Park, Maryland, USA; 3The Bionics Institute, East Melbourne, Victoria, Australia; and 4Department of Medical Bionics, University of Melbourne, Melbourne, Australia.
Abstract
OBJECTIVES: Several studies have investigated the feasibility of using electrophysiology as an objective tool to efficiently map cochlear implants. A pervasive problem when measuring event-related potentials is the need to remove the direct-current (DC) artifact produced by the cochlear implant. Here, we describe how DC artifact removal can corrupt the response waveform and how the appropriate choice of stimulus duration may minimize this corruption. DESIGN: Event-related potentials were recorded to a synthesized vowel /a/ with a 170- or 400-ms duration. RESULTS: The P2 response, which occurs between 150 and 250 ms, was corrupted by the DC artifact removal algorithm for a 170-ms stimulus duration but was relatively uncorrupted for a 400-ms stimulus duration. CONCLUSIONS: To avoid response waveform corruption from DC artifact removal, one should choose a stimulus duration such that the offset of the stimulus does not temporally coincide with the specific peak of interest. While our data have been analyzed with only one specific algorithm, we argue that the length of the stimulus may be a critical factor for any DC artifact removal algorithm.
OBJECTIVES: Several studies have investigated the feasibility of using electrophysiology as an objective tool to efficiently map cochlear implants. A pervasive problem when measuring event-related potentials is the need to remove the direct-current (DC) artifact produced by the cochlear implant. Here, we describe how DC artifact removal can corrupt the response waveform and how the appropriate choice of stimulus duration may minimize this corruption. DESIGN: Event-related potentials were recorded to a synthesized vowel /a/ with a 170- or 400-ms duration. RESULTS: The P2 response, which occurs between 150 and 250 ms, was corrupted by the DC artifact removal algorithm for a 170-ms stimulus duration but was relatively uncorrupted for a 400-ms stimulus duration. CONCLUSIONS: To avoid response waveform corruption from DC artifact removal, one should choose a stimulus duration such that the offset of the stimulus does not temporally coincide with the specific peak of interest. While our data have been analyzed with only one specific algorithm, we argue that the length of the stimulus may be a critical factor for any DC artifact removal algorithm.
Authors: L M Friesen; K L Tremblay; N Rohila; R A Wright; R V Shannon; D Başkent; J T Rubinstein Journal: Clin Neurophysiol Date: 2009-02-27 Impact factor: 3.708